Land Clearing and the Biofuel Carbon Debt

Abstract

Increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to low-carbon fuels a high priority. Biofuels are a potential low-carbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food crop-based biofuels in Brazil, Southeast Asia, and the United States creates a "biofuel carbon debt" by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions that these biofuels would provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on degraded and abandoned agricultural lands planted with perennials incur little or no carbon debt and can offer immediate and sustained GHG advantages.

Evaluating the Global Role of Woody Biomass as a Mitigation Strategy

“…Second, the results reveal the advantage of using woody biomass rather than crop bio-energy. Crop bio-energy will have exactly the opposite effect on forest carbon sequestration because it would increase the relative value of cropland causing forestland to shrink (Fargione et al 2008;Melillo et al 2009;Searchinger et al 2009;Wise et al 2009). …”

“…It is also clear that this increase in forestland will cause overall carbon sequestration rates to increase (Malmsheimer et al 2011;Havlík et al 2011;Daigneault et al 2012;Sedjo and Tian 2012). Note that crop bio-energy would have the opposite effect on carbon sequestration because it would increase the relative value of cropland (Fargione et al 2008;Melillo et al 2009;Searchinger et al 2009;Wise et al 2009). …”

The Power of Biomass: Experts Disclose the Potential for Success of Bioenergy Technologies

“…Their widespread use could lead to high demand for feedstock and raise concerns with respect to the social and environmental sustainability of its supply, the potential competition for land with food production (Dornburg et al, 2008;Tilman et al, 2009), the threat for biodiversity and soil fertility (Lal, 2005), and the consequences on forests' carbon sinks (Böttcher et al, 2012). Recent research shows that land use and land cover changes driven by biomass production for energy purposes may negatively impact the life cycle GHG emissions balance (Gelfand et al, 2011;Fargione et al, 2008;Searchinger et al, 2008).…”

Is bioenergy for the birds? An evaluation of alternative future bioenergy landscapes

“…The consequences of increased demand for land associated with bioenergy crops initially gained attention because of the implications for carbon emissions associated with land clearing (2,3), but, more recently, the potential impacts of bioenergy's land demand on biodiversity have gained increased attention (4)(5)(6). The study by Meehan et al (7) in PNAS provides a quantitative look at predicted landscapescale biodiversity impacts under alternative bioenergy cropping scenarios.…”

“…Expansion of corn for ethanol is expected to exacerbate issues associated with nutrient pollution (10), air quality (11), greenhouse gas emissions from land use change (3), and habitat for biodiversity (4)(5)(6) in contrast to cellulosic ethanol, which offers the potential for environmental benefits in these areas (2,6,8,11,12).…”