How pumped hydro storage can help save the planet

In pumped hydro storage there is a tried-and-tested technology that not only fits the bill for future energy needs but has been doing the job for well over a century. Andrew Wade reports

It’s often assumed that to mitigate the worst effects of climate change we need an energy revolution incorporating a raft of new ideas. However, the core technologies needed to decarbonise the power sector already exist in the form of renewables, with wind and solar now the fastest-growing sources of new generation.

One major problem, as critics are quick to point out, is intermittency. If that problem could be solved, the energy sector could be transformed within a few short decades. And, as it happens, several countries are betting that we already have the answer.

In pumped hydro storage there is a tried-and-tested technology that not only fits the bill but has been doing the job for well over a century. First employed in the 1890s, pumped hydro makes up 97 per cent of energy storage worldwide, with around 168GW currently installed. Excess off-peak grid power – theoretically from renewables – is used to pump water uphill, where it’s stored as gravitational potential energy. When electricity demand is high, water is released downhill to power turbines, the elevated reservoirs essentially acting as giant batteries to help balance the grid.