Landfill gas produces renewable energy
A little known fact about Kate Valley is that the Landfill is one of the largest producers of ‘green energy’ in Canterbury at the Gareth James Energy Park. The Landfill is a large bio-digester that processes organic waste allowing its energy potential to be captured and used beneficially. Decomposing organic material in the Landfill such as food or garden waste produces gas, predominantly methane. In the old-style rubbish dumps the methane, which is a greenhouse gas, would escape into the atmosphere. As the Kate Valley Landfill is constructed and expanded a network of pipes is installed to collect the methane. The gas is drawn out of the Landfill and used to drive generators to produce electricity for the national power grid. The first two generators were installed at the end of 2014 producing about 2MW of electricity. Two more generators were installed in June 2019 doubling the potential electricity production to 4MW. Any surplus gas is destroyed in a high temperature flare or used in the treatment of leachate. As waste continues to decompose increasing volumes of methane will be produced. At its peak the Landfill methane gas is expected to generate 8MW, enough to power 8,000 homes. Gas will continue to be produced and harvested long after the Landfill stops accepting waste.
Water management makes wetlands thrive
There’s another environmental victory that’s occurring thanks to the Landfill. The existing natural wetlands in the lower Kate Valley have been greatly enhanced as a result of the development of the Landfill further up the valley. At the Landfill, rainwater and runoff is collected and filtered before being released into the Kate Stream that flows down the valley into Kate Pond. This stream used to dry up in summer, which meant the wetlands consequently dried up. By collecting and managing the water flow year round, Kate Pond and the natural Ella Ponds are no longer seasonal wetlands, but have grown in size to 12 hectares and now support a wide variety of native species, such as harakeke/flax growing at the verges, and trees that like having their roots in damp soil. The wetlands are also a habitat for birds including rare species such as the spotless crane. Even after the Landfill stops accepting waste, the water management measures will continue to provide a regular flow of water through the Kate Valley wetlands.