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Comment by layer8 | Hacker News Reader

80% of global energy consumption is still fossil fuels (oil/coal/gas), however.

Yes but primary energy isn't a good metric. There's 40-60% loss when converting fossil fuel to final energy being consumed.

That’s fair, but factoring the energy loss in, it still remains the clearly larger share.

Does it, though? Assuming 80% of energy use is fossil and fossil has a 50% loss, if all that fossil were to transition to ~100% efficient electricity[0] we'd already be at 33% of our renewable electricity needs. That's quite a bit more than the 20% the "80% fossil" seems to suggest!

"One-third done" sounds an awful lot like we're going to start seeing optimistic "we'll be halfway there at the end of the decade" headlines soon...

[0]: Things like the grid and car batteries don't operate at 100% but closer to 95%, but things like heat pumps operate at 300% efficiency, so I reckon that'll more-or-less cancel out for back-of-the-napkin math.

Yes we're not done yet, but renewable only started gaining share again around 2010, and how quickly solar/battery is being deployed is really impressive.

A lot of energy is used for heating, heating water is more efficient with fossil fuel than with electricity - because for electricity you have transmission loss.

That used to be the case, but with the efficient heat pumps that have come out in the last few years, that is no longer true. Since you’re using electricity to move heat rather than produce it, it’s two to three times more efficient than burning fossil fuels for heating.

Fossil fuels have transmission losses too. You just don't see them.

40% of all global shipping is used for fossil fuels. [1]

10% of the energy in a barrel of crude oil is used to refine it. [2]

I'm not even counting the energy cost of crude oil extraction, pipeline leaks, hauling gasoline, diesel and LPG to its final destination, or the million other places where energy is lost.

1. https://cleantechnica.com/2026/06/16/shipping-freight-energy...

2. https://autoexpert.com.au/posts/the-energy-cost-of-petrol-pr...

There's primary, final, and useful energy. Easy to confuse them. Final is what is delivered for consumption. Useful energy is what is actually delivered in a useful form (motion, light, etc.) The rest is rejected energy (heat). This terminology simplifies a complex chain of events that is about moving and transforming fossil fuels from well (primary energy) via refineries, shipping, trucking, pumping, etc. to gas tank in your car (final energy). After which you burn it to actually get useful energy. There are losses throughout this chain.

The fallacy here is counting barrels of oil, shipments of coal, or whatever and assuming it needs to be replaced 1:1 by what used to be called alternative energy to get the same useful energy. But of course with electrified systems, the losses from generation to use are a lot less. Things like wires and transformers have their own inefficiencies of course. But the numbers are pretty good. You end up with 80-90% useful energy. As opposed to 30-40% for typical fossil fuel plants. And far less for any combustion engine vehicles.

It's called the primary energy fallacy. As Michael Liebreich suggests, there are people using this term that genuinely don't get it. And there are those using it intentionally that do. But the bottom line is that their math tends to be off by about 3-5x.

That's primary energy, of which about half is wasted as heat. Electrification will bring this down by a lot.

And big usage of energy is actually heating home so heating water

Not going to happen in the foreseeable future. Fossil fuels did not change there relative share the past 30 years.

Between 1950 and 1980 the home market for computers was non-existent.

So of course this didn't change in the 30 years following 1980, right?

Which perfectly proves that 90% of the comments in this thread have no clue about energy and think that running a grid on solar and wind only plus some batteries is a solved problem.

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