Weed moves from bowels to biofuel
Ben Macintyre | July 30, 2007
THE jatropha bush seems an unlikely prize in the hunt for alternative energy, being an ugly, fast-growing, poisonous weed.
Hitherto, its use has principally been as a constipation remedy. Very soon, however, it may be powering your car.
Almost overnight, the unloved Jatropha curcus has become an agricultural and economic celebrity with the discovery that it may just be the ideal biofuel crop, an alternative to fossil fuels for a world dangerously dependent on oil supplies and deeply alarmed by the effects of global warming.
The hardy jatropha, resilient to pests and resistant to drought, produces seeds with up to 40 per cent oil content. When the seeds are crushed, the resulting jatropha oil can be burnt in a standard diesel car, while the residue can be processed into biomass to power electricity plants.
As the search for alternative energy sources gathers pace, the jatropha has provoked something like a gold rush. BP announced last week that it was investing almost pound stg. 32 million ($76million) in a jatropha joint venture with British biofuels company D1 Oils.
Even Bob Geldof has entered the fray, becoming a special adviser to Helius Energy, a British company developing jatropha as an alternative to fossil fuels. Lex Worrall, its chief executive, says: "Every hectare can produce 2.7 tonnes of oil and about four tonnes of biomass. Every 8000 hectares of the plant can run a 1.5 megawatt station, enough to power 2500 homes."
The jatropha grows in tropical and subtropical climates. Whereas other biofuel feedstocks, such as palm oil or corn for ethanol, require reasonable soils on which other crops might be grown, jatropha is prepared to put down roots almost anywhere.
Scientists say that it can grow in the poorest wasteland, generating topsoil and helping to stall erosion, but also absorbing carbon dioxide as it grows, thus making it carbon neutral even when burnt. A jatropha bush can live for up to 50 years, producing oil in its second year of growth, and survive up to three consecutive years of drought.
In India, about 11 million ha have been identified as potential land on which to grow jatropha. The first jatropha-fuelled power station is expected to begin supplying electricity in Swaziland in three years. And companies from Europe and India have begun buying land in Africa as potential plantations.
The jatropha, a native of Central America, was brought to Europe by Portuguese explorers in the 16th century and has since spread worldwide, even though, until recently, it had few uses: malaria treatment, a windbreak for animals, live fencing and candle-making. An ingredient in folk remedies around the world, it earned the nickname "physic nut", but its sap is a skin irritant, and ingesting three untreated seeds can kill a person.Although some places have embraced it, others are more cautious. Western Australia banned the plant last year as invasive and highly toxic to people and animals.
Yet a combination of economic, climatic and political factors have made the search for a more effective biofuel a priority among energy companies. Britain now requires that biofuels comprise 5 per cent of the transport fuel mix by 2010, and the European Union has mandated that all cars must run on 20per cent biodiesel by 2020. Biodiesel reduces carbon dioxide emissions by nearly 80 per cent compared with petroleum diesel.
China is planning an 80,000-acre plantation in Sichuan, and the BP-D1 team hopes to have one million ha under cultivation in four years.