Port Augusta is a small city in South Australia, a former seaport on the Spencer Gulf.
North of the city, the gulf narrows to a tidal estuary – surrounded by land that is too dry for growing crops.
This is the site where I propose to build a seawater pumped hydro scheme to serve all the electricity storage energy transition needs of South Australia’s grid, very well served by solar and wind power.
The upper reservoir is based on a 150GWh site found by the Global Pumped Hydro Atlas but I am proposing to build the dam slightly further south, as shown here, so as to increase the energy storage capacity of the scheme to 200GWh.
I am proposing to dispense with the GPH Atlas’s suggestion of the lower reservoir to pair with the upper and instead to use the sea as the lower reservoir, supplying the pumps & turbines via a power canal and the tidal estuary, suitably dredged etc. to allow for the required water flow rate which depends on the scheme’s designed maximum power.
The water flow can be estimated by noting that generating 1GW it would take 150 hours to drain the GPHA’s 150GWh reservoir whose volume is 224.4 GL, so 1GW requires a flow rate of about 224.4/150 = 1.5 GL/hour = 417m3/s or 54% of the discharge rate of the River Murray, Australia’s longest.
Considering that South Australia’s peak demand has reached 3.4GW
and that ideally, a grid-scale energy storage facility should be able to supply such a peak demand, what might this scheme’s limits to and constraints on water flow rates be and what can be done to mitigate them?
The Yorkey Crossing bridges severely limit the water flow rates under them and so they’d have to be altered or simply replaced with new bridges designed to allow the required water flow and, while we are at it, passage for dredging barges too.
I’ve emailed the Government of South Australia, Port Augusta City Council, ElectraNet, who own and operate the electricity transmission network there and a couple of companies involved with the Port Augusta Renewable Energy Park – DP Energy & Iberdrola – to see if the relevant people in South Australia might be interested in developing this concept further.
This scheme could provide all the grid-scale energy storage that South Australia will need for the foreseeable future.
Farm-scale production of green hydrogen by electrolysis is likely for other purposes but it is unlikely that hydrogen would be used for backup power if the grid has this pumped hydro scheme. The round-trip efficiency of power-to-hydrogen-to-power is lower than pumped hydro. But all my blog readers knew that already, right?
Scottish Scientist 