Land Matters

Sizing up the bioenergy potential of marginal lands

Reprinted with permission from Bioenergy Connection

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.”

Factoring in Economics

Campbell’s and Cai’s assessments identify lands suitable for biofuel crops. That’s not to say they are economically viable. The actual acreage used for biofuel feedstocks will depend on land ownership, transportation costs, markets, prices of other crops, the price of competing forms of hu Khanna, professor of agricultural and consumer economics at UIUC and, like Cai, a researcher with the Energy Biosciences Institute, “Geographical variations in the costs of producing these crops and in the opportunity costs of land are likely to make the economic viability of cellulosic biofuels differ across locations.”

In the Midwest, for example, Khanna found that the price farmers would need to turn a profit on a hypothetical Miscanthus crop varied from $40 per metric ton to over $100 per metric ton, depending on location, operating costs, and productivity.

In the United States, says Khanna, there is adequate rain-fed cropland/pasture that is currently not in crop production to meet the federal biofuel mandate for 20 billion gallons of cellulosic biofuels, provided high yielding energy crops such as Miscanthus are available. But, says Khanna, “even cellulosic feedstocks will divert some land from food crop production because it will be profitable to do so. There are some regions in the United States where the productivity of that land for corn and soybeans is relatively low but something like Miscanthus is very productive.

“Ultimately which land and how much of it gets used will depend on a number of factors like policy incentives, price of biomass, the current returns to that land and its suitability for producing energy crops,” says Khanna.

Policies that reward biofuel feedstocks that have low carbon intensity and contribute to biodiversity and other ecosystems can increase the economic viability of cellulosic feedstocks, she says. However, she adds, such policies need to be applied globally to prevent incentives for indirect land use changes in other parts of the world that could release carbon stocks and offset the benefits of biofuels. Biofuel certification standards, government regulations, and market-based pressures from biofuel consumers could encourage development of environmentally sustainable biofuels, says Khanna.

Developing World’s Issues

Farmers and other landowners will call the shots in the United States, Europe, and other countries where land ownership is clear. But in the developing world, land tenure is less secure and will play a major role in biofuel feedstock and other agriculture development.

Clearly, integrated food-energy agriculture can provide energy and income to Third World communities. According to the Food and Agriculture Organization (FAO) of the United Nations, a 100,000-hectare plantation in the Democratic Republic of Congo combines food crops and acacia forests, enabling farmers to earn up to $9,000 per year, four times the income of a taxi driver in nearby Kinshasa.

In the opening line of its report, Awakening Africa’s Sleeping Giant: Prospects for Commercial Agriculture in the Guinea Savannah Zone and Beyond, The World Bank states, “Stimulating agricultural growth is critical to reducing poverty in Africa.” It estimates that as much as one billion acres of underutilized land in Mozambique, Nigeria, and Zambia is available for expansion of agriculture, including biofuel crops.

“Less than 10 percent of this area is currently cropped, making it one of the largest underused agricultural land reserves in the world,” says the report. However, it also notes virtually all of this land is claimed by individuals and groups, and land tenure issues are likely to arise with any move to larger scale use.

According to the FAO, “In many cases, lands perceived to be ‘idle,’ ‘under-utilised,’ ‘marginal’ or ‘abandoned’ by government and large private operators provide a vital basis for the livelihoods of poorer and vulnerable groups, including through crop farming, herding and gathering of wild products.”

Examples abound. In Sierra Leone, for example, a plan announced in June by the Swiss group Addax & Oryx to grow thousands of hectares of sugarcane for ethanol has raised fears over food and land rights. And, in Tanzania, an area targeted for sugarcane production supports up to 1,000 rice farmers. Indonesian palm oil producers have been accused of clearing forests and driving off long-established communities that have used the land for generations.

Thus, the possible impacts of using land for biofuels production in developing countries may be quite different than in the developed world. This harsh reality may well polarize some, particularly NGOs, against even the idea of biofuels development in some regions. The pending development of international certification standards for biofuels may help to ensure that fuels produced in regions lacking social equity or using environmentally destructive practices do not find international markets.

