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  • 1.
    Bekele, Wondimagegne
    et al.
    Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden; Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia.
    Huhtanen, Pekka
    Production Systems, Natural Resources Institute Finland (LUKE), Jokioinen, Finland.
    Zegeye, Abiy
    Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia.
    Simachew, Addis
    Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia.
    Siddique, Abu Bakar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Albrectsen, Benedicte Riber
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ramin, Mohammad
    Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden.
    Methane production from locally available ruminant feedstuffs in Ethiopia: an in vitro study2024Ingår i: Animal Feed Science and Technology, ISSN 0377-8401, E-ISSN 1873-2216, Vol. 312, artikel-id 115977Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Achieving optimal nutrient composition in locally sourced ruminant feeds is important, but can be challenging in resource-limited production systems. For example, improving the composition of available local feed resources is a key obstacle to efficiently mitigating enteric methane (CH4) emissions in ruminants. This study characterized the nutritional content and in vitro methane (CH4) yield of ruminant feedstuffs accessible in Ethiopia. A survey of 60 experienced farmers in two representative districts in Amhara region, Ethiopia, provided 33 feed samples, which were classified into four ruminant feed categories: Grasses (n=10); indigenous plants (trees, shrubs, herbaceous plants) (n=13); crop residues (n=5); and agro-industrial by-products (n=5). Nutritional composition was assessed by proximate and detergent methods. Methane yield (g CH4/kg feed dry matter (DM)) and total gas yield (L/kg DM) were evaluated using a fully automated in vitro gas production system. A colorimetric assay was conducted to measure condensed tannin content (CT, mg/g) in relevant feeds. Lower crude protein (CP) values were observed for the grass (mean 65.2 g/kg DM) and crop residues (mean 54.5 g/kg DM) categories. Agro-industrial by-products had the highest CP (mean 260 g/kg DM), while indigenous plants exhibited intermediate levels (163 g/kg DM). There was significant variation in CH4 yield (P<0.01) between grasses (12.4–24.7 g/kg DM) indigenous plants (1.8–19.3 g/kg DM), and agro-industrial by-products (8.1–26.9 g/kg DM). The indigenous plant Trifolium acaule gave the lowest in vitro CH4 yield (1.8 g/kg DM). A positive relationship was observed between in vitro dry matter digestibility (IVDMD), CH4, and total gas yield. Percentage of CH4 in total gas production varied with feed category (grasses 14.5–19.6%; indigenous plants 3.1–16.9%; crop residues 15.8–20.6%; agro-industrial by-products 12.8–18.7%), and within category, e.g., Trifolium acaule (3.1%), Acacia nilotica L. (7.1%), Ziziphus spina-christi (9.9%), brewer's spent grains (BSG) (12.8%), local liquor (areki) residues (14.1%), and local beer (tella) residues (15.1%). A negative relationship was observed between CT content and in vitro CH4 yield, with a stronger (P<0.05) correlation for soluble CTs (R2 = 0.46) than cell-bound CTs (R2 = 0.25) and total CTs (R2 = 0.29). Based on methanogenic properties and effects of CTs on in vitro CH4 yield, indigenous plants should be prioritized in ruminant rations in Ethiopia. Making nutritional composition and CH4 data publicly available could help develop environmentally sound, cost-effective rations for ruminant livestock, benefiting local farmers and leading to more sustainable and efficient livestock production in Ethiopia.

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  • 2. Bergström, Dan
    et al.
    Israelsson, Samuel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Öhman, Marcus
    Dahlqvist, Sten-Axel
    Gref, Rolf
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Wästerlund, Iwan
    Effects of raw material particle size distribution on the characteristics of Scots pine sawdust fuel pellets2008Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 89, nr 12, s. 1324-1329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to study the influence of raw material particle size distribution on the pelletizing process and the physical and thermomechanical characteristics of typical fuel pellets, saw dust of Scots pine was used as raw material for producing pellets in a semi industrial scaled mill (similar to 300 kg h(-1)). The raw materials were screened to a narrow particle size distribution and mixed into four different batches and then pelletized under controlled conditions. Physical pellet characteristics like compression strength, densities, moisture content, moisture absorption and abrasion resistance were determined. In addition, the thermochemical characteristics, i.e. drying and initial pyrolysis, flaming pyrolysis, char combustion and char yield were determined at different experimental conditions by using a laboratory-scaled furnace. The results indicate that the particle size distribution had some effect on current consumption and compression strength but no evident effect on single pellet and bulk density, moisture content, moisture absorption during storage and abrasion resistance. Differences in average total conversion time determined for pellet batches tested under the same combustion conditions was less than 5% and not significant. The results are of practical importance suggesting that grinding of saw dust particle sizes below 8 mm is probably needless when producing softwood pellets. Thus it seem that less energy could be used if only over sized particles are grinded before pelletizing.

  • 3. Bergström, Dan
    et al.
    Israelsson, Samuel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Öhman, Marcus
    Dahlqvist, Sten-Axel
    Gref, Rolf
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Wästerlund, Iwan
    Effects of raw material particle size distribution on the characteristics of Scots pine sawdust fuel pellets2008Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 89, nr 12, s. 1324-1329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to study the influence of raw material particle size distribution on the pelletizing process and the physical and thermomechanical characteristics of typical fuel pellets, saw dust of Scots pine was used as raw material for producing pellets in a semi industrial scaled mill (similar to 300 kg h(-1)). The raw materials were screened to a narrow particle size distribution and mixed into four different batches and then pelletized under controlled conditions. Physical pellet characteristics like compression strength, densities, moisture content, moisture absorption and abrasion resistance were determined. In addition, the thermochemical characteristics, i.e. drying and initial pyrolysis, flaming pyrolysis, char combustion and char yield were determined at different experimental conditions by using a laboratory-scaled furnace. The results indicate that the particle size distribution had some effect on current consumption and compression strength but no evident effect on single pellet and bulk density, moisture content, moisture absorption during storage and abrasion resistance. Differences in average total conversion time determined for pellet batches tested under the same combustion conditions was less than 5% and not significant. The results are of practical importance suggesting that grinding of saw dust particle sizes below 8 mm is probably needless when producing softwood pellets. Thus it seem that less energy could be used if only over sized particles are grinded before pelletizing.

  • 4.
    Bozaghian Bäckman, Marjan
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Ume.
    Strandberg, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    De La Fuente, Teresa
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Umeå, Sweden.
    Karjalainen, Mikko
    Luke Natural Resources Institute Finland, Kokkola, Finland.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Thyrel, Mikael
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Umeå, Sweden.
    Bergström, Dan
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Umeå, Sweden.
    Larsson, Sylvia H.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Umeå, Sweden.
    Does mechanical screening improve fuel properties?: Effects of mechanical screening of stored logging residue chips on ash chemistry and other parameters relevant for combustion2019Konferensbidrag (Refereegranskat)
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  • 5.
    Broström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Holmgren, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ash fractionation and slag formation during entrained flow biomass gasification2018Konferensbidrag (Övrigt vetenskapligt)
  • 6. Buss, Wolfram
    et al.
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wurzer, Christian
    Masek, Ondrej
    Synergies between BECCS and Biochar-Maximizing Carbon Sequestration Potential by Recycling Wood Ash2019Ingår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, nr 4, s. 4204-4209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioenergy carbon capture and storage (BECCS) and biochar are key carbon-negative technologies. In this study, synergies between these technologies were explored by using ash from wood combustion, a byproduct from BECCS, as an additive (0, 5, 10, 20, and 50 wt %) in biochar production (wood pyrolysis at 450 degrees C). The addition of wood ash catalyzed biochar formation and increased the yield of fixed carbon (FC) (per dry, ash-free feedstock), i.e., the sequestrable carbon per spruce wood input. At the highest ash addition (50%), 45% less wood was needed to yield the same amount of FC. Since the land area available for growing biomass is becoming scarcer, our approach significantly increases biochar's potential to sequester carbon. However, increasing the feedstock ash content results in less feedstock carbon available for conversion into FC. Consequently, the yield of FC per pyrolysis run (based on dry feedstock) in the 50% ash-amended material was lower than in the control. An economic analysis showed that the 20% ash-amended biochar brings the biggest cost savings over the control with a 15% decrease in CO2-abatement costs. Biochar-ash composites increase the carbon sequestration potential of biochar significantly, reduce the CO2-abatement costs, and recycle nutrients which can result in increased plant growth in turn and more biomass for BECCS, bringing synergies for BECCS and biochar deployment.

  • 7. Capablo, Joaquin
    et al.
    Arendt Jensen, Peter
    Hougaard Pedersen, Kim
    Hjuler, Klaus
    Nikolaisen, Lars
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Frandsen, Flemming
    Ash properties of alternative biomass2009Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, s. 1965-1976Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ash behavior during suspension firing of 12 alternative solid biofuels, such as pectin waste, mash from a beer brewery, or waste from cigarette production have been studied and compared to wood and straw ash behavior. Laboratory suspension firing tests were performed on an entrained flow reactor and a swirl burner test rig, with special emphasis on the formation of fly ash and ash deposit. Thermodynamic equilibrium calculations were performed to support the interpretation of the experiments. To generalize the results of the combustion tests, the fuels are classified according to fuel ash analysis into three main groups depending upon their ash content of silica, alkali metal, and calcium and magnesium. To further detail the biomass classification, the relative molar ratio of Cl, S, and P to alkali were included. The study has led to knowledge on biomass fuel ash composition influence on ash transformation, ash deposit flux, and deposit chlorine content when biomass fuels are applied for suspension combustion.

