District cooling is not a new technology but Brisbane’s CBD will be the first city in Australia to implement the smart energy system on a larger scale than any other project in Australia’s history.
Brisbane City Council has signed an agreement for the design and planning phase for the flagship energy efficiency infrastructure project to the consortium of Cofely Australia and Thiess Services.
It will see a centralised water chilling system replace air conditioning chillers and cooling towers in individual CBD buildings with a centralised plant room that supplies chilled water via a system of underground pipes.
“When combined with Thermal Energy Storage, the district cooling system will chill water during off-peak periods and then supply it to CBD buildings during the day, resulting in significant energy savings and helping to deliver on Council’s vision for a clean, green city,” said acting Lord Mayor Cr Adrian Schrinner.
“We recognise the importance of smart energy solutions in the long-term development of the CBD and have been working towards this goal with CitySmart – our sustainability agency – and industry partners including Energex, who have provided significant financial and resource support for this project.”
Integral to the smart energy strategy of the new City Centre Master Plan, the system could potentially deliver energy savings of 10-30 per cent for individual buildings and reduce CO2 emissions by up to 24,000 tonnes per annum.
The project will negate the need to replace old chilling machines, which has a significant capital expenditure attached, and aid a shift to off-peak energy consumption, with peak energy demands expected to drop by up to 20 megawatts per annum.
“Initial investigations show a CBD-wide project could deliver more than $230 million worth of private sector infrastructure, create more than 500 construction jobs and benefit the economy to the tune of $530 million,” said Schrinner.
Elsewhere in the world, Toronto, Canada has the world’s largest lake-source cooling system, which uses Lake Ontario’s icy water as a renewable energy source.
Three high-density polyethylene (HDPE) pipes are positioned along the natural slope of the lake bottom to pump water from a depth of 83 metres and transport it to the Toronto Island Filtration Plant. There, the cold water is processed before being directed to an Energy Transfer Station. Heat exchangers then facilitate an energy transfer between the cold lake water and a closed chilled water supply loop. Once the energy transfer process is complete, the lake water continues on its path to the city’s potable water system.
Only the coldness of the lake water is harnessed, rather than the water itself.
It is estimated that the process eliminates 145 tonnes of nitrogen oxide and 318 tonnes of sulphur oxide.
Meanwhile, Helsinki, Finland has turned the ground beneath a city centre park into a subterranean lake which holds nine million gallons of cold water.
This water is pumped into the city during the day’s hottest hours to cool buildings and other civic operations in place of traditional air conditioning systems.