Land-Use and Climate Effects of Bioenergy: Carbon balances of Swedish forest bioenergy systems – and – Geospatial biomass supply-and-demand matching for Europe
In order to keep global warming below 2 degrees Celsius, greenhouse gas emissions have to be drastically reduced. Bioenergy can play a role in climate change mitigation by substituting for energy from fossil fuels; however, biomass is a limited resource associated with emissions from land use and land-use change. Climate benefits of using biomass for energy have been called into question, with studies reaching conflicting conclusions. These conflicts can in part be explained by differences in methodological approaches and critical parameters, as well as by differences among the assessed bioenergy systems, e.g., the geographic location and associated land use.
This thesis combines five papers to provide a better understanding of the interactions between biomass supply and demand and the implications for land use and for climate change and other environmental impacts. Papers I and II bring together different methodological perspectives to analyze the effects on land use, biomass production, and forest carbon balances of using forest bioenergy. The papers show how the climate benefits of forest bioenergy systems can depend on the scale of the assessment, structure of the forests studied, market prospects for bioenergy and other forest products, and energy system developments. Paper III analyzes the role of the Swedish forest sector in future energy scenarios and in reaching the 2050 goal of climate neutrality. The paper finds that the Swedish forest can make an important contribution by supplying forest fuels and other products while maintaining or enhancing carbon storage in vegetation, soils, and forest products. The results are placed in the context of the 2-degree target by allocating a CO2 emissions budget to Sweden. Paper IV presents a geographical information system modeling framework (1,000 m resolution) for assessing and analyzing the availability and cost of forest and agricultural residues in relation to localized biomass demand for co-firing with coal. The paper shows that using agricultural residues reduces transport distances and thereby transport costs. Paper V extends the modeling framework used in Paper IV to include energy crops in assessing biomass availability and costs in the context of bio-electricity and bio-refineries, and considers potential environmental consequences associated with energy crops. The paper shows that lignocellulosic crops can complement residues and help mitigate a selected number of environmental impacts on agricultural land.