[binoct]

Ah, seems like I was missing some context where the fossil fuel and anti-renewable folks have been using the term in arguments against trying to change.

I’m not sure of Smil’s politics but to be fair, there’s nothing in that quote that is inherently misleading. I can see through how others could spin it, and I’ll be more careful knowing the term has some politics behind it now. To me his argument in the article is that it’s not practical to expect a transition in a 25-year timescale, not that it’s impossible or not worth working on.

Heat pumps are a good example where the practice has been a lot harder than we might hope. Sure COP > 4 for heating is great, but the units are very expensive today, and in most of the US and Europe with sub-zero winter temps operate with much worse efficiencies, making them significantly more expensive to operate. I’m sure with effort those issues will improve, and major policy shifts can help mitigate some of the costs. But especially without a strong will today those changes are practically too far off for the 2050 target.

[_aavaa_]

> there’s nothing in that quote that is inherently misleading

The discussion of the issue in terms of primary energy is the very thing that's inherently misleading. To move away from fossil fuels we do not have to replace the primary energy, we have to replace the useful energy that comes out the other side. From the Sankey diagram in the article I linked [0], 67.5 units of energy are not useful energy.

To put it to an extreme, instead of 67.5 units beings wastes, it could be 100 billion units for 32.5 units of useful energy produces. Focusing on the 100 billion is inherently misleading since they are irrelevant when the replacement technology basically creates the useful energy with over 100% efficiency at times.

Heat pumps. Yes their COP is lower during cold winters, but that brings in 2 discussions.

1) any COP value above 1 means that we'll need less primary energy than when buying something, and even in cold weather they manage a COP above that [1].

2) Lower COPs will cost you more, depending on what your natural gas prices are like due to any crazed lunatics invading their neighbours. Which conincidentally is only what pushes electricity prices up in many places that use natural gas for electricity (even just peak demand).

The capital cost difference also depends drastically on situation. Many climates need both heating and cooling, so the price of heat pump versus furnace + AC unit is much smaller than heat pump versus furnace.

> But especially without a strong will today those changes are practically too far off for the 2050 target.

I agree, and even replacing the 1/3rd of the primary energy will be a tough challenge. But Vaclav continual framing in terms of primary energy is actively used to push inaction. His critics have been vocal about this point (and others) for a while, he should know better by now.

[0]: https://spitfireresearch.com/wp-content/uploads/2024/06/LLNL...

[1]: https://www.sciencedirect.com/science/article/pii/S254243512...

[binoct]

Thanks, you have helped at least me think a bit differently about this. I still believe primary energy is a valid way to look at the problem, but see more clearly how easily it can lead an uninformed audience to a bad conclusion.

And on heat pumps - it’s sad to reflect that even if we replaced all heating, it’s still only a couple % of the total rejected heat. There are few easy wins in this game, just many different ways we need to chip away at it.

[measurablefunc]

> the replacement technology basically creates the useful energy with over 100% efficiency

I think you're confused. There is no way to avoid the laws of thermodynamics so where are you getting more than 100% efficiency?