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Can biofuels rescue American prairies?
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Can biofuels rescue America’s prairies? Perhaps, say ecologists, but not if the current enthusiasm for corn ethanol continues to hold sway
JAMES NEDRESKY/AG PIX
This Thisweek– week– Ethanol– grants aimed at encouraging farmers to set aside marginal land to protect soils and biodiversity are going unused. This trend is especially damaging for birds that nest in the grass that grows on set-aside land. Sample estimates that 16 per cent of land protected under the set-aside scheme will be lost this year. In Wisconsin, the figure could exceed one-third. “Marginal land is being developed for corn, but corn is pretty much useless as a habitat for the birds we care about,” says Sample. Such sacrifices might be considered justified if corn ethanol were having a big impact on greenhouse gas emissions. However, corn requires large amounts of fertiliser, which is energy-intensive to produce.
“Corn ethanol production is damaging soils and threatening wildlife, while doing little to cut greenhouse gas emissions”
JIM GILES, SAN JOSE
IT IS boom time in the agricultural states of the American Midwest. On bumper stickers and billboards, locals are celebrating the arrival of a profitable industry. Golden corn cobs are being turned into ethanol, an alternative to gasoline. If you believe the posters, corn ethanol will enrich the environment as well as the region, while reducing dependence on foreign oil. But one group definitely does not buy the sales talk. Last week in San Jose, California, ecologists lined up to criticise corn ethanol. At a special session of the annual 8 | NewScientist | 18 August 2007
meeting of the Ecological Society of America (ESA), they argued that the expansion of corn ethanol is damaging soils and threatening wildlife, while doing little to cut US greenhouse gas emissions. Ecologists also fear that the corn boom will suck resources away from the development of cellulosic ethanol, extracted from fast-growing wild grasses. They claim that this technology could deliver cleaner energy while simultaneously helping to restore one of the country’s disappearing ecosystems: the mixed grasslands of the American prairie. Spurred on by rising oil prices and the 2005 Energy Policy Act,
As a result, corn ethanol releases at most only 25 per cent more energy than is required to grow and process the crop, according to calculations published last year by a team led by Alex Farrell of the University of California at Berkeley (Science, DOI: 10.1126/ science.1121416). His team calculated that the total –Put some grass in your tank– greenhouse gas emissions associated with running a car on corn ethanol are just 13 per cent which demanded that at least lower than gasoline. The fertilisers 28 billion litres of ethanol be used on corn also pollute streams produced annually by 2012, the number of US corn ethanol plants and create dead zones – water so low in oxygen it kills marine life – has doubled to around 120 in at the mouths of rivers. the past five years. Indeed, the Yet studies presented at the industry is already close to the ESA meeting suggest that 2012 target, according to figures cellulosic ethanol from native from the Renewable Fuels grasses could fix many of these Association, an ethanol industry problems. Ethanol is fermented body based in Washington DC. from sugars, which can be This rapid development has produced easily from corn starch come at a cost. David Sample of or extracted directly from sugar the Wisconsin Department of cane (see “All aboard the Brazilian Natural Resources in Madison bandwagon”). But sugars can also told the ESA meeting that corn be produced from cellulose, which production jumped 10 per cent makes up most of the biomass of last year in his state alone. As the fast-growing prairie grasses. cornfields expand, government www.newscientist.com
In this section
Although the process of extracting sugar is more complex than for corn starch, cellulosic ethanol from wild grasses has big potential energetic and environmental advantages. Robert Mitchell of the University of Nebraska in Lincoln has been monitoring 10 farmscale plots of switchgrass since 2000. Based on yields from these plots, and models describing the production of cellulosic ethanol, he told the ESA meeting that ethanol produced from such grasses would yield up to 15 times more energy than it uses during production, a huge improvement on corn. Jason Hill of the University of Minnesota in St Paul has come up with similarly impressive projections. Hill did not add the fertiliser that Mitchell’s group used, so the energy yield from his grasses was 2 to 6 times less. Significantly, though, the grasses took in more carbon dioxide from the atmosphere than was released from the fuel used to grow and process them. The carbon dioxide removed – around a third of a tonne per hectare per year – was taken up by the roots and so remained in the soil after the harvest. This means that the greenhouse gas savings from wild-grass ethanol could be up to 16 times as great as those from corn (Science, DOI: 10.1126/ science.1133306). Hill’s work also suggests that wild grass could be farmed more efficiently in mixed species plots, mimicking the make-up of www.newscientist.com
