A recent research report
detailed the water utility for 12 energy crops and concluded that the oil crop jatropha (Jatropha curcas)
utilized about 20,000 liters of water to produce 1 liter of biodiesel, compared to 14,000 liters for rapeseed and soybean. The implication being that its much-acclaimed ability to thrive on marginal soils is incorrect. The report conceded that while the data for other crops were obtained from countries around the world, those for jatropha were obtained from India, Indonesia, Nicaragua, Guatemala and Brazil. It also admitted that jatropha can indeed thrive on arid soil but that its oil yield would then be low.
Jatropha may indeed be a “water hog
” as has been attributed but the limited data for such attribute in comparison with the other crops may render that report inconclusive. The use of water resources varies quite substantially around the world and as such applying utility data for 5 countries in the assessment of any crop, may not reflect the true global utility values for that crop.
Table 1 shows the biodiesel yield for common crops. While jatropha does have high biodiesel productivity, its value is certainly not the highest.
Palm oil, from the oil palm (Elaeis guineensis) for example, yields about four times as much biodiesel per hectare of cultivated land than jatropha and that does not include the added yield from the palm kernel. A crop of oil palm trees also has the advantage of extended productivity sometimes for decades.
The oil yield from some oil palm varieties has benefited from cross-breeding over the years. For example, in West Africa, the thick-shelled Dura variety has been crossed with the shell-less Pisifera variety to produce the Tenera, which has much larger pulp and smaller kernels, hence optimizing yield. The Tenera has now become the breeding and planting standard.
Such modification (for such qualities as improved yield, hardiness and climatic adaptation for example) is common agricultural practice and has been used in food and other crops such as wheat, soybeans, rice, sugarcane, etc. If indeed jatropha were a water hog, it would certainly benefit from such “tweaking” to produce “less thirsty” varieties for growth in regions where water resource utility is of concern.
One further note on crop resource utility: When crops are grown in their natural environment, natural resources utility may be of little concern. The oil palm for example thrives in the main, in the equatorial regions (with their ample rainfall and sunshine) of West Africa and Southeast Asia. For the vast oil palm plantations in these regions therefore, irrigation or water utility concerns do not arise, even if the oil palm were a monster of a water hog.