Biofuels

Abstract

Biofuels were humanity’s earliest energy carrier in the form of firewood. Forest biomass energy was the dominant energy form used in the United Kingdom, United States, and other industrialized countries before the Industrial Revolution when coal took over. Traditional biomass energy resources such as firewood and straw still dominate energy consumption today in sub-Saharan Africa, Myanmar, Nepal, Pakistan, Cambodia, Guatemala, and Haiti, and it is the largest renewable energy source used worldwide. However, biomass energy sources are not always used sustainably. Since these energy sources are used for heating and cooking, they can be considered biofuel, though most 21st-century analysts more commonly think of biofuel as alternative transportation fuels such as ethanol, biodiesel, methanol, and biobutanol. These modern, “advanced” forms of biofuel are divided into “first generation”—based on food sources such as starch, sugar, animal fats, and vegetable oils (especially corn oil, soy oil, and sugarcane); “second generation”—based on non-food feedstocks such as lignocellulosic biomass (e.g., agricultural and forestry residues, short rotation woody crops, Miscanthus and switchgrass); and “third generation”—based on algae and synthetic biology. This bibliography will address the considerable scholarship and special concerns raised by ecologists over biofuel feedstock production and use. To accurately analyze the ecological effects of biofuel crop growth, baseline land use, and indirect land-use change caused by their production must be considered. It should also be noted that biofuel crops produce multiple products that are used in multiple markets, including human food, animal feed, specialty chemicals, electricity, among others. Since biofuels and ecology is a somewhat interdisciplinary and transdisciplinary subject, however, not all works listed herein have been authored by ecologists. Readers may also want to see the separate Oxford Bibliographies article “Geography of Biofuels.” The next section of this article will cover some broad overviews written by ecologists on the topic. Following that, we will list some of the major journals that have published much of the leading scholarship on biofuels and ecology. The rest of this review is divided into four main sections, though these are not mutually exclusive: Land Use and Land-Use Change, Ecosystem Services, Biodiversity, and Alternative Ecologies. In each section, relevant subthemes of importance to ecologists will be identified and discussed.