much too high and also argues that much of the land suitable for grasses is already used to produce fodder for livestock, limiting how much could be switched over. The biggest obstacles may be political, however. For grass cultivation to really take off, government incentives will be needed to build new facilities for large-scale processing of cellulose and to rival the generous subsidies currently paid to corn growers. Yet the powerful agricultural lobby is doing all it can to get politicians to focus on corn ethanol, which promises more immediate gains for farmers. Roger Samson, a specialist in biofuels policy at Resource Efficient Agricultural Production Canada, a not-for-profit organisation based in St Anne de Bellevue, believes corn ethanol is the wrong approach. “If this is a horse race, the US government has bet on a donkey,” he says. ●
of the type that would be suitable for biofuel farming. He found that a typical plot hosted three threatened bird species, while the average for corn was less than one species per plot. Harvesting the grass should not wipe out these gains in biodiversity, because it would have a similar effect to the fires that sweep through natural prairies most years. It all suggests that America’s prairies, which now cover just 1 per cent of their original area, could be –A familiar sight in the American Midwest– partially restored by biofuel farming, Hill says. natural prairie. When his group However, the ecologists who combined eight species of grass presented their results at the ESA in a single plot, yields were more meeting face some hurdles in than 150 per cent higher than bursting the corn ethanol bubble. from grass monocultures. In For instance, David Pimentel, an 16-species plots, the improvement agricultural scientist at Cornell was 238 per cent. University in Ithaca, New York, Such diverse mixes provide questions the assumptions of better havens for wildlife. In the models wild-grass researchers Wisconsin, Sample has studied use to calculate energy yields. He field-sized plots of mixed grasses claims the resulting estimates are
ALL ABOARD THE BRAZILIAN BANDWAGON Last week, two Latin American presidents embarked on separate tours of neighbouring countries to sell their conflicting visions of the future of energy. While firebrand Hugo Chavez of Venezuela went to Argentina, Ecuador, Bolivia and Uruguay to talk about oil and gas, Brazil’s Luiz Inàcio Lula da Silva headed to Mexico, Honduras, Nicaragua, Jamaica and Panama to try and export his nation’s experience in making ethanol from sugar cane. But can Brazil’s biofuel boom, which has seen the nation switch 30 per cent of its demand for automobile fuel over to ethanol from sugar cane, really be reproduced elsewhere? Brazil’s expertise in growing and processing sugar cane is certainly transferable. The Brazilian Agricultural Research Corporation, or Embrapa, has developed hundreds of varieties of sugar cane, each adapted to a certain climate and soil. Plantations mix and match varieties to obtain maximum yields. Factories use the Brazil’s president Lula da Silva wants to convert his neighbours to using biofuel
crop to produce sugar or ethanol, and can switch back and forth depending on which commodity is trading at a higher price on any given day. However, Brazil’s bioethanol success is also tightly linked to its particular environmental and economic circumstances. In south-east Brazil, where most of the sugar cane is produced, land is still relatively cheap. It is also flat, making it easy to mechanise sugar cane production, and the crops are entirely rain-fed. With no need for ORLANDO KISSNER/AFP
STEVE HERBERT/EYEVINE
● Tunnelling photons travel faster than speed of light, page 10 ● Climate change: the tipping points, page 13 ● Correcting mitochondrial disease, page 14
irrigation, sugar can be extracted with little expenditure of energy. “The cane is simply squeezed and the sugar runs out,” says Alex Farrell of the University of California at Berkeley. Unfortunately for Lula, this happy combination of factors cannot easily be exported. Brazil has created a guaranteed market by demanding that fuel pumps supply either ethanol or a gasoline mix containing 25 per cent ethanol. As countries elsewhere adopt targets for mixing ethanol with gasoline, Lula sees an important export opportunity. Still, the US and other developed countries would be nervous about depending on a single nation for the majority of their ethanol imports. Hence Lula’s determined efforts to get other Latin American nations on the biofuel bandwagon. “The Brazilian government has the sophisticated view that it will do well if there are multiple producers in the world,” says John Briscoe, director of the World Bank in Brazil. “A market five times bigger that they have 50 per cent of is a lot better than a market the current size which they have 90 per cent of.” Catherine Brahic
18 August 2007 | NewScientist | 9
Can biofuels rescue America’s prairies? Perhaps, say ecologists, but not if the current enthusiasm for corn ethanol continues to hold sway
JAMES NEDRESKY/AG PIX
This Thisweek– week– Ethanol– grants aimed at encouraging farmers to set aside marginal land to protect soils and biodiversity are going unused. This trend is especially damaging for birds that nest in the grass that grows on set-aside land. Sample estimates that 16 per cent of land protected under the set-aside scheme will be lost this year. In Wisconsin, the figure could exceed one-third. “Marginal land is being developed for corn, but corn is pretty much useless as a habitat for the birds we care about,” says Sample. Such sacrifices might be considered justified if corn ethanol were having a big impact on greenhouse gas emissions. However, corn requires large amounts of fertiliser, which is energy-intensive to produce.
