South Taranaki District Council will replace the natural gas-fired boilers at the Hāwera Aquatic Centre with electric heat pumps. Photo / Supplied

South Taranaki District Council plans to reduce its greenhouse gas emissions by around a third, mainly by replacing the natural gas-fired boilers at the Hāwera Aquatic Centre with electric heat pumps.

Property and facilities manager Phil Waite said installing heat pumps at the aquatic centre would have the single biggest impact on reducing the council's emissions across all its facilities.

"It's estimated to reduce the aquatic centre's annual carbon emissions by 324 tonnes, the equivalent of taking 118 cars off the road," Waite said.

The aquatic centre accounted for about 97 per cent of the council's annual natural gas use, which represented a third of its total carbon emissions.

"In addition, there will be significant energy savings to be made through the upgrade, so it's a win-win for the council, our ratepayers and the environment."

Environment and sustainability officer Tarin Hunt said the conversion to electricity would reduce emissions because the heat pumps produced nearly half the carbon dioxide (CO2) emissions per kilowatt hour (kWh) compared to the boilers.

"Grid electricity in New Zealand is predominantly generated from renewable sources and has relatively low average carbon emissions, unlike the carbon emissions created from the creation of fossil fuel combustion," she said.

Hunt said New Zealand grid electricity uses 0.00010 tonnes of CO2 per kWh, while natural gas produces 0.00019 tonnes of CO2 per kWh.

She said the emission factor for electricity should also head downwards over time as the grid worked to decarbonise and move gas and coal-powered power plants towards last resort options rather than standard go-to's for power.

In contrast, the emission factor for gas was determined by the chemical composition of the gas.

Electric heat pumps were also significantly more efficient than boilers, Hunt said.

"Also with a gas boiler, roughly 20 per cent of the input energy is lost up the stack, so the actual emissions per unit of delivered heat would be higher. There is also the purge losses with the burner starting up."

Waite said the cost of replacing the boilers was estimated to be $448,500.

The council has received $174,000 from the Energy Efficiency and Conservation Authority's (EECA) technology demonstration fund for the installation of the heat pumps.

Waite said the rest of the installation costs would be paid for by a loan which would be paid off in seven years with the savings made from the aquatic centre's reduced energy costs, making the project cost neutral.

EECA's business group manager Nicki Sutherland said the project demonstrated the feasibility and benefits of public pools, many of which were still powered by fossil fuels, switching to heat pumps.

"We're so pleased we can help the council take out a third of its emissions, and that the South Taranaki community can relax, play and exercise in this pool knowing it's no longer polluting the beautiful Taranaki air," Sutherland said.

Sutherland said the project would be a great example for other councils to follow.

A Whanganui District Council spokesperson said the Splash Centre had a gas-powered boiler for heating water and air, as well as electric heat pumps for heating water and air. The Whanganui East Pool was unheated.

The council said it currently had no plans to replace the gas boiler at the Splash Centre with electric heat pumps.

As part of the council's climate change work, it would assess climate change mitigation options across services and facilities.

The work to install the electric pumps at Hāwera Aquatic Centre will get under way at the end of the summer season.

He has some sorting out to do in the next few weeks.