During 2007-8, world food prices exploded. Rising corn prices triggered Mexico’s “tortilla riots.” The sudden quadrupling of rice prices alarmed East Asia policymakers.
Soaring prices triggered a wave of speculation about underlying causes. One frequent explanation in the popular press was that the threefold increase in bioethanol and biodiesel production worldwide between 2000 to 2007 was responsible. The United States, the world’s largest ethanol producer, converts 40 percent of its corn to fuel and has committed to roughly tripling its production of biofuels by 2022 (but 60 percent of this is to be produced using non-corn-based feedstocks.)
Did demand for biofuel feedstocks, such as corn, sugarcane, rapeseed, and soybeans, drive the high cost of food? Many analysts later pinned most of the blame on commodities speculation, oil prices, and weather—not biofuels production. Indeed, while biofuels production continued to expand, crop prices declined back to the levels of long-term trends at the end of 2008 as petroleum prices declined. But the food-versus-fuel debate had begun.
Today, looking beyond corn for ethanol toward the possibility of producing cellulosic and other new biofuels on a meaningful commercial scale, researchers and policymakers are asking: How can we raise new non-food feedstocks without displacing food crops? Where can we raise these fuel crops without impairing biodiversity or competing with wildlife habitat, and yet address global warming? Where is this land? And how much energy might it produce?
The devil, they are discovering, is in the details. As University of Minnesota ecologist David Tilman and colleagues wrote in an influential Science essay in 2009, “Society cannot afford to miss out on the global greenhouse gas emission reductions and the local environmental and societal benefits when biofuels are done right. However, society also cannot accept the undesirable impacts of biofuels done wrong.”
And much of what is right or wrong comes down to land.
How Much Land Is There?
In their 2009 Science essay, Tilman, Jason Hill, and colleagues set the tone for much of the current work of finding land for next-generation biofuels. New development, they said, should reduce greenhouse gas emissions, support biodiversity, and improve both energy and food security.
“There’s been this hope that because biofuels are ‘bio,’ they are green and that is not the case necessarily,” says Hill, assistant professor of bioproducts and biosystems engineering at the University of Minnesota and a co-author of both Science papers. “You have to ensure they are produced in a way that is responsible and that absolutely is going to be better rather than worse. Let’s make sure we’re not trading one set of problems for another.”
They suggested several ways to “do biofuels right” by finding feedstocks in crop and forestry residue, household trash and industrial waste, and second crops on existing land. Foremost among their recommendations: producing cellulosic ethanol from perennial grasses and broadleaf herbaceous plants grown on marginal or abandoned agricultural land. Such a strategy avoids competition with food crops. It minimizes the pressure to clear land elsewhere. No new land clearing means no carbon debt. “Moreover,” they wrote, “if managed properly, use of degraded lands for biofuels could increase wildlife habitat, improve water quality, and increase carbon sequestration in soils.”
Such concerns have driven the search for abandoned land. J. Elliott Campbell, assistant professor of engineering at the University of California, Merced and colleagues from Stanford University consulted historical land-use data dating to 1700, satellite land-cover imagery, and global ecosystem modeling to identify lands worldwide that had once been farmed but now lay idle.
They found a lot—in the range of 385 to 472 million hectares (a hectare equals 2.47 acres), an area larger than India, roughly 3 percent of the earth’s land area. The potential for biofuel production, based on the natural production of the land, amounted to only 8 percent of the world’s current energy use, but about 40 percent of transportation fuels.
“Everyone has a different reaction to that number,” says Campbell. “Some are fairly excited by that. Others say, ‘Gee, this isn’t the solution we’re looking for.’ But it certainly sounds like it could be a piece of the solution. I think most people who work on renewable energy agree we need an ‘all of the above’ type of plan for solving our energy challenges.”
A similar analysis published in 2010—of available land in Africa, China, Europe, India, South America, and the continental U.S. —paints a more optimistic picture. Ximing Cai, associate professor of civil and environmental engineering at the University of Illinois at Urbana- Champaign (UIUC), and colleagues assembled data for soils, soil temperature, and humidity, and satellite imagery for topography. They then subjected data to a mathematical “fuzzy logic” probability assessment to smooth over uncertainty and ambiguity.
They estimated that marginal land, including abandoned and degraded cropland, available to biofuels production in those six highly productive agricultural regions of the world totaled from 320 to 702 million hectares. If these lands were planted in high-yield biofuel crops such as Giant Miscanthus grass they estimated the land could supply 10 to 52 percent of the world’s current liquid fuel supply “without compromising the use of land with regular productivity for conventional crops and without affecting the current pasture land.” Says Cai, “That’s quite significant.”
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Fuente: Environment. University of Minnesota