The role of renewable energy for a local swedish utility under various market conditions

摘要

The expansion of renewable energy depends on the conditions for the renewable and competing energy carriers. Prices, taxes and availability of the energy source alternatives decide the benefit of fuel switching from fossil fuels to biomass. In a liberalised electricity market, the success of wind power, hydropower and biomass-based cogeneration is dependent on the market price of electricity, which is influenced by the demand for electricity and the supply of non-renewable power, such as nuclear and coal-fired condensing plants. Energy taxation schemes that promote environmental sustainability, and possibly governmental subsidies, are essential for increased use of renewable energy sources. In this paper, a representative local Swedish electricity and district-heating utility has been analysed with the MODEST energy-system optimisation model. MODEST uses linear programming to find the equipment and operation that cause the lowest total cost. The optimal kinds, sizes and occasions for profitable investments have been calculated for various cases. If the current conditions remain, it would be most beneficial for the utility to increase its heat-production capacity using woodchips. If electricity prices increase, industries and service facilities would find it profitable to replace electric heating with biofuel and to introduce energy conservation measures. At a rapid increase of electricity prices, the local utility should build wind power plants and a woodchips-fired steam-cycle combined heat and power (CHP) unit if governmental grants can be received. For this utility, current energy and CO_2 taxes are sufficient to make the investment in a fossil-fuel-fired cogeneration unit unfavourable.