Net Zero Energy

A proposed 600 MW long‑duration energy storage project in County Carlow, Ireland, using surplus renewable electricity to produce green hydrogen, store it underground in lined rock caverns, and reconvert it into electricity for the national grid.

Green hydrogen production in this context refers to generating hydrogen via water electrolysis powered by renewable electricity, such as wind or solar, so that the resulting hydrogen has very low lifecycle greenhouse gas emissions.[6] In the Rathrush project, surplus renewable electricity that would otherwise be curtailed is intended to drive electrolysers that split water into hydrogen and oxygen, with the hydrogen stored for later use in electricity generation.

Lined rock caverns are engineered underground chambers excavated in competent rock, whose walls are sealed with a tight lining so gases such as hydrogen can be stored safely under high pressure.[8] This approach has been used for storing natural gas and other hydrocarbons and is now being adapted for hydrogen, particularly in regions lacking suitable salt formations for conventional salt‑cavern storage.[8]

Long Duration Energy Storage refers to technologies that can store energy for many hours, days, or even seasons, going beyond the few hours typically provided by lithium‑ion batteries.[9] Hydrogen‑based LDES uses green hydrogen as the storage medium, enabling large‑scale, long‑term storage of energy that can support high shares of variable renewables in the power system.[6][9]

County Carlow

A proposed 600 MW long‑duration energy storage project in County Carlow, Ireland, using surplus renewable electricity to produce green hydrogen, store it underground in lined rock caverns, and reconvert it into electricity for the national grid.