There’s an advert on a lamp-post half-way up White Abbey Road offering fuel at half the price of petrol. It’s LPG – liquid petroleum gas or auto gas.

It has much to recommend it apart from the price, and even though it’s made from natural gas, it still produces a fifth less CO2 than petrol.

However, it gets even better as it can be made as a by-product of a waste treatment process, anaerobic digestion, and the biogas so produced, mainly methane, is carbon neutral as the vegetation, paper and card products that decompose have already taken the CO2 out of the atmosphere and are just putting it back.

Biogas is used more extensively in Europe than the UK, with more than 3,000 anaerobic digesters in Germany, compared with about 30 here, and in Sweden buses and some trains are so fuelled. The biggest development is in China and Vietnam with the digesters providing gas and electricity for more than a third of households.

Methane, or biogas, is naturally produced in landfill sites, but because it is a serious climate change gas (20 times as powerful as CO2), venting it into the atmosphere is no longer acceptable.

Some of it can be captured at the landfill site and burned to produce electricity, but with the EU directive on reducing such sites this is no longer acceptable.

Anaerobic digestion involves the construction of a number of closed containers in which micro-organisms break down bio-degradable matter in the absence of oxygen. The result is a gas made of methane, CH4, and some carbon dioxide, CO2, and this can be used for producing the autogas or for heating to produce electricity.

Relatively inexpensive medium-scale plants can be constructed at a variety of farming and waste sites to meet local needs and surpluses could be fed into the national gas and electricity grids, as in Germany where there is a feed-in law that encourages this form of renewable energy.

Anaerobic digestion can work well as an important part of dealing with household waste, particularly if the metals, glass and plastic are removed first for recycling, preferably by sorting at the kerbside.

Despite developments in Doncaster, Norwich and in Shropshire, little is happening in the UK, though The Archers are showing considerable interest, and it’s a missed opportunity as LPG could fuel 17 per cent of UK vehicles.

This would reduce the CO2 emitted by transport, and should be encouraged by zero fuel duty and zero parking fees.