  • 8.
    Carvalho, Ricardo L.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Centre of Environment and Marine Studies, University of Aveiro, Aveiro, Portugal.
    Yadav, Pooja
    Dept. of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    García-López, Naxto
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nyberg, Gert
    Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Diaz-Chavez, Rocio
    Stockholm Environment Institute, Africa Centre, c/o World Agroforestry Centre, P.O. Box 30677, Nairobi, Kenya.
    Upadhyayula, Venkata Krishna Kumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Athanassiadis, Dimitris
    Dept. of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Bioenergy strategies to address deforestation and household air pollution in western Kenya2019Ingår i: European Biomass Conference and Exhibition Proceedings, ETA-Florence Renewable Energies , 2019, s. 1536-1542Konferensbidrag (Refereegranskat)
    Abstract [en]

    Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden disease due to household air pollution. The Long-Range Energy Alternatives Planning (LEAP) system and the Life-Cycle Assessment tool Simapro 8.5 were applied for analyzing biomass strategies for the region. The calculation of the residential energy consumption and emissions was based on scientific reviews and original data from experimental studies. The research shows the effect of four biomass strategies on the reduction of wood fuel use and short-lived climate pollutant emissions. A Business As Usual scenario (BAU) considered the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) considered the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluated a mix of the ICS, PGS and BGS. The study shows that, energy use will increase by 8% (BGS), 20% (INT), 26% (PGS), 42% (ICS) and 56% (BAU). The BGS has the lowest impact on global warming, particle formation, terrestrial acidification, fossil resource scarcity, water consumption, as well as on eutrophication followed by the PGS and INT.

  • 9.
    Carvalho, Ricardo Luís
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, Aveiro, Portugal.
    Yadav, Pooja
    García-López, Naxto
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nyberg, Gert
    Diaz-Chavez, Rocio
    Upadhyayula, Venkata Krishna Kumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Athanassiadis, Dimitris
    Environmental Sustainability of Bioenergy Strategies in Western Kenya to Address Household Air Pollution2020Ingår i: Energies, E-ISSN 1996-1073, Vol. 13, nr 3, artikel-id 719Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden of disease due to household air pollution. Efficient biomass cooking is a local-based renewable energy solution to address this issue. The Life-Cycle Assessment tool Simapro 8.5 is applied for analyzing the environmental impact of four biomass cooking strategies for the Kisumu County, with analysis based on a previous energy modelling study, and literature and background data from the Ecoinvent and Agrifootprint databases applied to the region. A Business-As-Usual scenario (BAU) considers the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) consider the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluates a mix of the ICS, PGS and BGS. In the BGS, the available biomass waste is sufficient to be upcycled and fulfill cooking demands by 2035. This scenario has the lowest impact on all impact categories analyzed followed by the PGS and INT. Further work should address a detailed socio-economic analysis of the analyzed scenarios.

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  • 10.
    Chacón-Navarrete, Helena
    et al.
    Department of Agricultural Chemistry, Edaphology and Microbiology, Agrifood Campus of International Excellence ceiA3, University of Cordoba, Cordoba, Spain.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Moreno-García, Jaime
    Department of Agricultural Chemistry, Edaphology and Microbiology, Agrifood Campus of International Excellence ceiA3, University of Cordoba, Cordoba, Spain.
    Yeast immobilization systems for second-generation ethanol production: actual trends and future perspectives2021Ingår i: Biofuels, Bioproducts and Biorefining, ISSN 1932-104X, E-ISSN 1932-1031, Vol. 15, nr 5, s. 1549-1565Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Yeast immobilization with low-cost carrier materials is a suitable strategy to optimize the fermentation of lignocellulosic hydrolysates for the production of second-generation (2G) ethanol. It is defined as the physical confinement of intact cells to a certain region of space (the carrier) with the preservation of their biological activity. This technological approach facilitates promising strategies for second-generation bioethanol production due to the enhancement of the fermentation performance that is expected to be achieved. Using immobilized cells, the resistance to inhibitors contained in the hydrolysates and the co-utilization of sugars are improved, along with facilitating separation operations and the reuse of yeast in new production cycles. Until now, the most common immobilization technology used calcium alginate as a yeast carrier but other supports such as biochar or multispecies biofilm membranes have emerged as interesting alternatives. This review compiles updated information about cell carriers and yeast-cell requirements for immobilization, and the benefits and drawbacks of different immobilization systems for second-generation bioethanol production are investigated and compared.

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  • 11.
    Chen, Feng
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Grimm, Alejandro
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Eilertsen, Lill
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden; Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, SE-901 8, Umeå, Sweden.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Arshadi, Mehrdad
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Xiong, Shaojun
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83, Umeå, Sweden.
    Integrated production of edible mushroom (Auricularia auricular-judae), fermentable sugar and solid biofuel2021Ingår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 170, s. 172-180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aimed to develop an energy- and resource-efficient process for the coproduction of edible mushroom, fermentable sugar and solid biofuel from wood residues. A promising potential was revealed for wood ear fungus (Auricularia auricular-judae), which yielded about 200 g mushroom per kg dry birch-based substrate, with concomitant degradation of 76.8 and 85.7% of lignin and xylan, respectively, in the substrate. Substrate pasteurisation by hot-air (85–100 °C) was as effective as by energy intensive autoclaving (121 °C), resulting comparable mushroom growth and degradation of lignocellulose. The spent mushroom substrate (SMS) contained 28–33% glucan, which upon analytical enzymatic saccharification released around 46% of the potentially-achievable glucose, corresponding to a 2.3–fold enzymatic digestibility compared with that of the raw substrate. The solid leftover generated after enzymatic hydrolysis revealed high thermal energy value and promising combustion characteristics, showing a plausibility to be recycled as solid fuel for self-supporting energy system and space heating.

  • 12.
    Chen, Feng
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Umeå, Sweden.
    Xiong, Shaojun
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, Umeå, Sweden.
    Gandla, Madhavi Latha
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Stagge, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Inland Norway University of Applied Sciences, Department of Biotechnology, Hamar, Norway.
    Spent mushroom substrates for ethanol production – Effect of chemical and structural factors on enzymatic saccharification and ethanolic fermentation of Lentinula edodes-pretreated hardwood2022Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 347, artikel-id 126381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spent mushroom substrates (SMS) from cultivation of shiitake (Lentinula edodes) on three hardwood species were investigated regarding their potential for cellulose saccharification and for ethanolic fermentation of the produced hydrolysates. High glucan digestibility was achieved during enzymatic saccharification of the SMSs, which was related to the low mass fractions of lignin and xylan, and it was neither affected by the relative content of lignin guaiacyl units nor the substrate crystallinity. The high nitrogen content in SMS hydrolysates, which was a consequence of the fungal pretreatment, was positive for the fermentation, and it ensured ethanol yields corresponding to 84–87% of the theoretical value in fermentations without nutrient supplementation. Phenolic compounds and acetic acid were detected in the SMS hydrolysates, but due to their low concentrations, the inhibitory effect was limited. The solid leftovers resulting from SMS hydrolysis and the fermentation residues were quantified and characterized for further valorisation.

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  • 13.
    Díaz-Ramírez, Maryori
    et al.
    Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain; Centre of Research for Energy Resources and Consumption, CIRCE Foundation, Zaragoza, Spain.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Sebastián, Fernando
    Centre of Research for Energy Resources and Consumption, CIRCE Foundation, Zaragoza, Spain.
    Royo, Javier
    Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain.
    Xiong, Shaojun
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Environmental performance of three novel opportunity biofuels: poplar, brassica and cassava during fixed bed combustion2013Ingår i: Herbaceous plants: cultivation methods, grazing and environmental impacts / [ed] Florian Wallner, Nova Science Publishers, Inc., 2013, s. 133-147Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In the last few decades several types of solid biofuels have been proposed as possible sources for heat generation because of growing concerns about environmental pollution, and future fossil fuel supply uncertainties. Among other biomass assortments, short rotation coppice and herbaceous species have been considered. An important aspect to be evaluated to enable a sustainable introduction of such novel fuels is related to their environmental performance during combustion. In this work, three fuel types; one herbaceous energy crop and one short rotation coppice (both cultivated and pelletized in Spain), together with one agricultural residue (cultivated in China) have been assessed in terms of their emission levels of gases (CO and NOX) and particulate matter. The experiments showed that combustion of the fuels was attained under an acceptable level of CO emissions. However, concentration of NOX was rather high, but perhaps more important, a considerably high formation of fine particle emissions was observed. Consequently, the incorporation of primary or secondary particle precipitating reduction measures might be needed. In addition, the high ash content in these fuels can severely deteriorate the combustion performance and reliability. Thus, specially designed burners/grate units are therefore needed if a utilization of these fuels in small and medium scale combustion systems seeks to be feasible. Although the applicability of introducing this kind of biofuels to the residential heating sector perhaps seems to be rather limited, it should not always be rejected. Nevertheless, technology improvements would have to be considered to manage the current limitations. 

