Some of Christchurch’s wastewater will be redirected into a building in the Metro Sports Facility’s car park, where the heat can be extracted through heat exchangers and used to warm the water being supplied to the facility’s heat pumps
Metro Sports Facility’s eco-friendly energy system a New Zealand first
People in central Christchurch will no longer be watching valuable energy go down the drain, with the Metro Sports Facility set to include New Zealand’s first wastewater heat recovery system.
Otakaro Ltd chief executive John Bridgman says the location of the Metro Sports Facility on St Asaph Street has made incorporating the eco-friendly energy system possible. “Showers, sinks, dishwashers, washing machines and even toilets all result in hot water going down the drain. This lifts the temperature of the major wastewater pipe running down St Asaph Street to a useful 17 degrees C. With this system we will be able to capture and recycle this otherwise wasted energy to help heat the pools and building.”
Part of the St Asaph Street wastewater pipe flow will be redirected into a building in the Metro Sports Facility’s car park, where the heat can be extracted through heat exchangers and used to warm the water being supplied to the facility’s heat pumps, Mr Bridgman explains. “First, the sewage will be ‘screened’ to filter unwanted material and enable the flow to pass through a heat exchanger. By using the exchanger, there is no contact between the sewage and the pool.”
The wastewater heat recovery system is being supplied by Melbourne-based Environmental Technology Solutions and will cost about $1.5 million to install. Company director Rick Edwards says wastewater heat recovery energy systems have been very successful in the Northern Hemisphere already.
“This waste heat recovery project will provide significant benefits to the Christchurch community by reusing waste heat energy that has already been paid for to produce approximately 3500 kW of energy per annum for heating at the Metro Sports Facility, which is the equivalent of powering up to 2000 homes per day.”
A valuable energy resource
Nigel Cox, head of recreation, sports and events for Christchurch City Council, says the innovative heating system is a major step towards removing the word ‘waste’ from wastewater and instead recognising a valuable energy resource.
“It’s great to see Christchurch leading the way with alternative energy solutions, and the council is grateful for the grant towards the project from the Energy Efficiency and Conservation Authority (EECA). To be able to make efficient use of our wastewater for the benefit of the city is an exciting new string to our bow and a really smart investment. The wastewater heat recovery system will save $100,000 a year compared to groundwater-sourced heating and help lower greenhouse gas emissions.”
Sewage water is between five degrees and nine degrees warmer than groundwater, so the heat from sewage water is more efficient than that from a cooler groundwater-sourced system, he adds. “The Metro Sports Facility requires a great deal of heating, so the St Asaph Street pipe is in an ideal area by the venue to help deliver a very clever energy system. Council staff have also organised a map that shows the ‘hotspots’, and how much heat is potentially available at other locations with this renewable energy source,” Mr Cox says.
There will be some disruption to traffic on St Asaph Street (between Hagley Avenue and Antigua Street) while the system is installed in 2021, so contractors can access the wastewater pipe.
Set to open in early 2022, the Metro Sports Facility will be the largest aquatic and indoor recreation and leisure venue of its kind in New Zealand, accessible to people of all ages and abilities.
Watch how the wastewater heat recovery system works here