Pumped Hydro is cheap

Kidston pumped hydro.  Source: RenewEconomy.

There are three pumped hydro projects either in a late planning/funding stage or already under construction in Australia.  (Snowy 2.0, which might potentially be a very large fourth pumped hydro project still seems to be at the air bubble phase)

Pumped hydro can store power like a battery.  When electricity is plentiful or demand is low, water is pumped uphill into a dam.  When demand is high, the water flows back downhill and turns the turbines, generating electricity which is fed into the grid.  It's easy to confuse conventional hydro with pumped hydro.  Conventional hydro "uses" the water once: it flows through the turbines and away.  Pumped hydro re-uses the water, again and again.  The only losses are via evaporation.  Pumped hydro dams are about 1% of the size of conventional hydro dams.  Unlike conventional hydro which can produce continuous baseload generation, or, if needed, dispatchable generation up to the maximum capacity, pumped hydro power plants will only produce power when it's needed, for a few hours each day.  Because pumped hydro only needs small dams, there are far more suitable sites than is the case with conventional hydro.  And pumped hydro is a cheap form of storage.   Molten salt storage is also cheap, but only when it's part of a CSP plant. Pumped hydro on the other hand can be used for wind, solar and even baseload (to handle demand variations.)


The three projects are at Kidston in northern Queensland, Oven Mountain in NSW, and  Cultana in South  Australia, which will be the first salt-water pumped hydro in Australia.

Let's compare the projects.  I've also included Tesla's South Australian "big battery" for comparison.

Right now, pumped hydro is still a lot cheaper than li-ion batteries.  Even assuming that battery prices fall more slowly (20% p.a.) over the next 5 years than they did for the last 3 (30% p.a.) then  li-ion battery storage will be close to pumped hydro in 5 years.  But as I've said before, diversification in both sources of supply and sources of storage is sensible, because it reduces risks.