Powering the Whanganui wastewater treatment plant makes up the lion's share of Whanganui District Council's energy costs.
The plant accounted for 43 per cent of the council's total energy costs last year, amounting to $1m in electricity and $140,000 in gas.
Water supply is the second biggest expense, making up 30 per cent of the total and costing $800,000 last year.
The council's property and services committee received a report from senior property analyst Graeme Paulger at its meeting this week.
Councillor Kate Joblin questioned the necessity of the information being presented to the committee.
The request for the report was made by councillor Rob Vinsen who said it was important information.
"Because the council has declared a climate emergency, the first thing we should be looking at is how we can make some savings in emissions," he said.
"Who would have thought that the consumption of electricity for wastewater is more than three [times] greater than it is for roading?"
Vinsen said the figures gave credibility to the need for council climate change action.
Councillor Hadleigh Reid said he agreed with Vinsen that the figures were important.
The high usage of electricity and gas for wastewater and water supply was of great concern, he said.
"What is really interesting about these two locations is that they have heaps of space - not just on the roofs but heaps of space around them," Reid said.
"As we look into our solar options with $6m earmarked over the next 10 years, I imagine we'll have solar farms all around these places and, as we can see, all the power is going to get used as it's made which will give us an obvious return."
Paulger said the energy usage was not only for the plants themselves but for the ancillary sites as well.
"What's in there is the whole wastewater activity," he said.
"It includes not just the treatment plant but a huge network of pumps getting the sewage to the treatment point.
"And it is the same for our water supply - we have pumps bringing the water in from Kai Iwi and other locations to our reservoirs. It's not just one site for each."
Mayor Hamish McDouall said there were two parts to the council's response to climate change.
"There is mitigation and then there is adaptation," he said.
"If we don't model by examining our energy usage and emissions then how can we step forward and start the adaptation when we're not mitigating us as a business?"
McDouall said harnessing the energy generated by the wastewater plant itself was another option.
Councillor Alan Taylor said the LED streetlights introduced in Whanganui five years ago had considerably reduced the council's energy costs for roading.
"The mayor's comments about the capture of energy from the wastewater treatment plant and other sources are already in the long term plan.
"All of these figures help to inform where our climate action will go."
Joblin questioned whether the committee would simply receive the energy reports on a regular basis or whether there would be mitigation on reducing costs and emissions.
"I simply want to know where we're headed with these reports," she said.
Deputy mayor and acting committee chairwoman Jenny Duncan said although the information came through the property committee, it was the infrastructure committee's role to progress plans for water supply and waste treatment.
"I look forward to seeing the infrastructure committee's reports," she said.
• An earlier version of this story incorrectly stated the plant used $1.4m worth of gas.