Report: carbon-negative biomethane cleanest and most efficient biofuel for cars

The UK's Renewable Energy Centre today released its assessment of responses to the King Review of Low Carbon Cars’ call for evidence. It supports the findings of the Biomethane for Transport organisation which found that biogas is the cleanest and most efficient of all transport fuels. Biomethane is carbon-negative, can be readily used in CNG cars and makes use of a wide variety of biomass feedstocks.

In the continuing fight against climate change there have been an increasing number of targets set in the UK and internationally for varying types of energy use and generation. One of the most important areas in which the UK needs to reduce carbon emissions is the transport sector, but it has also proven to be one of the most expensive areas in which to make any significant technological development and improvements.

The King Review of Low Carbon Cars, announced in June as part of the country's 2007 Budget, was intended to build on the progress made in recent reports including the 2007 Energy White paper and examine the vehicle and fuel technologies which over the next 25 years could help to decarbonise road transport, particularly cars. Following the publication of the report issued by HM Treasury and led by professor Julia King of Aston University, Gordon Brown issued a call for evidence from all interested parties on how best to reduce emissions from road transport.

The Renewable Energy Centre commented that the report was long overdue, as whilst emissions from other sectors, such as the use of domestic energy, has fallen or become more stable, the transport sector's emissions continue to increase and currently accounts for over 20% of the UK’s total CO2 output. The Cambridge report produced this year, estimates that the UK will be unable to meet the reduction targets set following the Kyoto agreement in 1997.

The Biomethane for Transport organisation responded to the King Review and stated that the one of the most economically viable directions to take would be vehicle and fuel improvements that can be adapted to existing internal combustion engines.

The Renewable Energy Centre supported the organisation’s findings that the use of biogas for transport had many advantages over many of the other technologies proposed. Biomethane has the lowest gas emissions of any biofuel and the capture, upgrading and burning of the gas actually produces fewer emissions than if the organic waste used was left to decompose naturally. The organisation confirms findings from previous research as well as results from longstanding trials in continental Europe.

An overview of the strong arguments in favor of biomethane for transport, summarized from the Biomethane for Transport King Review Response [*.pdf]:

• Negative Carbon Balance – Biomethane produced from the decomposition of organic waste (e.g. anaerobic digestion) actually has a negative ‘well to wheel’ carbon balance. This is due to the fact that capturing, upgrading and burning the gas prevents methane from being released into the atmosphere when waste naturally decomposes, and also because methane is an inherently low carbon fuel. The ‘Biogas as a Road Transport Fuel’ report estimated that using biomethane as a fuel in the HGV and LGV fleets could provide a saving of up to 9.1 million tonnes of CO2 per year.
• Low Emissions of Local Pollutants – Methane fuelled vehicles have extremely low emissions of local pollutants, including NOx and particulates when compared to modern petrol and diesel vehicles. Substitution of diesel and petrol vehicles with biomethane (and also fossil methane) would have a beneficial effect on air quality.
• Low Noise – Methane fuelled engines run more quietly than petrol and diesel, vehicles, particularly so when compared with the latter. This can have a beneficial effect on urban environmental quality, and also have economic benefits where vehicle movements are restricted because of noise limitations.
• Link With Waste Management – Many local authorities are either developing, or planning to develop, anaerobic digestion facilities as an alternative pathway to landfill for organic waste. Vehicles are one of the best ways of using the biomethane produced from these plants. By tying the two areas together local authorities are provided with a disposal pathway for organic waste, reducing the amount of waste sent to landfill, and vehicles are provided with fuel. Costs are reduced for all parties through a joint approach.
• Compatibility With Existing ICE Technology – Methane fuel is used in modified internal combustion engines, therefore the fuel is able to take advantage of improvements in this technology. Using biomethane alongside other technologies can therefore provide significant co-benefits, e.g. a hybrid running on biomethane would benefit from the inherent carbon reductions produced by both technologies

When biomethane is produced from dedicated energy crops, it can yield more energy than any other current type of biofuel. The green gas can be made from a very wide range of biomass crops as well as from abundant crop residues. Scientists have found [*.pdf] that for temperate grass species, one hectare can yield between 2,900–5,400 cubic meters of methane per year, enough to fuel a passenger car for 40,000 to 60,000 kilometers (one acre of crops can power a car for 10,000 to 15,000 miles).

