Energy company Corre Energy said that construction of four salt caverns at its two Ahaus energy storage projects in Germany are now 75% complete.
Corre said this represents the equivalent of over 60 hours of storage capacity at each project, with a completed target of 84 hours each and a combined generating capacity of 640MW.
It said its progress underpins the company's target of delivering about €500m of project value and about €2 billion in net revenues through 15-year contracts at the Ahaus site.
Corre concentrates on the development, construction and future operation of grid-scale underground renewable energy storage facilities, as well as the production and sale of green hydrogen.
It has projects in the Netherlands, Denmark and Germany.
Corre said that permits for underground construction are already in place at Ahaus and it is now amending the existing operating permits from natural gas to air storage as part of the site's transition to clean energy.
Works are being carried out by Solvay, a multinational chemical company, as part of its agreement with Corre Energy to hand over all four salt caverns in an above-ground, build-ready state.
Corre Energy is also exploring further potential new locations with Solvay in Germany and southern Europe.
Last month it agreed a deal with Eneco for the company's first Compressed Air Energy Storage (CAES) project in Germany.
The deal will see Eneco buy a 50% interest in the project, at economics to be agreed, which will include both development capital and construction equity.
Keith McGrane, CEO of Corre Energy, said the company's latest milestone combined with its recent strategic investment and offtake partnership with Eneco shows vast momentum in Germany, with critical read-across to the rest of its portfolio.
"With underground construction so advanced, we believe this is the biggest multi-day storage project in development anywhere in the world outside China. With the total German site targeting about €500m of value and 15-year net revenues of about €2b billion, our substantial value-creation plans are even closer to being crystalised," he added.