  • 14. Falk, Joel
    et al.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Grimm, Alejandro
    Ohman, Marcus
    Systematic Evaluation of the Fate of Phosphorus in Fluidized Bed Combustion of Biomass and Sewage Sludge2020Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 34, nr 4, s. 3984-3995Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Comprehensive knowledge concerning the behavior of phosphorus (P) during combustion is necessary to enable more efficient recovery of P from combustion ashes for agricultural purposes. To this end, parameters that influence the distribution and speciation of P in combustion ashes are important because they may influence which ash fractions are suitable for P recovery. This study aims to determine the fate of P as a result of fuel ash composition and chemical association in the fuel during fluidized bed combustion by a systemic review of previous work. The synthesis was performed by comparing scanning electron microscopy–energy-dispersive X-ray spectroscopy and X-ray diffraction chemical analyses of bed ash, fly ash particles, and deposits from fluidized bed combustion of different blends of P-poor (logging residues or wheat straw) and P-rich (sewage sludge, dried distiller’s grain with solubles, or phosphoric acid) fuels and additives. The blends were produced to have a similar ash composition but with a different P source. The distribution of P among ash fractions indicated that P is mainly found in the coarse ash fractions (bed and cyclone ash), irrespective of fuel ash composition or chemical association in the fuel. The chemical speciation of P in coarse ash fractions differed between biomass blends containing sewage sludge compared to blends with phosphoric acid or dried distiller’s grain with solubles. Phosphates in the ash from the two sewage sludge blends included predominantly Ca with minor inclusion of other cations. In contrast, ashes from the blends with phosphoric acid or dried distiller’s grain with solubles contained phosphates with a significant amount of K, Ca, and Mg. The difference in phosphate speciation could not solely be explained by the combustion conditions and the elemental composition of the ash fractions. These results show that it is necessary to consider the chemical association of P in the fuel to predict the type of phosphates that will form in fluidized bed combustion ashes.

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  • 15.
    Faust, Robin
    et al.
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, Gothenburg, Sweden.
    Valizadeh, Ali
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Qiu, Ren
    Chalmers University of Technology, Department of Physics, Kemigården 1, Gothenburg, Sweden.
    Tormachen, Alyona
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, Gothenburg, Sweden.
    Maric, Jelena
    Division of Energy Technology, Department of Space, Earth, Environment (SEE), Chalmers University of Technology, Gothenburg, Sweden.
    Vilches, Teresa Berdugo
    Division of Energy Technology, Department of Space, Earth, Environment (SEE), Chalmers University of Technology, Gothenburg, Sweden.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Seemann, Martin
    Division of Energy Technology, Department of Space, Earth, Environment (SEE), Chalmers University of Technology, Gothenburg, Sweden.
    Halvarsson, Mats
    Chalmers University of Technology, Department of Physics, Kemigården 1, Gothenburg, Sweden.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Knutsson, Pavleta
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, Gothenburg, Sweden.
    Role of surface morphology on bed material activation during indirect gasification of wood2023Ingår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 333, artikel-id 126387Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Olivine and alkali-feldspar were utilized in separate campaigns in an indirect dual fluidized bed gasification campaign with woody biomass as fuel. After three days, both bed materials were reported to be active towards tar removal and exhibited oxygen-carrying abilities and had formed an ash layer consisting of an outer ash deposition layer and an inner interaction layer. X-ray microtomography analysis concluded that a preferred deposition of ash happens onto convex regions of the bed particles, which results in an increase in thickness of the ash layer over convex regions. This effect is most pronounced for the outer layer which is a product of ash deposition. The inner layer exhibits a homogeneous thickness and is probably formed by interaction of Ca from the outer layer with the particles. Transmission electron microscopy revealed the presence of Fe and Mn on the surface of the particles in a solid solution with Mg. The oxygen-carrying effect which is found for aged particles is therefore attributed to the presence of Fe and Mn on the surface of aged particles. Alkali were found on the surface of both particles which are likely contributing to the catalytic activity of the material towards tar removal.

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  • 16.
    Gandla, Madhavi Latha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. KBC Chemical-Biological Centre, Umeå University.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. KBC Chemical-Biological Centre, Umeå University.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. KBC Chemical-Biological Centre, Umeå University.
    Analytical Enzymatic Saccharification of Lignocellulosic Biomass for Conversion to Biofuels and Bio-Based Chemicals2018Ingår i: Energies, E-ISSN 1996-1073, Vol. 11, nr 11, artikel-id 2936Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Lignocellulosic feedstocks are an important resource for biorefining of renewables to bio-based fuels, chemicals, and materials. Relevant feedstocks include energy crops, residues from agriculture and forestry, and agro-industrial and forest-industrial residues. The feedstocks differ with respect to their recalcitrance to bioconversion through pretreatment and enzymatic saccharification, which will produce sugars that can be further converted to advanced biofuels and other products through microbial fermentation processes. In analytical enzymatic saccharification, the susceptibility of lignocellulosic samples to pretreatment and enzymatic saccharification is assessed in analytical scale using high-throughput or semi-automated techniques. This type of analysis is particularly relevant for screening of large collections of natural or transgenic varieties of plants that are dedicated to production of biofuels or other bio-based chemicals. In combination with studies of plant physiology and cell wall chemistry, analytical enzymatic saccharification can provide information about the fundamental reasons behind lignocellulose recalcitrance as well as about the potential of collections of plants or different fractions of plants for industrial biorefining. This review is focused on techniques used by researchers for screening the susceptibility of plants to pretreatment and enzymatic saccharification, and advantages and disadvantages that are associated with different approaches.

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  • 17.
    García López, Natxo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Biomass utilization for energy purposes in Kenya: Fuel characteristics and thermochemical properties2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Around forty percent of the world´s population, mostly inhabitants of countries with developing economies, rely on the traditional usage of biomass for energy purposes. The major negative consequences are environmental and health effects. Additionally, the most remarkable social consequence is rural poverty which is directly linked to lack of access to electricity. This places the questions related to biomass utilization for energy production at the core of global welfare.

    The present work was performed as a part of a larger research project funded by Formas and which involves Swedish and Kenyan partners. The aim of this study was to gather basic knowledge about the characteristics of relevant biomass from sub-Saharan Africa, more specifically from Kenya. Eight different types of biomass, including agroforestry trees, agricultural residues, and water hyacinth, were evaluated according to fuel characteristics and thermochemical properties. Ultimate and proximate analyses of the collected biomass were carried out, in addition to heating values analyses. Moreover, the biomass was pelletized and a thermogravimetric analysis was performed in a single pellet reactor.  Finally, the composition of the residual ashes was determined. The results show that there was a large variation in the fuel characteristics and thermochemical behaviour of the studied agricultural residues and water hyacinth biomass types, whereas agroforestry trees had rather similar properties and thermochemical behaviour when combusted at the same temperature. In addition, results from the ash composition analyses showed large differences among the studied biomass types, which can be used to better predict and solve problems related to the combustion of these biomass types. 

  • 18. Gilbe, Carl
    et al.
    Lindström, Erica
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Samuelsson, Robert
    Burvall, Jan
    Ohman, Marcus
    Predicting slagging tendencies for biomass pellets fired in residential appliances: a comparison of different prediction methods2008Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 22, nr 6, s. 3680-3686Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a comparison between four different types (both empirical and theoretical) of techniques to predict the slagging tendencies in residential pellet combustion appliances was performed. The four techniques used were the standard ash fusion test (SS ISO-540) used in the Swedish pellet standard (SS 18 7120), thermal analysis (TGA/DTA), thermochemical model calculations, and a laboratory-scale sintering test. The tests were performed with 12 pelletized biomass raw materials, and the results were compared with measured slagging tendencies in controlled combustion experiments in a commercial under-fed pellet burner (20 kW) installed in a reference boiler. The results showed significant differences in the prediction of slagging tendencies between different predicting techniques and fuels. The method based on thermal analysis (TGA/DTA) of produced slags must be further developed before useful information could be provided of the slagging behavior of different fuels. The used sintering method must also be further improved before the slagging tendency of fuels forming slags extremely rich in silicon (e.g., some grasses) can be predicted. Relatively good agreement was obtained between results from chemical equilibrium calculations and the actual slagging tendencies from the combustion tests. However, the model calculations must be further improved before quantitative results can be used. The results from the standard ash fusion test (SS ISO 540) showed, in general, relatively high deformation temperatures, therefore predicting a less problematic behavior of the fuels in comparison to the actual slagging tendencies obtained from controlled combustion experiments in commercial pellet burner equipment. Nevertheless, the method predicted, in most cases, the same fuel-specific slagging (qualitatively) trends as the corresponding combustion behavior.

  • 19.
    Goswami, Rahul Kumar
    et al.
    Bioprocess and Bioenergy Laboratory, Department of Microbiology, Central University of Rajasthan, Rajasthan, India.
    Mehariya, Sanjeet
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Karthikeyan, Obulisamy Parthiba
    Department of Engineering Technology, College of Technology, University of Houston, TX, Houston, United States; Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, SD, Rapid City, United States; Institute of Bioresource and Agriculture, Hong Kong Baptist University, Hong Kong SAR, China.
    Gupta, Vijai Kumar
    Center for Safe and Improved Food, Scotland's Rural College (SRUC), Kings Buildings, West Mains Road, Edinburgh, United Kingdom; Biorefining and Advanced Materials Research Center, Scotland's Rural College (SRUC), Kings Buildings, West Mains Road, Edinburgh, United Kingdom.
    Verma, Pradeep
    Bioprocess and Bioenergy Laboratory, Department of Microbiology, Central University of Rajasthan, Rajasthan, India.
    Multifaceted application of microalgal biomass integrated with carbon dioxide reduction and wastewater remediation: A flexible concept for sustainable environment2022Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 339, artikel-id 130654Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Microalgae are ubiquitous, diverse, and photosynthetic organisms in nature and have prominent applications in carbon dioxide (CO2) mitigation and wastewater remediation. This review has compiled the recent trends in the potential application of microalgae for wastewater treatment and combating CO2 emissions and multifaceted use of its biomass for the co-production of bioenergy and human health products. In specific, this review critically addressed; (a) global scenario of carbon footprint and wastewater remediation and concept of circular bioeconomy, (b) approaches of sterile and non-sterile cultivation of microalgae, (c) state-of-art biorefinery especially for harvesting of algal biomass, d) details of microalgal high-value compounds (HVAC) such as lipids, fatty acids, carbohydrates, carotenoids, sterols, and polyphenolic compounds, (e) recent biomass to biofuel strategies, and (f) market analysis, recent challenges and future progress. The review establishes that the microalgae can simultaneously treat different types of wastewater, recover nutrients/metals, and mitigate CO2 from flue gas via its biofixation ability. The flocculation method is found to be best for harvesting the algal biomass. The non-sterile cultivated biomass can be utilized for biofuels production, and sterile biomass can be used to produce HVAC compounds that have significant application in human health.

