New Zealand’s biggest solar farm will float on waste-water treatment plant

Auckland utilities Vector Limited and Watercare have announced this week plans to build what will be New Zealand’s first floating solar array and the country’s largest solar array of any type.

Vector and Watercare say the floating solar array will be built atop the Rosedale wastewater treatment pond in Auckland.

No capacity has been given for the project, but the two companies claim that the project will generate enough electricity for the equivalent of 200 average households and reduce emissions by 145 tons of CO2 each year.

That suggests a size of around 1MW, or more than double the country’s current biggest solar installation, a 410kW facility at Yealands Estate Winery, although a 26MW project is being considered to supply power to the NZ Oil Refinery at Marsden Point.

Nevertheless, the Rosedale Waste Water Treatment Plant Floating Solar project is set to mark a number of firsts for New Zealand.

“It’s the first time floating solar will be seen in New Zealand and the first megawatt-scale solar project to be confirmed,” said Vector Group CEO Simon Mackenzie.

“Even larger systems are already common overseas and with reports out of Australia of costs as low as 4-5c per kWh, when that scale arrives here we’ll see solar’s real potential to set a new cap on the wholesale market which over the past few days has been around double that.

“Vector PowerSmart’s capability to design and deliver this innovative system shows how new energy solutions are key to helping business reach their economic and environmental goals, and we’re proud to be working with Watercare to help it achieve both.”

“The project is a fantastic example of how utilities can work together for the benefit of their communities,” added Watercare chief executive Raveen Jaduram. “As a large user of energy, it’s important that we look at ways of reducing our environmental footprint and becoming more self-sufficient.  Innovative solutions like this on top of wastewater ponds are a smart way to reduce operational costs.”

Power generated from the floating solar array would be used to supply electricity to the wastewater treatment plant, supplementing electricity from the grid as well as cogeneration from biogas already generated on-site.

Watercare is currently aiming to reduce its energy use by 8 GWh by 2022 and to achieve energy self-sufficiency at its Mangere and Rosedale wastewater treatment plants by 2025.

Solar in general is not widely used in New Zealand, and most recent reports put total solar capacity across the two islands at around 85MW.

However, a February report published by Transpower, New Zealand’s state-owned transmission grid operator, suggests that if rooftop solar was installed across the country total solar capacity could grow to as much as 11GW– a figure which could then grow to as much as 27 GW by 2050.

Currently, New Zealand’s electricity is primarily generated by hydroelectricity – which accounts for the lion’s share in the South Island, but which competes with wind, geothermal, coal, and gas on the North Island (according to Transpower’s live generation data). As of writing, renewables accounted for 80% of the country’s electricity generation.