A total energy system of fuel upgrading by drying biomass feedstock for cogeneration: a case study of Skelleftea bioenergy combine

Emissions of greenhouse gases, such as CO2, need to be greatly reduced to avoid the risk of harmful climate changes, One way to mitigate emissions is switching fuels, from fossil fuels to renewable energy, e.g., biomass. In this paper we investigate a new approach for improving the performance of biomass-based cogeneration plants, a bioenergy combine. The system is a conventional biomass-based combined heat and power (CHP) plant with integrated pellet production, where part of the CHP plant's heat is used for drying biomass feedstock for producing pellets, This unique integration enables increased annual operational hours and an increased use of biomass because the upgraded pellets as an energy carrier can be economically and technically transported from regions with a surplus biofuel to regions with demand for biofuel. In the studied case of this paper, the produced pellets are transported to another CHP plant for substituting fossil fuels. The total energy system of the bioenergy combine and the linked CHP plant is analysed from a perspective Of CO2 reduction and energy efficiency. The results show that the system has great potential for reducing CO2 and increasing the efficiency. Furthermore, the non-technical factors influencing the realisation of the project has also been studied through interviews, showing that the main criterion behind the investment was the potential for profitability. In addition, an important factor that facilitated the realisation was the co-operative environment between the municipality and Skeileftei Kraft. Environmental issues appeared not to be influencing direct, but indirect through government subsidies. (C) 2002 Elsevier Science Ltd. All rights reserved.