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There are several barriers to increased use of biofuel in the transport sector (e.g., shortage of feedstocks, high production costs, and relatively low energy yields from standalone biofuel plants). One possible solution is integration of biofuel and district heating (DH) production. This study aims (1) to identify challenges (e.g. tradeoffs) related to integration and to suggests possible ways of dealing with these challenges, (2) to highlight factors that may influence effects on global GHG emissions from integration, (3) to highlight factors which should be considered when evaluating economic aspects related to integration. After conducting a systematic review using a prescribed and structured protocol, 38 articles were identified as relevant for this study. These articles present four different approaches for integration: delivering the excess heat from biorefineries to DH networks, utilising DH in biofuel production processes, integrating biofuel production with existing DH facilities, and building new polygeneration biofuel production facilities in DH systems (DHS).If investments in biofuel compete with combined heat and power (CHP) production, the electricity price and the premium paid for renewable electricity influence profitability in CHP plants investments and therefore even profitability in investments in biofuel production. Competition should also be considered when weighing environmental benefits (the influence on global GHG emissions). Competition can create trade-offs related to DHSs operating conditions, limited local and global biomass availability, and limited available heat sinks. To deal with these trade-offs and to avoid suboptimization, stakeholders in regional planning, investors and policymakers should cooperate.All identified studies noted that a comprehensive approach is needed to evaluate profitability aspects and effects on global GHG emissions.For instance, utilising excess heat or residues from a biofuel production process in a DHS requires consideration of alternative DH production and alternative fuels. If electricity is one of the by-products from the biofuel production, alternative electricity production should also be considered. The majority of the studies dealt with economic performance of integration. Some of the factors found to influence profitability include available heat sink, alternative DH and electricity production, expected operation patterns, energy policy and energy market conditions. The potential for reducing global greenhouse gases (GHG) emissions depends on alternative DH and electricity production but also on biomass availability and alternative biomass users.

LiLinköping municipality has managed biogas driven buses in the regional transport system since 1997 and all buses in the municipality have run on biogas since 2015. Biogas is a renewable fuel and by replacing fossil fuels it can help to lower net CO2 emissions. However, Internal Combustion Engines (ICE) in buses still have a rather low efficiency, in the range of 15–30%. If the combustion of biogas instead takes place in a combined cycle gas turbine (CCGT) efficiency could be higher and heat losses reduced. This could be a feasible solution if the transport system instead used electric buses charged with electricity generated by the CCGT. This article has a top-down perspective on the regional transport system and the regional district heating system (DHS) in Linköping municipality. Two alternative systems are compared regarding CO2 emissions, electricity production and component efficiencies. The first system that is studied is in operation today and uses locally produced biogas in the ICE buses. In parallel the combined heat and power (CHP) system delivers electricity and heat to households in the region. The second system that is studied is a system with electric buses and a CHP system that uses biogas in the CCGT to deliver electricity and heat to the regional power grid and DHS. The study shows that emissions would be reduced if biogas use is changed from use in ICE buses to use in the CCGT in the CHP-DHS. Improved biogas use could lower CO2-eq emissions by 2.4 million kg annually by using a better fuel-energy pathway.

A hydronic pavement system (HPS) is an alternative method to clear snow and ice, which avoids the use of salt, sand, and fossil fuel in conventional snow clearance, and minimizes the risk of accidents. The aim is to analyze the performance of different control strategies for a 35,000 m2 HPS utilizing heat from a district heating and cooling (DHC) system. The key performance indicators are (1) energy performance of the HPS, and (2) primary energy use, (3) electricity production and (4) greenhouse gas (GHG) emissions from the DHC system. The methodology uses a simulation model of the HPS and an optimization model of the DHC system. Three operational strategies are analyzed: A reference scenario based on the current control strategy, and scenarios where the HPS is shut down at temperatures below &minus, 10 &deg, C and &minus, 5 &deg, C. The study shows that the DHC return temperature is suitable for use. By operational strategies, use during peak demand in the DHC system can be avoided, resulting in reduced use of fossil fuel. Moreover, the energy use of the HPS could be reduced by 10% and the local GHG emissions by 25%. The study emphasizes that the HPS may have positive effects on global GHG emissions, as it enables electricity production from renewable resources.

When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system. Funding Agencies|industrial post-graduate school Reesbe; Knowledge Foundation (KK-stiftelsen); AB Borlange Energi; AB Stora Tunabyggen