For a primarily renewable energy system, energy storage is needed. An estimated 310GW of grid-connected energy storage will be needed before 2050 to meet the 2°C Paris Agreement target. Energy storage is provided by a diversity of technologies, only a few of them mature, from an at-present nebulous industry. However, current technologies are similar in that their implementations store energy at day-to-week-long capacities. In an energy system with greater than 80% renewable energy, however, energy storage must provide month-long levels of capacity to support seasonal variations in electricity demand (the UK demands 25% more electricity in its winter months than its summer ones).
On 21 January, researchers at the University of Edinburgh and the University of Glasgow published a study of porous media compressed-air energy storage (PM-CAES) used in sedimentary basins in the North Sea. CAES is one of the more mature energy storage technologies, but its application to porous media is novel. The large number of sedimentary basins known to exist makes the concept of PM-CAES worth investigating. Sites can be evaluated using a wealth of existing geological data derived from resource exploration. The researchers modelled a PM-CAES system to supply the UK and estimated 77-96TWh could be stored—equivalent to 160% of the country’s January and February electricity demand.
This research has been released in the lead-up to the Energy Storage Summit, a February conference in London that brings together actors developing, promoting, and legislating for energy storage. A theme in this year’s Summit is expected to be behind-the meter storage (energy storage decentralised to household and business levels). The Summit and its themes should not necessarily be contrasted with the PM-CAES study. The Summit addresses the present and short-term future of energy storage, with less consideration given to technology studies. Nevertheless, the juxtaposition of an ostensible PM-CAES infrastructure megaproject with the UK energy system, which is tending towards decentralisation, is an interesting one. Future discussions may consider the roles of decentralised, behind-the meter and centralised, front-of-meter systems for providing energy security when seasonal capacity energy storage is demanded.