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Comment by oifjsidjf | Hacker News Reader

How exactly will you be 100% renewable during a cloudy and windless period with solar and wind?

Pumped hydro storage, batteries, and/or long-distance grid interconnection. It's not often overcast in the Sahara, as far as I know, and solar power imported from far to the east and west can mitigate the day/night cycle problem.

It's reasonable to keep ICE power plants around as an emergency backup; if you have to use them for a week in January or when infrastructure breaks for whatever reason it's not the end of the world. Ideally things would run smoothly enough that they'd never be used.

You are assuming geopolitical realities that will... never be reality. The entire issue of Germany's dependence on energy from another country makes this obvious.

You also assume that power plants can just be flipped on and off like a light switch. They can't.

Transmitting energy over long distances is way more difficult than you make it out to be: https://www.youtube.com/watch?v=7OpM_zKGE4o

It'd be expensive, but it's technically feasible. I'd also expect there's economies of scale involved; building a cable with twice the capacity doesn't cost twice as much; you might even just use the same cable and run it at a higher voltage.

Expensive but technically feasible, plus making Europe at the mercy of unstable regimes across the Mediterranean. That worked just fine with natural gas imports from Russia right?

At least Morocco/Algeria/Libya/Egypt/Tunisia don't have nuclear weapons or large conventional militaries and aren't generally much of a threat to anyone but themselves and sometimes their immediate neighbors.

There is a political risk that the governments of those countries change and they seize the energy-producing assets and sell surplus power to someone other than Europe. Perhaps a mutually-beneficial arrangement would be the best way to reduce the risk of it falling apart; for instance, if Morocco has the solar panels and Switzerland has the pumped-hydro storage facility to buffer out day/night cycles, both sides can trade power to their mutual benefit. Without both parts of the whole system, the other half is less useful.

> It'd be expensive, but it's technically feasible.

So is nuclear fusion. You have provided no evidence or even argument that it is practical.

Proposing that you can compensate day night cycle with transmission is surely a joke, no infrastructure of such scale has ever been built.

Fusion is not, in fact, technically feasible.

Anything not built yet has not been built. After it is built, it will then have been built.

Those things aren't equivalent. Useful nuclear fusion (i.e. more electrical power out than in) has not been demonstrated yet, and probably relies on techniques and technologies that haven't been invented yet.

On the other hand, we know how to make high-voltage DC transmission lines -- the only real questions are: how much will it cost, and is there some way we can do it better and cheaper?

There have already been DC lines over 2,000 miles long built that run at 800 kV or more. That's already long enough to reach several time zones away, and it's not a conceptual stretch to imagine linking several of these together to reach further. According to wikipedia:

> In 2010, ABB Group built the world's first 800 kV UHVDC in China. The Zhundong–Wannan UHVDC line with 1100 kV, 3400 km (2100 miles) length and 12 GW capacity was completed in 2018. As of 2020, at least thirteen UHVDC transmission lines in China have been completed.

> While the majority of recent UHVDC technology deployment is in China, it has also been deployed in South America as well as other parts of Asia. In India, a 1830 km (1140 mile), 800 kV, 6 GW line between Raigarh and Pugalur is expected to be completed in 2019.[58] In Brazil, the Xingu-Estreito line over 2076 km (1290 miles) with 800 kV and 4 GW was completed in 2017, and the Xingu-Rio line over 2543 km (1580 miles) with 800 kV and 4 GW was completed in 2019, both to transmit the energy from Belo Monte Dam. As of 2020, no UHVDC line (≥ 800 kV) exists in Europe or North America.

https://en.wikipedia.org/wiki/High-voltage_direct_current#Ad...

Which country situated in Sahara would you consider to be stable enough politically, and unlikely to enter in geopolitical alliances that are adversarial to Europe, to place your primary energy infrastructure in?

Deserts are a stupid place to plant solar farms, so the question is moot.

Numerous politically stable European countries have plenty of room for solar installations.

Dunkelflaute is 0.5% - 1.5% of the year and most of the events last shorter than 24h

https://en.m.wikipedia.org/wiki/Dunkelflaute

in my book 98.5% easily fits the bill of "close to 100%"

so the answer is exactly what we do today: have a reserve capacity. part of that may even be traditional peaker power plants that remain turned off most of the year just like today.

I'd be curious about climate data on the distribution of Dunkelflaute duration, by region.

I believe the difference is that during a Dunkelflaute, peaker plants might have to generate a large amount of or the majority of electricity, whereas today, peaker plants are build to only generate relatively small amount of power at the margin.

So, we'd have to build a large number of peaker plants, which are really expensive in that they have to amortize their costs over a small amount of uptime.

short term weather forecasts are amazingly accurate. this allows us to deliberately "extend" the "range" of buffer storage. and even today in some situations some energy intense heavy industries have to pause production for a few hours if there is a lack of energy supply.

It's a political problem, not a technical one, and we do not, absolutely not have to build up new parallel peaker capacity. we can simply keep select plants alive.

Figuring out how much extra capacity is needed still needs to be done.

Simply stating that no new peaker plants are needed "because storage capacity will be there" is a bit too simplistic.

I'd be glad if that's the case, but I'm not convinced it's actually true.

right we have 7 years to figure this out for 80% renewables and 17 years to figure it out for close to 100%

it took 1 year to build and start operation of giga Shanghai, and not much longer for giga Berlin.

it's a political challenge, not a technical one.

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