At the Rosedale site, the gas quantities and qualities proved to be sufficient to justify commercial utilisation, as opposed to simply being flared. Gas to energy generation plants were commissioned at both sites in 1992, employing state of the art design and construction technologies in what was the first venture of this type in New Zealand.
The project began as an unincorporated joint venture in 1990 between Northern Disposal Systems and the Auckland Electric Power Board to generate electricity. This is now a venture between EnviroWaste and Mighty River Power. Under the terms of the joint venture, EnviroWaste collects the gas, cleans and dries it and pipes it to generating plant on each site operated by Mighty River Power. Electricity generated at these sites is on-sold for distribution via the Vector network.
Greenmount and Rosedale between them employ nine gas engines which consume up to 7,000 cubic metres per hour of gas to produce a peak of 10MW of electricity. At peak production the combined sites produce enough electricity to supply almost 10,000 homes.