Nature sets the record straight on Brazilian ethanol
Nature, one of the more important science journals, has a free-access feature article in its magazine edition on Brazilian ethanol. It gives an overview of the history of the country's Pro-alcool programme, discusses the reasons as to why sugar cane is such an efficient plant and looks at the environmental problems associated with its large-scale adoption as a biofuel feedstock.
Some excerpts.
On the energy balance of sugar cane ethanol compared to that of ethanol made from lobby corn (earlier post):
Ethanol made from the sweet grass species results in considerable greenhouse gas savings. This makes the biofuel a strong weapon in the fight against dangerous climate change, the biggest threat to the planet's environment. But environmentalists are right to weigh off these advantages to more local problems:
ethanol :: biodiesel :: biomass :: bioenergy :: biofuels :: energy :: sustainability :: sugar cane :: energy balance :: Brazil ::
As Emma Marris writes:
"Environmentalists are watching all this expansion carefully. The Macedo analysis suggests that a tonne of cane used as ethanol fuel represents net avoided emissions equivalent to 220.5 kilograms of carbon dioxide when compared with petroleum with the same energy content. The team extrapolates that ethanol use in Brazil reduces greenhouse-gas emissions by the equivalent of 25.8 million tonnes of carbon dioxide equivalent a year. For comparison, Brazil's total carbon dioxide emissions from fossil fuels is 92 million tonnes a year, according to the US Department of Energy. The improvement is thus substantial, if not out-of-this-world.
But there are environmental worries that go along with the ethanol industry too: as well as fertilizer and fuel use, there are also pesticides and pollutants such as liquid waste and smoke from burning fields to take into account. Last year, a paper by a group at Washington State University in Richland made headlines by claiming that in this broadest perspective, Brazil's ethanol was bad for the environment2.
This result, though, is disputed — and the industry seems to be getting greener as it goes hunting for efficiency gains. As Christopher Flavin, an analyst at the World Watch Institute, a green pressure group in Washington DC, points out, expansion will generally mean that a higher percentage of the industry will be using newer, cleaner technology (although by the same token it will also be offering fewer unskilled distillery jobs). The leftovers from distillation, once commonly thrown into rivers, are now often spread on fields as potassium fertilizer. Field burning, which by scorching the cane makes it easier to harvest with machetes, is decreasing both as a result of legislation and the increased use of mechanized harvesters. "Thirty-five per cent of cane harvesting is already mechanized," says Nastari, "and it will increase," although because the machines work only on very flat land some burning is likely to continue. Research on planting methods that involve less or no tilling should lead to reduced erosion, too.
Perhaps the biggest environmental worry is that expanding ethanol production will lay waste to natural forests in its path, reducing biodiversity and releasing stored up carbon:
The first thing to remember on this front, say the Brazilians, is that Brazil is big. It is big enough to expand its sugar-cane fields massively without either displacing necessary food crops or getting anywhere near the rainforest that the rest of the world seems to have decided is international property. São Paulo state itself is as big as the United Kingdom. Although Brazil is already by far the largest producer of sugar cane in the world, sugar cane is only its fourth biggest commodity, in terms of revenue, with cattle, chicken and soya all bringing in more money. The limiting factor in expansion is capital rather than land."
Land in abundance, 'food versus fuel' argument is 'nonsense'
According to Nastari, cane fields account for just 5.7 million hectares in a country of 850 million hectares. There are already 100 million hectares of old agricultural land or pasture land in the centre-south available for the industry to expand into. Eduardo Pereira de Carvalho, president of Unica, the union of cane-growers in São Paulo, welcomes such expansion with open arms:
"As for conflict between food and energy, the fantastic increase in productivity has made all these Malthusian arguments completely nonsense, and we have hundreds of millions of hectares of idle land."
Expansion into at least some of those millions of hectares would probably be more or less carbon-neutral, says Robert Boddey, a soil chemist at Embrapa, the Brazilian agricultural research unit. "For degraded pastures, which are slowly losing carbon, it is not such a bad change. And almost 70% of the Cerrado [Latin America's savanna, of which Brazil has some 200 million hectares] has already been cleared." Because it needs a dry season, sugar cane would not be a good crop to move into cleared rainforest areas, even if that was what anyone wanted. In this respect, cane is more environmentally friendly than palm oil, the most energy-intensive source of biodiesel. Palm-oil plantations for biofuel are having serious effects on the primary forests of Indonesia, but are not as yet big business in Brazil.
