Electrical energy storage combined with renewable hydrogen production

• -Large-scale electrical energy storage in renewable hydrogen production was studied. • -Three storage technologies were compared based on their levelized costs. • -Flexibility of the electrolyzer and over-investing in renewable capacity were required. • -Additional use of storage was required to lower the levelized cost of storage. • -The lowest levelized cost was achieved with sand electro-thermal energy storage. The applications and need for large-scale, long-duration electrical energy storage are growing as both the share of renewable energy in energy systems and the demand for flexibility increase. One potential application is the renewable hydrogen industry, where temporal matching of renewable electricity generation and hydrogen production will be required in the future according to the new European Union regulations. In this paper, a case study of electrical energy storage utilization in hydrogen production is conducted in the Nordic context, with a high share of wind production. The storage is used in the hydrogen production process for temporal matching. The levelized cost of storage of three medium- to long-term storage technologies is assessed using an Excel-based model, with four case approaches. In the first case approach, the electrolyzer load is inflexible, while the other approaches explore how the flexibility of the electrolyzer and the increase in renewable production capacity affect the size and cost of the storage. Electro-thermal energy storage, based on sand as storage material, presented the lowest levelized cost of storage (114–198 €/MWh) due to its low energy-related investment cost. However, the results show that additional usage purposes for all examined storage technologies are required to avoid high investment costs. Additionally, flexibility from the electrolyzer load and over-investing in renewable capacity is required. In conclusion, storage should not be the only component providing flexibility in the studied system, and it should be used to integrate multiple assets in the wider energy system to reach cost-effectiveness. This paper brings novelty by expanding on the storage technology options considered in previous literature and deepening the perspective of storage as a component in renewable hydrogen production. Future research should assess the effect of electricity prices and emissions allowance prices from the regulatory perspective, which could further reduce the storage investment.