Elon Musk’s Tesla batteries beware – there’s a new, cheaper and more sustainable way of storing rooftop solar on the rise, and it’s made in Wollongong.

“At Green Gravity, we are an energy storage developer and we've developed a technology called Gravitational Energy Storage,” says CEO Mark Swinnerton.

“This is about lifting very heavy objects up a legacy mine shaft, when we have excess renewable energy, and then lowering those weights back down again through the mine shaft when we want to release the energy back to the grid, which means we can take solar energy and we can reproduce it at night.”

An ingenious way to repurpose old mine shafts, the technology also has the potential to be “very competitive” price wise, Mark says.

“We believe already we'll be competitive on a capital basis with lithium ion …

“On a levelised basis – so an all-in economic cost – we think we're extremely low-cost because we're reusing infrastructure and we have very, very long-life assets.”

Council shows support

Wollongong Lord Mayor Tania Brown is excited about Green Gravity’s  prospects. Yesterday she chose the company as the first focus for Council’s new #MadeInWollongong monthly series, which will feature business leaders who are putting the city on the global map.

The launch took place in the Gravity Lab, an old shed in the Port Kembla steelworks complex where a small-scale model tower is set up to demonstrate Green Gravity's technology.

“It's a great showcase for that innovation that we want to be known for,” the Lord Mayor says. “Using clean green energy, I think is the way of the future and to be here at the coalface of this new innovation, it's fabulous.”

Council can play a key role in supporting innovation, she says.

“Through Invest Wollongong, which is a partnership with the university and the state government, we can partner together to look for grant opportunities, but it is about advocacy on their behalf, as well as promoting the good work and any assistance we can provide them in drawing attention to the type of workers that they need, or customers. We are there to help with that.”

The Lord Mayor would like to inspire more businesses to set up locally.

“I'm all about talking ourselves up – telling the world the great things that are happening here.”

Mark says council’s support is a “very big help”.

“We need a home base, and we need champions politically and community wise to be able to form that base to be able to make sure that we can be seen as credible and that we have the right credentials when we're dealing with counterparts.”

Huge international potential

Mark “very proudly” worked at BHP for 25 years before founding Green Gravity in 2021 as a response to climate change. Already his idea has attracted $15 million in investment – from the likes of BlueScope and HMC Capital – and there’s more to come. Customers are lining up not only in Australia, where we have 100,000 legacy mines, Mark says, but also in India, Eastern Europe and North America.

“In calendar 2025, we're going to complete production testing in mine shafts and be ready for first sales at the end of the year."

Repurposing old mine shafts is sustainable thinking on a grand scale.

“We have no waste because we don't use any fuel, and gravity's free and waste free,” Mark says.

It’s also timely technology, with Australia last month hitting a new record four million homes with solar, and the Australian Energy Market Operator calling for "emergency backstop" powers to switch off or turn down rooftop solar systems.

Local solution for sunset industries

Green Gravity is not only a Wollongong innovation, it could have a Wollongong application too. Tania Brown and Mark Swinnerton stand within the circle drawn on the floor to represent the old mine shaft at Russell Vale, where discussions with the owners, Wollongong Resources, are ongoing.

“We have I think over 20 coal mines around our escarpment, some of them are already not used,” the Lord Mayor said. “So if we can repurpose them to create energy in this way that they're proposing, that's got to be good for the region.”

She wants Wollongong to be known as a great place to do business. 

“We are open to innovation. The fact that Green Gravity has come here to test this new technology shows that we have the workers here and the skills to be a good testing ground, but also we then have the ability with the manufacturing sector to deliver on it as well.”

Last week Wollongong’s role as a crucible for change was officially recognised with funding announced to establish the Illawarra Heavy Industry Manufacturing Centre of Excellence at TAFE NSW Wollongong.

“The announcement by the Minns' government and Albanese government last week of the $47 million Centre for Excellence in manufacturing means we'll have the skilled people to work in these industries, and that's so important for our community,” the Lord Mayor says.

Mark says there’ll be jobs ahead for everyone from engineers to project managers at Green Gravity.

“We have 15 full-time and we have about 10 volunteers. We’d like to double the team this next year.”

Future made in Wollongong

Media coverage of CSIRO’s GenCost report released yesterday has focussed on the costs of nuclear and the polarised debate between two political parties on the war path to a federal election.

For Mark, the most important message in the national science organisation's report was the “undeniable” economics of renewable energy.

“The one and only winner when it comes to the cost of energy production is solar. Solar technology continues to scale and is outpacing cost out versus any other technology … and solar needs storage. And so I see our future as very bright.”

He also believes clean energy investment will thrive no matter what the politics at home or abroad. “It's economically rational to do what we're doing. And I think that that holds up in any political context.”