“Corn ethanol production is damaging soils and threatening wildlife, while doing little to cut greenhouse gas emissions”
JIM GILES, SAN JOSE
IT IS boom time in the agricultural states of the American Midwest. On bumper stickers and billboards, locals are celebrating the arrival of a profitable industry. Golden corn cobs are being turned into ethanol, an alternative to gasoline. If you believe the posters, corn ethanol will enrich the environment as well as the region, while reducing dependence on foreign oil. But one group definitely does not buy the sales talk. Last week in San Jose, California, ecologists lined up to criticise corn ethanol. At a special session of the annual 8 | NewScientist | 18 August 2007
meeting of the Ecological Society of America (ESA), they argued that the expansion of corn ethanol is damaging soils and threatening wildlife, while doing little to cut US greenhouse gas emissions. Ecologists also fear that the corn boom will suck resources away from the development of cellulosic ethanol, extracted from fast-growing wild grasses. They claim that this technology could deliver cleaner energy while simultaneously helping to restore one of the country’s disappearing ecosystems: the mixed grasslands of the American prairie. Spurred on by rising oil prices and the 2005 Energy Policy Act,
As a result, corn ethanol releases at most only 25 per cent more energy than is required to grow and process the crop, according to calculations published last year by a team led by Alex Farrell of the University of California at Berkeley (Science, DOI: 10.1126/ science.1121416). His team calculated that the total –Put some grass in your tank– greenhouse gas emissions associated with running a car on corn ethanol are just 13 per cent which demanded that at least lower than gasoline. The fertilisers 28 billion litres of ethanol be used on corn also pollute streams produced annually by 2012, the number of US corn ethanol plants and create dead zones – water so low in oxygen it kills marine life – has doubled to around 120 in at the mouths of rivers. the past five years. Indeed, the Yet studies presented at the industry is already close to the ESA meeting suggest that 2012 target, according to figures cellulosic ethanol from native from the Renewable Fuels grasses could fix many of these Association, an ethanol industry problems. Ethanol is fermented body based in Washington DC. from sugars, which can be This rapid development has produced easily from corn starch come at a cost. David Sample of or extracted directly from sugar the Wisconsin Department of cane (see “All aboard the Brazilian Natural Resources in Madison bandwagon”). But sugars can also told the ESA meeting that corn be produced from cellulose, which production jumped 10 per cent makes up most of the biomass of last year in his state alone. As the fast-growing prairie grasses. cornfields expand, government www.newscientist.com
In this section
Although the process of extracting sugar is more complex than for corn starch, cellulosic ethanol from wild grasses has big potential energetic and environmental advantages. Robert Mitchell of the University of Nebraska in Lincoln has been monitoring 10 farmscale plots of switchgrass since 2000. Based on yields from these plots, and models describing the production of cellulosic ethanol, he told the ESA meeting that ethanol produced from such grasses would yield up to 15 times more energy than it uses during production, a huge improvement on corn. Jason Hill of the University of Minnesota in St Paul has come up with similarly impressive projections. Hill did not add the fertiliser that Mitchell’s group used, so the energy yield from his grasses was 2 to 6 times less. Significantly, though, the grasses took in more carbon dioxide from the atmosphere than was released from the fuel used to grow and process them. The carbon dioxide removed – around a third of a tonne per hectare per year – was taken up by the roots and so remained in the soil after the harvest. This means that the greenhouse gas savings from wild-grass ethanol could be up to 16 times as great as those from corn (Science, DOI: 10.1126/ science.1133306). Hill’s work also suggests that wild grass could be farmed more efficiently in mixed species plots, mimicking the make-up of www.newscientist.com