  • 20.
    Hagman, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Co-combustion of Animal Waste, Peat, Waste Wood, Forest Residues, and Industrial Sludge in a 50 MWth Circulating Fluidized-Bed Boiler: Ash Transformation, Ash/Deposit Characteristics, and Boiler Failures2013Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 10, s. 5617-5627Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In strive to lower the energy conversion cost and CO2 net emission, more complex biofuels are used. The combustion of these fuels often creates aggressive and problematic fireside environments in boilers, resulting in reduced availability, which, in turn, may lead to increased usage of fossil fuel in backup boilers. The objective of the present work was to contribute to the efforts of maximizing the availability of a 50 MWth circulating fluidized-bed (CFB) boiler firing complex fuels with high amounts of P, Ca, S, Cl, N, K, and Na. In the present work, ash and deposit samples collected from the flue gas system of a CFB boiler were further analyzed with X-ray powder diffraction, complementing earlier analysis made on the same sample set with scanning electron microscopy equipped with energy-dispersive spectrometry. Thermodynamic calculations were also made. The results clarify details about the ash speciation and transformation as well as effects on boiler operation. A suggestion of a control strategy to minimize corrosion rates in superheaters and SO2 emission to downstream cleaning equipment in full-scale industrial boilers is made. An equation for rough estimation of fuel mix corrosion tendencies is also presented.

  • 21. He, Hanbing
    et al.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Öhman, Marcus
    Time-Dependent Crack Layer Formation in Quartz Bed Particles during Fluidized Bed Combustion of Woody Biomass2017Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, nr 2, s. 1672-1677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bed agglomeration during combustion and gasification of woody biomass fuels in quartz beds has been frequently studied, and chemical mechanisms responsible for bed agglomeration have been suggested: However, few studies have focused on the bed material deposition on walls, in cyclones, and return legs in fluidized bed combustion. Part of these bed material depositions originates from sticky fragments of alkali-rich silicates formed after crack formation in older quartz bed particles. The crack layer formation in quartz bed particles in fluidized bed combustion of woody biomass was therefore investigated by collecting bed material samples of different ages from full-scale bubbling and circulating fluidized bed facilities. Scanning electron microscopy/energy-dispersive spectroscopy was used to analyze the crack morphology and composition of the layer surrounding the cracks. For quartz bed particles with an age of some days, a crack in the quartz bed particle was observed in connection to the irregular interface between the inner layer and the core of the bed particle. The crack layer composition is similar for quartz particles with different ages and for samples taken from different fluidized bed techniques. Their composition is dominated by Si, K, Ca, and Na (except O). These crack layers become deeper, wider, and more common as bed particle age increases. The crack layers eventually connect with each other, and the whole quartz particle is transformed into smaller quartz cores surrounded by crack layers, which were observed in particles older than 1 week. From the characterization work, a crack formation process including three phases is proposed on the basis of the presumption that the initial crack layer formation resulted from the presence of induced cracks in the inner quartz bed particle layer. Fragmentation after the third phase is likely responsible for the formation of sticky alkali silicate deposit formation, and a weekly complete exchange of the bed is therefore recommended to avoid problematic deposits in combustion of woody-type biomass in fluidized bed combustion.

  • 22.
    Hedayati, Ali
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Kienzl, Norbert
    BEST - Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Ash Transformation during Single-Pellet Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus2021Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 35, nr 2, s. 1449-1464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, ash transformation and release of critical ash-forming elements during single-pellet combustion of different types of agricultural opportunity fuels were investigated. The work focused on potassium (K) and phosphorus (P). Single pellets of poplar, wheat straw, grass, and wheat grain residues were combusted in a macro-thermogravimetric analysis reactor at three different furnace temperatures (600, 800, and 950 °C). In order to study the transformation of inorganic matters at different stages of the thermal conversion process, the residues were collected before and after full devolatilization, as well as after complete char conversion. The residual char/ash was characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography, and the interpretation of results was supported by thermodynamic equilibrium calculations. During combustion of poplar, representing a Ca-K-rich woody energy crop, the main fraction of K remained in the residual ash primarily in the form of K2Ca(CO3)2 at lower temperatures and in a K-Ca-rich carbonate melt at higher temperatures. Almost all P retained in the ash and was mainly present in the form of hydroxyapatite. For the Si-K-rich agricultural biomass fuels with a minor (wheat straw) or moderate (grass) P content, the main fraction of K remained in the residual ash mostly in K-Ca-rich silicates. In general, almost all P was retained in the residual ash both in K-Ca-P-Si-rich amorphous structures, possibly in phosphosilicate-rich melts, and in crystalline forms as hydroxyapatite, CaKPO4, and calcium phosphate silicate. For the wheat grain, representing a K-P-rich fuel, the main fraction of K and P remained in the residual ash in the form of K-Mg-rich phosphates. The results showed that in general for all studied fuels, the main release of P occurred during the devolatilization stage, while the main release of K occurred during char combustion. Furthermore, less than 20% of P and 35% of K was released at the highest furnace temperature for all fuels.

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  • 23.
    Hedayati, Ali
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Sefidari, Hamid
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden; RISE ETC (Energy Technology Centre) AB, Box 726, Piteå, Sweden.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kienzl, Norbert
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Ash transformation during single-pellet gasification of agricultural biomass with focus on potassium and phosphorus2021Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 217, artikel-id 106805Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Agricultural biomasses and residues can play an important role in the global bioenergy system but their potential is limited by the risk of several ash-related problems such as deposit formation, slagging, and particle emissions during their thermal conversion. Therefore, a thorough understanding of the ash transformation reactions is required for this type of fuels. The present work investigates ash transformation reactions and the release of critical ash-forming elements with a special focus on K and P during the single-pellet gasification of different types of agricultural biomass fuels, namely, poplar, grass, and wheat grain residues. Each fuel was gasified as a single pellet at three different temperatures (600, 800, and 950 °C) in a Macro-TGA reactor. The residues from different stages of fuel conversion were collected to study the gradual ash transformation. Characterization of the residual char and ash was performed employing SEM-EDS, XRD, and ICP with the support of thermodynamic equilibrium calculations (TECs). The results showed that the K and P present in the fuels were primarily found in the residual char and ash in all cases for all studied fuels. While the main part of the K release occurred during the char conversion stage, the main part of the P release occurred during the devolatilization stage. The highest releases – less than 18% of P and 35% of K – were observed at the highest studied temperature for all fuels. These elements were present in the residual ashes as K2Ca(CO3)2 and Ca5(PO4)3OH for poplar; K-Ca-rich silicates and phosphosilicates in mainly amorphous ash for grass; and an amorphous phase rich in K-Mg-phosphates for wheat grain residues.

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  • 24.
    Huber, Miriam
    et al.
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Getreidemarkt 9/166, Vienna, Austria.
    Benedikt, Florian
    TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Getreidemarkt 9/166, Vienna, Austria.
    Karel, Thomas
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Getreidemarkt 9/166, Vienna, Austria.
    Binder, Matthias
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Getreidemarkt 9/166, Vienna, Austria.
    Hochstöger, Daniel
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Getreidemarkt 9/166, Vienna, Austria.
    Egger, Anna
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Getreidemarkt 9/166, Vienna, Austria.
    Fürsatz, Katharina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria.
    Kuba, Matthias
    BEST – Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria.
    Tar conversion and recombination in steam gasification of biogenic residues: the influence of a countercurrent flow column in pilot- and demonstration-scale2024Ingår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 364, artikel-id 131068Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    First experiments with biogenic residues and a plastic-rich rejects and woody biomass blend were conducted in an advanced 1 MW dual fluidized bed steam gasification demonstration plant at the Syngas Platform Vienna. Wood chips, bark, forest residues, and the plastic-rich rejects and woody biomass blend were tested and the tar composition was analyzed upstream and downstream of the upper gasification reactor, which is designed as a high-temperature column with countercurrent flow of catalytic material. Each feedstock was gasified with olivine as bed material in demonstration scale and is compared to the gasification of softwood pellets with olivine and limestone in pilot scale. A reduction in tar content was observed after countercurrent column for all feedstocks. However, a shift in tar species occurred. While styrene, phenol, and 1H-indene were predominant upstream, naphthalene and polycyclic aromatic hydrocarbons (PAHs) were the prevailing tar species downstream the countercurrent column. Hence, an increase of i.e. anthracene, fluoranthene, and pyrene from the upstream concentration was observed. For pyrene, up to twice the initial concentration was measured. This recombination to PAHs was observed for all feedstocks in demonstration- and pilot-scale. The only exception occurred with limestone as bed material, characterized by a higher catalytic activity in comparison to the typically used olivine. In the perspective of the integrated product gas cleaning, tar with higher temperature of condensation are separated more efficiently in the installed scrubbing unit. Hence, the recombination facilitates an overall decline of tar content after the gas cleaning.

