Biomethane-fuelled vehicles - The carbon-neutral option

2009 could be the beginning of something big – the introduction of more means of transport run on natural gas.

2009 could be the beginning of something big the introduction of more means of transport run on natural gas. John Baldwin looks at new the NGV launches, explains biomethane and the connections with the waste management industry

by John Baldwin

2008 may well be recognized as a turning point for moving away from fossil fuels, and this has major implications for the waste management industry. The increase in oil price to $140 per barrel is the market signalling that, in the words of Shell CEO Jeroen van der Veer, ‘easy oil’ is running out. The large oil fields that have supplied the world with oil are starting to decline and new resources, such as oil sands in Canada, have much higher levels of CO2 emissions associated with their extraction.

These factors have caused some of the major car makers to look at natural gas vehicles as an attractive new opportunity. Whilst there are now around eight million natural gas vehicles in the world, with Brazil, Argentina and Pakistan the volume leaders, it is the developments for the first quarter of 2009 in Germany that could transform everything and offer a compelling vision for the waste management industry.

New biomethane-fuelled vehicles

In 2004 a group of VW engineers set out with a vision for a large car that could be fuelled by natural gas (fossil or renewable) delivering high performance, a long range, low CO2 per kilometre and no loss of boot space. That vehicle is about to come off the production line in Germany as the VW Passat TSI EcoFuel. The combination of twin superchargers and a turbocharger provide exceptional performance, with 150 bhp and 0 to 60 mph in 9.7 seconds. Its range on biomethane is 420km with a further 400km on petrol. Whilst it is carbon-neutral on biomethane, even on fossil natural gas it has class-leading low CO2 of 129 g/km.


The Passat EcoFuel features a 1.4 litre engine that runs on both petrol and compressed gas Click here to enlarge image

By putting the compressed natural gas tanks under the floor, VW have engineered a carbon neutral vehicle with no loss of boot space. With 800 filling stations in Germany for the car, VW are expecting a breakthrough in terms of sales 25,000 per annum a reasonable target. With fuel at half the cost of petrol and good performance, the VW Passat TSI EcoFuel can be expected to achieve a high level of sales.

The Passat is joined by General Motors’ Zafira Turbo which also offers great performance with low CO2 emissions. Then there are a suite of vehicles from Mercedes-Benz: the B Class, the Sprinter van and the Econic truck. Together, with other vehicles (from cars to buses and trucks) we now have a family of vehicles that are unbeatable in environmental performance when fuelled on compressed biomethane.


Biomethane-fuelled Norba refuse trucks in Malmö, Sweden Click here to enlarge image

UK water companies are introducing the new VW Caddy and Mercedes-Benz Sprinter, to allow their vehicles to be powered by carbon-neutral biomethane rather than diesel.

Each m³ of biomethane used to fuel a VW Passat or MB Econic displaces a litre of diesel and means some ‘hard to extract and high CO2 to produce’ oil is left in the ground.

Natural gas was made from dinosaur faeces some 150 million years ago … but now we can make renewable natural gas/biogas, from organic waste in around 20 days using anaerobic digesters (AD). It is straightforward and low cost to remove water, H2S and CO2 from this biogas, producing biomethane, a perfect vehicle fuel which, with these new vehicles, provides a carbon-neutral motoring opportunity for ‘eco-leadership’ companies.

‘Second generation’ biofuels are defined as those which are made from organic waste not food crops. Statistics show that biomethane is now clearly established as the leading fuel used for vehicle fleets in most EU countries. Sweden has around 15,000 natural gas vehicles (NGVs) with 55% of the fuel from biomethane. Fifteen Swedish cities have biomethane-powered bus fleets, such as Stockholm, which is replacing bioethanol-fuelled buses with 100% biomethane-fuelled vehicles from 2009.

Injection of biomethane into the gas grid

Whilst the production of biomethane is well established, transporting this gas to consumers via the existing gas grids within Europe is an innovation being promoted by the EU in its new Renewable Energy Directive.

In the UK, there is an extensive AD industry but the biogas produced has only been used to generate electricity. High energy prices mean that the overall efficiency of such schemes (less than 40% due to limited use for waste heat) is causing a rethink as to the appropriate use of the biogas. The high quality of the new biomethane-fuelled vehicles and the relatively poor CO2 performance of on-site electricity generation, means that injection of biomethane into the gas grid and its use as a vehicle fuel is now attractive. See Figure 1 below.


