Wollongong startup inks deal with local miner to examine deploying gravity storage in 8 disused mine shafts

Green Gravity, an Illawarra-based startup proposing to use old mine shafts for gravitational energy storage, has inked a deal with local mining company Wollongong Resources to examine deploying the technology in up to eight decommissioned and inactive mineshafts in the Illawarra. 

The two companies have agreed to work collaboratively to size and design gravitational energy storage systems. If found to be feasible, the partnership could deliver more than 100 MWh of storage within the greater Sydney metropolitan area, Green Gravity says. The study will also assess the positive impacts to mine closure, rehabilitation, and ecological impacts that Green Gravity’s technology can enable. 

Headed up by former BHP executive Mark Swinnerton, Green Gravity is proposing to lift and release ultra heavy weights in legacy mine shafts to turn a turbine that creates electricity – essentially providing an alternative to pumped hydro or batteries without the need for water or chemicals. Swinnerton is adamant his company has distinct merits, many of which stem from the fact its concept is rooted in redeploying abandoned but very abundant infrastructure, lowering both the capital and environmental outlay of the projects.

This year, the startup signed similar deal with another miner, Yancoal, as well as with Romanian state-owned energy company Complexul Energetic Valea Jiului SA, seeking to examine opportunities in Europe. In total, these deals pertain to 23 different sites.

The company commissioned its Gravity Lab demonstration plant earlier this year in Port Kembla, also on the New South Wales south coast. “The facility enabled accelerated technical research, resulting in the need for site deployment studies,” Swinnerton said.

Of the Wollongong Resources partnership, he added: “Wollongong is an ideal location… the region has large industrial power demand combined with a rich coal mining history.”

“Green Gravity provides important diversification in the energy storage mix. The technology benefits from having no waste streams, minimal land and aesthetic impacts, and offers energy security benefits by reusing infrastructure we already have right here in Australia.”

Green Gravity’s technology is flexible in two keys ways, Swinnerton previously told pv magazine Australia. “The first one is the power of the system is associated with how fast we move the weights through the mine shafts. Of course a motor can go at different speeds, therefore we can elect to change the duration and ratings of that dynamically, if we need to.”

“We’re also designed to have multiple durations and we think these deep mine shafts [which can be double the height of the Sydney tower in depth] have a real opportunity for mid or long duration storage.”