much too high and also argues that much of the land suitable for grasses is already used to produce fodder for livestock, limiting how much could be switched over. The biggest obstacles may be political, however. For grass cultivation to really take off, government incentives will be needed to build new facilities for large-scale processing of cellulose and to rival the generous subsidies currently paid to corn growers. Yet the powerful agricultural lobby is doing all it can to get politicians to focus on corn ethanol, which promises more immediate gains for farmers. Roger Samson, a specialist in biofuels policy at Resource Efficient Agricultural Production Canada, a not-for-profit organisation based in St Anne de Bellevue, believes corn ethanol is the wrong approach. “If this is a horse race, the US government has bet on a donkey,” he says. ●
of the type that would be suitable for biofuel farming. He found that a typical plot hosted three threatened bird species, while the average for corn was less than one species per plot. Harvesting the grass should not wipe out these gains in biodiversity, because it would have a similar effect to the fires that sweep through natural prairies most years. It all suggests that America’s prairies, which now cover just 1 per cent of their original area, could be –A familiar sight in the American Midwest– partially restored by biofuel farming, Hill says. natural prairie. When his group However, the ecologists who combined eight species of grass presented their results at the ESA in a single plot, yields were more meeting face some hurdles in than 150 per cent higher than bursting the corn ethanol bubble. from grass monocultures. In For instance, David Pimentel, an 16-species plots, the improvement agricultural scientist at Cornell was 238 per cent. University in Ithaca, New York, Such diverse mixes provide questions the assumptions of better havens for wildlife. In the models wild-grass researchers Wisconsin, Sample has studied use to calculate energy yields. He field-sized plots of mixed grasses claims the resulting estimates are
ALL ABOARD THE BRAZILIAN BANDWAGON Last week, two Latin American presidents embarked on separate tours of neighbouring countries to sell their conflicting visions of the future of energy. While firebrand Hugo Chavez of Venezuela went to Argentina, Ecuador, Bolivia and Uruguay to talk about oil and gas, Brazil’s Luiz Inàcio Lula da Silva headed to Mexico, Honduras, Nicaragua, Jamaica and Panama to try and export his nation’s experience in making ethanol from sugar cane. But can Brazil’s biofuel boom, which has seen the nation switch 30 per cent of its demand for automobile fuel over to ethanol from sugar cane, really be reproduced elsewhere? Brazil’s expertise in growing and processing sugar cane is certainly transferable. The Brazilian Agricultural Research Corporation, or Embrapa, has developed hundreds of varieties of sugar cane, each adapted to a certain climate and soil. Plantations mix and match varieties to obtain maximum yields. Factories use the Brazil’s president Lula da Silva wants to convert his neighbours to using biofuel
crop to produce sugar or ethanol, and can switch back and forth depending on which commodity is trading at a higher price on any given day. However, Brazil’s bioethanol success is also tightly linked to its particular environmental and economic circumstances. In south-east Brazil, where most of the sugar cane is produced, land is still relatively cheap. It is also flat, making it easy to mechanise sugar cane production, and the crops are entirely rain-fed. With no need for ORLANDO KISSNER/AFP
STEVE HERBERT/EYEVINE
● Tunnelling photons travel faster than speed of light, page 10 ● Climate change: the tipping points, page 13 ● Correcting mitochondrial disease, page 14
irrigation, sugar can be extracted with little expenditure of energy. “The cane is simply squeezed and the sugar runs out,” says Alex Farrell of the University of California at Berkeley. Unfortunately for Lula, this happy combination of factors cannot easily be exported. Brazil has created a guaranteed market by demanding that fuel pumps supply either ethanol or a gasoline mix containing 25 per cent ethanol. As countries elsewhere adopt targets for mixing ethanol with gasoline, Lula sees an important export opportunity. Still, the US and other developed countries would be nervous about depending on a single nation for the majority of their ethanol imports. Hence Lula’s determined efforts to get other Latin American nations on the biofuel bandwagon. “The Brazilian government has the sophisticated view that it will do well if there are multiple producers in the world,” says John Briscoe, director of the World Bank in Brazil. “A market five times bigger that they have 50 per cent of is a lot better than a market the current size which they have 90 per cent of.” Catherine Brahic
18 August 2007 | NewScientist | 9