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  • Writer's pictureGeoff Russell

Grid capacity and keeping the lights on (prelude)

[ This is just a taste of a longer post to appear later this week ].

How do you climb a mountain? Do you look just 50 metres in front of your feet and pick a path that looks like it's headed to the summit? If you had foresight you'd scan the entire length of any proposed route and check for summit-stoppers like rock faces that require a 3m reach; because you don't have one.

Do you head out along a route because the first bit looks easy? Do you proudly boast about your progress along the first kilometre of this route?

Plenty of countries trying to decarbonise their electricity grids are starting with the easy bit and hoping that technology will materialise in due course to solve the hard bit. This is stated quite explicitly in the IEA's Net Zero by 2050 plan. They know that plenty of the required technology for their plan doesn't exist, but they assume that it will.

Solar power isn't new, nor is wind power. They are the easy path.

Not so easy is generating carbon-free electricity on still nights; preferably without losing money.

Not so easy is rapidly increasing carbon-free electricity to match a rise in demand at precisely the point when the wind is dropping and the sun is vanishing; preferably without losing money.

The word "dispatchable" almost captures both hard problems. An electricity source is dispatchable if you can choose when to use it rather than have it decide when it is available. Private cars and bicycles are dispatchable, buses and trains usually follow a timetable and taxis arrive when they can.

Hydroelectricity is an old dispatchable technology that is well proven, but environmentally problematic at scale; flooding valleys is something that most of us would rather not do. Burning biomass simply sucks. Trees are much more useful as wildlife habitat and for sucking down carbon than generating toxic pollution in a furnace; even if it is dispatchable toxic pollution. As it happens, one of sawdust's many health problems is being a Class 1 carcinogen; they don't suck it out of wood working factories for fun. Wood will also be useful and probably unavoidable to decarbonise the building industry; but burning? Preferably not.

But dispatchability doesn't capture the other really hard bit about decarbonising; which is scaling. That's the bit that University scientists typically ignore; almost as a matter of honour. Ensuring that a technology can be rolled out at scale typically gets filed in the "grubby little details" folder. When I said solar and wind were easy, I ignored the difficulties of scaling; both technologies, at scale, involve a vast global mining expansion that is genuinely hard. Not quite in the same sense that fusion electricity is hard, but hard in the sense that it can't be rushed and it will incur a high environmental cost.

The dispatchability problem according to AEMO

So much for theory. What does the dispatchability problem look like in practice.

Here's an Australian Energy Market Operator (AEMO) graph that shows the dispatchability problem in the Australian context. The open blue bars on the top right show the dispatchable electricity capacity that we will need in the coming decade as our coal plants shut down. The solid blue bars on the left show the dispatchable electricity capacity that we have built in the past decade.

Can you see the problem?

We have been doing the easy stuff and crowing loudly about how easy it is while ignoring the hard stuff. Engineers have always known that the hard stuff is hard, but who listens to experts when there is so much money to be made doing the easy stuff?

Most of Australia's power plant additions over the past 15 years have been of the IKEA kind. Buy it from somewhere and assemble it. Snowy 2.0 and the various transmission infrastructure expansions are exceptions. Did markets give us Snowy 2.0? Of course not, markets are intrinsically short-sighted selfish beasts. They excel at cheap and nasty half-arsed hacks. Markets love the easy profitable stuff. It's like when you privatise a mass transit system. There is no shortage of companies bidding to run the dense profitable peak hour services; not so many want to handle the after hours travellers.

In the absence of nuclear power, the only low carbon dispatchable electricity technologies are flooded valleys (aka pumped hydro) or flaming forests (aka biomass). I'm ignoring niche technologies like geothermal (really just another form of nuclear power, harnessing the power of radioactive decay instead of fission) and wave power ... because they are just that ... niche. In the long form of this post, I'll discuss storage, including batteries.

Hydroelectricity requires real engineering, and we have mostly IKEA experts; so while there has been plenty of talk about pumped hydro, construction is pitifully absent. There are 6 pumped hydro projects on Wikipedia for South Australia, but AEMO's database lists just 3 and they are much much smaller!

Why are they smaller? It's because our pursuit of the easy has made the hard part of the problem even harder.

It should be blindingly obvious why people are only building (at best) tiny pumped hydro schemes (except for Snowy 2.0 which has Government backing). Think about it. When you make a massive investment you want to be selling stuff for many hours a day to pay back the bank. Only selling stuff on still nights might cut it if you can charge 250 times the going rate; but mostly not. So people go into their pumped hydro scheme with huge expectations until they run the numbers; at which point they realise that only small schemes are profitable.

The Energy Security Board's capacity mechanism, to be discussed more fully in the long form of this post, however it finally turns out, will be an attempt to spur somebody to invest in filling the blue bars on the graph above. But with the IKEA experts dominating energy development in Australia, this isn't likely.

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Jul 22, 2022

Thanks Geoff, clear and engaging as usual.

The reliability of both storage and pumped storage hydro will surely become increasingly vulnerable to more intense droughts and increased evaporation rates. The Snowy's capacity was threatened by drought in 2007 and 2014. Tasmanian hydro will also become more unreliable for the same reasons. Victoria is relying on expensive transmission links to both to underpin its proposed massive expansion of solar and wind. SA pumped hydro will suffer high evaporation rates. Is anybody in AEMO factoring in this risk?

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