Hydrogen storage

Hydrogen on these sites is stored as a compressed gas. An electrolyser does not produce at the same rate the plant uses hydrogen, and the use — injection into a digester, a separate methanation step, or another process load — does not follow the sun. Compression and buffer storage sit between those two rates.

The store is a set of 40-foot ISO containers, with compressors that take the electrolyser output up to storage pressure and let it down again for the user. The design problem is the sizing: how much compressor capacity, how many containers, and what pressure band keeps the electrolyser from tripping when the sun is strong and keeps the process supplied when it is not. That optimisation is part of the same solar and battery model, because the electricity, the electrolyser, and the store are one system.

The hydrogen is then used in biological methanation or in green ammonia synthesis. The store does not replace either step.