Energy storage from a wind, tidal, and wave farm via hydrogen

As renewable energy penetration increases, energy storage becomes essential. Hydrogen offers a viable option for seasonal storage, with reversible solid oxide cells enabling both hydrogen production via electrolysis and electricity generation from stored hydrogen in fuel cell mode. We investigate a cost-optimized, self-sufficient island grid near Ramsey Sound and the Celtic Sea—conceptualized as a localized grid without external power exchange. The grid aims to meet an annual energy demand (AED) of 807 GWh, equivalent to the annual energy production (AEP) of tidal energy in Ramsey Sound, using electricity from offshore renewable energy (ORE) farms and stored hydrogen. A model using Python for Power System Analysis (PyPSA) optimizes installed capacities for ORE farms and reversible solid oxide cells, compares underground geological storage with compressed pressure vessel storage, and determines recommended hydrogen storage volumes. Hydrogen production location (onshore vs. offshore) and heat storage—used to recover heat from fuel cell mode to improve electrolyzer efficiency—are also optimized. Subsea cable capacity is selected by the model rather than being fixed. Results show that wind farms require the lowest hydrogen production capacity among ORE types (17% lower than wind farm capacity), while tidal farms need the least hydrogen storage (two-thirds of wind and one-third of wave requirements). Wave farms, with a lower capacity factor (47% vs. 66%–67% for wind/tidal), demand high hydrogen production (96% of wave farm capacity) and storage (three times tidal and double wind). Under current 2050 cost predictions and capacity factors, wind combined with hydrogen storage is preferred. Tidal energy is recommended to contribute to the energy mix (34%–57% of total installed electricity production capacity), when only expensive compressed pressure vessel storage (∼40× costlier than geological storage) is available as it significantly reduces storage needs. Future improvements in wave and tidal costs or wave capacity factors could make them valuable contributors, potentially halving overall storage requirements. Most simulations favor onshore hydrogen production for storage purposes.