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  • 25.
    Ilanidis, Dimitrios
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hydrothermal Pretreatment of Wheat Straw: Effects ofTemperature and Acidity on Byproduct Formation andInhibition of Enzymatic Hydrolysis and Ethanolic Fermentation2021Ingår i: Agronomy, E-ISSN 2073-4395, Vol. 11, nr 487Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biochemical conversion of wheat straw was investigated using hydrothermal pretreatment, enzymatic saccharification, and microbial fermentation. Pretreatment conditions that were compared included autocatalyzed hydrothermal pretreatment at 160, 175, 190, and 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment at 160 and 190 °C. The effects of using different pretreatment conditions were investigated with regard to (i) chemical composition and enzymatic digestibility of pretreated solids, (ii) carbohydrate composition of pretreatment liquids, (iii) inhibitory byproducts in pretreatment liquids, (iv) furfural in condensates, and (v) fermentability using yeast. The methods used included two-step analytical acid hydrolysis combined with high-performance anion-exchange chromatography (HPAEC), HPLC, ultra-high performance liquid chromatography-electrospray ionization-triple quadrupole-mass spectrometry (UHPLC-ESI-QqQ-MS), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Lignin recoveries in the range of 108–119% for autocatalyzed hydrothermal pretreatment at 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment were attributed to pseudolignin formation. Xylose concentration in the pretreatment liquid increased with temperature up to 190 °C and then decreased. Enzymatic digestibility was correlated with the removal of hemicelluloses, which was almost quantitative for the autocatalyzed hydrothermal pretreatment at 205 °C. Except for the pretreatment liquid from the autocatalyzed hydrothermal pretreatment at 205 °C, the inhibitory effects on Saccharomyces cerevisiae yeast were low. The highest combined yield of glucose and xylose was achieved for autocatalyzed hydrothermal pretreatment at 190 °C and the subsequent enzymatic saccharification that resulted in approximately 480 kg/ton (dry weight) raw wheat straw.

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  • 26.
    Ilanidis, Dimitrios
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wu, Guochao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Stagge, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Effects of redox environment on hydrothermal pretreatment of lignocellulosic biomass under acidic conditions2021Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 319, artikel-id 124211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of the redox environment on acidic hydrothermal pretreatment were investigated in experiments with sugarcane bagasse (190 degrees C, 14 min) and Norway spruce (205 degrees C, 5 min). To modulate the redox environment, pretreatment was performed without gas addition, with N-2 , or with O-2. Analyses covered pretreated solids, pretreatment liquids, condensates, enzymatic digestibility, and inhibitory effects of pretreatment liquids on yeast. Addition of gas, especially O-2 , resulted in increased severity, as reflected by up to 18 percent units lower recoveries of pretreated solids, up to 31 percent units lower glucan recoveries, improved hemicellulose removal, formation of pseudo-lignin, improved overall glucan conversion, and increased concentrations of several microbial inhibitors. Some inhibitors, such as formaldehyde and coniferyl aldehyde, did not, however, follow that pattern. TAC (Total Aromatic Content) values reflected inhibitory effects of pretreatment liquids. This study demonstrates how gas addition can be used to modulate the severity of acidic hydrothermal pretreatment.

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  • 27. Jogi, Ramakrishna
    et al.
    Mäki-Arvela, Päivi
    Virtanen, Pasi
    Kumar, Narendra
    Hemming, Jarl
    Russo, Vincenzo
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lestander, Torbjörn A.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo/Turku, Finland.
    Understanding the formation of phenolic monomers during fractionation of birch wood under supercritical ethanol over iron based catalysts2020Ingår i: Journal of the Energy Institute, ISSN 1743-9671, E-ISSN 1746-0220, Vol. 93, nr 5, s. 2055-2062Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-150 and 5 wt % Fe–SiO2, respectively. Based on the results, the reaction mechanism for the formation of lignin degradation products was proposed. The main phenolic product was isoeugenol over 5 wt % Fe-Beta-H-150 while intermediate products, i.e. such as coniferyl, and sinapyl alcohol, 4-propenyl syringol, syringaresinol, as well as syringyldehyde reacted rapidly further. The thermodynamic analysis was performed by Joback approach and using Gibbs-Helmholtz equation supporting the obtained results.

  • 28.
    Jonsson, Leif J.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Martin, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pretreatment of lignocellulose: Formation of inhibitory by-products and strategies for minimizing their effects2016Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 199, s. 103-112Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Biochemical conversion of lignocellulosic feedstocks to advanced biofuels and other commodities through a sugar-platform process involves a pretreatment step enhancing the susceptibility of the cellulose to enzymatic hydrolysis. A side effect of pretreatment is formation of lignocellulose-derived by-products that inhibit microbial and enzymatic biocatalysts. This review provides an overview of the formation of inhibitory by-products from lignocellulosic feedstocks as a consequence of using different pretreatment methods and feedstocks as well as an overview of different strategies used to alleviate problems with inhibitors. As technologies for biorefining of lignocellulose become mature and are transferred from laboratory environments to industrial contexts, the importance of management of inhibition problems is envisaged to increase as issues that become increasingly relevant will include the possibility to use recalcitrant feedstocks, obtaining high product yields and high productivity, minimizing the charges of enzymes and microorganisms, and using high solids loadings to obtain high product titers.

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  • 29.
    Jönsson, Leif J.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Alriksson, Björn
    Nilvebrant, Nils-Olof
    Bioconversion of lignocellulose: inhibitors and detoxification2013Ingår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 6, artikel-id 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioconversion of lignocellulose by microbial fermentation is typically preceded by an acidic thermochemical pretreatment step designed to facilitate enzymatic hydrolysis of cellulose. Substances formed during the pretreatment of the lignocellulosic feedstock inhibit enzymatic hydrolysis as well as microbial fermentation steps. This review focuses on inhibitors from lignocellulosic feedstocks and how conditioning of slurries and hydrolysates can be used to alleviate inhibition problems. Novel developments in the area include chemical in-situ detoxification by using reducing agents, and methods that improve the performance of both enzymatic and microbial biocatalysts.

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  • 30.
    Khokarale, Santosh G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shelke, Ganesh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Department of Chemical Engineering, Åbo Akademi University, Åbo-Turku, Finland.
    Integrated and Metal Free Synthesis of Dimethyl Carbonate and Glycidol from Glycerol Derived 1,3-Dichloro-2-propanol via CO2 Capture2021Ingår i: Clean Technologies, ISSN 2571-8797, Vol. 3, nr 4, s. 685-698s. 685-698Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dimethyl carbonate (DMC) and glycidol are considered industrially important chemical entities and there is a great benefit if these moieties can be synthesized from biomass-derived feedstocks such as glycerol or its derivatives. In this report, both DMC and glycidol were synthesized in an integrated process from glycerol derived 1,3-dichloro-2-propanol and CO2 through a metal-free reaction approach and at mild reaction conditions. Initially, the chlorinated cyclic carbonate, i.e., 3-chloro-1,2-propylenecarbonate was synthesized using the equivalent interaction of organic superbase 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and 1,3-dichloro-2-propanol with CO2 at room temperature. Further, DMC and glycidol were synthesized by the base-catalyzed transesterification of 3-chloro-1,2-propylenecarbonate using DBU in methanol. The synthesis of 3-chloro-1,2-propylenecarbonate was performed in different solvents such as dimethyl sulfoxide (DMSO) and 2-methyltetrahydrofuran (2-Me-THF). In this case, 2-Me-THF further facilitated an easy separation of the product where a 97% recovery of the 3-chloro-1,2-propylenecarbonate was obtained compared to 63% with DMSO. The use of DBU as the base in the transformation of 3-chloro-1,2-propylenecarbonate further facilitates the conversion of the 3-chloro-1,2 propandiol that forms in situ during the transesterification process. Hence, in this synthetic approach, DBU not only eased the CO2 capture and served as a base catalyst in the transesterification process, but it also performed as a reservoir for chloride ions, which further facilitates the synthesis of 3-chloro-1,2-propylenecarbonate and glycidol in the overall process. The separation of the reaction components proceeded through the solvent extraction technique where a 93 and 89% recovery of the DMC and glycidol, respectively, were obtained. The DBU superbase was recovered from its chlorinated salt, [DBUH][Cl], via a neutralization technique. The progress of the reactions as well as the purity of the recovered chemical species was confirmed by means of the NMR analysis technique. Hence, a single base, as well as a renewable solvent comprising an integrated process approach was carried out under mild reaction conditions where CO2 sequestration along with industrially important chemicals such as dimethyl carbonate and glycidol were synthesized.

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  • 31. Kirtania, Kawnish
    et al.
    Haggstrom, Gustav
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Umeki, Kentaro
    Furusjo, Erik
    Cogasification of Crude Glycerol and Black Liquor Blends: Char Morphology and Gasification Kinetics2017Ingår i: Energy Technology, ISSN 2194-4288, Vol. 5, nr 8, s. 1272-1281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, we assessed the feasibility of black liquor/glycerol blends as a potential gasification feedstock. The char gasification reactivity and kinetics were studied at T=750, 800, 850, and 900 degrees C for 20 and 40% blends of glycerol with black liquor. Three qualities of glycerol were used including two industrial-grade crude glycerols. The gasification rates were similar for all blends; therefore, the alkali-metal catalysis is also sufficient for the char blends (alkali/C atomic ratio between 0.45 and 0.55). The blends with the most impure glycerol (containing K) had the lowest activation energies (approximate to 120 kJ mol(-1)) and reaction times for char gasification and, therefore, had fuel properties suitable for gasification. The char particles from different blends showed surface morphologies similar to those of black liquor chars with an even surface distribution of alkali elements. A loss of alkali (mainly K) from the fuel blends during pyrolysis indicated the necessity to perform gas-phase studies of alkali release. Overall, these results encourage the use of glycerol as a potential gasification feedstock for catalytic-gasification-based biorefineries.

