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Currently, renewable gas production in the form of landfill gas and sewage gas represents a significant proportion of the UK's current renewable energy portfolio. In the region of 1.4bcm (billion cubic meters) of renewable gas are produced in the UK at the moment - which could meet around 1% of total UK gas demand.

However, because of the commercial incentives (the Renewable Obligation Scheme), all of this gas is used to generate electricity at efficiency levels of around 30% in most cases. The report suggests injecting biogas into the gas grid which can then be delivered straight into consumers' homes and utilised for heating at efficiency rates in excess of 90%. This would in itself more than double the contribution of existing renewable gas sources to the renewables target.

Biogas is produced by two main processes. Anaerobic digestion which turns wet waste such as sewage and animal manure into biomethane and gasification which is better suited to drier wastes and energy crops.

Before renewable gas can be injected into the UK gas network, it must be cleaned or "upgraded" to meet UK gas pipeline specifications. The main purpose of this process is to remove gases such as carbon dioxide and hydrogen sulphide to leave an almost pure (~98%) methane gas. This upgraded gas is often termed biomethane. Renewable gas upgraded to biomethane followed by injection into the gas grid is a technology which is already being deployed in many countries in Europe - including Germany, France and Austria. In the US, National Grid takes landfill gas from the Staten Island landfill and injects the cleaned gas into its New York Grid.

It is estimated that biogas would be a similar price to other renewable energy sources. However because the UK already has an extensive gas grid, there would be little need for disruptive infrastructure development or any major inconvenience to consumers in their homes or streets.

The report concludes that there are no insurmountable technical difficulties to delivering biogas. The main hurdle will be about getting the right commercial incentives in place so waste can be turned into biomethane for gas grid injection rather than electricity. This, the report concludes, needs to be allied with a comprehensive waste management policy.