ABSTRACT
Bioenergy was the first source of energy utilized by humankind. Fossil energy, in contrast, has only been utilized for two to three centuries. The scarcity of fossil energy carriers is not the only reason why a transformation of energy systems is essential. The other is that their use causes the bulk of anthropogenic greenhouse gas emissions, which lead in turn to dangerous climate change (IPCC, 2007d). Transforming energy systems towards sustainability has top political priority in order both to mitigate climate change and overcome energy poverty (Chapter 2).
