Integration of Heat Recovery from BECCS in a Multi-source Heat and Power Plant : Case Study of Stockholm Exergi

Abstract: Rising global temperatures and other extreme weather phenomena have been linked to increasing carbon dioxide (CO2) content in the atmosphere. The damaging impact carbon dioxide (CO2) has on the climate is cumulative. It is essential to reduce the CO2 emissions to hinder further long-lasting negative impacts. Bioenergy Carbon Capture and Storage (BECCS) can be a tool to reduce CO2 emissions or to offset emissions from fossil fuels. BECCS requires energy to operate, reducing the efficiency of powerplants. However, the energy used can be recovered as heat for the district heating network. This master thesis investigates the impact BECCS has on the internal energy flow in a CHP plant in Stockholm, Sweden. As a part of this study, an energy model over internal flows of a CHP plant were developed, assessing the temperature and flow changes of district heating within the plant. It was found that a BECCS unit may contribute and improve the current set up in the Värtan harbor CHP plant. By increasing the availability for the low-temperature units and reducing overproduction. It was also found that increased overproduction contributes to higher CO2 emissions as the flue gas caused by overproduction is not treated in the BECCS unit. With low insight in the integration, the flow from the BECCS unit will lock current heat-producing units in the power plant and increase heating, contributing to CO2 emission. As a result, the BECCS unit will have a lower impact on CO2 emission in these circumstances.