A Wittig ROW 120 G was installed at the Bromley WWTW in Christchurch, New Zealand to replace troublesome reciprocating compressors. The compressor package takes biogas from anaerobic digesters, via a sand filter and small gas holder and feeds the gas to the power generation room adjacent where there are 3 biogas powered generator sets, 1 large Waukesha and 2 smaller Allen generators with a total installed power output of 2.4 MW. Actual electricity output averages 1.24 MW burning 730 m3/hr of biogas.
These buildings were using LPG and now burn landfill gas in cogeneration engines and boilers. At the Civic Centre waste hot water from the engines provides building heating in winter and feeds absorption chillers providing air conditioning in the summer. This replaces 2.1 million litres of LPG each year with direct savings to local taxpayers of NZ$ 3M. In addition, the City Council sells carbon credits for up to NZ$ 4M each year.