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ajmmsr t1_japf8d9 wrote

Reply to comment by DisasterousGiraffe in Electric world that kicks out fossil fuels will cost less than combustion economy. 30TW of wind and solar PV will take 0.2% of earth's surface. by DisasterousGiraffe

The USA uses about 100 Quad of energy per year, that’s 29PWh (peta Wh)

30TW 8760 hr/year = 26.2PWh per year at 100% capacity factor

What am I getting wrong here?

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SandAndAlum t1_japly12 wrote

Order of magnitude error and a factor of 2-3 on topof that for work vs heat (if TW is net generation rather than peak). 30TW net is ten USAs of final energy, not one USA of primary energy.

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ajmmsr t1_jaqr4hs wrote

TW is power so multiply by a time to get energy

Here’s my reference to USA energy https://www.energy.gov/sites/default/files/2022-08/Energy_2021_United-States_0.png

Don’t know what you mean by ‘net’

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SandAndAlum t1_jaqrcr1 wrote

30 * 8.760 is 260 not 26.

Net implying average output over the year. Ie. A 3.3kW nameplate tilting solar system in California is 1kW net. Primary energy is input, final energy is what is achieved. A 25% efficient gas engine running on tar sand oil with an EROI of 3 needs about 6kW of primary energy for 1kW of output. The 500GW or so of primary energy powering US transport can be replaced by 100GW of electricity. Similarly 200GW of gas heating can be 50GW of electric heat pump.

If the 30TW is nameplate then the capacity factor cancels some of the waste heat, so it's merely 10x what the US uses not 30x.

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ajmmsr t1_jaqs9iv wrote

Arrrgh

Yeah 262PWh at 100% capacity factor

Since wind cf is about 30% That’s 78.8PWh of energy, so 2.7 times the USA energy.

No where in that article does it mention nameplate

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SandAndAlum t1_jaqsy07 wrote

It's ambiguous then as to what cf they mean.

New western offshore wind is in the 40-50% cf range. EU solar is 13% so there's a big range there.

10TW net final energy to replace existing 18TW of world wide primary energy and cover some growth sounds pretty close to most ballparks so 30TW of 30% cf sounds reasonable.

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