After years of research and a prototype built in an industrial warehouse, a renewable energy company has signed a deal it hopes will make it the first company in the world to turn a disused mine shaft into a battery.
Green Gravity’s test site will be established at Russell Vale Mine Shaft 4, a coal mine shaft that has not operated since 2015.
It is one of five mine shafts at Russell Vale owned by Wollongong Resources in the Illawarra escarpment.
The technology lowers dense weights down a mine shaft to spin a turbine to create electricity during peak demand, then draws on solar power to pull the weights back up during the day.
“This is the most important step Green Gravity has had since setting up our first trials at Port Kembla in 2020,” CEO Mark Swinnerton said.
“We’re going to take the mine shaft and insert new equipment and new lifting gear, and that equipment will help us move very large masses up and down the mine shaft.
“When it’s upgraded to a commercial level, it could power up to 10,000 homes in the evening when they’re using their electricity.”
It comes nearly a year after the company partnered with Glencore to establish its technology at the former Mount Isa copper mine in north-west Queensland.
Mr Swinnerton said deployment at Russell Vale would happen first at a cost of $10 million.
“We’ll be installing some safety and monitor equipment immediately and we expect trials to run right through 2026,” he said.
Mine turns to renewables after closure
Two other gravitational energy storage companies in the UK and US have launched above-ground systems in recent years.
Meanwhile, Green Gravity aims to be a pioneer in deploying gravity batteries in old mine shafts.
The trial at Mine Shaft 4 will be conducted at 150 kilowatts of power, but the company said on a commercial scale, it could deliver increments of up to 10 megawatts over 20 hours.
Wollongong Resources closed Russell Vale Colliery in 2024 after the Resources Regulator issued a prohibition order that stopped work at the site after five underground fires.
Company secretary Sanjay Sharma said after investing $1.5 billion trying to keep the mine productive, investors decided to “give up and see what we can do with the remaining assets now”.
“It was the saddest day when we had to let more than 200 people go,” he said.
Mr Sharma said the idea of reusing the mine shafts for renewable energy came at a perfect time.
“We weren’t sure whether we would be able to sell the mine … nothing was decided yet,” he said.
“So when Mark [Swinnerton] came to me and shared the idea, I was excited because we are always happy to support any project that can help the environment.”
Mr Sharma did not rule out any future sale of the Russell Vale mine, but Green Gravity said its lease would be a condition of any future sale.
haft’s proximity to substation
One of the major challenges facing any renewable energy project is how to get the electricity generated into the grid.
Mines require significant electricity, and Shaft 4 has its own electrical substation on site.
“We don’t need to take new land and convert it to a renewable energy project,” Mr Swinnerton said.
“That makes it easier and faster for us to connect to the grid.”
Mr Sharma said using existing infrastructure benefited both parties.
“Most likely we would’ve ended up spending millions of dollars to close these shafts and rehabilitate them,” he said. “It was a mutually beneficial situation and it was a no-brainer.”
Focus on post-mining land
Five months ago, the New South Wales parliament tabled its Beneficial and Productive Post-Mining Land Use Inquiry report, of which Mr Swinnerton gave evidence.
It made five findings and issued 13 recommendations aimed at opening up tourism, manufacturing and renewable energy development opportunities at disused mine sites.
Energy Futures Network director and former general manager of Endeavour Energy, Ty Christopher, said energy innovations such as Green Gravity addressed this very issue.
“It uses sunk capital costs like mine shafts and electricity connections … which is what makes Green Gravity so sensible and so viable,” he said.
“And because this technology mixes together so many different but proven pieces of technology … I think an accelerated program for commercial production is perfectly achievable.”