In Brazil, alcohol made from sugar cane is mixed with lime juice and a little of the cane sugar itself to make caipirinhas — and it’s a fine way to get the weekend off to a flying

start. But come Monday morning, sober Brazil-ian commuters are still using cane liquor — in their fuel tanks. Most Brazilian petrol is gasohol, which by government mandate is currently 23% ethanol. Next to the gasohol pumps at the petrol stations are pumps that offer pure ethanol.

Ethanol from sugar cane has been power-ing cars in Brazil on and off since the 1930s, and with government backing since the OPEC price rises in the 1970s. It makes fairly obvi-ous sense. Brazil’s tropical sun makes it a great place for growing sugar cane: it is the largest cane producer in the world, producing more than twice as much as the number two, India. Just crush out the sucrose solution, ferment it into alcohol with the help of yeast and distill it to the desired concentration; burn the ‘bagasse’ — the fibrous pulp left over when the sugar is squeezed from the cane — to power the process along. Put the alcohol into your gas tank and you are effectively driving it on sunlight.

In the past few years, Brazil’s bioethanol industry has sprouted new wings thanks to higher petrol prices and ‘flex-fuel’ cars, which can sense different mixtures of petrol and ethanol and adjust their workings accord-ingly. Introduced to the mass market in 2003, these cars changed everything; flex-fuel vehi-cles now account for well over half of Brazil’s new cars. Their attraction is that they allow the owner to trade off continually between the advantages of neat ethanol — which gives 20% to 30% fewer kilometres to the litre — and gasohol depending on the current prices and the local tax rates. (Tax alone means that if you were to take a road trip across Brazil, you’d switch back and forth a couple of times as you crossed from state to state.)

Sweet solution?Flex-fuel cars have created an expanded home market for Brazil’s ethanol, and production is up. The country produced 282,000 barrels (45 million litres) a day in 2005, up from 192,000 in 2001. The ministry of agriculture is projecting 442,000 barrels a day by 2010. Oil is still very much ethanol’s big brother, and in the first part of 2006 the country was producing an average of more than 2 million barrels a day while con-suming a bit more. But 40% of the fuel power-ing Brazil’s cars is home-grown ethanol. The sugar cane industry supports more than a mil-

lion jobs, in a country with an unemployment rate of 10%. Some bagasse-powered mills sell surplus power back to the grid. And although the carbon put into the atmosphere by petrol-powered cars comes out of fossil reserves, the carbon from ethanol is carbon that was in the atmosphere just a couple of years ago, before the sugar cane got hold of it and worked its photosynthetic miracle. There are thus, in principle, no net emissions.

This all sounds a bit like a free lunch, or at least a free ride, and everyone knows they don’t exist. Growing sugar cane, harvesting it, fermenting and distilling it and then distrib-uting it is a complex business. It uses inputs — fuel for harvesters, nitrogen fertilizers for the cane — that themselves require energy from elsewhere. And it has potentially dam-aging side-effects, such as soil erosion and the emission of nitrous oxide, a greenhouse gas, from farmland. Taking all the complexities into account, is ethanol still as good a deal as it seems? And if it is, how much of this good thing can Brazil — and the rest of the world — get its hands on?

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.

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 irri-gation. 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 anhy-drous ethanol (the kind mixed into gasohol) is about 27 cents.

Because of this a lot of money is pouring

Drink the best and drive the restBrazil’s sugar-cane ethanol industry is the world’s best and able to get better, says Emma Marris.

Cleaning up: Brazil’s use of sugar cane, here being washed for refining, significantly reduces CO2 emissions.

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SUGAR CANE

FUEL PRODUCT: Ethanol (from sugar)CLIMATE: Tropical, subtropicalANNUAL YIELD: 5,300–6,500 litres ha–1

GREENHOUSE GAS SAVINGS:87–96% (vs petrol)CONSIDERATIONS: In newer facilities,

crop residue powers fuel production and adds power to grid

PALM

FUEL PRODUCT: Biodiesel (from fruit)

CLIMATE: Humid tropical

ANNUAL YIELD: 5,000–6,000 litres ha–1

GREENHOUSE-GAS SAVINGS:

No data

CONSIDERATIONS: Plantations

carved from tropical forest raise

environmental concerns

CASSAVA

FUEL PRODUCT: Ethanol (from starch)CLIMATE: Tropical, subtropicalANNUAL YIELD: No data GREENHOUSE-GAS SAVINGS:No dataCONSIDERATIONS: Most cultivatedcrop in sub-Saharan Africa

into the centre-south region of Brazil, where the sugar cane grows best. But that does not necessarily mean that investors believe Brazil-ian cane ethanol is sure to become the planet’s biofuel of choice. A range of other emerging liquid-fuel technologies, including biodiesel, butanol, coal to liquid, and the buzz leader at the moment, cellulosic ethanol (see page 673), are attracting investment around the world, too. And the investors are typically backing a range of possibilities while they wait to see how the market pans out.

