The UK's first ever bus powered by gas from food waste and human excrement has taken to the road in Bristol today (20 November).

The 40-seater Bio-Bus, which runs on gas generated by anaerobically digesting sewage and food waste, has been developed by Bristol-based renewable energy company GENeco, a subsidiary of Wessex Water, to demonstrate how public transport can be sustainably fuelled, whilst helping to reduce traffic pollution.

Where the gas comes from

The biomethane used to power the bus comes from GENeco’s sewage treatment works in Bristol, which currently treats around 75 million cubic metres of sewage waste and 35,000 tonnes of food waste (collected from households, supermarkets and food manufacturers) every year.

Around 17 million cubic metres of biomethane – enough to power 8,300 homes – is produced by the plant every year through a process of anaerobic digestion, which involves using microorganisms to break down biodegradable material in the absence of oxygen.

GENeco became one of the first companies in the UK to start injecting biomethane into the National Grid’s gas pipelines earlier this week, and at the same time installed a gas refuelling plant for the bus. Unlike the gas pumped into the grid network, the vehicle fuel has had the carbon dioxide removed, propane added and impurities removed to produce a fuel with ‘virtually odour-free emissions’.

Once pumped into the bus, the compressed gas is stored in dome-like tanks on the roof of the Bio-Bus.

‘Powered by people living in the local area’

General Manager of GENeco Mohammed Saddiq commented: “Through treating sewage and food that’s unfit for human consumption we're able to produce enough biomethane to provide a significant supply of gas to the national gas network that's capable of powering almost 8,500 homes as well as fuelling the Bio-Bus.”

The unveiling of the bus coincides with yesterday’s European Court of Justice ruling that ministers must clean up the quality of the UK’s urban air as soon as possible, after it was found that nitrogen dioxide levels (from diesel engine emissions) in several UK cities were illegally high.

Saddiq commented: “Gas powered vehicles have an important role to play in improving air quality in UK cities, but the Bio-Bus goes further than that and is actually powered by people living in the local area, including quite possibly those on the bus itself.

“Using biomethane in this way not only provides a sustainable fuel, but also reduces our reliance on traditional fossil fuels.”

The gas used to power the Bio-Bus reportedly produces around 30 per cent less carbon dioxide equivalent than a diesel-powered equivalent.

Bio-Bus route

The Bio-Bus, built by vehicle manufacturers Scania and operated by the Bath Bus Company, made its inaugural journey from Bristol Airport to Bath city centre today (20 November), and can travel 300 kilometres on a full tank of gas. According to GENeco, if the vehicle were to use the annual waste generated from one bus-load of passengers, it would have enough power to travel a return journey from Land’s End to John O’Groats.

The bus will carry its first fare-paying passengers from Bath to Bristol Airport at 8am on Monday (24 November 2014).

Speaking of the new A4 service using the Bio-Bus, Collin Field, Engineering Director at the Bath Bus Company, said: “Up to 10,000 passengers are expected to travel on the A4 service in a month, which is available not only for airport travel, but also local journeys along the route through Saltford, Keynsham, Brislington, Knowle and Hengrove.

“As part of the RATP Dev UK group, this represents RATP Dev's involvement in the latest of a number of initiatives to gain experience of alternative fuels, with sister companies also experimenting with different alternatives.

“The timing of this initiative could not be more appropriate as we approach 2015 when the city of Bristol itself becomes European Green Capital. With so much attention being directed towards improving air quality generally, the public reaction to the appearance of this bus on a service between a World Heritage City and an airport will further focus on the potential for this particular fuel.”

Melanie King, Bristol Airport’s Environmental Manager, added: “Sustainability and surface access are key areas of focus for us and we welcome new technologies which could reduce the environmental impact of getting to and from the airport.

“With Bristol set to be European Green Capital in 2015, this is one of several exciting initiatives we hope to be involved with over the course of the year.”

ADBA welcomes Bio-Bus

The Bio-Bus has been welcomed by Charlotte Morton, Chief Executive of the Anaerobic Digestion & Bioresources Association (ADBA), who said: “GENeco’s Bio-Bus is an excellent demonstration of biomethane’s unique benefits – decarbonising areas other renewables can't reach. A home-generated green gas, biomethane is capable of replacing around 10 per cent of the UK’s domestic gas needs and is currently the only renewable fuel available for HGVs [heavy goods vehicles].

“The bus also clearly shows that human poo and our waste food are valuable resources. Food which is unsuitable for human consumption should be separately collected and recycled through anaerobic digestion into green gas and biofertilisers, not wasted in landfill sites or incinerators. The Bio-Bus will also help to demonstrate the true value of separate food waste collections, which are now obligatory in all other regions, to the English government.”

The Bio-Bus has received backing from a number of businesses including Scania, Roadgas, CNG Services Ltd, Dampney’s Agri Environmental, Trant, Grontmij, and AIR Decker.

Bio-Bus is the second foray GENeco has made into biomethane-powered vehicles, after it unveiled the Bio-Bug car in 2010.

Watch a video of the Bio-Bus in action below, or find out more about the technology from GENeco’s website.