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Green buildings need green transportation, right? by Laura Roberts, Telegraph, August 2010 - A car that runs on methane gas produced by human waste has been launched and its makers claim drivers cannot tell the difference. The Bio-Bug has been converted by a team of British engineers to be powered by biogas, which is produced from human waste at sewage works across the country. They believe the car is a viable alternative to electric vehicles. Excrement flushed down the lavatories of just 70 homes is enough to power the car for 10,000 miles - the equivalent of one average motoring year. This conversion technology has been used in the past but the Bio-Bug is Britain's first car to run on methane gas without its performance being reduced. It can power a conventional two litre VW Beetle convertible to 114mph. Mohammed Saddiq, of sustainable energy firm GENeco, which developed the prototype, claimed that drivers "won't know the difference". He said: "Previously the gas hasn't been clean enough to fuel motor vehicles without it affecting performance. "However, through using the latest technology our Bio-Bug drives like any conventional car and what's more it uses sustainable fuel."If you were to drive the car you wouldn't know it was powered by biogas as it performs just like any conventional car. It is probably the most sustainable car around."
The Bio-Bug is a conventional 2 litre VW Beetle convertible, which has been modified to run on both conventional fuel and compressed methane gas. The car is started using unleaded petrol but automatically switches to methane when the engine is "up to temperature". If the methane tank runs out the Bio-Bug reverts back to petrol. Around 18 million cubic metres of biogas is produced from human waste every year at Wessex Water's sewage treatment works in Avonmouth, Bristol.
The gas is generated through anaerobic digestion - where bugs which are starved of oxygen break down biodegradable material to produce methane. However, before the gas can be used to power vehicles it must undergo "biogas upgrading" where carbon dioxide is removed to improve performance.
The Bio-Bug does 5.3 miles per cubic metre of biogas, which means that just one sewage works could power 95,400,000 miles per year saving 19,000 tonnes of CO2. Lord Rupert Redesdale, chairman of The Anaerobic Digestion and Biogas Association, believes that the Bio-Bug could prove to be the future of green motoring. He said: "This is a very exciting and forward-thinking project demonstrating the myriad benefits of anaerobic digestion. "Biomethane cars could be just as important as electric cars, and the water regulator Ofwat should promote the generation of as much biogas as possible through sewage works in the fight against climate change."
GENeco, a sustainable energy company owned by Wessex Water, plans to convert its fleet of vehicles if the Bio-Bug trial proves to be successful. The Bio-Bug emits three tonnes of carbon dioxide in an average year whilst a conventional vehicle emits 3.5 tonnes. However, the Bio-Bug is carbon neutral because all of its CO2 would have been released into the atmosphere anyway in the form of methane gas.
Conventional vehicles use fossil fuels, a non-renewable, finite source of energy, and the CO2 they emit would not otherwise have been released into the atmosphere.
Following article by Siobhan Wagner
The Engineer, August 2010
Human waste powers VW Beetle
A Volkswagen Beetle that runs on methane produced from human waste in sewage sludge has been unveiled in Bristol.
Bath-based Greenfuel Company converted the ‘bug’ so it could run on biogas generated at the Bristol sewage treatment works in Avonmouth.
With support from the South West Regional Development Agency, GENeco, a Wessex Water-owned company, imported specialist equipment to purify biomethane in a way that doesn’t affect the vehicle performance.
If both tanks were filled up with methane the car would travel for 250 miles
The biogas is enough to power a conventional two-litre VW Beetle convertible to 114mph.
According to GENeco, waste flushed down the toilets of just 70 homes in Bristol is enough to power the ‘Bio-Bug’ for a year, based on an annual mileage of 10,000 miles.
Countries including India and China use compressed natural gas (CNG) to power vehicles and a number of companies in the UK are now using CNG mainly to fuel buses and commercial vehicles. In Sweden, more than 11,500 vehicles already run on biomethane produced from sewage plants.
But using biogas from sewage sludge is yet to take off in the UK despite a significant amount being produced everyday at sewage plants around the country.
In order to produce methane from sewage, it first must be treated with anaerobic digestion, a process in which microorganisms - in the absence of oxygen - break down biodegradable material to produce methane.
In an extra step to purify the methane, the GENeco engineers used specialist equipment to strip carbon dioxide from the biogas.
The methane is stored in two pressurised storage tanks in the boot of the Bio-Bug vehicle. If both tanks were filled up with methane the car would be able to travel for 250 miles.
Ingram Legge, director at Greenfuel Company, which converted the car, said filling it up with methane is fairly simple. ‘The storage tanks are pressurised to about 200 bar and you connect the vehicle up and it basically equalises pressure so the tanks in the vehicle are 200 bar with methane in them,’ he explained. ‘There’s no pump in effect, which is quite clever.’
The vehicle still depends on petrol but only for a moment after starting the engine. Once the engine’s temperature reaches 30ºC, the petrol injectors shut down and the methane ones open up. If methane runs out, the car will switch back to running on petrol.
While the Bio-Bug is being touted as environmentally friendly, Legge acknowledged that does not mean the vehicle produces no emissions. ‘It’s producing CO2 out the tailpipe but it’s important to know where that CO2 is coming from,’ he said. ‘Of course it’s not coming from yesterday’s CO2 buried in the ground as oil, it’s today’s CO2 from waste. So it’s very environmentally friendly.’
Mohammed Saddiq, GENeco’s general manager, said he was confident that methane from sewage sludge could be used as an alternative energy source and was an innovative way of powering company vehicles.
He added: ‘Our site at Avonmouth has been producing biogas for many years, which we use to generate electricity to power the site and export to the National Grid.
‘With surplus gas available, we wanted to put it to good use in a sustainable and efficient way.
‘We decided to power a vehicle on the gas offering a sustainable alternative to using fossil fuels that we so heavily rely on in the UK.
‘If you were to drive the car, you wouldn’t know it was powered by biogas as it performs just like any conventional car. It is probably the most sustainable car around.’