Wind farm and hydrogen storage co-location system for frequency response provision in the UK

Hydrogen-based storage systems (HSS) are becoming increasingly important in the transition to low-carbon energy systems with the aim of a net-zero carbon future [1, 2]. In particular, they are increasingly explored for the provision of ancillary services by co-location with renewable energy generators, such as wind farms. An HSS for the frequency response provision can work as follows: an electrolyser splits the water into hydrogen (H2) and oxygen using an electric current passed through a chemical solution, which delivers high-frequency (HF) responses. The H2 produced at a low-pressure is then pressurised using a compressor and stored in a H2 storage tank at a high-pressure for later use. To transform the H2 back to electricity, a fuel cell stack is used, where the H2 taken from the storage tank reacts with a catalyst, often platinum, stripping it of its electrons that are forced to move along an external circuit, creating electricity for low-frequency (LF) responses [3]. Considering the great investment and the existence of multiple components in an HSS, it is necessary to optimise the capacity and coordination of different HSS components so as to evaluate the techno-economic feasibility of the HSS project. Previous work by the University of Strathclyde and the Offshore Renewable Energy Catapult has optimised the use of battery energy storage systems (BESS) in delivering frequency response services to the AC grid [4, 5]. From an economic optimisation perspective, the optimal BESS size and operating strategies were determined to maximise the profitability of a wind farm co-located with a BESS for frequency response provision. The aim here is to adapt the optimisation algorithm to explore the feasibility of an HSS in providing Dynamic Regulation (DR) that is one of the end-state frequency response products introduced by the National Grid Electricity System Operator (NGESO) in the GB. Based on the DR market mechanisms and the technical characteristics of HSS components, an operating strategy is developed to dispatch power and hydrogen flows within an onshore HSS that delivers DR responses to the AC grid through the existing connection point of a particular wind farm. The resulting DR payments and other cash flows are translated into the net profit of the HSS co-location project, which is then maximised by a particle swarm optimisation (PSO) algorithm, suggesting the best sizes of the HSS components and the optimal strategy variables for their coordination