New research peels prawns to make biodiesel

A Saudi vendor sells shrimp at a seafood market in Dammam August 4, 2009.

LONDON (Reuters) - Environmentally-friendly fuel does not immediately spring to mind when peeling prawns but Chinese scientists claim shrimp shells may have an important role to play in improving biodiesel production efficiency.

Scientists at Hua Zhong Agriculture University in the Wuhan province of China experimented with chitin, the main component in prawn shells, and found it helped convert organic oils into biodiesel at a rate of 89 percent in three hours.

"They can achieve as much speed and efficiency as traditional catalysts in biodiesel production without environment pollution and resource waste," Xinsheng Zheng, one of the scientists involved in the research, told Reuters.

Biodiesel is designed to replace carbon-heavy diesel oil and can be made from sunflower or rapeseed oils.

To covert organic oils faster and under less extreme heat, a liquid catalyst, such as sodium hydroxide, is usually used.

The university's scientists found that when they carbonized a small amount of chitin it became very porous, making it easier for a catalyst to attach itself and do its work.

Traditional catalysts have to be neutralized and washed after a reaction, creating large amounts of waste water. Prawn shells remain solid, can be reused up to 10 times in the production process and are biodegradable so will not harm the environment when eventually discarded.

"It looks like a serious bit of science. Chitin is cheap, available and the conversion rate is good," said Richard Templer, director of the Porter Institute of biofuels at London's Imperial College.

SCALING UP

Zheng believes shrimp shell conversion could be ramped up if carried out in fixed-bed catalytic reactors which have enough volume to process large amounts of shells.

Even though China is the world's biggest prawn producer at 1 million tons a year, it only produces around 100,000 tons of biodiesel, mainly using waste cooking oils.

Production is limited because China cannot produce enough vegetable oils for human consumption and has to import a large amount each year.

Prawn shells are a plentiful, cheap resource and could be used elsewhere in Asia, however. Every year, five million tons of shrimp are produced globally and the Asia Pacific region accounts for 88 percent of them, according to a United Nations Food and Agriculture Organization report in 2008.

Nevertheless, some biofuel experts are cautious about the large-scale prospects of the technology.

"For making and selling biodiesel locally it could work. But a big refinery might want something much more recyclable," said Templer.

Finland's VTT Technical Research Center has already tapped into Vietnam, one of the global hubs of fish processing, with a 5 million euro project to build a biodiesel production unit by 2011 at a fish processing plant in the south of the country.

Catfish waste, rather than shrimp shells, is used in the catalyst process to make biodiesel for local energy production.

(Additional reporting by Niu Shuping in Beijing; editing by James Jukwey)