Dunkelflaute

Exactly.

This is known in the industry as the Dunkelflaute, which is a German term meaning dark doldrums, a period of cold, windless, sunless weather.

Lithium-ion is just too expensive to scale up for days or weeks of backup storage.

You would literally go bankrupt buying enough battery packs.

So what is the technological solution for long-duration storage if lithium-ion isn't the answer for a week-long Dunkelflaute?

This is where researchers are looking at alternative chemistry, like redox flow batteries.

Flow batteries.

You know what the limitations are.

So although in the future, when the world has massively overbuilt wind and solar to largely cope with the lulls in energetic weather that our German friends call the Dunkelflaute, In the near term we are going to need to plug the gaps if we want to keep the lights on 24 7.

You've no doubt seen these types of charts before, with a logarithmic scale going up the y-axis representing the most economically optimum discharge times for various energy storage technologies.

I won't show you every option here because it'd get too busy, but you've got things like flywheels down here that can discharge relatively small amounts of residual energy for short periods to help with a bit of grid frequency regulation, Then at the other end of the scale you've got so-called power to gas, which typically uses excess electricity to combine hydrogen with carbon dioxide to make methane.

Where batteries are thriving, it's generally because markets allow them to compete on an even playing field with fossil plants, avoiding artificial support for gas capacity, and where they can earn decent revenue for flexibility and reliability services.

We haven't quite arrived at the holy grail of grids run on 100% renewables plus energy storage just yet though, have we? In fact, we're still some way off, not least because in many parts of the world, those pesky multi-day low renewable events that our friends in Germany call the Dunkelflaut still need careful planning and robust, reliable solutions.

But there's no mistaking the trajectory of travel.

Gas peakers that were once considered essential and indispensable are now looking increasingly uneconomical.

So I think there's probably a combination of both.

There's gonna be a need for, you know, gas turbines to deal with, you know, what the industry calls Dunkelflaute, which is, you know, for your listeners, it's effectively just a, a nice German-sounding word for, um, cold and, you know, kind of those dark, you know, nights where there's no wind, there's been no solar, and it's just miserable conditions.

You know, kind of think of winter.

Um, so those Dunkelflaute, you need some gas turbines that occasionally can get you through those periods.

But then on the, the reliability firming side, a lot of the data centers will probably bring their own backup generation anyway.

Yeah.

Yeah.

And the effect of a Dunkelflaute across the whole of Northern Europe in the middle of winter when energy demand is at its peak-

And the wind collapses, that's what that is

... and the wind collapses as well.

So this is mostly a gas coal story that we talk about, but it's also a power story.

And just in, in Europe, um, this winter, you know, you could have Dunkelflaute, uh, conditions, which is that dark doldrums, uh, with low wind.

Um, and, you know, so we're gonna try to watch the power markets here too.

Um, but margins, margins for this winter still look really good for, for coal, for ARA.

Although mild weather may reduce gas demand, other and near-term weather factors can have the opposite effect.

This applies especially to the Dunkelflaute, or the dark doldrums, a phenomenon comprised of periods of low sunshine and reduced wind energy.

These periods increasingly influence the German power market and reinforce the need for firm generating capacity rather than variable renewable energy.

These events, which occur on average more frequently than every three days, last on average for over twelve hours and increase power market price volatility as well as the need for unforeseen increases in gas-fired power.

So part of the fluctuations in the electricity system that are available for hours or maybe for one or two days can be backed up by batteries, and I think that's an important game changer, and it's important for a decarbonized electricity system.

And then the rest, for a longer, so-called Dunkelflaute, so when we have the dark weather with no sun and little wind, and that can take up to 10 days maybe in the winter.

And for that, we need hydrogen to provide the backup.

Green hydrogen stored underground in caverns and then used for a couple of days to stabilize the electricity system.