Overall, the environmental problems with cane production, says Flavin, are "dwarfed by the land use issues posed by soyabeans and cattle". But they may get worse — or exacerbate the problems elsewhere in agribusiness. Jason Clay of environmental group the WWF points out that "the push of sugar cane is going to displace other crops, and some of them can be grown in the Amazon — cotton, soya, livestock". Some of that soya could be for biodiesel use.
Alex Farrell, head of the Energy and Resources Group at the University of California, Berkeley, adds that for all the enthusiasm there is still a dearth of evidence on the long-term sustainability or otherwise of cane farming. But, he adds, that is pretty much par for the agricultural course: "All around the world, every government has agriculture — they never ask 'is this agriculture sustainable?' Not for sugarcane, not for rutabagas."
Potential
To replace a tenth of today's global petrol production, Brazil's ethanol production would have to grow by a factor of 40 or so. Few see that as likely in itself. Even Unica's de Carvalho, who is undeniably bullish, sees only a doubling by 2014, though he does not see that as the end of the story. Enthusiasts for new cane varieties talk of doubling the yield per hectare, but not necessarily going much further.
But a doubling or two is not to be sniffed at, and there is increasing interest in spreading the techniques developed in this most cane-friendly of countries to others in Latin America and elsewhere, with the details changed to fit local conditions. Already, ethanol is becoming a large enough business for the price of sugar on world markets to respond to changes in the oil markets — so the price of your caipirinha is now, in a very small way, susceptible to the manoeuvres of OPEC.
More information:
Marris, E. Sugar cane and ethanol: Drink the best and drive the rest, Nature, Dec. 7, 2006
Some excerpts.
On the energy balance of sugar cane ethanol compared to that of ethanol made from lobby corn (earlier post):
In 2004, Isaias de Carvalho Macedo at the University of Campinas did a study for the state of São Paulo that considered energy inputs such as fertilizer manufacture and agricultural machinery in the sugar-cane industry1. He and his colleagues estimate that the whole shebang costs about 250,000 kilojoules per tonne of cane. That tonne of cane in turn yields about 2 million kilojoules in ethanol and surplus electricity made by burning bagasse. That's an eight-fold return.Environmental worries
This is a lot better than ethanol-makers in the United States manage, and the reason is clear to anyone who's ever strolled through a cane field chewing on a bit of the stuff; cane is a far more prolific plant than corn (maize), from which the United States makes almost all its ethanol, and it puts a great deal of its — or rather the Sun's — energy into making sugar.
What's more, sugar cane needs less by way of inputs, and in the parts of Brazil where most of it is grown at the moment it needs no irrigation. It needs only to be ploughed up and replanted every five years; between times it can be cropped repeatedly and will simply grow back, although the yields drop a bit with each harvest. For all these reasons, sugar-cane ethanol is also currently the cheapest ethanol to produce in the world. A litre costs about 25 cents to make. The commodity price for anhydrous ethanol (the kind mixed into gasohol) is about 27 cents.
Ethanol made from the sweet grass species results in considerable greenhouse gas savings. This makes the biofuel a strong weapon in the fight against dangerous climate change, the biggest threat to the planet's environment. But environmentalists are right to weigh off these advantages to more local problems:
ethanol :: biodiesel :: biomass :: bioenergy :: biofuels :: energy :: sustainability :: sugar cane :: energy balance :: Brazil ::
As Emma Marris writes:
"Environmentalists are watching all this expansion carefully. The Macedo analysis suggests that a tonne of cane used as ethanol fuel represents net avoided emissions equivalent to 220.5 kilograms of carbon dioxide when compared with petroleum with the same energy content. The team extrapolates that ethanol use in Brazil reduces greenhouse-gas emissions by the equivalent of 25.8 million tonnes of carbon dioxide equivalent a year. For comparison, Brazil's total carbon dioxide emissions from fossil fuels is 92 million tonnes a year, according to the US Department of Energy. The improvement is thus substantial, if not out-of-this-world.
But there are environmental worries that go along with the ethanol industry too: as well as fertilizer and fuel use, there are also pesticides and pollutants such as liquid waste and smoke from burning fields to take into account. Last year, a paper by a group at Washington State University in Richland made headlines by claiming that in this broadest perspective, Brazil's ethanol was bad for the environment2.
