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With the exception of pumped hydro storage, the deployment of electricity storage is at an embryonic stage
Electricity storage is not a new concept. At the end of 2012, the installed power capacity of electricity storage plants amounted to more than 128 GW. However, its development has been restricted to one technology: pumped hydro storage. Development of pumped hydro storage started in the 1960s, and the technology accounts for 99% of global installed capacity and for 78% of future storage projects – with 8.2 GW under construction and 8.2 GW planned, mostly in the US (41%) and China (25%).
After a slow start, compressed air energy storage may take off in the next few years. The first plant, a 290 MW facility in Germany, was commissioned in 1978. The second, a 110 MW plant in the US, was not built until 1991. Two large plants, with capacities of 300 MW and 150 MW, are under construction in the US, and further projects are planned in Germany and South Korea. However, the outlook is uncertain, given that several other compressed air projects have been suspended in the US, including a 2,700 MW venture in Norton, Ohio.
At the same time, large batteries are also being developed, with installed capacity amounting to almost 750 MW. Driven by development in Japan, sodium-sulfur batteries became the dominant technology in the 2000s and account for nearly 60% of stationary batteries installed (441 MW out of a total of 747 MW). In recent years, lithium-ion batteries have become more popular and account for the majority of planned battery projects. Although at a very early phase of deployment, with few projects announced, flow batteries could be a game changer in the medium term; research is being carried out at an intense rate in China and Australia.
With the exception of thermal storage, developed in recent years in conjunction with concentrating solar power plants, all other electricity-storage technologies remain marginal in terms of installed capacity. Despite the recent commissioning of a 20 MW plant in the US, flywheels struggle to find a sustainable value proposition; electrical storage technologies, either supercapacitors or superconducting magnetic energy storage, remain at an early phase of demonstration. Finally, interest in chemical storage is high in Europe, with several large-scale demonstration projects in Germany, Denmark and the UK. However, the primary aim of these projects is usually not to inject electricity back to the grid, but to green the gas or provide alternative transportation fuels.
Overall, interest in electricity storage is increasing, as indicated by the development of roadmaps by the International Energy Agency, the US and the UK.