§ Mr. Jon Owen JonesTo ask the Secretary of State for the Environment from how many active sites in England and Wales the estimate of methane emissions from landfills in the "Digest of Environmental Protection and672W Water Statistics" No. 14 is derived; how many other landfills in England and Wales are estimated to emit methane; and what is their total annual contribution.
§ Mr. MacleanThe landfill gas methane emissions estimate in the "Digest of Environmental Protection and Water Statistics" No. 14 is derived from data on 453 sites in England and Wales.
There are many additional landfill sites in which methane may be generated to some extent, but biological conditions in these sites are much less favourable for methane generation and it is thought unlikely that they constitute a significant additional source.
§ Mr. Jon Owen JonesTo ask the Secretary of State for the Environment at the sites where gas control and capture measures are in place, what are the realistic figures from field studies of(a) the efficiency of capture and (b) the escape of methane through leaky pipeworks, valves and burners.
§ Mr. MacleanField studies suggest that methane capture efficiencies of between 50 and 90 per cent. are achieved by landfill gas control and capture measures. The escape of methane from leaky pipe work, valves and burners is likely to be negligible.