The role of grid-scale energy storage in deep decarbonisation

The role of grid-scale energy storage in deep decarbonisation

Help us bring you a brighter local energy infrastructure. Image credit: hanu_q, used via Flickr CC BY-SA 2.0 licence

Help us bring you a brighter local energy infrastructure. Image credit: hanu_q, used via Flickr CC BY-SA 2.0 licence

ECOE member Jeff Ridley recently attended an Imperial College London seminar with the above title. Jeff produced the following summary to share with the organisation.

The notion here was that we will need seasonal timescale energy storage to fill the gaps in renewable generation. Clearly battery storage can handle the day-to-day fluctuations. However, the presenter said that seasonal hydrogen storage is too difficult in practice. Instead she argued that methane storage and consequent burning in existing gas power stations might be the solution.

We can make methane from renewable energy, using CO2 and hydrogen from water. Then, we can remove the CO2 directly from the atmosphere or from carbon capture at fossil-fuel power stations. As part of this system, we can store methane, the same as natural gas, in deep reservoirs, salt caverns perhaps. We can then release and burn it as required with no net emissions. It is, however, an inefficient process at just 35% efficiency. Other storage methods, such as water pumping for hydro-electric storage, reach 80%. Depending on the national mix of generation, it will be used rarely – when there is low wind or solar for more than 2 days.