Land and climate effects of bioenergy - Brazilian sugarcane ethanol and combined biofuel-district heating in Europe

Sammanfattning: According to the Intergovernmental Panel on Climate Change, the largest source of increased atmospheric CO2 concentration is fossil fuel use. The second largest is land-use change. Emissions from fossil fuel combustion and land-use change will need to be reduced in order to reach stringent climate targets. Biomass is one of the renewable energy sources that could be used to replace fossil fuels. Biomass is however limited and expected to become scarce compared to future demand; therefore, it is desirable to use it as efficiently as possible. Further, when biofuels expand into new areas resulting in land-use change, the total biospheric carbon stock (the sum of soil and above ground carbon) may increase or decrease, thereby influencing the net greenhouse gas savings achieved. This thesis, which consists of five separate papers, analyses different aspects associated with two bioenergy options: (i) combined biofuel and district heat production in EU, and (ii) sugarcane for ethanol in Brazil. Integration with existing food and energy systems are given special attention. The overall aim of this thesis is to investigate specific options for improving options to manage land use and LUC, efficient use of resources and GHG balances for some specific bioenergy systems. In Paper I we study biomass gasification to produce biofuels and heat for district heating systems in Europe. We find that each investigated country, except Italy, has a heat sink capacity in its district heating systems that is larger than the amount of heat that would be co-generated in plants producing biofuel volumes corresponding to national biofuel targets. In Paper II-IV we study expansion of sugarcane ethanol production in Brazil at regional, state and national levels. Conventional sugarcane ethanol systems are studied and also combined ethanol-milk production systems where sugarcane residues are used as animal feed. We find that the effects of sugarcane production on soil carbon content and the harvest practice for sugarcane both have an influence on total greenhouse gas emissions from sugarcane-based ethanol production. How the by-product bagasse is used also affects the results. For Paper V we interviewed Brazilian farmers and landholders regarding their actions connected to their engagement with sugarcane production. We found that it was common among the interviewees to maintain and improve the beef and milk production systems they had managed before beginning with sugarcane production. This behaviour likely effects indirect land use change connected to the sugarcane expansion on their former pastures.