As the global energy market, piece by piece, slowly but surely, moves towards a renewables-centred paradigm, dispatchable solar and uncurtailed wind, along with other forms of clean energy, are requiring longer and longer durations of storage to integrate them to the grid. While there’ll be a place for lithium-ion for many years yet, the technology really excels at applications of up to around four hours. For everything else, there’s a growing list of contenders, with diverse technologies and at different stages of commercialisation. Here’s a handy guide to some of those technologies and their providers, electrochemical and otherwise, that promise anything from five hours to even days or weeks of storage.
Who’s got a head start
It’s worth remembering that more than 90% of the world’s installed base of energy storage in megawatt-hours is still pumped hydro. Lithium-ion may take the plaudits and the new market share today, but historically, the legacy of pumped hydro remains huge.
Water is elevated using pumps into a retained pool behind a dam. When electricity is required, the water is unleashed and runs through turbines, which then creates electricity. While the amount of energy required to pump the water back up is far less than the amount generated as it falls, systems can also be paired with renewable generation to pump the water back to the top. However, while the system is cheap once built and can last for many years, finding appropriate sites and getting permission to build pumped hydro plants remains an obstacle to widespread further development in most parts of the world.
In June 2019, Australia-based firm Genex Power announced it was set to receive a second round of debt funding from the Northern Australia Infrastructure Facility (NAIF), for what will be the world’s first pumped hydro project to utilise an abandoned gold mine.
In Chile, a 300MW pumped hydro project is under development, having recently received an injection of US$60 million in fresh funding from the Green Climate Fund. The Espejo de Tarapacá project, which will also see a 561MW solar PV plant, is being developed by Chilean renewable developer Valhalla and construction is set to begin next year.
French energy giant Engie is also a proponent of the technology, with its First Hydro Company owning the Ffestiniog and Dinorwig pumped hydro assets in Wales. Engie lauds Dinorwig as the fastest power generation asset in the UK, with the ability to deliver 1.7GW in 16 seconds.