  • 32.
    Kuba, Matthias
    et al.
    BEST Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Vienna, Austria.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Öhman, Marcus
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Hofbauer, Hermann
    TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Vienna, Austria.
    A review on bed material particle layer formation and its positive influence on the performance of thermo-chemical biomass conversion in fluidized beds2021Ingår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 291, artikel-id 120214Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Bed material particle layer formation plays a significant role in thermo-chemical conversion of biomass. The interaction between biomass ash and bed material in fluidized bed conversion processes has been described for a variety of different applications and spans from fundamental research of formation mechanisms to effects of this layer formation on long-term operation in industrial-scale. This review describes the current state of the research regarding the mechanisms underlying layer formation and the positive influence of bed material particle layer formation on the operation of thermo-chemical conversion processes. Thus, the main focus lies on its effect on the catalytic activity towards gasification reactions and the impact on oxygen transport in chemical looping combustion. The review focuses on the most commonly investigated bed materials, such as quartz, feldspar or olivine. While the most relevant results for both the underlying mechanisms and the subsequently observed effects on the operation are presented and discussed, knowledge gaps where further research is necessary are identified and described.

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  • 33. Lage, Sandra
    et al.
    Kudahettige, Nirupa P.
    Ferro, Lorenza
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Matsakas, Leonidas
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rova, Ulrika
    Gentili, Francesco G.
    Microalgae Cultivation for the Biotransformation of Birch Wood Hydrolysate and Dairy Effluent2019Ingår i: Catalysts, E-ISSN 2073-4344, Vol. 9, nr 2, artikel-id 150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to investigate environmentally sustainable sources of organic carbon and nutrients, four Nordic green microalgal strains, Chlorella sorokiniana, Chlorella saccharophila, Chlorella vulgaris, and Coelastrella sp., were grown on a wood (Silver birch, Betula pendula) hydrolysate and dairy effluent mixture. The biomass and lipid production were analysed under mixotrophic, as well as two-stage mixotrophic/heterotrophic regimes. Of all of the species, Coelastrella sp. produced the most total lipids per dry weight (~40%) in the mixture of birch hydrolysate and dairy effluent without requiring nutrient (nitrogen, phosphorus, and potassium—NPK) supplementation. Overall, in the absence of NPK, the two-stage mixotrophic/heterotrophic cultivation enhanced the lipid concentration, but reduced the amount of biomass. Culturing microalgae in integrated waste streams under mixotrophic growth regimes is a promising approach for sustainable biofuel production, especially in regions with large seasonal variation in daylight, like northern Sweden. To the best of our knowledge, this is the first report of using a mixture of wood hydrolysate and dairy effluent for the growth and lipid production of microalgae in the literature.

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  • 34.
    Larsson, Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Nordin, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Warnqvist, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Eriksson, Gunnar
    Influence of black liquor variability, combustion, and gasification process variables and inaccuracies in thermochemical data on equilibrium modeling results2006Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 20, nr 1, s. 359-363Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work is a systematic sensitivity study of how inaccuracies in thermochemical data influence important parameters resulting from chemical equilibrium modeling of black liquor combustion and gasification processes. These effects have also been compared with those originating from normal variations in process variables and black liquor composition. Determination of the effects was achieved by performing a large number of equilibrium calculations structured according to statistical designs. Evaluation of the chemical equilibrium model calculations was facilitated by regression analysis. From the results, it can be concluded that uncertainties in thermochemical data of several key components have significant effects on important chemical and physical modeling responses in black liquor combustion and gasification. These effects are in many cases comparable to, or larger than, the effects from variation in fuel and process variables. Experimental redetermination of thermochemical data for Na2S, K2S, and gaseous NaOH is suggested.

  • 35.
    Li, Gule.
    et al.
    Centre for Energy Technology, School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, Australia.
    Nathan, Graham J.
    Centre for Energy Technology, School of Mechanical Engineering, The University of Adelaide, Adelaide, Australia.
    Kuba, Matthias
    BEST Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, Graz, Austria; Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Getreidemarkt 9/166, Vienna, Austria.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ashman, Peter J.
    Centre for Energy Technology, School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, Australia.
    Saw, Woei L.
    Centre for Energy Technology, School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, Australia.
    Agglomeration of olivine with potassium- or silicon-rich agricultural residues under conditions relevant to dual fluidized bed gasification2022Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 36, nr 23, s. 14253-14266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The agglomeration characteristics of olivine- and potassium (K)-rich grape marc or silicon (Si)-rich wheat straw were studied in a laboratory-scale fluidized reactor and compared under air combustion, steam gasification, or CO2 gasification atmospheres at temperatures relevant to a dual fluidized bed gasifier. Agglomeration with grape marc is found to be induced mostly by the formation of adhesive K-rich layers onto the olivine, a process that is significantly augmented in a steam atmosphere compared to that in the air or CO2. The formation of an initial K-rich outer layer, which is caused by the mere physical attachment of K-species onto the olivine surface, facilitated the formation of an inner layer. This inner layer exhibits chemical reactions between grape marc ash and olivine, with the ash elements involved in the chemical reactions differing between combustion and steam gasification environments. Agglomeration with a wheat straw is most significant under air combustion conditions and depends primarily on the temperature rather than on the atmosphere.

  • 36. Lienqueo, María Elena
    et al.
    Ravanal, María Cristina
    Pezoa-Conte, Ricardo
    Cortínez, Victoria
    Martínez, Loreto
    Niklitschek, Tomas
    Salazar, Oriana
    Carmona, René
    García, Alejandro
    Hyvärinen, Sari
    Mäki-Arvela, Päivi
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Second generation bioethanol from Eucalyptus globulus Labill and Nothofagus pumilio: ionic liquid pretreatment boosts the yields2016Ingår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 80, s. 148-155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The depletion of petroleum reserves and the high level of pollution caused by fossil fuels have led to enhancing renewable energy and fuel production from biomass. Eucalyptus globulus and Nothofagus pumilio residues could constitute an interesting source of biomass for second generation biofuel production. Lenga residues were pretreated with the ionic liquid (IL) 1-N-ethyl-3-methylimidazolium chloride (C2mimCl), followed by subsequent fermentation using both the strategy of Simultaneous Saccharification and Fermentation (SSF) as well as Separate Hydrolysis and Fermentation (SHF). The SHF process yielded 0.134 g ethanol/g glucose (26.3 wt-% of the theoretical yield) compared to the SSF process which yielded 0.173 g ethanol/g glucose (33.9 wt-% of the theoretical yield) within the first 24 h of fermentation. In case of Eucalyptus residues, another IL, 1-N-ethyl-3-methylimidazolium acetate (C2minOAc) was applied. The SSF process was applied for a period of three days. As a result, 3.7 g ethanol/L (corresponding to a yield of 0.19 g of ethanol/g of glucose or 38.0 wt-% of the theoretical maximum) was obtained at 72 h. When fresh Lenga and Eucalyptus residues were fermented without any pretreatment, the SSF process yielded 0.017 and 0.002 g of ethanol/g of glucose, respectively (3.33 wt-% and 0.48 wt-% of the theoretical maximum, respectively). Thus, the pretreatment procedures resulted in a significant increase in ethanol production, therefore justifying the need of pretreatment prior to the co-enzyme hydrolysis and fermentation for this type of biomass. Further, the combination of IL pretreatment and use of SSF process demonstrated the high potential for bioethanol production from Lenga and Eucalyptus residues. Nevertheless, further improvement by optimization of operational conditions is required to maximize the ethanol yield.

  • 37.
    Ma, Charlie
    et al.
    Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, Sweden.
    Carlborg, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Hedman, Henry
    Wennebro, Jonas
    Weiland, Fredrik
    Wiinikka, Henrik
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Öhman, Marcus
    Ash Formation in Pilot-Scale Pressurized Entrained-Flow Gasification of Bark and a Bark/Peat Mixture2016Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 30, nr 12, s. 10543-10554Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pressurized entrained-flow gasification (PEFG) of bark and a bark/peat mixture (BPM) was carried out in a pilot-scale reactor (600 kWth, 7 bar(a)) with the objective of studying ash transformations and behaviors. The bark fuel produced a sintered but nonflowing reactor slag, while the BPM fuel produced a flowing reactor slag. Si was enriched within these slags compared to their original fuel ash compositions, especially in the bark campaign, which indicated extensive ash matter fractionation. Thermodynamically, the Si contents largely accounted for the differences in the predicted solidus/liquidus temperatures and melt formations of the reactor slags. Suspension flow viscosity estimations were in qualitative agreement with observations and highlighted potential difficulties in controlling slag flow. Quench solids from the bark campaign were mainly composed of heterogeneous particles resembling reactor fly ash particles, while those from the BPM campaign were flowing slags with likely chemical interactions with the wall refractory. Quench effluents and raw syngas particles were dominated by elevated levels of K that, along with other chemical aspects, indicated KOH(g) and/or K(g) were likely formed during PEFG. Overall, the results provide information toward development of woody biomass PEFG and indicate that detailed understanding of the ash matter fractionation behavior is essential.

  • 38. Ma, Charlie
    et al.
    Weiland, Fredrik
    Hedman, Henry
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ohman, Marcus
    Characterization of Reactor Ash Deposits from Pilot-Scale Pressurized Entrained-Flow Gasification of Woody Biomass2013Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 11, s. 6801-6814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O-2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.

