Cairns isn’t letting water or solar go to waste


Two things to know about Cairns, it’s hot and wet. Thankfully, the North Queensland brains-trust has got together and found a way to simplify things by bringing those two facts together: solar-powered Waste Water Treatment Plants (WWTP). 

Four small-scale solar farms are currently under construction across five of Cairns’ WWTPs, a constellation of solar PV that will generate approximately 2.92 GWh of energy annually, and meet a quarter of the plants total energy requirements.

Moreover, this investment in renewable energy will reduce Cairns Council’s absolute emissions by 7%. Cairns Council has yet to commit to any emissions targets, although it did say a report with options (and associated pathways) for a 2030 emissions reduction target would be presented to Council in the first half of 2020. There has been no word yet on this report. 

Although, this is not to say that Cairns is a complete clean energy neophyte. The imminent completion of these four mini solar farms will take the Council’s solar capacity to almost 2.8 MW. “This is a significant project,” said Cairns Mayor Bob Manning, “especially when you consider that once complete, there will be a total of 4200 panels installed across five sites; the average house has 20-30 panels on its roof.” 

Unless it’s solar, it’s a waste 

According to a paper published in the International Journal of Environmental Research and Public Health, solar PV, and particularly solar thermal energy, are ideal energy sources for wastewater treatment plants. Wastewater treatment plants operate 24/7 with a stable load, meaning that electricity consumption takes up more than 30% of total production costs. As the paper’s authors note: “The combination of photovoltaic power and wastewater treatment with the implementation of contract energy management can further reduce the cost of wastewater treatment.”

The Cairns Regional Council’s installations are taking place at Marlin Coast WWTP (756 ground-mounted panels), Northern WWTP in Aeroglen (1484 panels), Southern WWTP (1,484 ground mounted panels), Edmonton WWTP (combination of 392 ground and rooftop panels) and Gordonvale WWTP (84 roof panels). 

The $3 million construction, expected to see completion in July 2020, has been undertaken by Solgen Energy Group, whose CCO David Naismith said that local businesses and resources had been tapped for the job that would see 1.7 MW rolled out across the various WWTPs. 

Solgen Energy Group is no stranger to commercial and industrial solar installations, indeed it was the EPC contractor behind the 2.1 MW rooftop installation atop Hilton Foods Australia thought to be Australia’s second-largest privately-owned rooftop PV array.

The panels, said Naismith, are bifacial and entirely made of glass, systems that will maximise solar production through converting sunshine and its reflections to electricity via both sides of the panel. “Cairns Regional Council’s solar initiatives are an outstanding example of reducing costs and reducing emissions while utilising redundant space such as rooftops and reclaimed land.” 

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