Arnaldo Vieira de Carvalho, an energy spe-cialist at the Inter-American Development Bank in Washington DC, sees current invest-ment in bioethanol as, among other things, a way of building up a better stake today for whatever the most impressive biofuel technology turns out to be tomorrow. “If you now put your money in distilleries, in five years you have made your money,” says de Carvalho, “and then you put your investment in the technology that is coming.”

Fuelling changeAs the rest of the world gets interested in etha-nol, both as a fuel in its own right and as a fuel additive (to replace methyl tertiary-butyl ether, or MTBE, an anti-knocking additive that is on its way out for environmental reasons), Brazil is ramping up exports (see ‘Key companies). Brazilian manufacturers are actively promot-ing ethanol distribution systems in other countries. Petrobras, until the 1990s the state oil monopoly and

still the biggest player in Brazilian oil, is plan-ning to build an ethanol pipeline from the centre to the south, out to the ports. It will be the first of its kind. Pipelines for ethanol have long been considered problematic, as it tends to absorb moisture and impurities as it flows. Construction will start in January, according to Plinio Mario Nastari, president of Datagro in São Paulo.

Not all foreign markets are easily tapped. Increasing Brazilian ethanol imports to the United States led the United States to slap on a tariff of 14 cents per litre (54 cents per gallon), to protect its highly subsidized corn ethanol makers. One effect of this has been to put Jeb Bush, Florida’s governor, at odds with his brother President George W. Bush; the governor would rather buy cheap ethanol from Latin America than expensive stuff from the Midwest.

Environmentalists are watching all this expansion carefully. The Macedo analysis sug-gests 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 mil-lion 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 improve-ment 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 head-lines by claiming that in this broadest per-spective, 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 Insti-tute, 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 riv-ers, 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

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CORN EARS

FUEL PRODUCT: Ethanol (from starch)

CLIMATE: Temperate

ANNUAL YIELD: 3,100–3,900 litres ha–1

GREENHOUSE-GAS SAVINGS:

10–20% (vs petrol)

CONSIDERATIONS:

High fertilizer and agricultural input

front, say the Brazilians, is that Brazil is big. It is big enough to expand its sugar-cane fields mas-sively 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 Bra-zil 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.

Growth areaAccording 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 com-pletely nonsense, and we have hundreds of millions of hectares of idle land.”

Expansion into at least some of those mil-lions 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 hec-tares] 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-inten-sive 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 exacer-bate 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 Califor-nia, Berkeley, adds that for all the enthusiasm there is still a dearth of evidence on the long-term sustainability or otherwise of cane farm-ing. 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.”

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. ■

Emma Marris is a reporter for Nature based in Washington DC.

1. Macedo, I. et al. Assessment of Greenhouse Gas Emissions in the Production and Use of Fuel Ethanol in Brazil (prepared for the Government of the State of São Paulo) (March 2004). 2. Dias de Oliveira, M. E., Vaughan, B. E. & Rykiel, E. J. Bioscience 55, 593–602 (2005).

See Editorial, page 654.

Interior designs: some of Brazil’s Cerrado region could be cleared for sugar-cane plantations.

Cosan, based in São Paulo, is the largest sugar-cane producer in the world, and the second-largest producer of ethanol. It has been gobbling up smaller ethanol mills right, left and centre, which has given it a very respectable growth curve. In the 2005–06 crop season, it reported revenues of US$1.1 billion and produced about 8.7 million barrels of ethanol. Cosan went public in November of 2005 at about $19 a share, and prices were close to $60 this summer.

Copersucar, a cooperative of sugar and ethanol mills, was founded in 1959. In the 2005–06 crop season, its revenues were $2.1 billion, and it produced 23 million barrels of alcohol.

Key companies

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