  • 39. Ma, Chunyan
    et al.
    Wang, Nan
    Chen, Yifeng
    Khokarale, Santosh Govind
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bui, Thai Q.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Weiland, Fredrik
    Lestander, Torbjörn A.
    Rudolfsson, Magnus
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo-Turku, Finland .
    Ji, Xiaoyan
    Towards negative carbon emissions: Carbon capture in bio-syngas from gasification by aqueous pentaethylenehexamine2020Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 279, artikel-id 115877Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, an aqueous pentaethylenehexamine (PEHA) solution was studied for CO2 removal from bio-syngas for the first time. Firstly, pure CO2 absorption in aqueous PEHA solution under different conditions was conducted, and 20 wt% PEHA solution was identified as the best option. Secondly, the capture of CO2 was tested with synthetic syngas from a gas cylinder, and the species other than CO2 showed a negligible impact on CO2 removal. Finally, to evaluate the practical feasibility of using aqueous PEHA solution on the downstream CO2 capture, the pilot experiments of gasification with boreal forest-based biomasses were designed to provide real syngas with a realistic distribution in composition for further testing. The results showed that the operating conditions and the type of feedstocks affected the distribution in the bio-syngas composition. Among these feedstocks, at the optimal oxygen supply, using spruce needles generated the highest yields of CO and H2 and, meanwhile, gave rise to similar yields of other gases such as CO2, CH4, etc. The influence of the species other than CO2 for CO2 removal was negligible. Additionally, aqueous PEHA solution was tested as a biomass pretreatment agent, showing that no significant changes could be identified by the ultimate analysis (except for increased nitrogen content), but the yields of CO were affected negatively. On the other hand, when using the pretreated biomass by the aqueous PEHA solution, the NH3 concentration in bio-syngas reached to the highest (4000 parts per million), which slightly affected the CO2 absorption capacity and initial absorption rate of 20 wt% PEHA solution in a positive way.

  • 40.
    Martin, Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Biotechnology, Inland Norway University of Applied Sciences, Hamar, Norway.
    Dixit, Pooja
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Momayez, Forough
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hydrothermal Pretreatment of Lignocellulosic Feedstocks to Facilitate Biochemical Conversion2022Ingår i: Frontiers in Bioengineering and Biotechnology, E-ISSN 2296-4185, Vol. 10, artikel-id 846592Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Biochemical conversion of lignocellulosic feedstocks to advanced biofuels and other bio-based commodities typically includes physical diminution, hydrothermal pretreatment, enzymatic saccharification, and valorization of sugars and hydrolysis lignin. This approach is also known as a sugar-platform process. The goal of the pretreatment is to facilitate the ensuing enzymatic saccharification of cellulose, which is otherwise impractical due to the recalcitrance of lignocellulosic feedstocks. This review focuses on hydrothermal pretreatment in comparison to alternative pretreatment methods, biomass properties and recalcitrance, reaction conditions and chemistry of hydrothermal pretreatment, methodology for characterization of pretreatment processes and pretreated materials, and how pretreatment affects subsequent process steps, such as enzymatic saccharification and microbial fermentation. Biochemical conversion based on hydrothermal pretreatment of lignocellulosic feedstocks has emerged as a technology of high industrial relevance and as an area where advances in modern industrial biotechnology become useful for reducing environmental problems and the dependence on fossil resources.

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  • 41. Martinsson, J
    et al.
    Eriksson, A C
    Nielsen, I Elbaek
    Berg Malmborg, V
    Ahlberg, E
    Andersen, C
    Lindgren, R
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nyström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nordin, E Z
    Brune, W H
    Svenningsson, B
    Swietlicki, E
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pagels, J H
    Impacts of Combustion Conditions and Photochemical Processing on the Light Absorption of Biomass Combustion Aerosol2015Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, nr 24, s. 14663-14671Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim was to identify relationships between combustion conditions, particle characteristics, and optical properties of fresh and photochemically processed emissions from biomass combustion. The combustion conditions included nominal and high burn rate operation and individual combustion phases from a conventional wood stove. Low temperature pyrolysis upon fuel addition resulted in "tar-ball" type particles dominated by organic aerosol with an absorption Angstrom exponent (AAE) of 2.5-2.7 and estimated Brown Carbon contributions of 50-70% to absorption at the climate relevant aethalometer-wavelength (520 nm). High temperature combustion during the intermediate (flaming) phase was dominated by soot agglomerates with AAE 1.0-1.2 and 85-100% of absorption at 520 nm attributed to Black Carbon. Intense photochemical processing of high burn rate flaming combustion emissions in an oxidation flow reactor led to strong formation of Secondary Organic Aerosol, with no or weak absorption. PM1 mass emission factors (mg/kg) of fresh emissions were about an order of magnitude higher for low temperature pyrolysis compared to high temperature combustion. However, emission factors describing the absorption cross section emitted per kg of fuel consumed (m(2)/kg) were of similar magnitude at 520 nm for the diverse combustion conditions investigated in this study. These results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.

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  • 42. Matsakas, Leonidas
    et al.
    Sarkar, Omprakash
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rova, Ulrika
    Christakopoulos, Paul
    A novel hybrid organosolv-steam explosion pretreatment and fractionation method delivers solids with superior thermophilic digestibility to methane2020Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 316, artikel-id 123973Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rising environmental concerns and the imminent depletion of fossil resources have sparked a strong interest towards the production of renewable energy such as biomethane. Inclusion of alternative feedstock’s such as lignocellulosic biomass could further expand the production of biomethane. The present study evaluated the potential of a novel hybrid organosolv-steam explosion fractionation for delivering highly digestible pretreated solids from birch and spruce woodchips. The highest methane production yield was 176.5 mLCH4 gVS−1 for spruce and 327.2 mL CH4 gVS−1 for birch. High methane production rates of 1.0–6.3 mL min−1 (spruce) and 6.0–35.5 mL min−1 (birch) were obtained, leading to a rapid digestion, with 92% of total methane from spruce being generated in 80 h and 95% of that from birch in 120 h. These results demonstrate the elevated potential of the novel method to fractionate spruce and birch biomass and deliver cellulose-rich pretreated solids with superior digestibility.

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  • 43.
    Mehariya, Sanjeet
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Goswami, Rahul Kumar
    Bioprocess and Bioenergy Laboratory, Department of Microbiology, Central University of Rajasthan, Rajasthan, India.
    Verma, Pradeep
    Bioprocess and Bioenergy Laboratory, Department of Microbiology, Central University of Rajasthan, Rajasthan, India.
    Lavecchia, Roberto
    Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, Rome, Italy.
    Zuorro, Antonio
    Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, Rome, Italy.
    Integrated approach for wastewater treatment and biofuel production in microalgae biorefineries2021Ingår i: Energies, E-ISSN 1996-1073, Vol. 14, nr 8, artikel-id 2282Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The increasing world population generates huge amounts of wastewater as well as large energy demand. Additionally, fossil fuel’s combustion for energy production causes the emission of greenhouse gases (GHG) and other pollutants. Therefore, there is a strong need to find alternative green approaches for wastewater treatment and energy production. Microalgae biorefineries could represent an effective strategy to mitigate the above problems. Microalgae biorefineries are a sustainable alternative to conventional wastewater treatment processes, as they potentially allow wastewater to be treated at lower costs and with lower energy consumption. Furthermore, they provide an effective means to recover valuable compounds for biofuel production or other applications. This review focuses on the current scenario and future prospects of microalgae biorefineries aimed at combining wastewater treatment with biofuel production. First, the different microalgal cultivation systems are examined, and their main characteristics and limitations are discussed. Then, the technologies available for converting the biomass produced during wastewater treatment into biofuel are critically analyzed. Finally, current challenges and research directions for biofuel production and wastewater treatment through this approach are outlined.

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  • 44.
    Michel, Julie
    et al.
    Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft, Delft, Netherlands; Univ Grenoble Alpes, CEA, LITEN, DEHT, Grenoble, France.
    Rivas-Arrieta, María J.
    Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft, Delft, Netherlands.
    Borén, Eleonora
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Simonin, Loïc
    Univ Grenoble Alpes, CEA, LITEN, DEHT, Grenoble, France.
    Kennedy, Maria
    Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft, Delft, Netherlands.
    Dupont, Capucine
    Department of Water Supply, Sanitation and Environmental Engineering, IHE Delft, Delft, Netherlands.
    Fate of biomass inorganic elements during hydrothermal carbonization: an experimental study on agro-food waste2023Ingår i: Biomass Conversion and Biorefinery, ISSN 2190-6815, E-ISSN 2190-6823Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The distribution of inorganic elements between solid and liquid phases during biomass hydrothermal carbonization (HTC) is a poorly investigated topic despite its importance for process optimization. To fill in this gap, the distribution of inorganic elements and their forms were determined for three agro-food waste feedstocks converted at HTC temperatures of 180, 220, and 260 °C in 12 h. Satisfactory balances were achieved, with values between 80 and 92% for C and N, and 80 and 110% for most inorganic elements. At 180 °C, over 90% of P, Mg, Ca, K, Na, and Mn were removed from hydrochars whatever feedstock. At higher temperatures, P, Mg, Ca, and Mn were partly reincorporated into hydrochars (between 7 and 53%), possibly due to the formation of insoluble precipitates, while K and Na remained in the liquid. On the opposite, some minor elements, Cu and Al, remained in the hydrochars, whatever temperature. Si showed different removal behaviors according to feedstock and temperature. These results show the possibility of optimizing the removal of inorganic elements from hydrochars using different temperatures.

