Desert 'carbon farming' to curb CO2

1 August 2013

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By Matt McGrath

Environment reporter, BBC News

Scientists state that planting large numbers of jatropha trees in desert areas might be a reliable method of curbing emissions of CO2.

Dubbed "carbon farming", researchers state the concept is economically competitive with high-tech carbon capture and storage projects.

But critics state the concept might be have unexpected, unfavorable impacts including driving up food costs.

The research has been released, external in the journal Earth System Dynamics.

Seeds of modification

Jatropha curcas is a plant that came from in America and is really well adjusted to severe conditions including exceptionally dry deserts.

It is already grown as a biofuel, external in some parts of the world because its seeds can produce oil.

In this research study, German scientists showed that one hectare of jatropha might capture up to 25 tonnes of carbon dioxide from the atmosphere every year. The scientists based their estimates on trees currently growing in trial plots in Egypt and in the Negev desert.

"The results are frustrating," stated Prof Klaus Becker, from the University of Hohenheim in Stuttgart.

"There was excellent growth, a great action from these plants. I feel there will be no problem trying it on a much larger scale, for instance 10 thousand hectares in the start," he stated.

According to the scientists a plantation that would cover 3 percent of the Arabian desert would absorb all the CO2 produced by cars and trucks in Germany over a 20 year duration.

The scientists say that a crucial element of the plan would be the schedule of desalination centers. This suggests that initially, any plantations would be restricted to coastal areas.

They are intending to develop larger trials in desert locations of Oman or Qatar. Prof Becker states that unlike other schemes that just offset the carbon that individuals produce, the planting of jatropha might be a great, short term service to climate change.

"I believe it is an excellent idea since we are actually drawing out carbon dioxide from the atmosphere - and it is completely different in between drawing out and preventing."

According to the scientist's estimations the expenses of suppressing co2 through the planting of trees would be in between 42 and 63 euros per tonne. This makes it competitive with other strategies, such as the more high tech carbon capture and storage, external (CCS).

A variety of countries are presently trialling this innovation, external but it has yet to be deployed commercially.

Growing jatropha not just takes in CO2 however has other benefits. The plants would help to make desert locations more habitable, and the plant's seeds can be harvested for biofuel state the researchers, providing an economic return.

"Jatropha is ideal to be developed into biokerosene - it is even much better than biodiesel," stated Prof Becker.

But other experts in this location are not encouraged. They indicate the reality that in 2007 and 2008 large numbers of jatropha trees were planted for biofuel, particularly in Africa. But a number of these ventures ended in tears,, external as the plants were not very effective in handling dry conditions.

Lucy Hurn is the biofuels campaign supervisor for the charity, Actionaid. She says that while jatropha was once seen as the great, green hope the reality was very different.

"When jatropha was presented it was viewed as a wonder crop, it would grow on scrubland or marginal land," she stated.

"But there are often people who need limited land to graze their animals, they are getting food from that location - we would not class the land as minimal."

She pointed out that jatropha is extremely harmful and can contaminate the land it is grown on, even in a desert. And she also had issues about the fairness of the idea.

"It is still somebody else's land. Why go in and grow these enormous plantations to handle a problem these people didn't in fact trigger?"

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Related web links

Universität Hohenheim

European Geosciences Union

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