The first landfill gas utilisation scheme in the UK was commissioned in 1980. That and subsequent projects used the gas directly in industrial boilers and kilns in sectors such as brick manufacture, and it was not until 1985 that the first scheme to generate electricity from landfill gas was commissioned.
The emphasis has slowly switched to power generation. In 1990, there were 17 schemes using landfill gas directly, while 12 were consuming it to produce electricity. But all the projects commissioned since then have been for power generation.
According to data compiled by the Department of Trade and Industry's Energy Technology Support Unit (ETSU) at Harwell Laboratory, the number of schemes in operation passed the 50 mark in January 1993. Five use gas in boilers and eight in kilns or furnaces, while the remaining 37 are power generation projects.
The Non-Fossil Fuel Obligation (NFFO), under which renewable energy projects receive a premium price for electricity, has given a major boost to power generation from landfill gas. Contracts for 53 projects were offered under the first two tranches of the NFFO in 1990 and 1991. Many of these have yet to be commissioned, but ETSU expects at least another 12 power generation schemes to come into operation during 1993.
The total installed capacity of the 37 schemes operating in January was 63MW. The project with the highest capacity, 5.25MW, is at the Appley Bridge landfill in Lancashire. Another four schemes have capacities of 4MW.
The operator with the largest power generation capacity in January was Shanks & McEwan, with a total of 8.4MW at four landfills, followed by Blue Circle, with 7.75MW, also at four sites. NORWEB and Landfill Gas Ltd also operate power generation schemes at four landfills with a total capacity of 5.54MW.
According to ETSU's calculations, the energy produced by all 50 landfill gas schemes in existence in January was equivalent to 313,000 tonnes of coal per annum. This compares with a figure of 184,000 tonnes in 1990. The total is projected to increase to more than 350,000 tonnes by the end of 1993. Direct consumption of landfill gas contributes 50,000 tonnes per annum to the current total, and power generation 263,000 tonnes.
The power generation technologies used are dominated by small spark ignition engines, present at 28 of the 37 schemes and contributing 38MW to the total installed capacity of 63MW. Larger dual fuel engines have been installed at six landfills, and contribute 13MW to the total capacity. Gas turbines with a total capacity of 12MW are in operation at three sites.