Integrering av pelletsfabrik med Rya kraftvärmeverk i Göteborg : en teknisk och ekonomisk utredning

Sammanfattning: Göteborg Energi has a surplus of district heating during spring, summer and fall. The heat surplus is due to a constant production of waste heat from oil refineries and heat from waste incineration over the year. It would be desirable to increase the demand for heat and the uptime for the newly built combined heat and power generation plant, Rya Kraftvärmeverk. One alternative could be to integrate Rya Kraftvärmeverk with a pellet production facility. By producing heat, electricity and pellet in a joint process the energy use can be decreased. The production can also be more cost efficient due to a lower investment cost when using the same boiler etc, for different purposes. The purpose of the thesis is to investigate the technical and economical possibilities for an integration of pellet production with Rya Kraftvärmeverk. In order to find a suitable system for the integration, different methods for drying biomass and existing pellet production plants have been studied. Eight different alternatives (two production capacities, two pressures of drying steam and two drying systems) have been evaluated based on electricity production, heat production, pellet production, profitability, environmental impact, transports and area needed for the pellet production plant. Finally, a recommendation has been given to Göteborg Energi whether they should continue to investigate an integration of Rya Kraftvärmeverk and pellet production and if so, what further studies are needed.