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A change of fuel

New Scientist

With the US about to ban the fuel additive MTBE, battle has commenced over its successor. Could this be the chance the ethanol industry has been waiting for?

IT WAS once the hero of the oil industry. The fuel additive MTBE was supposed to be the answer to air pollution. Instead, it turned out to be a villain, causing groundwater pollution that has left aquifers from New England to California reeking. Now, with the US on the brink of banning MTBE, the question is what will come next.

American farmers are hoping it will be alcohol. Like MTBE (methyl tertiary-butyl ether), ethanol can reduce emissions from cars. Unlike MTBE, any ethanol that leaks into the environment quickly breaks down. And farmers love it because most ethanol is produced from maize, so it promises a lucrative new market for their crops. "Depending on how it's handled, the MTBE phase-out could be a huge boost for the ethanol industry," says Monte Shaw of the Renewable Fuels Association in Washington DC. "This is the year."

Once seen as a potential fuel in its own right, ethanol proved too expensive to compete with petrol. There are exceptions, such as Brazil, where fuel is up to 24 per cent ethanol made from sugar cane-but only with the help of government subsidies.

In the US, ethanol's first hope of hitting the big time came with the Clean Air Act of 1990, which required petrol sold in polluted cities to contain at least 2 per cent of oxygen by weight. This means petrol must be around 6 per cent ethanol by volume, or 11 per cent MTBE-a huge market.

By releasing oxygen when the fuel is burnt, these "oxygenates" ensure complete combustion, particularly when engines are cold. This reduces levels of pollutants such as carbon monoxide.

The fledgling ethanol industry, how-ever, lost out to cheaper MTBE. Then MTBE began to turn up in wells, lakes and aquifers around the country. "Santa Monica has lost its entire groundwater supply," says Bill Magavern of the environmental group Sierra Club California. "MTBE is wreaking havoc on this state."

The trouble is that MTBE is water-soluble, so leaks from underground tanks can spread through water supplies (New Scientist, 22 November 1997, p 24). It has an unpleasant smell and taste, and may also be a carcinogen. "We're the damn skunk at the picnic," complains Thomas Adams, whose Oxygenated Fuels Association near Washington DC represents MTBE producers.

Apart from the US, few countries make much use of MTBE. But in Europe its future could be boosted by plans to remove benzene from petrol. The European Union intends to cut the level of this potent carcinogen in fuel by 75 per cent by 2005, which could lead to a big increase in the use of MTBE.

In the US, however, its prospects look bleak. Some oil companies, including Chevron, support a ban and a handful of states are already moving to outlaw it. Now Congress looks likely to rule against it.

The crucial questions are whether the 2 per cent oxygen requirement will survive an MTBE ban, and whether the law will stipulate that renewable fuels should be gradually introduced. Either would be a boost for ethanol-but both would be fiercely opposed by oil companies.

Citing ethanol's already heavy subsidies, Senate power brokers John Breaux of Louisiana and John McCain of Arizona are formidable opponents. Yet the ethanol lobby is confident, listing Senators Bob Smith, head of the Environment and Public Works Committee, and Democratic leader Tom Daschle as allies. Even oilman-turned-president George W. Bush has made overtures to the ethanol industries. The biggest hurdle is likely to be fears that imposing ethanol on the fuel industry could increase prices at the pumps.

Bill Bush of the American Petroleum Institute, which lobbies for the oil companies, says that the 2 per cent requirement is too rigid. There are other ways of making clean-burning fuels. "Tell us what the emission goals are," says Bush, "and we'll figure out the best way to get there."

Some scientists agree. They argue that the drop in pollution in the US in recent years is due to the introduction of cata-lytic converters rather than the use of oxygenated fuels (New Scientist, 22 May 1999, p 20 and 15 July 1995, p 24).

Ethanol's supporters counter that oxygenates are essential for maintaining good engine performance, and that maize farmers depend on the market. "Don't throw out the oxygenate standard with the MTBE-polluted bathwater," says Eric Vaughn of the Renewable Fuels Association. "George W. Bush has pushed 'dom-estic' sources of fuel," adds his colleague Shaw. "What could be more domestic than ethanol, which comes from corn?"

Industry sources predict that the ethanol industry will continue to grow slowly even if left to itself. But legislation that calls for ethanol could help kick-start biomass fuels (see below). "It would create a 2 billion-bushel demand for grain to be used towards the production of ethanol," says Vaughn. "That's huge."

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Eli Kintisch writes for The New Republic magazine in Washington DC

New Scientist issue: 20 January 2001

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