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Comment by mono442 | Hacker News Reader

Can batteries store enough energy for dunkelflaute in winter? I don't think it's possible with the current technology.

Batteries are not appropriate for dealing with Dunkelflauten. There's very little energy flowing through there, so what you want to do is trade lower round trip efficiency for lower capex. The high capex of batteries is best amortized over many charge/discharge cycles, for example for daily storage.

I mean, who cares? Fire up the gas plants in the one week a year you have weather anomalies. We’d still be 90+% carbon free which would be incredible. The last gap can be solved at a later point as technology evolves

And replacing the natural gas burned in those turbines with hydrogen won't be very expensive, since they will be used so infrequently. Storing energy as hydrogen is much cheaper than storing it in batteries, as measured by cost of storage of capacity.

My friend, renewables only have a capacity factor of .1 (10%). That means those "gas plants" (really coal, and the worst quality coal on the planet too) are running 90% of the time. There is a reason why France's grid makes 7x the power for the same CO2 emissions as Germany.

A single energy source having a capacity factor of 10% does not imply that gas plants will have to run 90% of the time.

It ignores storage, over-provisioning, aggregation of uncorrelated sources etc.

Not to mention that wind typically has a much higher capacity factor than 10%.

I don't know what the true number is, but I think this is a low effort take.

Wind turbines across a whole region you'd be looking at 30% maybe 35% or even 40% if they're off-shore. Off-shore the winds aren't slowed by all the random structures humans build but also the turbines are much taller and as your elevation increases the reliability of the wind increases.

PV it varies by how far you are from the equator, 10% is realistic for a Northern country like the UK or Germany whereas in Africa you might see 25% or even 30%

It's not. Germany would need an insane amount, about 3twh based on recent data and much more looking at 30y weather data

Batteries can store as much energy as you are willing to buy.

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