Energy efficiency and competitiveness of biomass-based energy systems

Abstract

Biomass accounts for 17% of the total Swedish energy supply. The potential increase in annual domestic biomass production is considerable. The costs and primary energy use required for producing one unit of electricity and one unit of heat, as well as the CO 2 emissions involved, were analysed for different biomass- and fossil-fuel-based systems. Supply systems based on cogeneration plants are more energy- and cost-efficient than those based either on heat pumps and condensing plants or on boilers and condensing plants. Less efficient systems lead to greater CO 2 emissions, except for bioniass systems involving a CO 2-neutral fuel cycle. They also lead to an increase in primary energy use. In Sweden, significant reductions in the price of forest fuel during the past two decades and increases in fossil fuel taxes have made bioenergy competitive with fossil fuels for heat production. Current taxes on oil used for heat production are as high as the price of the oil itself. Coal taxes were low until 1982 but are now about four times as high as the price of coal. From 1990 to 1994, the use of wood fuels for district-heat production increased from 3.6 TWh to 10.7 TWh and it is also expected to increase further. Expanded use of biomass-based boilers may prove an obstacle to future cogeneration investments. From 1990 to 1994, use of biofuels for the cogeneration of electricity in district heating systems was less than 0.5 TWh/yr. Low electricity prices in Sweden have limited the competitiveness of cogeneration. The tax advantages of biomass-based electricity production are slight since carbon and fuel taxes are only applied to heat production. Such taxation increases the tax disadvantages for more energy-efficient systems.