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Flush Hour: Oslo to Run Buses On Biomethane

Free, friendly and non-fossil – biomethane from human waste will soon power public transport in the capital city


It is available for free in huge quantities, is not owned by Saudi Arabia and it contributes minimally towards climate change. The latest green fuel might seem like the dream answer to climate crisis, but until recently raw sewage has been seen as a waste disposal problem rather than a power source. Now Norway's capital city is proving that its citizens can contribute to the city's green credentials without even realising it.

In Oslo, air pollution from public and private transport has increased by approximately 10% since 2000, contributing to more than 50% of total CO2 emissions in the city. With Norway's ambitious target of being carbon neutral by 2050 Oslo City Council began investigating alternatives to fossil fuel-powered public transport and decided on biomethane.

Biomethane is a by-product of treated sewage. Microbes break down the raw material and release the gas, which can then be used in slightly modified engines. Previously at one of the sewage plants in the city half of the gas was flared off, emitting 17,00 tonnes of CO2. From September 2009, this gas will be trapped and converted into biomethane to run 200 of the city's public buses.

Project leader, Ole Jakob Johansen said: "The city of Oslo has great visions for Oslo as a green capital. Oslo aims to be one of the most environmentally sustainable capitals of the world. Using biomethane makes sense. Not only would the biomethane otherwise be wasted, but the reduction in emissions per bus will go a long way to achieving our carbon-neutral target. What's more, aside from the intial set-up costs, we expect to see an average saving of €0.40 per litre of fuel (based on an average diesel price of €0.67 per litre compared with biomethane at €0.27 per litre)".

The city's diesel public buses will only require minor modifications to their engines to run on methane, which is stored on tanks on top of the vehicles. The only noticeable difference will be how quietly they drive.

"Biogas is popular in Sweden, but they have very few vehicles powered by biomethane. We chose to focus on biomethane as this emits less carbon and is easier and cheaper to produce," said Johansen.

The net emissions from a biomethane operated bus are zero, because the carbon originally came from the atmosphere rather than fossil fuels, but electricity is used at the sewage plant to convert the gas from the waste into fuel for the buses. Oslo city council is taking the electricity used to generate the fuel into consideration and calculate that carbon emissions per bus are 18 tonnes per year, a saving of 44 tonnes of C02 per bus per year.

The city's two sewage plants have enough biomethane to provide fuel for the 80 buses, but if the trial is successful Oslo city council plans to convert all 400 of the public buses to run on biogas. The biogas will be created from a mixture of biomethane and biogas from the incineration of kitchen waste from the capital's restaurants and domestic kitchens. Eventually, the council hopes that cars will also be able to run on biogas sourced locally from biomethane and converted kitchen waste.

What do you think? Should this be deployed more widely?

This piece originally appeared in the Environment section of The Guardian

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Of course this idea should be applied more widely and it will be. Methane management is essential to stopping climate change and may be more immediately important than managing CO2. Methane is a much more powerful greenhouse gas although it is resident in the atmosphere for much less time. We should be figuring out ways to clean methane from our atmosphere before catastrophic methane releases from permafrost or clathrates.

Posted by: gmoke on 30 Jan 09

I was pleased to read about Oslo City Councils attemps and Plans. Its a great step forward on 3 'R's, and all concerned should continue to explore. I certainly would be happy to hear more infor, and share with decision makers of my Country -Sri Lanka.

Posted by: Suren Abeyagoonasekera on 10 Feb 09

"The net emissions from a biomethane operated bus are zero, because the carbon originally came from the atmosphere rather than fossil fuels"

Hmm... this statement makes no sense. Where do you think the original fossil fuels came from?? Did they just appear in the ground?? NO - fossil fuels are created by the build up of organic matter from a kajillion years ago that is subjected to immense pressures. Where did this ancient organic matter get its carbon??

Why, the atmosphere! Yep.

Posted by: Johan on 5 Nov 09

This is interesting news, we would wish that it could be introduced rapidly and more effectively in Developing countries. The Human waste pollution is tremendous due to inadequate collection / treatment facilities, this technology could help address myriad problems as well as very importantly the availability of cooking fuel, reducing potential and actual damage to forests. This technology needs to be looked at seriously.

Posted by: Dr. Ahmad on 11 Jul 10

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