In this year's Annual Plan, Councillors have approved projects to increase power generation at the Turitea Water Treatment Plant and at the Awapuni Landfill.
The Council's mini hydro station was commissioned in 2002 and provides sufficient energy to operate the treatment plant and sell excess power to the national grid.
In the Annual Plan, it's proposed to install a $300,000 dedicated turbine which will supplement the four water pumps and generate power from water in the upper dam. The four pumps will instead generate electricity from excess water that currently spills over the dam in wet weather.
Water and Waste Services Manager, Chris Pepper, says the detailed design work is currently being commissioned and the new turbine is scheduled for installation in 2009.
"The outcome will be more effective utilisation of the hydro scheme and additional revenue for the Council through the sale of excess power under its arrangement with Mercury Energy," Chris Pepper says.
It is also proposed that more methane gas can be extracted from the former landfill and converted to electricity.
The Council is proposing to purchase a generator which will be co-located alongside the existing one. The likely outcome will a doubling of the present generation.
Chris Pepper explains that at present the City Council has 17 active gas wells to collect the methane gas from the landfill. The Council intends to drill eight further wells and connect these with the new generator.
"With the additional wells we're hoping to double the generation capacity subject to the availability of methane gas which will be determined through testing the wells later this year," he says. "If tests prove successful the generator will be fully commissioned by June 2009."
The Council has budgeted $1.35 million for the generator, wells, the installation of pipes and the electrical work.
As part of the landfill gas development, the Council is also investigating the harnessing of methane gas generated from digesters at the Totara Road Treatment Plant. The digesters are part of a process to treat wastewater at the plant.
Chris says the proposal is to pipe the methane gas to the generators at the landfill and, in return, receive hot water as a by-product to maintain the temperature of the digesters.
Since its commissioning in 2005, the methane gas plant has powered the wastewater treatment plant, the landfill operations and has sold additional energy to the national grid.
However Chris Pepper points out that, to achieve a sustainable financial return from the second generator, the Council will offer carbon credits for sale under the proposed New Zealand Emissions Trading Scheme.
"We are recognised as a leader in renewable energy and these projects will retain our status as an innovative city that is at the forefront of sustainable, alternative energy," he says.