Polly, Do you know the yield per acre of Jatropha? I've heard some good things from friends, but can't find any good projections to compare it to soy or rapseed.

3000 square kilometers is not a lot at all. My understanding is that yield of Jatropha are not well establish since they can varry a lot depending how and where you grow them, plus the extensive culture of this true was non existant until now so they probably need a few years to optimise it, the number I have in mind was about 1 Ton of biodiesel per acre not as good as palm tree on which they get 2 ton/acre and can go well beyond that. Tallow chinese tree can yield 3 Ton/acre but the harvest of the oily fruit has to be manual...Tallow chinese tree is even more robust plant than Jatropha but it's an invasive pest though a beautiful tree.

Here are some quotes regarding jatropha yield:

"A hectare of jatropha produces 1,892 liters of fuel, which is better than rapeseed and far better than soybean or corn, according to data gathered by the Global Petroleum Club, an energy networking organization funded by the private-equity firm Forrest Equity Management."

"The Energy and Resources Institute (TERI), an Indian research group, launched a 10-year, $9.4 million project to research issues involved in taking jatropha from seed to filling station. One challenge is growing the plant in poor soil.

Some governments and some corporations consider the jatropha plant, common in hot climates, one of the most promising sources of biodiesel. The plant can grow in wastelands, and it yields more than four times as much fuel per hectare as soybean, and more than ten times that of corn. But the commercial-scale cultivation of jatropha, which has not previously been grown as a crop, raises several significant challenges.

The first crops of jatropha, planted in what was wasteland, have now flowered, says Alok Adholeya, director of TERI's Biotechnology and Management of Bioresources division. "It proves that we can do this," he says. He and other researchers at TERI spent five years testing different mycorrhiza microorganisms, symbiotic fungi that improve the ability of many plants to grow in poor soil. Adholeya's team found that the most effective was a fungus in the glomus species (he is not currently disclosing the exact fungus), which improves jatropha yields by 15 percent.

The TERI project is working in rural Andra Pradesh, a state in southeast India, collaborating with local financial institutions to develop loan guarantees to fund seed purchases; it's also collaborating with insurers to back the farmers against potential losses. In addition, it had to educate the farmers on how to cultivate the plant.

So far, the project has signed up 5,000 farmers representing 1,000 hectares of land. The goal is to have 8,000 hectares under cultivation by March 2008, and Adholeya says that the success of the first crops has drawn interest from many more farmers. By the end of 2008, TERI plans to have a production facility producing biodiesel from jatropha. Eventually, it aims to produce 90 million liters of biodiesel annually."

"Adholeya is also working on breeding jatropha to improve its yields. He leads a team of 20 microbiologists, molecular biologists, and field breeders who are looking for the genes in jatropha that cause it to fruit so that they can enhance the percentage of oil in the seed. He expects that it will take 18 months to isolate the genes and begin working to enhance them. The researchers plan to use a technique called molecular-assisted breeding, in which they identify a gene of interest, select particular genotypes, and breed them. Adholeya expects that by 2012, modified jatropha plants will be in cultivation.

He says that the Indian government, taking note of a report by TERI, is considering a national initiative around developing jatropha crops as a major source of fuel. That report calls for India to plant 400,000 hectares of jatropha in 22 of India's 28 states.

India is not alone in its interest in jatropha. Indonesia's government is promoting jatropha cultivation, as are several governments in Africa. Jatropha is attractive because of several desirable properties: it can grow in poor soil and survive drought; it's a perennial with an economic life of about 35 to 40 years; and it only needs two to three years to develop into a cash crop.

Jatropha seeds, when crushed, produce large quantities of an oil that can easily be converted to biodiesel that performs at levels close to that of conventional diesel oil.
'Jatropha is a one-stage conversion [to biodiesel],' says Adholeya, explaining that converting the plant oil to an oil that can be burned as fuel requires only one stage of heating and mixing with methanol.'"

By contrast BTL, CTL & CBTL require vast capital investment in sophisticated equipment, so they need capital and highly skilled staff.

Jatropha can provide a cash crop from the parts of farms with marginal soils which are unsuited to other crops.

Also Jatropha oil or biodiesel can be used in farm tractors and machinery displacing expensive diesel from imported crude oil. This will reduce the impact of high crude oil prices on farming costs.

Hence there is a niche for jatropha in rural areas of developing countries.

I concluded that green algae farming is the only sustainable method to produce biofuel and that foods need to be eaten before becomming fuels at the sewage treament plant.

E-P, that occurred to me as well, but I kept thinking of the Indian farms of Half Cocked Jack in the Baroque Cycle and the image just seemed to fit. My comment was intended to be ironic but it didn't translate.
I come from a ranching/farming family and you are right, no farmer is going to convert more than a fraction of their land to a long-term test of a new crop.