Pumped Hydro Electricity Storage (PHES)

On this page:-

  • Why I used to hate pumped-hydro dams
  • Now I love them!
  • The advantages of off-river pumped-hydro
  • Almost anywhere
  • What about the area required to be flooded?

Either read my post below or watch Professor Andrew Blakers on the world’s potential for off-river pumped hydro below.

Pumped hydro section goes for 8 minutes

Why I used to hate pumped hydro dams

I used to point out the potential ecological dangers of normal Pumped Hydro dams being built everywhere for backing up a grid that didn’t need to be backed up if we just built nuclear. I mean, I’m a conservationist for crying out loud! The very formation of the Australian Greens – one of the earliest Green parties in the world – resulted from the Franklin Dam controversy. This dam threatened to drown vast areas of beautify Tasmanian wilderness – and so weaponised environmentalists it formed the world’s first Green party.

When half the rivers in the world don’t reach the sea because we are already overusing them, and when almost any last surviving bit of river needs to be protected from further interruption as biodiversity and fisheries hotspots – how could I support building these monsters across our last surviving rivers?

Not only this, but most of the best sites were already used.

Now I love them!

The answer hit me like a thunderbolt when I first understood it. What if we looked for appropriate off-river sites? They are also called Closed-Loop pumped-storage because once you build the dam and pipe the water in from a nearby river – you just keep reusing the same water. (You cover it in floating solar panels to reduce evaporation, and slowly pipe more water in from the river every few months to offset evaporation.)

Advantages of off-river pumped hydro! Going off-river lets you:-

Build it fast – there’s no river to divert and you can build the tunnels, turbine room and prepare the reservoir bases all at once. Built in 3 years.

Build it cheap – there’s no spillways required to prepare for a once in a century flood. (Which is a good fraction of the cost of an on-river pumped hydro dam.) There’s a cost calculator here if you’re technical.

Build it almost anywhere – that has the right terrain and a river within a few dozen km to pump the water in after it’s built. Australia has something like 300 times the off-river pumped hydro sites we could use – and most continents have at least 100 times.

Build it safe – because we have over a century of experience using pumped hydro. There’s no new inventions here. We can build it safe for us and safe for nature. Pick THE best site with no ecological concerns or biodiversity hotspots, no beautiful valleys or holiday destinations, or any other other environmental concern. Some boring hill in outback Australia could do the job for that region.

Build it to scale – either gigantic for Sydney’s 5 million, or tiny like Walpole’s town of 500.

Build it with hardly any metal – as it’s all water. Pumped hydro is a few big turbines, some concrete and pipes. It has a materials footprint roughly like a coal fired power station. But it’s main ingredient is water and gravity – not all the metals it would require to build chemical battery storage!

Almost anywhere

Off-river closed loop pumped hydro dams solve all this! They open up a vast range of choice. Anywhere with a 100 meter hill or cliff can be used. The Australian National University have used Satellites to map the topology and the world has on average 100 times the storage we need to choose from. America has 100 times, Australia has over 300 TIMES what we need! That means you can avoid every controversial thing you can think of. Avoid biodiversity hotspots, avoid conservation areas, first nations land rights, even high tourism areas. They can be built on private or public land as long as everyone’s agreeable and fairly compensated. As the Blakers team said:

“So what have we found? An abundance of choice, with pumped hydro storage options ranging from 2 to 500 gigawatt hours (GWh). To put that into perspective, 500GWh is enough to supply all of Sydney’s electricity for about four days…

…The Snowy Mountains have large numbers of excellent sites of all sizes, located not far from the Snowy 2.0 scheme. If we built reservoirs at the three largest, we’d have double the storage capacity we’d need to support a 100% Australian renewable energy system when everything is electrified and there are no fossil fuels. That’s because the amount of storage needed to support a clean grid is actually quite modest.”

What about the area required to be flooded?

Legacy fossil fuels can support and balance an electrical grid with a large proportion of variable renewable energy (solar PV and wind). However, as the renewable fraction approaches 100% then substantial storage is needed. Analysis of Australia showed that about 500 GWh of storage is needed to balance a 100% renewable electricity grid for 25 million people that includes strong interconnection over large areas (to smooth-out local weather) [2]. If the storage is mostly in the form of pumped hydro then 2-5 km2 is required per million people for the upper + lower reservoirs. This is smaller than one tenth of the area of land required for the corresponding solar and wind energy systems that the storage supports. Most of the identified sites are not near significant rivers. Larger reservoirs (50-150 GWh) are more economical with land than smaller reservoirs
Global Greenfield Pumped Hydro Energy Storage Atlas

Storage = 10% the solar area required. What does that look like? See the little squares on each of these continents? That’s the solar required if we were going to run that country of solar alone. Add 10% of that area again for the backup – and that’s a rough idea. Click to see larger. Not measured on the graph below is the fact that they use 10% the water of coal power! One tenth. We’ll SAVE 90% of today’s energy-water by switching to renewables with PHES.

Some of them could be really large. Some of them like the one being constructed in Walpole WA could be much smaller – and just back up that town, not a whole city or state. Once the construction is finished they will look like two normal dams – one higher than the other.

This means there are no new inventions required for a 100% renewable grids.

Watch REAL ENGINEERING on how pumped hydro actually works. However, be aware he does not seem to have read the Blakers team about the vast potential for off-river pumped hydro. I’ve checked the Blakers atlas and Ireland has more than enough sites.

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