Just Grow More

As many biofuel researchers evaluate possible sources of idle cropland, Bruce Dale believes that in the United States, at least, we should focus on land already in use.

“It’s reasonable to look at marginal and abandoned land, but I think they’re abandoned for a reason. They are not particularly productive,” says Dale, a professor of chemical engineering at Michigan State University. “The fact is, we have lots of land. We’ve been taking land out of agricultural production for years, for decades. It’s just a mistake to think we can’t increase agricultural output.”

In a paper published in Environmental Science and Technology (titled, in a riff on Tilman and Hill’s paper, “Biofuels Done Right”), Dale argues that more efficient production of animal feed and aggressive double-cropping can feed livestock and boost production of biofuels, while reducing greenhouse gas emissions (by sequestering carbon), building soil fertility, and reducing runoff and erosion—while not raising food prices.

First, says Dale, it’s important to find alternative high-quality livestock feeds. As he notes, more than 80 percent of total agricultural production in the U.S. is used to feed animals, especially beef cattle. (Humans directly consume only about 3 percent of the U.S. corn crop.) Dale highlights two technologies—one using ammonia and the other by pulping and pressing—to convert cellulosic feedstocks to high-protein cattle feed.

Second is planting a crop such as winter rye on corn and soy lands. The winter crop would take up nutrients such as nitrogen that might otherwise run off into nearby waterways, provide protection from wind erosion, and build soil fertility. In the spring, the crop would be harvested as biofuel feedstock. About 5 percent of corn and soy land is already doublecropped for dairy animal feed, Dale says. That could rise to a third if there were demand for cellulosic feedstocks.

“Using less than 30 percent of total U.S. cropland, pasture, and range, 400 billion liters of ethanol can be produced annually without decreasing domestic food production or agricultural exports,” Dale reports. That amount is four times the federal mandate for all biofuels by 2022, and 56 percent of current U.S. transportation fuel needs.

The University of Minnesota’s Jason Hill, among others, says Dale is overly optimistic about the potential of double-cropping to meet biofuel and environmental goals, and is too sanguine that his plan won’t bring new land into production.

But Dale responds that field trials of double-cropping convince him he is being conservative. “If anything we’ve understated the potential for this idea. I actually think this is going to be hard for people to swallow. What has happened is that agriculture, particularly around the world, has not been invested in enough because agricultural prices have not been high enough—not so much prices, but per acre revenues. If there’s an additional demand for biomass because of the cellulosic biofuels industry—our fuel market is just huge—this can provide additional investment in agriculture, additional opportunities for farmers to profit while not, I believe, hiking up prices, just because there is more output per acre.”

Technology for such a plan, says Dale, is close at hand. “I actually think we’re a lot closer than people think. If gas prices stay in this range of $3.50 to four bucks a gallon, I think there are several different approaches out there that are actually technically feasible on the commercialization side,” he says.

Whichever approach is ultimately taken— growing perennial grasses on abandoned and marginal land, intensely managing crops on prime farmland, employing technological improvements to expand benefits from existing acreage, something entirely new, or “all of the above” – the answer to how best to use the world’s finite land will be pivotal to biofuels’ ultimate contribution to the world’s energy future. 

Further Reading

Land Availability for Biofuel Production by Ximing Cai, Xiao Zhang and Dingbao Wang (2010)

Fueling Exclusion? The Biofuels Boom and Poor People’s Access to Land by Lorenzo Cotula, Nat Dyer and Sonja Vermeulen (2008)

The Global Potential of Bioenergy on Abandoned Agriculture Lands J. Elliott Campbell, David B. Lobell, Robert C. Genova and Christopher B. Field (2008)


Mapping the World's Potential for New Energy Crops


Text by Marie Felde; Graphics by Haley Ahlers [used with permission]

Researchers at the University of Illinois and the University of Central Florida reviewed physical conditions to estimate land available to grow second-generation biofuels crops. The 2010 study found that between 320 and 702 million hectares of marginal land, including abandoned and degraded crop lands, may be available in the six most productive regions of the world without affecting current productive crop and pasture land.


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