CO₂ from cars to feed algae

the use of algae as a source of biofuel has gained popularity in the last few years. In July 2007, three entrepreneurs from the uk came out with a way to feed algae by capturing carbon dioxide (co₂) from automobiles. This co₂ was used to feed algae which then produced biofuel.

Welsh engineers Ian Houston and John Jones, together with organic chemist Derek Palmer, call it the 'green box'. The invention, the first of its kind to check transport emissions, is actually a box that is fitted at the end of the exhaust pipe. It captures 95 per cent of an engine's co₂ emissions and releases water vapour, thus reducing air pollution, say the inventors.

The captured co₂ could later be collected in a tank at petrol stations and finally be taken to a plant to produce biodiesel from genetically modified algae, they say. "An acre (0.4 hectare) of algae produces about 137,000-170,000 litres of biofuel on a continual growing cycle. A tonne of co₂ is sufficient to feed the algae for a day," says Houston. Unlike jatropha or other plant-based fuels, algae need less land to grow. It can grow in a close-controlled environment or in an open pond. All it needs is water, co₂ and sunlight.

But the industry is sceptical of the invention. H M Behl of D1 Oils India Private Ltd says capturing co₂ before feeding it to algae is a redundant method, as the latter grows well enough on airborne co₂. But Charles Blair, chief executive officer of me-cwb Energy Ltd, fears the method may emit more co₂ than it captures, as the whole process of transporting and producing biofuel would lead to more emissions and expenditure. Even the volume of co₂ captured from the exhaust will be high, thus requiring a bigger box, he says. Houston says though the box is of the size of a small cupboard, a smaller one could be built.

The inventors are yet to figure out the amount of energy and co₂ emissions needed to produce the biofuel from algae. Behl says the box could be useful if it purifies or liquifies co₂.

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