Nothing says energy transition quite like a renewable energy facility being built on an old fossil fuel asset. Solar farms have been built on or near several old coal plants, and now the South Australia state government utility SA Water plans to build a new solar farm with more than 35,000 solar PV panels on the site of a former oil refinery.

SA Water said on Thursday that it has agreed to purchase 14 hectares of land at the former ExxonMobil Port Stanvac oil refinery, next to the Adelaide Desalination Plant which the solar farm will help power. and as part of the utility’s push to a “zero cost energy future” that involves more than 150MW of solar across dozens of sites, and 34 megawatt hours of battery storage.

The ExxonMobil refinery was closed in 2003 and demolished in 2014, and the overall 240 hectare site is being remediated to pave the way for other industry activity.

“The site will see a complete turnaround from facilitating a traditional energy source to housing renewable energy resources that will reduce our carbon emissions by 10,710 tonnes per year,” said Nicola Murphy, the head of SA Water’s Zero Cot Energy Future division.

“Solar panels are already being installed on our existing land across the road at the Adelaide Desalination Plant and we’re hoping to start construction on this new site in mid-2020.”

The new solar farm will feature fixed-tilt racking systems and is expected to generate an average total of 21 gigawatt hours (GWh) of electricity per year, which combined with a battery storage system will offset around half the plant’s energy costs, and sometimes produce more than required.

“During high production mode the combined solar generation and battery storage will offset around 50% of the plant’s energy costs, with the facility’s existing hydro turbines making additional smaller contributions,” Murphy said.

“In times of higher rainfall when the plant operates in a lower production mode, the combined solar generation and battery storage will provide more energy than the facility requires and return the excess to the National Electricity Market.”

SA Water is one of the largest single electricity consumers in the state, and its drinking water and wastewater pumping and treatment operations throughout a dry 2018/19 cost $83 million.

In all, SA Water plans to install more than 500,000 solar panels across 37 of its sites across the state to produce 242 GWh of electricity, along with 34 megawatt hours of battery storage.