We have a bio-gas generator located at the Totara Road Wastewater Treatment Plant, which supplies power to the treatment plant and Awapuni Resource Recovery Centre.
Methane gas is captured from the retired Awapuni Landfill – decommissioned in 2001 – and from sludge digesters at the wastewater plant. The digestors use a biological process to break down sewage sludge. The process is designed to capture the bi-product – methane gas – before feeding the gas into the generator as a fuel source to produce electricity.
Not only does this prevent methane gas from polluting the environment, but the electricity produced offsets about 40-50 per cent of the total annual power requirements for our wastewater plant.
In the year to March 2021, the bio-gas generator made 1,992 Megawatts an hour, while consumption at the treatment plant was 1,885MWh. That means 107MWh was sold back to the grid.
Since February 2018, we have made $11,600 from selling electricity back to the national grid.