Armed with £2 million ($2.7 million) in grants from the U.K. government, EDF UK will demonstrate innovative energy storage technologies with potential for the longer duration energy storage required to support balancing of the intermittency of wind and solar energy sources.

One project to be conducted in partnership with the University of Bristol and Urenco will test the storage of electricity as hydrogen in metal hydride form in depleted uranium, with release via a reversible fuel cell. When stored in this form, hydrogen has approximately two times the volumetric energy density of liquid hydrogen, enabling it to be stored more efficiently. Urenco will supply depleted uranium 238 as a waste product from fuel production and reprocessed spent mixed oxide fuel.

Pivot Power, a part of EDF Renewables, will participate in a two-part demonstration project, with Invinity Energy Systems. The first venture will establish the feasibility of developing one of the largest storage-enabled solar power resources in the U.K. The second initiative would see delivery of a solar-coupled 10 MW/40 MWh Invinity vanadium flow battery. Technology that stores energy in zinc, an inexpensive and high energy density metal, will also be explored.

Stratostore, the final project, will explore how electricity can be stored as compressed air and released to meet system demand. The storage is proposed in mothballed EDF-owned gas cavities in Cheshire to test prospects for a 5 MW plant to supply more than 8,000 homes and to determine the feasibility of scaling up to a 100 MW or greater capacity system.

Each of these projects will be evaluated for the storage of energy over daily, weekly or monthly fluctuations and for the provision of vital backup for times when renewable energy is not being produced.