Comparative Assessment of Fuel-Based Systems for Space Heating

Replacing fossil fuels by biofuels and increasing energy efficiency are often considered to be options for reducing the net emission of greenhouse gases. This thesis presents the results of analyses of energy efficiency, emission and cost of whole energy system chains, from the natural resource to the end user when heating detached houses in a Swedish context. External costs and taxes of the energy systems were analysed. District heating using cogeneration, fuel-based electric heating and local boilers were considered. The electricity production was seen from a marginal perspective. The method and assumptions used are of great importance for the results. Therefore, a range of alternatives was analysed. The heat-pump and district-heating systems are found to be the most energy-efficient, followed by the local boiler systems. A reduction in the primary energy use typically leads to a reduction in emissions and cost. The wood-fuel-based systems emit about one tenth of the CO2 emitted by the fossil-fuel-based systems. CO2 sequestration does not reduce the CO2 emission from natural-gas-based systems to the low level of the wood-fuel-based systems and, in addition, makes the natural-gas-based systems more expensive than the wood-fuel-based systems. The fossil-fuel-based local boiler systems are found to be the most cost-efficient, followed by the heat-pump and district-heating systems. Systems based on natural gas are less expensive than the corresponding wood-fuel-based systems, but the difference in cost between the same types of wood-fuel- and fossil-fuel-based systems is less than 12%. External costs are highly uncertain, but applying external costs that were estimated based on a high cost level can make the wood-fuel-based systems the most cost-efficient. Taxes levied on all fossil-fuel-related emission and fuel use in the systems will tend to lower energy use and CO2 emission. Consumer electricity and heat taxes have an impact on the total cost, regardless of the fuel used, and benefit local boiler systems. (Less)