An investment model of a future CO2 free district heating system - Evaluation of the district heating system in Gothenburg in the year 2030

Abstract

District heating is an energy efficient way of providing space heating. The city of Gothenburg owns and operates a district heating network and heat plants through the company Göteborg Energi. The city of Gothenburg has set out environmental targets for the city and one of the targets are explored in this thesis. The target states that by 2030 the district heat generation should be free from fossil fuel usage. The goal of this target is in this thesis interpreted as achieving a fossil CO2 free district heat generation. The CO2 emissions from waste and excess heat are outside the system boundary. Several scenarios for 2030 are studied, each constructed to explore a possible future. An investment model is run for each scenario. This is done in order to evaluate the robustness and cost efficiency of the studied technologies in a future fossil CO2 free district heating system. The investments are evaluated from a socio-economic perspective. From the scenario studies it is shown that a fossil CO2 free district heating system is achievable. It is also shown that large scale thermal storage can be utilized to lower system costs through load shifting seasonal and daily demand variations. Thermal storage can be used to incorporate large amounts of solar heating panels into the system. Furthermore it is shown that care must be taken during the planning of the future district heating system in order to avoid overexposure to the price of fuel. Fossil free heating originate from a few primary energy sources. The price of biomass and/or electricity can heavily influence system costs if alternative technologies are not available to counteract high prices. An increased variability in electricity price can be efficiently utilized through use of heat pumps and CHP technologies. These technologies enable district heating to play a role in demand side management of future electricity generation.