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This study explores the potential and impact of electricity cogeneration using Organic Rankine Cycle (ORC) integrated with small-scale biomass boilers within district heating systems. An analysis is conducted on a 3 MWth biomass-fired district heating plant in southern Sweden. Process monitoring data, collected over a one-year period from the plant, serves as the basis for simulation and analysis. The study examines operational changes and fuel usage at a local level, together with an extension to a regional scale considering both short-term and long-term energy system implications. The results show that integrating a 200 kW_e ORC unit with the existing boiler having a flue gas condenser is cost-optimal and could cogenerate approximately 1.1 GWh electricity annually, with a levelized electricity cost of €64.4 per MWh. This is equivalent to a system power-to-heat ratio of 7.5%. From a broader energy system perspective, this efficient integration could potentially reduce CO₂ emissions by 234∼454 tons per year when the saved energy locally is used to replace fossil fuels in the energy system, depending on how biomass is utilized and what type of fossil fuels are replaced. Increasing installed capacity of ORC unit to maximize electricity co-generation could result in a carbon abatement cost ranging from €204 to €79 per ton CO₂. This cost fluctuates depending on the installed capacity, operation of the ORC units, and prevailing electricity prices. The study highlights the trade-off between financial gains and CO₂ emission reductions, underscoring the complex decision-making involved in energy system optimization.

The use of pit thermal energy storages (PTES) enables higher solar fraction in district heating networks by counteracting the mismatch between heat demand and production in solar district heating (SDH) installations. Capital costs linked to land areas with site-specific geological conditions are the deciding factors for PTES constructions. This study investigates non-technical and technical factors for the implementation of PTES in Swedish district heating networks. Having several SDH and PTES installations in operation the country of Denmark is used as a reference. This study, based on literature review, discusses the drivers and challenges for the use of PTES in district heating networks.

A wider deployment of nearly zero energy buildings (NZEBs) is expected to contribute to the transition to a decarbonized and energy-efficient building sector in Europe. This study proposed an integrated energy-economic analysis to exemplify the feasibility of NZEB renovation in temperate climate. A parametric analysis was performed to identify technical building system configurations that give minimum share of renewable energy systems contributing to NZEB level. Final energy savings, global costs and cost-effectiveness of renovating a building to NZEB level are analysed, considering active and passive energy efficiency measures (EEMs). The active EEMs included efficient water taps and heat recovery ventilation, and the passive EEMs encompassed insulations to roof, exterior walls and ground floor, and improvements of windows and doors. The building had initial final energy use of 133 kWh/m2 year for space heating, domestic hot water production (DHW) and facility electricity. The results show that NZEB level is achieved with active and passive EEMs, without renewable energy systems for scenarios with low discount rates and high future energy price escalations. The annual final energy use for space heating, DHW and facility electricity is reduced cost-effectively by 37-54%. Furthermore, increasing size of PV-system enhanced cost-effectiveness by lowering total global costs.

This study investigates primary energy use and CO₂ emission reduction potential resulting from the integration of solar thermal heating in biomass-based district heating systems in high-latitude regions. A newly commissioned solar thermal system based on parabolic trough collectors for an existing district heating network in Häarnösand, Sweden, is used as a case study, and its hourly one-year measured data are used as inputs for the analysis. The changes in operation and fuel use for local district heat production are extended to a regional context, considering the short- and long-term perspectives of the energy system. The results show that during the studied period, the solar water heating system provided 335 MWh of heat to the existing district heating system with a supply/return temperature of approximately 80/45 °C. Consequently, 339–382 MWh of biomass fuel consumption could be reducedannually with such an installation, depending on the district heat production technologies being substituted. An annual CO₂ reduction of 65.3–189 tons can be achieved in an overall energy system perspective when the saved biomass substitutes fossil fuels. The reduction of CO₂ emission depends on the fuels being substituted and energy conversion technology.

Currently, companies in the solar heating sector may choose from a wide range of tools for modelling and simulating solar thermal power. However, due to the deviant design of some collectors, conventional simulation tools may be inadequate in correctly assessing the performance of such collectors. This study aims to test and validate an in-house simulation model for T160 PTC collectors developed by the company Absolicon Solar Collector AB by comparing measured data with simulated results. A solar district heating (SDH) plant in Härnösand, Sweden featuring 192 parabolic trough collectors (PTC) is used as a case study for the validation. Operational data such as weather data,solar heat production and collector loop/ambient temperatures were collected from the facilities of Absolicon. The data was compiled and simulated using a Python model developed for the T160 collectors. The study shows anacceptable correlation between simulated and measured data during periods with high DNI where a relatively highamount of heat is delivered to the district heating. Deviations are present during periods of low DNI and can bederived from inadequate assessments of heat losses from the piping of the installation in addition to inaccurate measurement data. 

This study investigates the climate change effects in terms of greenhouse gas emissions and radiative forcing resulting from different pathways of processing wood materials when they reach the end-of-life stage. The shares of combustion, landfill, recycling, and reuse, which vary with the pathways of post-use wood, influence the material and energy production systems. The dynamics of CO2 and CH4 emissions, together with the cumulative radiative forcing of each pathway, are evaluated from various regional system perspectives. The results show that the choice of a treatment pathway for post-use wood could strongly influence the profile of greenhouse gas emissions and, consequently, the global warming potential. Taking into account the situation of the reference material and energy production systems, the post-use wood can have unfavorable consequences for the climate, as in the case when the material and energy production systems are based on the low-carbon energy of natural gas. However, from the perspective where the treatment of post-use wood influences the quantity of forest biomass on the forest floor, the increased share of reuse and recycling contributes positively to the climate change mitigation, but only during the early stage. Under such a context, options relying on carbon capture and storage to handle biogenic CO2 emissions at energy conversion facilities could cause a cooling effect on the Earth's atmosphere.

A major challenge in building energy renovation is to cost effectively achieve notable energy savings. This paper investigates cost-effective passive energy-efficiency measures for thermal envelope retrofit of a typical Swedish multi-apartment building from the 1970s. Here, the use of different types of insulation materials for the retrofits of roof, exterior walls, and ground floor are analyzed along with changing windows and doors with varying thermal transmittance values. The cost-effectiveness analysis is based on the net present value of the investment costs of the energy-efficiently measures and the achieved energy cost saving. Different economic scenarios and renovation cases are considered in techno-economic analyses to determine the cost-effective energy-efficiency retrofit measures. The results indicate that improved windows reduce energy demand for space heating by up to 23% and yield the highest final energy savings. However, additional mineral wool roof insulation is the most cost-effective measure under all economic scenarios. This measure gave the lowest ratio of cost effectiveness of about 0.1, which was obtained under the stable scenario. The final energy savings that can be achieved in a cost-effective manner vary between 28% and 61%, depending on the economic scenario and renovation case. This analysis emphasizes the influence of different renovation cases and economic parameters on the cost effectiveness of passive energy-efficiency measures.