Efficient heat supply and use from an energy-system and climate perspective

Abstract: The aim of this thesis is to illustrate whether the heat demand in district heating systems can be seen as a resource that enables efficient energy utilization, how this can be achieved and to discuss consequences of this assumption. Based on the answers to posed research questions and on the studies included in this thesis, it is concluded that the hypothesis “A common system approach for energy supply and heat demand will show climate and economic efficient solutions” is true.In cold-climate countries, energy for heating of buildings is essential and heating options that interplay with the power system through electricity use or generation have potential for efficiency improvements. In Sweden, district heating is used extensively, especially in large buildings but to a growing extent also for small houses. Some industrial heat loads and absorption cooling can complement space heating demand so that the production resources may be more evenly utilised during the seasons of the year.Rising electricity prices in recent years cause problems for the extensive use of electric heating in Sweden and further switching to district heating should be a possible option. To be economically favourable, district-heating systems require a certain heat load density. New low-energy houses and energy-efficiency measures in existing buildings decrease the heat demand in buildings and, thus, in district heating systems. Optimisation models have been used in several studies of large, complex energy systems. Such models allow scenarios with changing policy instruments and changed consumer behaviour to be analysed. Energy efficiency measures as well as good conditions for efficient electricity generation, which can replace old, inefficient plants, are needed to reduce carbon dioxide emissions from the energy sector.Results when having a European energy perspective to studies of changes in Sweden differ from when having for example a Swedish energy system perspective The effects on global carbon dioxide emissions, when studying combined heat and power electricity generation in Sweden, are greater than it is on local emissions.