Beyond hydrogen: The long-duration energy storage potential of emerging renewable fuels in UK

The United Kingdom (UK) has ambitious targets to transform its energy system away from fossil fuels towards sustainable alternatives. Today, the predominant share of the primary energy supply is covered by gas and oil, but with the UK government’s Clean Power 2030 Action Plan, the UK aims for a fast acceleration towards renewables: By 2030, clean sources should constitute at least 95% of the UK’s electricity generation. The ambitions were recently substantiated with a record-breaking 8.4 GW offshore wind action, being the biggest ever in Europe. The UK government expects approximately 50 GW offshore wind, 30 GW onshore wind, and 50 GW solar PV installed by 2030. To accommodate such high penetration of renewable electricity generation capacities, energy storage and adequate energy reserves are essential to ensure a stable power supply.  

Using the open energy system model PyPSA-Eur, we optimize the transition pathway for the UK energy system towards a net-zero emissions system in 2050. For this, we use high spatiotemporal resolution, allowing us to derive energy strategies on a regional level. For an integrated energy system, with electricity, heating, industry, shipping, aviation, and land transport sectors coupled, we inspect the aspect of energy reserves from a wider perspective. Replacing fossil fuels with e-fuels at the sectoral end-users also brings additional benefits, since the conversion from electricity also eases storability and enables long-duration energy storage, which can be exploited in the power sector.

Inspired by recent market trends and research studies, our study investigates whether cost-efficient alternative strategies to a future hydrogen infrastructure exist, to link the power sector with industry sectors and for a provision of long-duration energy storage in a highly renewable energy system. In this work, we evaluate a ladder of energy storage solutions. The first step covers technologies seemingly preferred today, e.g., Li-ion batteries, which have seen high learning rates in combination with low energy conversion losses. The second step includes technologies that are cheap due to their low complexity, e.g., electrical boilers in large hot water tanks, but require more centralization of the supply. The further steps represent technologies with increasingly conversion losses and expenses for the conversion links but offering a medium more suitable to store at large volumes. Using a techno-economic optimization approach, we evaluate the cost of distinct systems that rely on either battery, hydrogen, e-methane, or methanol storage, while we assess their operational and practical benefits. To address meteorological uncertainties, the pathway optimization is performed for a range of reanalysis years.

From our study, strategic allocation of storage and energy reserves on a regional level for the UK can be derived, and our results contribute to the planning of a resilient and sustainable national energy system.