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  • 45. Mohammadi, Marzieh
    et al.
    Shafiei, Marzieh
    Abdolmaleki, Amir
    Karimi, Keikhosro
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Larsson, Christer
    A morpholinium ionic liquid for rice straw pretreatment to enhance ethanol production2019Ingår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 139, artikel-id 111494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rice straw was successfully pretreated with a novel and inexpensive morpholinium ionic liquid, 1-H-3-methylmorpholinium chloride ([HMMorph][Cl]). The influence of water (30, 40, 50% w/w) and dimethyl sulfoxide (DMSO) (10, 30% w/w), as co-solvents, pretreatment time (2, 3, 5 h), temperature (90, 105, 120 °C), solid loading (5, 6.7, 10% w/w), and straw particle size (<0.177, 0.177–0.841 mm, and 0.841–2 mm) were investigated for maximum ethanol production. The best results were obtained in 50% water, at 120 °C and 5% (w/w) solid loading for 5 h from 0.177 – 0.841 mm straw particles. The hydrolysis yield was increased from 33.2% to 70.1%, while ethanol production yield was improved from 21.9% to 64% of the theoretical maximum. The performance of the IL was comparable to 1-ethyl-3-methylimidazolium acetate. Simple synthesis process and dilute solution required for the pretreatment with [HMMorph][Cl] offers cost reductions in the use of ILs in biofuel production.

  • 46. Moradian, Farzad
    et al.
    Tchoffor, Placid A.
    Davidsson, Kent O.
    Pettersson, Anita
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Thermodynamic equilibrium prediction of bed agglomeration tendency in dual fluidized-bed gasification of forest residues2016Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 154, s. 82-90Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dual fluidized-bed (DFB) gasification is one of the recently developed technologies for production of heat, power, transportation fuels and synthetic chemicals through steam gasification of biomass. Bed agglomeration is a serious ash-related problem that should be taken into account when biomass-based fuels are selected for fluidized bed gasification and combustion. This study developed a thermodynamic equilibrium model to assess the risk of bed agglomeration in gasification and combustion reactors of a DFB gasifier using biomass (forest residues) as feedstock. The modelling approach combined thermodynamic equilibrium calculations with chemical fractionation technique to predict the composition and melting behaviour of the fuel-derived ash as well as bed particles coating layer in the gasification and combustion reactors. FactSage was employed for the thermodynamic equilibrium calculations. The modelling results were then compared with experimental data obtained from a full-scale DFB gasifier to estimate the reliability and validity of the predictive model. In general, a good agreement was found between the modelling results and experimental observations. For the forest residues as feedstock and olivine as bed material, the modelling results indicate a low risk of bed agglomeration in the DFB gasifier, as long as the dominant temperature in the combustion zone is below 1020 degrees C. In contrast, quartz as bed material in the DFB gasifier was shown to significantly increase the risk of bed agglomeration through coating-induced agglomeration mechanism. 

  • 47. Mäkelä, Mikko
    et al.
    Wai Kwong, Chi
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Yoshikawa, Kunio
    Hydrothermal treatment of grape marc for solid fuel applications2017Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 145, s. 371-377Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The treatment and disposal of grape marc, a residue from grape processing, represents a significant economic and environmental challenge for the winemaking industry. Hydrothermal treatment of grape marc could be an efficient way for producing solid fuels on-site at the wineries. In this work the effects of treatment temperature and liquid pH on grape marc char and liquid properties were determined based on laboratory experiments and the combustion characteristics of char were assessed through thermogravimetric analysis and fuel ash classification. The results showed that hydrothermal treatment increased the energy and carbon contents and decreased the ash content of grape marc. The effect of liquid pH was statistically significant (p < 0.05) only for the determined carbon yield of liquid samples. The energy yield from grape marc was maximized at lower treatment temperatures, which also decreased the content of less thermally stable compounds in the attained char. Higher treatment temperatures decreased grape marc solid, carbon and energy yields and led to an increase in thermally labile compounds compared to lower temperatures likely due to the condensation of liquid compounds or volatiles trapped in the pores of char particles. The alkali metal contents of char ash were reduced coupled with an increase in respective phosphorus. Overall the results support the use of hydrothermally treated grape marc in solid fuel applications, if elevated levels of ash phosphorus can be tolerated.

  • 48. Nielsen, Ingeborg E.
    et al.
    Eriksson, Axel C.
    Lindgren, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Martinsson, Johan
    Nyström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nordin, Erik Z.
    Sadiktsis, Ioannis
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nojgaard, Jacob K.
    Pagels, Joakim
    Time-resolved analysis of particle emissions from residential biomass combustion: Emissions of refractory black carbon, PAHs and organic tracers2017Ingår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 165, s. 179-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Time-resolved particle emissions from a conventional wood stove were investigated with aerosol mass spectrometry to provide links between combustion conditions, emission factors, mixing state of refractory black carbon and implications for organic tracer methods. The addition of a new batch of fuel results in low temperature pyrolysis as the fuel heats up, resulting in strong, short-lived, variable emission peaks of organic aerosol-containing markers of anhydrous sugars, such as levoglucosan (fragment at m/z 60). Flaming combustion results in emissions dominated by refractory black carbon co-emitted with minor fractions of organic aerosol and markers of anhydrous sugars. Full cycle emissions are an external mixture of larger organic aerosol-dominated and smaller thinly coated refractory black carbon particles. A very high burn rate results in increased full cycle mass emission factors of 66, 2.7, 2.8 and 1.3 for particulate polycyclic aromatic hydrocarbons, refractory black carbon, total organic aerosol and m/z 60, respectively, compared to nominal burn rate. Polycyclic aromatic hydrocarbons are primarily associated with refractory black carbon-containing particles. We hypothesize that at very high burn rates, the central parts of the combustion zone become air starved, leading to a locally reduced combustion temperature that reduces the conversion rates from polycyclic aromatic hydrocarbons to refractory black carbon. This facilitates a strong increase of polycyclic aromatic hydrocarbons emissions. At nominal burn rates, full cycle emissions based on m/z 60 correlate well with organic aerosol, refractory black carbon and particulate matter. However, at higher burn rates, m/z 60 does not correlate with increased emissions of polycyclic aromatic hydrocarbons, refractory black carbon and organic aerosol in the flaming phase. The new knowledge can be used to advance source apportionment studies, reduce emissions of genotoxic compounds and model the climate impacts of refractory black carbon, such as absorption enhancement by lensing. 

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  • 49.
    Nilsson, Håkan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cournac, Laurent
    Rappaport, Fabrice
    Messinger, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lavergne, Jerome
    Estimation of the driving force for dioxygen formation in photosynthesis2016Ingår i: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1857, nr 1, s. 23-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photosynthetic water oxidation to molecular oxygen is carried out by photosystem II (PSII) over a reaction cycle involving four photochemical steps that drive the oxygen-evolving complex through five redox states S-i (i = 0, ... , 4). For understanding the catalytic strategy of biological water oxidation it is important to elucidate the energetic landscape of PSII and in particular that of the final S-4 --> S-0 transition. In this short-lived chemical step the four oxidizing equivalents accumulated in the preceding photochemical events are used up to form molecular oxygen, two protons are released and at least one substrate water molecule binds to the Mn4CaO5 cluster. In this study we probed the probability to form S-4 from S-0 and O-2 by incubating YD-less PSII in the S-0 state for 2-3 days in the presence of O-18(2) and (H2O)-O-16. The absence of any measurable O-16,18(2) formation by water-exchange in the S-4 state suggests that the S-4 state is hardly ever populated. On the basis of a detailed analysis we determined that the equilibrium constant K of the S-4 --> S-0 transition is larger than 1.0 x 10(7) so that this step is highly exergonic. We argue that this finding is consistent with current knowledge of the energetics of the S-0 to S-4 reactions, and that the high exergonicity is required for the kinetic efficiency of PSII.

  • 50. Norheim, Arnstein
    et al.
    Lindberg, Daniel
    Hustad, Johan E
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Equilibrium calculations of the composition of trace compounds from biomass gasification in the solid oxide fuel cell operating temperature interval2009Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, nr 2, s. 920-925Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The solid oxide fuel cell (SOFC), due to its high operating temperature and high fuel flexibility, may be fueled by biomass gasification producer gases. Based on the main gas components of typical producer gases (CO, CO(2), H(2), H(2)O, N(2), and light hydrocarbons), the expected SOFC performance will be in the range of cells that use, for example, reformed natural gas as fuel. However, other minor components such as compounds of S, Cl, Na, and K may form species that degrade the SOFC fuel electrode and thus have a negative influence on SOFC performance. Knowledge of the composition of the minor components and the expected level of these compounds is therefore of great importance to be able to perform a detailed experimental study and thus evaluate the expected SOFC performance. The present work comprises results from equilibrium calculations of the composition of biomass gasification gases from two types of biomass gasifiers, one that uses air as gasifying agent and one that uses steam, in the SOFC operating temperature interval (750-1000 degrees C). The major trace components present in biomass gasification producer gases have been identified for several levels of sulfur, potassium, chlorine, and sodium in the SOFC operating temperature interval. Sulfur is present mainly as H(2)S(g), whereas potassium is mainly present as KOH(g) and to some extent K(g), depending mainly on temperature. High chlorine content in the fuel favors KCl(g) production. In the temperature interval between 750 and 900 degrees C there are, in the cases investigated here, small amounts of carbonate-rich liquid phase and solid carbonates in equilibrium with the gasifier gas.

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