There's a lot of talk about Jatropha as being a suitable plant to produce biofuels in the future, mostly because it can grow on bad soil in pretty dry conditions and the nut is not edible. But there's a note of warning from a recent Dutch Study Claims and Facts on Jatropha curcas. In one of its conclusions they say
However, as soon as J curcas is related to high oil yield production [report's emphasis], a claim which in itself is not backed up by any scientific findings so far, (especially not on a large scale), a risk warning should be given about the validity of these claims. Especially the claims of low nutrient requirements (soil fertility), low water use, low labour inputs, the non-existance of competition with food production, and tolerance to pests and diseases are definitely not true in combination with high yield oil production.The report is particularly worried about the ability of jatropha to produce high yeilds in marginal conditions.