patented Large-scale, long-duration
GREEN Energy Storage

Many nations have the potential to be energy-independent through renewable energy. However, the missing piece of the green energy puzzle is storing that renewable energy at TWh-scale; dispatchable at any time, in any season.

Green Energy Storage will power the Energy Transition.

Green energy storage caverns


Our system stores green energy in underground salt caverns – of which there are thousands in existence already.

Making use of these relics of the fossil fuel industry uses fewer resources in setup and operation then alternate battery solutions.

Salt Caverns have been used historically to store natural gas and petroleum, and in the past 40 years to store Compressed Air for Electricity generation, but our technologies do this with higher efficiencies, as well as having the capability to safely store Hydrogen.


What can carry Hydrogen can also carry air – but not vice versa. We retrofit existing air caverns and pipes to accommodate for the specific storage requirements of Hydrogen; whether produced by us on site via electrolysis, or imported. 

Our solutions transform previous gas and petroleum storage sites to multi-use green energy storage sites; providing both Compressed Air Energy Storage (CAES) and Hydrogen storage side-by-side.

compressed air energy storge
how it works


Renewable energy or excess energy from the grid is used to drive air through a compressor.


The pressurised air is stored in underground salt caverns until there is demand for it.


When required, the air is delivered back to the surface where it is heated and expanded.


The expanded air is sent through a turbine, driving a generator and producing power.

green energy storage diagram

Heat Management
How we make our technology so efficient

Hydrogen CAES™

Efficiencies are increased with the addition of a gas turbine in our Hydrogen CAES™ system. 

Whilst hydrogen costs are reducing, natural gas can be used instead in part or full, its use decreasing as the grid decarbonises.

Hydrogen energy storage
CAES green energy storage

Green CAES™

For optimum efficiency, recovered heat can be repurposed in industrial applications, or put back into the power cycle. 

We do this with the use of Thermal Energy Management & Storage in our Green CAES™ system.

In Hybrid CAES mode, the plant switches between the two systems; burning fuel only when stored energy resources are depleted.


Zero or low emissions

Operational configurations include emission-free option and fossil fuel option with a greatly reduced carbon footprint.

Grid Scale, Long duration storage

Up to 100’s+ MW, multi-GWh+, 4 hour to multi-day storage tackles the renewable energy intermittency dilemma  

built to last

30+ Years without efficiency loss on mechanical and up to 100 years on underground caverns (and counting!)

highly efficient

Independently verified to achieve high efficiencies:
Green CAES ™ 62%-70%;
Hydrogen CAES ™ 50%->60%

asset repurposing

Utilising existing infrastructure from coal plants and salt mines results in lower financial and environmental costs with added revenue streams

proven yet unique

Based on a proven CAES system but improved upon with a more compact arrangement, greater efficiencies and lower CAPEX costs.

“If we find ways of generating AND STORING power from renewable resources, we will make the problem…disappear”

(Interview with Barack Obama)