Gravitricity, a Scottish energy storage company, has revealed plans to expand their underground gravity energy system to include hydrogen and heat storage.
Gravitricity has filed a global patent application to convert purpose-built shafts into pressurised energy stores capable of safely storing large amounts of gas.
Each Gravitricity shaft, according to Wright, will act as a large, sealed pressure vessel. The shaft will be used to store large amounts of gas, which will be more cost-effective and safer than above-ground pressure storage vessels. Furthermore, it will increase the system’s storage capacity.
The Gravitricity team intends to construct a single or multiple shafts alongside a green hydrogen electrolysis plant. The plant’s output would be stored as a buffer into the gas grid and excess electricity would be stored for use by the electrolysers when needed.
“The future hydrogen economy will need to find economic and safe ways to store hydrogen where it’s needed,” says company founder Martin Wright. “At present, our domestic gas network has vast amounts of storage built in – under the North Sea. The gas grid of the future will be powered by intermittent renewables – and that means we need to find ways to store green hydrogen when energy is plentiful, close to where it’s required”.
Says Wright: “This will not only smooth the input and output of the green hydrogen plant, but it will improve the economics, bringing down the cost of green H2. The hydrogen store could also be used as a fuelling point, providing low (or zero) carbon hydrogen fuel for heavy goods vehicles, ships or trains, or be used to generate significant additional quantities of electricity if required.”
Wright believes a pilot hydrogen storage system can be in place within a few years.
Company managing director Charlie Blair explains the company’s goal: “The majority of early schemes will be built in existing mine shafts, but we are already in discussion with a major UK concern with plans to build a purpose-built shaft – solely for our gravity system.
