By 2050, it is estimated that up to 20 GW of long-duration energy storage could be required to ensure the security of energy supply as the increasing reliance on intermittent generation sources continues. With decreasing capital expenditure costs and the potential for higher revenues, there is expected to be a significant rise in battery energy storage systems (BESS), especially those designed to operate for six to eight hours. This follows a similar trajectory observed in other global markets, such as California.
Pumped storage hydro (PSH) is currently the primary competitor for long-duration storage. While definitions of long-duration energy storage vary, the Department for Energy Security and Net Zero (DESNZ) defines it as the ability to discharge at full power for at least six hours. Alongside PSH, other competing technologies include compressed air storage, liquid air storage, iron-air systems, and vanadium flow batteries. However, apart from BESS, PSH remains the only commercially proven long-duration storage solution at scale.
In terms of technological specifics, BESS stores energy chemically using lithium-ion batteries. PSH, on the other hand, pumps water between two reservoirs at different elevations, releasing it to generate electricity. Compressed air energy storage (CAES) operates by compressing air into underground reservoirs and releasing it to drive a generator. Liquid air storage (LAES) functions by compressing air into a liquid and later expanding it to generate electricity, with Highview Power leading developments in this area. Iron-air systems, currently being developed by Form Energy, use the chemical process of iron rusting to store energy. Similarly, vanadium flow batteries, under development by Invinity, store energy through redox reactions involving vanadium.
Britain’s pumped storage facilities have been in operation for several decades, with the first plant introduced in 1963. At present, there are four operational PSH plants in the country, with a total capacity of 2.8 GW and an average duration of 17 hours. These early projects were designed to capture surplus nuclear power, charging during off-peak hours and discharging when demand increased. Despite their ability to provide long-duration storage, current market conditions still drive them to follow a single daily cycle, charging overnight and discharging during the evening.
The construction of new pumped storage facilities has stagnated, with no new plants introduced in nearly 40 years. However, Glyn Rhonwy, the first new plant in decades, is set to go online next year. This development is expected to contribute to a 70% increase in Britain’s pumped storage capacity by 2050, with an average storage duration exceeding ten hours. Other storage technologies are predicted to add up to 10 GW of capacity by 2050, although this is only expected to occur after 2030.
While PSH continues to play a dominant role in long-duration energy storage, the growing presence of BESS and emerging technologies may drive further diversification in energy storage solutions, ensuring a more secure and flexible power grid by 2050.
SAE Renewables Limited (LON:SAE) was founded in 2005 as a supplier of tidal stream turbines, SAE quickly grew to include development of tidal stream projects and is the majority owner of MeyGen, the world’s largest tidal stream energy project.
