The impact of seasonal and interannual variation of renewables on the potential of Power-to-Gas in the UK

Power-to-Gas is the process of converting electricity into hydrogen gas by rapid response electrolysis and subsequent injection into the gas network for heating and transportation. Power-to-Gas provides a potential solution by using renewable energy and making use of existing gas infrastructure. Through the energy vector of hydrogen, rather than electricity, both the gas and electricity network infrastructure can potentially be better used to help increase the renewable penetration and also facilitate a transition from natural gas to a ‘greener’ mixed gas. Many issues surrounding renewable Power-to-Gas are currently uncertain and require analysis. To reduce the cost of Power-to-Gas, a widely accepted approach is to use excess or otherwise-wasted renewable electricity. Excess electricity can be the result of the limited electricity network transfer capacity and/or due to a mismatch between demand and renewable generation. While the excess electricity is at low cost for Power-to-Gas, it is not consistently available. In fact, its availability could be much less than the variable renewable source itself, since excess only occurs when renewable output is high. Given that the variation of renewables could significantly impact the performance of Power-to-Gas systems, the modelling of Power-to-Gas with renewables at high temporal and spatial resolutions across multiple years is essential to capture the accurate availability of Power-to-Gas, and therefore study the potential value and optimise its deployment. One of the challenges to understand such impacts is the lack of available tools with which to study Power-to-Gas at high temporal and spatial resolutions and also across multiple years. Using a high-resolution model of the GB integrated power and gas system and 15 years of simulated wind and PV generation data, this study identified the location and availability of excess electricity across the lifetime of Power-to-Gas system. This enabled comparison of levelised cost of electricity (LCOE) between Power-to-Gas and other alternatives of low-carbon approaches in future energy systems. The preliminary analysis shows that while power-to-gas availability increases with greater installed capacity of renewable generation, it shows significant regional imbalance and daily, seasonal and interannual variation, which limits the overall capacity factor and could significantly challenge the value of Power-to-Gas systems.