Article: Fargione, J. (2012). Boosting biofuel yield. Nature Climate Change 1: 445-446.
Background: One of the main concerns with biofuel production centers on land use change; if we convert natural ecosystems or food croplands to biofuel crops, we may be worsening other environmental and food security problems. There is debate over the extent to which biofuel production directly competes with the food market and increases food prices. In order to increase global biofuel production without the agricultural expansion, biofuel yields would have to increase.
Summary: Fargione explains that Johnston et al. have calculated that an extra 112.5 billion liters of ethanol and 8.5 liters of biodiesel could be produced if global yield for crops used to make biofuels increases (with crop area staying constant). They determined the potential yield gain by comparing current production levels with a scenario in which the half of the world’s farmers having below median yield increased yields to median levels. Separate median yield values were identified for each major crop used to produce ethanol and biodiesel in each climate zone. Thus, yields from locations that have similar numbers of growing degree-days and soil moisture/types (such as Indonesia and Brazil) and grow the same crop (like sugar-cane) were grouped together. The variation in yields of a given biofuel crop creates a “yield-gap” that would ideally be reduced by adjusting management practices, inputs, equipment, or the cultivar variety. For example, if Madagascar were to have its lower-yielding half of farmers produce at median yield levels, they could double sugar-cane yields.
Despite the great potential for energy crop yield increases, the means by which this can occur are not straightforward. Especially in developing countries, yields are often lower due to lack of capital, access to equipment, and education on farm management. Solutions require some combination of monetary aid, educational outreach, and investment in infrastructure and technology. However, closing the energy crop yield gap also has concerning realities – more fertilizers and irrigation will be needed, and with global food demand growing, policy-makers have to decide what proportion of resources should go toward biofuel versus food crops.
CATF take-away message: Boosting agricultural yields is essential to meet the growing demand for food, animal feed, and other plant-based products. However, the idea that increasing yield/acre of biofuel crops is always a “win-win” – i.e., because it would increase energy production while preventing detrimental land-use change – needs to be considered carefully. Before pouring resources into efforts to make higher yielding energy crops, we must make sure that the carbon footprint and energy balances of the biofuel production process (currently, as well as with the adjustments for higher yield) are acceptable to in the first place.