Availability of Land for Biofuel Production - But That is Only Part of the Story
Cai, X., Zhang, X., and Wang, D. 2011. Land Availability for Biofuel Production. Environmental Science and Technology 45: 334-339.
In conducting their analysis, the authors estimated for six regions/areas the amount of mixed crop and vegetation land with marginal productivity (Land Group 1); cropland with marginal productivity (Land Group 2); grassland, savanna, and shrubland with marginal productivity (Land Group 3); and pastureland (Land Group 4). They contend that Land Groups 1 and 2 consist of abandoned, degraded or idle cropland, and mixed crop and vegetation land. They used a two-step process. First, they identified land with marginal agricultural productivity and the current cover of that land. Next, they determined the land available for bioenergy feedstock production for the various land groups specified above. A fuzzy logic modeling (FLM) technique is employed to assess the land productivity. The outputs from the FLM are refined using a learning approach that extracts the criteria determining land categories from the existing land use data from remotely sensed world cropland maps. However, the study did not look at water availability or the impacts on the rest of nature of converting existing non-agricultural land and biomass to the use of biofuels, nor did they look at the issue of whether farmers would convert part of existing cropland currently used to produce food and feed to producing biomass for biofuels.
Based on their analysis the authors estimate that the six areas/regions contain: (a) 320 million hectares (Mha) of mixed crop and vegetation land of marginal productivity (including idle land) (Land Group 1), and (b) 382 Mha of abandoned and degraded cropland (Land Group 2). These lands could be used to produce biofuel feedstock. They estimate that, in addition, there are 709 Mha of grassland, savanna, and shrubland with marginal productivity, but 304 Mha of these are probably pasture land. Thus, there may be as much as an additional 1,107 Mha of land that might be available to grow biofuels without touching current productive cropland.
Such results led them to conclude that, "Planting second generation biofuel feedstocks on marginal croplands and LIHD [low input high diversity] prairie on marginal grassland may fulfill 26-55% of the current world liquid fuel consumption, without compromising the use of land with regular productivity for conventional crops and without affecting the current pasture land."
In considering this analysis, Cai et al. address an interesting technical issue, namely, how much land that is not currently used for producing crops could be used to produce "second generation" biofuel feedstock and what fraction of liquid fuel consumption might that supply. However, even if there is sufficient land to theoretically meet the world's need for food and have sufficient land left over to produce such biofuel feedstock that does not mean that such biofuel production will not affect food prices, food availability, and global hunger and poverty rates. This is because in a relatively free market economic system (such as ours) which allows farmers to make their own decisions as to which crops they want to plant where (and when), farmers will use their cropland to maximize their net incomes. So long as they can make a larger profit from producing fuel feedstock rather than food, they will tend to cultivate the land for fuel. Thus regardless of how much marginal land is available, it is unrealistic to expect that productive cropland will not be converted to biofuel production, and that global food prices would be unaffected by an increase in demand for biofuels. Moreover, there is no reason to believe that additional land employed for producing fuel feedstock will not use water, fertilizers and pesticides to boost productivity, which will have negative environmental consequences.