this post was submitted on 16 Nov 2024
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Anon questions our energy sector (slrpnk.net)
submitted 14 hours ago by MataVatnik@lemmy.world to c/science_memes@mander.xyz
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[–] iii@mander.xyz 1 points 11 hours ago* (last edited 11 hours ago) (1 children)

Uptime is calculated by kWh, I.E How many kilowatts of power you can produce for how many hours.

That's stored energy. For example: a 5 MWh battery can provide 5 hours of power at 1MW. It can provide 2 hours of power, at 2.5MW. It can provide 1 hour of power, at 5MW.

The max amount of power a battery can deliver (MW), and the max amount of storage (MWh) are independant characteristics. The first is usually limited by cooling and transfo physics. The latter usually by the amount of lithium/zinc/redox of choice.

What uptime refers to is: how many hours a year, does supply match or outperform demand, compared to the number of hours a year.

So to match a 1gw nuclear plant, you need around 12gw of of storage, and 13gw of production.

This is incorrect. Under the assumption that nuclear plants are steady state, (which they aren't).

To match a 1GW nuclear plant, for one day, you need a fully charged 1GW battery, with a capacity of 24GWh.

Are you sure you understand the difference between W and Wh?

[–] mosiacmango@lemm.ee 1 points 8 hours ago* (last edited 8 hours ago) (1 children)

My math assumes the sun shines for 12 hours/day, so you don't need 24 hours storage since you produce power for 12 of it.

My math is drastically off though. I ignored the 12 hrs time line when talking about generation.

Assuming that 12 hours of sun, you just need 2Gw solar production and 12Gw of battery to supply 1Gw during the day of solar, and 1Gw during the night of solar, to match a 1Gw nuclear plants output and "storage."

Seeing as those recent projects put that nuclear output at 17 bil dollars and a 14 year build timeline, and they put the solar equivalent at roughly 14 billion(2 billion for solar and 12 billion for storage) with a 2 - 6 year build timeline, nuclear cannot complete with current solar/battery tech, much less advancing solar/battery tech.

[–] iii@mander.xyz 1 points 2 hours ago (1 children)

Assuming that 12 hours of sun, you just need 2Gw solar production and 12Gw of battery to supply 1Gw during the day of solar, and 1Gw during the night of solar,

Again, I think you might not understand the difference between W and Wh. The SI unit for Wh is joules.

When describing a battery, you need to specify both W and Wh. It makes no sense, to build a 12GW battery, if you only ever need 1GW of output.

[–] mosiacmango@lemm.ee 1 points 2 hours ago* (last edited 1 hour ago) (1 children)

If you want more exact details about the batteries that array used, click on the link in my comment.

The array has a 380 MW battery and 1.4Gwh of output with 690Mw of solar production for 1.9 billion dollars. Splitting that evenly to 1 billion for the solar and 1 billion for the battery, we get 2.1Gw solar for 3 billion, and 12.6Gwh for 9 billion.

So actually, the solar array can match the nuclear output for 12 billion, assuming 12 hours of sun.

For 17 billion, we can get a 3.3Gw generation, and 15.6Gwh of battery. That means the battery array would charge in 7-8hrs of sun, and provide nearly 16hrs of output at 1Gwh, putting us at a viable array for just 8hrs of sun.

Can solar + battery tech do what nuclear does today, but much faster, likely cheaper and with mostly no downsides? That is a clear yes. Is battery and solar tech advancing at an exponential rate while nuclear tech is not? Also a clear yes.

Nuclear was the right answer 30 years ago. Solar + battery is the right answer now.

[–] iii@mander.xyz 1 points 1 hour ago* (last edited 1 hour ago)

That means the battery array would charge in 7-8hrs of sun, and provide nearly 16hrs of output at 1Gwh

How many days a year does that occur? How much additional storage and production do you need add, to be able to bridge dunkelflautes, as is currently happening in germany, for example (1)?

That's why I mentioned the 90%, 99%, etc. If you want a balanced grid, you don't need to just build for the average day (in production and consumption), you need to build for the worst case in both production and consumption.

The worst case production in case for renewables, is close to zero for days on end. Meaning you need to size storage appropriatelly, in order to fairly compare to nuclear.