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Sewage-powered car promises end to dirty fuel

posted 8 Nov 2010, 06:52 by Sam Mbale   [ updated 8 Nov 2010, 06:55 ]

A VW Beetle, powered by human waste has taken to the streets of England in an attempt to encourage sustainable motoring. It's Britain's first car to run on gas produced from sewage sludge.

On the outside it appears to be an ordinary convertible Beetle. But this Beetle Bug isn't powered with petrol, nor does it use biofuel. This car runs on treated sewage.

Hidden in the boot are two large cylinders of methane. The car still has a fuel tank and a very small amount of petrol is used to start the engine, but the car switches to biogas after a matter of seconds, making it one of the most environmentally friendly cars in the world.

Wessex Water, who devised the biomethane powered car, estimate that the yearly waste from 70 average households would generate enough gas to run the car for 10,000 miles (16,100 kilometres).

With support from the South West Regional Development Agency, GENeco, a subsidiary of Wessex Water, imported specialist equipment to treat gas generated at Bristol sewage treatment works to power the VW Beetle in a way that doesn't affect its performance.

Mohammed Saddiq, GENeco's general manager, said that it was inspired by a company commitment to reduce its carbon footprint.

"Wessex Water have set themselves an objective of becoming a carbon neutral company by 2020 and at the same time a zero waste company in the same time frame," he said.

Saddiq explained the technology involved.

"The process of producing the biogas in a form that is suitable for the vehicle is very simple, we use a technology called Pressure Swing Absorption and that principally takes the two key components that are present in biogas, the methane and carbon dioxide and splits those two components and its the methane that we are interested in. We take that methane gas and we compress it so that its ready for being introduced into the vehicle," he said.

The gas is generated through anaerobic digestion, a process in which bugs, in the absence of oxygen, break down biodegradable material to produce methane.

"The process itself, the micro-organisms need around 15 to 20 days sometimes longer to work provided the temperature is operating at around 35 degrees, that is seen to be the most ideal and optimum to produce the maximum amount of biogas," Saddiq added.

The Beetle Bug can run for between 150 and 200 miles on two cylinders of gas and refuelling the car is relatively simple. "The refuelling of the car is incredibly simple, all we have are two refuelling points on the vehicle, one at the back of the vehicle and one within the front of the vehicle and its principally not too dissimilar to fuelling your car with petrol or diesel," Saddiq explained.

The company is considering making all their fleet of vehicles run on biomethane.

"The clean up of the gas to run a vehicle is a very serious trial for us, which we are running over a six month period of time and if that trial is successful there is absolutely no reason why we should not start looking at converting the rest of our fleet. We have over 300 vehicles in our fleet, we run a number of trucks and our ability to use the biogas to displace fossil fuels is something that we believe is certainly possible," he said.

The choice of car was inspired by students taking part in a workshop, who thought it appropriate that the sewage-powered car should be the classic VW Beetle Bug because of the fact that insects process the waste at the sewage works.

In the past attempts to fuel a car on this type of biogas had a detrimental effect on performance, however, through using the latest technology this Bio-Bug drives like any conventional VW Beetle.

In Sweden, more than 11,500 vehicles already run on biomethane produced from sewage plants so there is already a model that suggests this could be a viable proposition in Britain.

The Anaerobic Digestion and Biogas Association (ADBA) said the launch of the Bio-Bug proved that biomethane from sewage sludge could be used as an alternative fuel for vehicles.

For many households in Britain recycling is confined to sorting through rubbish, so producing fuel from human waste represents a huge leap in green endeavour.

One might imagine that a car powered by sewage would smell, but it is effectively odourless.