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Consortium Launches Britain’s First Dual Fuel Biomethane Bus; Emissions Cut in Half

Biomethane bus. Click to enlarge.

A consortium brought together by low carbon experts at the University of East Anglia (UEA) in the UK launched the first bus in the UK to run on biomethane gas. The dual-fuel diesel-biomethane powered bus is expected to reduce pollutant emissions and greenhouse gas emissions by around a half. It is hoped the technology will be rolled out to bus fleets across the country and further afield.

The dual-fuel vehicle is a standard Optare Solo single-deck diesel midibus from the Anglian Bus fleet. Originally powered entirely by diesel, the Mercedes-Benz engine has been adapted by the Hardstaff Group (earlier post) to run for 60-80% of the time on low-carbon biomethane. Biomethane is chemically identical to the methane in natural gas but it is made by bacterial action on biowastes. Biomethane is extracted from landfill sites or from biogas produced in purpose-built anaerobic digestion facilities.

The Hardstaff OIGI (Oil Ignition Gas Injection) is a dual-fuel system developed to substitute natural gas for diesel in light- and heavy-duty engines. Diesel is required as the ignition source in dual fuel engines. With the OIGI system the engine will use 100% diesel at idle; gas injection and diesel reduction commences when engine speed increases. Precise control of diesel reduction and gas injection quantities ensures efficient fuel use and performance equivalent to the original diesel engine.

The consortium behind the new bus is led by UEA’s Low Carbon Innovation Centre (LCIC) and includes leading independent bus operator Anglian Bus, bus manufacturer Optare plc, and engine conversion specialists Hardstaff Group of Nottingham.

Dual-fuel use is a very attractive option. The vehicle can still run on diesel, providing flexibility, but most of the time is running on biomethane gas which is a much cleaner and less polluting fuel. In particular, the cost of conversion of a diesel bus to dual-fuel use is a small fraction of the cost of a new natural gas bus. Conversion to dual-fuel use is potentially a viable option for most if not all diesel buses in the UK and, indeed, across Europe and more widely.

—Dr. Bruce Tofield, of UEA’ps Low Carbon Innovation Centre

Funding for the project came partly from an EU-sponsored Civitas programme in which UEA and Anglian Bus were partners with Norwich, Norfolk County Council and cities across Europe. The Civitas Initiative exists to promote cleaner and better transport in Europe’s cities.

LCIC scientists have been monitoring air pollution in Norwich since 2005 as part of the Civitas programme. In Norwich, as in many UK cities, emissions from buses are of particular concern. They noticed how the buses in Malmö in Sweden, a partner city in the Civitas program, were powered by methane, resulting in significantly lower levels of harmful emissions. Of special interest was the fact that Malmö was beginning to use biomethane rather than natural gas to reduce greenhouse gas emissions as well as pollutant emissions.

Benefits of using biomethane as a fuel include:

  • A reduction in particulate and NOx emissions levels of around half compared with diesel leading to cleaner air in towns and cities.
  • Reduced operating costs on a cost per mile basis.
  • A reduction in greenhouse gas emissions of around half as a result of using methane from landfill sites, food and agricultural waste.

Working with local bus company Anglian Bus, the LCIC organized for one of Anglian’s Optare Solo buses to be converted to dual-fuel use. The fuel tanks have been installed at Optare’s Leeds plant and the engine conversion undertaken at Hardstaff’s Nottinghamshire headquarters. In addition, Hardstaff is supplying a gas refuelling station to Anglian Bus and will keep it supplied with biomethane.

The bus will make its first public showing at LCV 2009, at the Millbrook Proving Ground in Bedfordshire on September 9 and 10. The event has been organized by Cenex (Centre of Excellence for low carbon and fuel cell technologies) and is expected to attract around 2000 specialists in low carbon technologies from around the world.

(A hat-tip to John!)


John Baldwin

Fossil CNG gives a 20% reduction in CO2 compared to diesel which is a significant reduction. Biomethane (CBM) is an unbeatable fuel, no food or sustainability issues, made from waste. It has an exceptionally good well to wheel CO2 performance because you make the fuel were the vehicles are.

THe Passat Ecofuel car is the benchmark - 0 - 60 in 9.3 secs, range of 400km on CNG or CBM (and 300 KM more on petrol).

UK is building 10 large new gas fired power stations to make electricity we are needing - far better for the plant to use this gas to run vehicles instead. The vehicles that use a lot of fuel like trucks and buses, not EVs that would replace (in my case) a low CO2 Petrol Smart.


It doesn't really matter where the methane comes from - Bio is ideal, but fossil will work just as well if you havn't enough bio-waste.

The major benefit of methane (in my opinion) would be the reduction in "local" pollution in urban areas.

Plus, you can avoid "range anxiety" by using diesel as a stop gap, making the buses more flexible.

The tank looks awful, but it is a bus, so this is not a problem - noone will be refused a date because the bus has a hump on the back.


I wonder what the range is. Range has always been a problem with CNG. However a CNG coupled with electric, full hybrid or start/stop, addresses all the issues. A CNG/Hybrid is as clean as a fuel-cell, at a fraction of the cost.

Henry Gibson

Actually there were buses during WWII or WWI or both that ran on biomethane in the UK. They had large balloons on the top of them. The truth is that these vehicles may average %80 methane fuel use, but every stroke of the piston requires some diesel for ignition. If organic materials are used that could have enriched the soil or be converted directly to food then the food fuel issue remains. Ethanol is itself a food that has a distinct and well known advantage over pure sugar or starch. ..HG..


I think this could serve as a model for private cars that may prove more popular and cheaper than PHEVs. I doubt that enough biomethane can be produced to satisfy demand but it can be blended with natgas and methanated syngas. On an interstate trip you may not find too many CNG filling stations for a few years but they can be phased in as the numbers of NGV or dual fuel cars increases.

I suspect cars of the future will van sized if they need a liquids tank, a CNG cylinder and a traction battery. A problem with cap-and-trade is that it will favour combined cycle gas electrical generation over coal and there may not be enough gas for vehicles. A percentage of NG needs to be guaranteed for transport.


The WWII buses and cars in London ran on town gas (from coal), not methane.

The town gas may be a better model than biogas, because it is closer to the product of biomass gasification.  If any source of wood chips is a supply of vehicle fuel, the amount of energy is considerably greater than if supplies are limited to landfills and manure.


My grandfather drove a cab in London, during WWII he converted it to run on wood gas.

Henry Gibson

Some WW vehicles ran on sewage digester gas(biomethane) in addition to the ones which ran on town gas. Many other vehicles were equipped to run on wood or charcoal. ..HG..

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