Moreover, biogas can be made even cleaner by coupling its production to dedicated carbon storage technologies and sites, independently from power stations. By capturing CO2 from biogas before it is combusted - the least costly carbon capture strategy for any fuel source - and sequestring the greenhouse gas under ground, the fuel becomes thoroughly carbon-negative. The use of this cleaned biogas, upgraded to biomethane, takes CO2 emissions from the past out of the atmosphere (more here and here). Only biofuels allow the creation of such carbon-negative energy systems - all other energy concepts are either carbon-neutral or carbon-positive:
climate change :: greenhouse gas emissons :: CNG :: energy :: sustainability :: biomass :: bioenergy :: biofuels :: carbon-negative :: carbon capture and storage :: waste :: energy crops :: biogas :: biomethane ::

The Biomethane for Transport organisation also suggests a way in which organic waste can be used more productively, whereby a waste management plant is linked with anaerobic digestion facilities to make use of the methane gas produced. This would provide a useful solution for organic waste, in turn reducing the amount of waste sent to a landfill and provides vehicles with a source of renewable fuel.

However, some argue that the results of this review will have little impact on the cars driven in the UK in the short term, particularly due to the fact that none of the major car manufacturing operations in the UK are British-owned anymore, and the review will only have limited influence on foreign-owned companies.

Richard Simmons, Founder of The Renewable Energy Centre commented “Biomethane should prove to be a very realistic part of the future alternative to fossil fuels but will only truly reduce the impact we are having on the environment if we realise that it cannot be used in isolation. It is important that we work towards more fuel efficient cars and reduce our often excessive use of vehicles. This is a particularly vital step for all car owners to play their part in reducing fuel emissions”.

Biogas is increasingly being used in Europe, both for electricity generation as for transport. A recent 'Biogas Barometer' report, published by a consortium of renewable energy groups led by France's Observ'ER, cites a 13.6% increase growth in biogas use for primary energy production between 2005 and 2006 in the EU (earlier post).

The total energy potential for biogas in the EU has been the subject of several projections and scenarios, with the most optimistic showing that it can replace all European natural gas imports from Russia by 2020 (more here). Germany recently started looking at opening its main natural gas pipelines to feed in the renewable green gas. And an EU project is assessing the technical feasibility of doing the same on a Europe-wide scale (previous post).

Biogas as a transport fuel offers particularly interesting prospects for the developing world, where oil infrastructures are not yet developed extensively. By relying on locally produced biomethane used in CNG cars, these countries could leapfrog into a clean, secure and green post-oil future. A country like Pakistan showed that converting the automobile fleet to CNG is feasible: in less than two years time, it converted 1 million cars to run on compressed gas (earlier post).

For comprehensive overviews of the latest developments in biogas research, development and applications, please search the Biopact website.


Graph: energy obtained per hectare of energy crops for selected bioconversion processes. Source: L-B- Systemtechnik GmbH Ottobrunn.

References:
HM Treasury: The King Review of low-carbon cars.

The UK's Renewable Energy Center.

National Society for Clean Air and Environmental Protection, Biomethane for Transport: Biomethane for Transport King Review Response [*.pdf] - August 16, 2007

Annimari Lehtomäki: Biogas production from energy crops and crop residues [*.pdf], Jyväskylä Studies in Biological and Environmental Sciences 163, PhD Dissertation, Faculty of Mathematics and Sciences, University of Jyväskylä, 2006.

Reinhold Wurster, GM Well-to-Wheel-Studie - Ergebnisse und Schlüsse sowie Vergleich mit anderen Arbeiten und Ausblick auf Kraftstoffpotentiale und -kosten [*.pdf], L-B- Systemtechnik GmbH Ottobrunn, November 2003.

Biopact: Experts see 2007 as the year of biogas; biomethane as a transport fuel - January 09, 2007

Biopact: Pre-combustion CO2 capture from biogas - the way forward? - March 31, 2007

Biopact: Biopact to chair Sparks & Flames conference panel on carbon-negative biofuels - August 08, 2007

Biopact: Hydrogen out, compressed biogas in - October 01, 2006