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Comment by jillesvangurp | Hacker News Reader

I love math like this. It makes things sound doable. 144 TWH is a lot of power. The world produces about 25000 TWH per year currently. So, we're talking less than a percent here of global electricity generation. Which over the course of the next decades is going to shift to be mostly/entirely generated by renewables.

This obviously won't happen overnight. But it suggests a few long term trends for steel production to move close to where renewable power is cheapest and most plentiful. E.g. Australia is a renewables power house and exports a lot of mined but unrefined materials. Long term it makes more sense to produce aluminium, steel, etc. locally instead of exporting the ore to China, India, etc. and then re-importing it the upcycled materials.

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Thank you. I actually have to point that 25,000 TWh (I have the number of 29 PWh) is electric production only. global energy consumption is ~180,000TWh (a drop of 10,000TWh during covid, yay!), 85% of it is (c)oil&gas.

My numbers might be slightly out of date. It makes sense for energy generation to have grown recently.

For oil and gas energy usage, you should take into account that usable energy and energy consumption are two things. When electrifying, you typically end up needing less energy overall. The notion of replacing oil twh with solar twh is simply wrong. This is something the IEA gets wrong in most of its reports. Which is one reason why their estimates and predictions keep having to be corrected by them every few years.

A good example is ICE cars vs. EVs. A gallon of gas represents about 33.7 kwh of energy. A Tesla can do over 4 miles per kwh. Most ICE cars get nowhere near 120 miles per gallon. Anything over 1 mile per kwh of gas is actually pretty good. Especially for bigger cars. So, an ICE car wastes about 70-80% or more of its energy (heat, noise, vibrations, friction, etc.). You see the same pattern in other sectors where electrifying usually also means improved efficiencies. Most Teslas only have 2-3 gallons worth of kwh in the car. An ICE car with a tank that small would have a terrible range.

So, a doubling or tripling of electricity generation might actually be good enough to replace most fossil fuel usage.

You are correct, but conversion from thermal to electricity is quite inneficient. and it represent 60% of global electricity production. So driving a tesla is more efficient IF it comes from renewable.

EVs (and heat pumps) do not require renewable grids to be more efficient than ICE cars (and gas boilers)

They are sufficiently more efficient (roughly 4x) than even adding the 60% inefficiency of gas turbines and electricity transmission, charging losses etc. do not destroy their inherent efficiency advantage.

That's one of the neat things about heat pumps. In my province in Canada about 25% of our energy is used as electricity and 75% is used as heat. This is ignoring cars, looking at residential, commercial, and industrial. The majority of our electricity generation comes from coal and natural gas, with some hydro and some wind/solar. People are very keen to close down the polluting power plants but are generally quite quiet on the topic of converting our residential and commercial heating to electric even though that covers 75% of our energy use.

But with heat pumps (backed up by resistive heating since we get cold enough to need it), we can still get a win there. Natural gas and coal generation can be ~30% efficient, but heat pumps can readily have a 4:1 COP or better. Even factoring in the inefficient generation of electricity we can still heat our homes with net less energy and then focus on replacing our electricity generation with less polluting sources (eg a mix of nuclear baseload, wind+solar+battery, and natural gas as a fallback)

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