This result, though, is disputed — and the industry seems to be getting greener as it goes hunting for efficiency gains. As Christopher Flavin, an analyst at the World Watch Institute, a green pressure group in Washington DC, points out, expansion will generally mean that a higher percentage of the industry will be using newer, cleaner technology (although by the same token it will also be offering fewer unskilled distillery jobs). The leftovers from distillation, once commonly thrown into rivers, are now often spread on fields as potassium fertilizer. Field burning, which by scorching the cane makes it easier to harvest with machetes, is decreasing both as a result of legislation and the increased use of mechanized harvesters. "Thirty-five per cent of cane harvesting is already mechanized," says Nastari, "and it will increase," although because the machines work only on very flat land some burning is likely to continue. Research on planting methods that involve less or no tilling should lead to reduced erosion, too.
Perhaps the biggest environmental worry is that expanding ethanol production will lay waste to natural forests in its path, reducing biodiversity and releasing stored up carbon:
The first thing to remember on this front, say the Brazilians, is that Brazil is big. It is big enough to expand its sugar-cane fields massively without either displacing necessary food crops or getting anywhere near the rainforest that the rest of the world seems to have decided is international property. São Paulo state itself is as big as the United Kingdom. Although Brazil is already by far the largest producer of sugar cane in the world, sugar cane is only its fourth biggest commodity, in terms of revenue, with cattle, chicken and soya all bringing in more money. The limiting factor in expansion is capital rather than land."
Land in abundance, 'food versus fuel' argument is 'nonsense'
According to Nastari, cane fields account for just 5.7 million hectares in a country of 850 million hectares. There are already 100 million hectares of old agricultural land or pasture land in the centre-south available for the industry to expand into. Eduardo Pereira de Carvalho, president of Unica, the union of cane-growers in São Paulo, welcomes such expansion with open arms:
"As for conflict between food and energy, the fantastic increase in productivity has made all these Malthusian arguments completely nonsense, and we have hundreds of millions of hectares of idle land."
Expansion into at least some of those millions of hectares would probably be more or less carbon-neutral, says Robert Boddey, a soil chemist at Embrapa, the Brazilian agricultural research unit. "For degraded pastures, which are slowly losing carbon, it is not such a bad change. And almost 70% of the Cerrado [Latin America's savanna, of which Brazil has some 200 million hectares] has already been cleared." Because it needs a dry season, sugar cane would not be a good crop to move into cleared rainforest areas, even if that was what anyone wanted. In this respect, cane is more environmentally friendly than palm oil, the most energy-intensive source of biodiesel. Palm-oil plantations for biofuel are having serious effects on the primary forests of Indonesia, but are not as yet big business in Brazil.
Overall, the environmental problems with cane production, says Flavin, are "dwarfed by the land use issues posed by soyabeans and cattle". But they may get worse — or exacerbate the problems elsewhere in agribusiness. Jason Clay of environmental group the WWF points out that "the push of sugar cane is going to displace other crops, and some of them can be grown in the Amazon — cotton, soya, livestock". Some of that soya could be for biodiesel use.
Alex Farrell, head of the Energy and Resources Group at the University of California, Berkeley, adds that for all the enthusiasm there is still a dearth of evidence on the long-term sustainability or otherwise of cane farming. But, he adds, that is pretty much par for the agricultural course: "All around the world, every government has agriculture — they never ask 'is this agriculture sustainable?' Not for sugarcane, not for rutabagas."
Potential
To replace a tenth of today's global petrol production, Brazil's ethanol production would have to grow by a factor of 40 or so. Few see that as likely in itself. Even Unica's de Carvalho, who is undeniably bullish, sees only a doubling by 2014, though he does not see that as the end of the story. Enthusiasts for new cane varieties talk of doubling the yield per hectare, but not necessarily going much further.
But a doubling or two is not to be sniffed at, and there is increasing interest in spreading the techniques developed in this most cane-friendly of countries to others in Latin America and elsewhere, with the details changed to fit local conditions. Already, ethanol is becoming a large enough business for the price of sugar on world markets to respond to changes in the oil markets — so the price of your caipirinha is now, in a very small way, susceptible to the manoeuvres of OPEC.
More information:
Marris, E. Sugar cane and ethanol: Drink the best and drive the rest, Nature, Dec. 7, 2006
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