Can we use hydrogen as a storage vector to reduce the cost of intermittent renewables?

29 August 2013

Hydrogen has long been identified as a zero-carbon energy carrier for transport applications. Yet there are other potential roles for hydrogen in low-carbon energy systems that have received relatively little attention. One option is power-to-gas, in which excess intermittent renewable generation is used to produce hydrogen that can be stored for subsequent electricity generation or injected into the natural gas network to avoid supply-demand imbalances. For countries that currently rely on piped high-carbon natural gas for heating buildings, hydrogen is a low-carbon heating fuel that could be delivered using the existing gas networks as an alternative to electrifying heat. The electricity and gas networks, which currently operate independently, could be integrated in the future, with the gas network providing an important short-term energy storage medium to cope with periods of peak energy demand. Larger storage (e.g. salt caverns) could be used for inter-seasonal storage of hydrogen to deal with winter peaks in heat demand. We have examined the potential for hydrogen to be a storage vector in the UK electricity and gas systems. First, using the UK MARKAL energy system model, we have examined the cost-optimal long-term use of hydrogen to decarbonise the gas network, through injection (Dodds and McDowall 2012; Dodds and McDowall submitted) or through conversion to deliver only hydrogen (Dodds and Démoullin in press). This model is not able to represent inter-seasonal hydrogen storage so we have created a new energy system model that is based on the TIMES platform to examine the potential benefits to the UK of these technologies. This new model also includes all greenhouse gas emissions, an improvement from UK MARKAL which represents only CO2 emissions, so it also allows us to assess the benefits of avoiding methane leakages from the gas networks. The representation of power-to-gas technologies is also much improved. In this paper, we discuss the prospects for using hydrogen as an energy carrier in the UK gas networks using UK MARKAL. We then introduce the new UK TIMES model and consider the potential for power-to-gas and inter-seasonal storage to contribute to the planned large-scale deployment of renewables in the UK in the future.