Watkins says the rest of his fortune lies in ethanol, a fuel additive usually made from corn.

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At present, ethanol is used mainly as a fuel additive, with the 85% ethanol-gasoline blend known as E85 sold only sparsely across the country.

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It aims to produce biobutanol (from sugar cane, in Brazil) for use as a fuel or fuel additive beginning in 2013 or 2014.

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Its cynics are arguing, however, that its existence is contingent on those federal rules and taxpayer-funded allocations that are giving it a higher place in the market one that is used as a fuel additive in the hopes of displacing petroleum usage.

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For example, work done at Princeton University in the US and published in 1994 to make the fuel additive methanol from CO2 has more recently been refined and spun into a company called Liquid Light that is aiming to do the same thing.

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He became a jobber, selling Sinclair fuel, whose Power-X additive was supposed to inhibit engine rust.

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Ethanol, which is used mainly as an additive to petrol, is not a particularly good fuel: it offers only about two-thirds as much energy as petrol and can corrode pipelines and car engines.

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In Brazil, ethanol is used both as a gasoline additive (20% to 22% blend) or as a pure motor fuel (100% ethanol).

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