RAK biofuel crop unlikely to thrive

Not all the UAE's emirates are equally well endowed with oil, and some of the have-nots are seeking to redress the balance.

To do this, they are eyeing the drought resistant shrub

Jatropha,

which has oily seeds that can be processed to yield a high quality biofuel for use in diesel engines. Click the video below for details of one such project in the emirate of Ras al Khaimah.

Unfortunately, such efforts to coax desert soils to yield unconventional oil may be doomed to failure, according to a recent study published in the scientific journal Global Change Biology Bioenergy.

The findings suggest the tropical plant needs twice as much water to thrive as previously thought. That means it would not grow well in extremely arid regions without a lot of irrigation.

Rather than confirming the mythical status of

Jatropha

as as "miracle crop" that can thrive in deserts without competing with food crops or encouraging deforestation, the study's authors draw the more mundane conclusion that it is "a very promising crop as a feedstock for the bio-energy sector" that nonetheless has limitations.

The study found the plants need a mean annual temperate between 18 and 29 degrees Celsius, with minimum winter temperatures above 8 degrees C. Between 500 and 1,400 millimetres of annual rainfall is also required for decent yields, as well as a dry season.

"At the beginning,

Jatropha

was sold as a plant that could produce seeds with as low precipitations as 300 millimetres," Antonio Trabucco, one of the scientists who wrote the report, told reporters. "Lately, practitioners have recognised that more than 300 millimetres of rainfall was required."

Commercial yields might require at least double that amount of rainfall, he added.

The Global Change study was the first to examine

Jatropha

seed yields according to climate, mapping the best and worst regions of the world for its growth. The findings suggest the plant, which is native to the northeastern corner of South America, would grow best in central America, parts of India, Vietnam, northern Thailand, northern Australia and the west coast of Africa. Anywhere with frost would be out.

How does Ras al Khaimah stack up?

Dry seasons are guaranteed. Frost is not an issue, except at the very top of the emirate's mountains, which in any case are inaccessible and lacking in soil. The mean annual temperature is 27.2 degrees Celsius, according to the US National Oceanic and Atmospheric Administration, which is within the tolerable range.

Ras al Khaimah's annual rainfall, however, is a scant 133mm.

That does not bode well for the crop trial, unless the emirate takes determined steps to collect and purify industrial "grey water" for irrigation. Even then, the economics might not be favourable.

Using desalinated water, which is energy intensive to produce, is extremely unlikely to make economic sense for growing a commercial biofuel crop.

Conclusion: Ras al Khaimah would be better off developing solar power.