Green hydrogen production and storage at wind farms: An economic and environmental optimisation

As the levels of variability on the electric grid increase, the occurrences and magnitude of curtailment increase accordingly. Powering electrolysers using curtailed wind is a potential means of employing this otherwise wasted energy, as well as displacing fossil fuels in sectors such as transport and heating. In this paper, an optimisation model, capable of determining the optimal sizing of a curtailed-wind-driven green hydrogen production to maximise profit is proposed. It considers system's technical characteristics; its location relative to the market, the regions wholesale electricity price, the target market selling price, and the windfarm's projected curtailment profile. The subsystems, including transport, storage, compression, and grid contribution as well as the electrolyser are sized to meet this optimal level. The hypothesis of whether the market into which the hydrogen is sold into plays a significant role in the sizing and profitability is addressed through 36 scenarios. A low curtailment, low distance scenario maximises the electrolysers size (60 MW) at a selling price of 6.7 €/kg or above, however, at 6.6 €/kg the electrolyser is sized at 14.86 MW. The storage decreases the profit by up to 40 % and when the transport is the dominant expense, it constitutes around 50 % of the expenditure. The variation in profitability from one curtailment profile to another is much more significant at a high electricity price compared to a low price. Furthermore, considering CO₂ emissions or reduction in the payback period in the analysis will result in a different system schematic.