Figure 1. Carbon dioxide savings using biogas Click here to enlarge image

There are no regulatory barriers for injecting renewable methane into the gas grid. In fact, whilst it does not happen yet, the UK pipeline system welcomes it with open arms, not even charging a fee to accept it at the lower pressures that local gas pipelines operate at. The raw biogas has to be dried, cleaned, enriched and odourized, but this is straightforward with a range of technologies widely used in Europe. The reason it does not happen is that, under a legal technicality, biomethane loses all its green benefits when it enters the mains. The UK Government has recognized this is bad for the environment and is in consultation in relation to this with the aim of encouraging ‘renewable’ gas in the same way it encourages renewable electricity.

European experience

Injection of biomethane into the gas grids is now happening across Europe, in a market growing at more than 25% per year. In Sweden, Switzerland, Austria, Germany and the Netherlands, the production of renewable methane from domestic waste offers a solution to the problems of waste recycling, the reduction in global warming and the reduction in natural gas imports. It is a compelling vision gas suppliers who already offer ‘green’ electricity tariffs could also offer ‘green’ gas tariffs. Supermarkets could recycle their green waste, turning it back into methane and run all their vehicles on carbon-neutral biomethane, so tapping into the premiums available for renewable biofuels. The residual digestate from the AD also has value as a fertilizer.

Fixing fuel prices for the life of the AD plant is also attractive as long as organic waste is produced, the fuel will be available. In Lille, France, 330 buses are fuelled on biomethane from domestic waste, this direct link between waste and bus fuel is something that leads to very high rates of organic waste recycling from consumers, as well as lower local council taxes.

For examples of biomethane-fuelled operations, visit www.cngservices.co.uk.

John Baldwin is managing director of CNG Services Ltd, Solihull, UK e-mail: john.baldwin@cngservices.co.uk

Biogas fact file

Biogas, or renewable natural gas, is the name given to the mixture of methane and carbon dioxide (CO2) gases that is formed whenever organic materials decompose in the absence of air. This process is known as anaerobic digestion, and when it occurs in nature the gases escape into the atmosphere. However, this natural process can be managed in an industrial plant. To make it more efficient the industrial process requires warmth and the exclusion of air. The organic material is usually prepared before being fed into tanks the tanks allow the gases to be captured and used. Modern industrial processes can make renewable natural gas in a matter of days rather than the thousands of years that were taken to produce natural gas.

Renewable natural gas is by far the most environmentally friendly fuel in the world when compared with other fuels currently available. Capturing the methane which would otherwise be emitted from decomposing organic materials, and preventing it from becoming a greenhouse gas that is 21 times worse than CO2 in terms of climate change, is actually improving the environment rather than just being ‘less bad’ by merely replacing fossil fuels with renewable fuels.

Nearly all countries now have a mission to work out schedules for sustainable development, and powering vehicles from fuel made from waste is a very obvious and direct example.

Manufacturing process

Biogas can be manufactured from just about any organic material. Historically, it has been produced from sewage sludge and animal slurries, but more recently the focus has been on producing gas from energy crops, such as grass or maize, and wastes such as those from food manufacturing, brewing, and household rubbish. On average, some 60% of the contents of a household dustbin are organic and can be used to make gas.

The biogas produced by natural processes contains about 65% methane, 35% CO2 and some trace gases, including hydrogen sulphide (HS). This raw biogas is mainly used in stationary engines that generate electricity. At sewage works it is used to power the machinery on site, and at landfill sites it is fed into the national electricity grid.

Biogas as a vehicle fuel

To use biogas as a vehicle fuel the CO2 needs to be removed so that the methane content is similar to that in natural gas. If the CO2 is allowed to remain in the biogas mixture the operating range of the vehicle is compromised as CO2 does not burn. Hydrogen sulphide also needs to be removed as this is corrosive. Treated biogas for automotive applications is referred to as biomethane.

Environmental option

In a report from the Swedish Committee of Alternative Fuel, biogas was acknowledged as the best alternative fuel available today with regards to climate, environment and health due to its low emissions and no net contribution to the greenhouse effect.