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That's based on the (flawed, IMO) idea that fusion just needs more resources to go faster [1]. We won't have serious fusion before decades, it's just too late to save our energy (and climate) problem.

Better go with fission at this point (preferably 4th gen because uranium 235 is limited).

[1]: https://en.wikipedia.org/wiki/The_Mythical_Man-Month




Hydro, wind, and solar backed by batteries looks like an ~90% solution to grid power / ground transportation reasonably quickly and we have enough fission power plants to make up the difference.

So we already have the short term solution, it’s really 25+ years out when things get more interesting. Existing nuclear power is going to get increasingly expensive to maintain and recent construction projects have been boondoggles. So fusion has a real shot here assuming the economics work out.

Fission has gotten safer as we’ve learned from past mistakes, but each of those lessens directly results in increasing costs. Not just in obvious ways but getting better at foreign material exclusion means it takes longer to do the same tasks. Multiply that by every significant indecent at any power plant and it’s no wonder things keep getting more expensive.


> So fusion has a real shot here assuming the economics work out.

They don't yet work out, and there's no evidence that they will. I would love it if they do, but I don't think past performance is evidence of future performance. We might run into a fundamental limitation at any moment, and that would be that.

Japan's median build time for fission is under 5 years[0]. If regulatory environments and engineering specialisms could be made to work, there's no reason (other than Greenpeace) that we couldn't massively curb CO2 production from power generation pretty soon; far sooner than we could do discovery and then build for fusion.

[0] https://www.sustainabilitybynumbers.com/i/111356564/which-co...


> Hydro, wind, and solar backed by batteries looks like an ~90% solution to grid power / ground transportation reasonably quickly

What? Currently, electricity makes for 20% of our global consumption. We're not remotely talking about replacing the 80% of fossil fuels with electricity, even with fission + hydro, wind and solar.

Batteries only work to store energy for a few days, not between seasons.

The reality is that we don't have a 90% solution to power. Not in the short term, not in the long term. Except if new technologies that do not exist yet appear. Have a look at all those huge boats that enable globalization: how do you propose we replace fossil fuels there? Or aviation.

The solution to the energy problem is to prepare to have (much) less energy. And a good way to prepare for that is to try to produce as much electricity as we can. And that quite obviously involves fission.


> What? Currently, electricity makes for 20% of our global consumption.

An apples to apples comparison gives very different numbers. A heat pump uses 1 kWh of heat to produce 3 kWh or more worth of heat. A furnace needs over 3 kWh worth of gas to produce just 3 kWh worth of heat.

An ICE engine is more extreme as extraction, transportation, refining, takes 1/3 of the energy in oil before you even out it in the gas tank. Net result under 20% of the energy in oil ends up being used at the end of the process.

> Batteries only work to store energy for a few days, not between seasons.

There’s no point in storing power between seasons, just add more generation. A seasonal battery storing 1 MWh gets used once a season. A solar panel only used in the winter is still useful for ~4h * ~90 days. But worst case a ~3kW of solar is equivalent to that 1 MWh battery at less than 1/100th the cost, and whisk generally redundant the rest of the year it’s still reducing outages.


> An apples to apples comparison gives very different numbers.

I don't see the relation with apples. If you take electricity where it works well, then it works well. But the fact that it accounts for 20% of our energy consumption today means that it does not work well everywhere. Try planes or merchant boats, for fun.

And that's not even mentioning that on those 20%, a good part is coming from coal.

> There’s no point in storing power between seasons, just add more generation.

You're saying "just waste solar panels during the summer so that you have enough during the winter", right? I thought it was pretty clear that wasting energy was not a good idea for the future.


> I don’t see the relation with apples.

Replacing an ICE with a EV results in a drop in energy by your calculations even if they are doing the exact same trip. Thus showing your argument is based on nonsense.

When someone burns oil in a car you measure the energy before it’s burned and therefore before engine inefficiency. If you burn oil in an electrical generator you measuring energy after the engine inefficiency.

Thus the amount of useful energy IE what people want in electricity vs other sources is closer to 50/50 than 80/20.

> You're saying "just waste solar panels during the summer so that you have enough during the winter", right? I thought it was pretty clear that wasting energy was not a good idea for the future.

People build grid infrastructure for the worst case. Nobody complains when a natural gas power plant is only turned on for 12 hours a year because without it you get a blackout. Hell dams build spillways that can sit unused for decades, you still need them.

Thus no the panels aren’t wasted, they are doing exactly the job someone built that infrastructure for.


> Thus showing your argument is based on nonsense.

My argument is that there is a lot more than just cars in the world. Even if Americans may not understand the concept. It's easy to say "replace oil with electricity, look, I have this one example where it works well". Then try to scale that one example, and then start looking at the rest. Again... planes and merchant boats for instance.


Many boats are going electric. Home heating, industrial processes, trains, mining, etc the vast majority of energy use you can swap without issue.

Rockets and big boats can swap to hydrogen with minor issues. Really aircraft are the odd man out, but remove bio fuels from other applications and you can largely replace aviation fuel.

After we drop CO2 emissions by 99% using existing tech we'll have decades to hit 100%.


> the vast majority of energy use you can swap without issue.

Then you completely misunderstand the scale of the problem.

> Rockets and big boats can swap to hydrogen with minor issues.

Say they can if they have the hydrogen, then you have to produce a whole lot of hydrogen and transport it for them. Do you know how inefficient that is?

Because you make it work for one does not mean that you make it work for the whole world. Your reasoning seems very naive.

> After we drop CO2 emissions by 99% using existing tech we'll have decades to hit 100%.

Except that the only way we drop CO2 emissions by a lot is with a ton of sobriety.


> scale of the problem.

Saying we don’t have the infrastructure is meaningless when building infrastructure is part of my argument. The only question is if we have the technology, and yes we do.

For scale, 350 gigawatts of PV was installed in 2023 that’s enough to meet ~3% of the words 25,000 TWh annual electricity demand (after accounting for capacity factor) and the rate of PV installed per year has been accelerating. Battery manufacturing capacity is already at weeks of global electricity demand per year. Utilities haven’t been building grid scale energy storage because they don’t need it, but it’s ready when they want it.

Over the next 20+ years a great deal of current infrastructure will need to be replaced simply because of age. What replaces it could be very green without significant issue.


> Saying we don’t have the infrastructure is meaningless when building infrastructure is part of my argument.

Again, you don't understand. I am not just saying that we don't have the infrastructure. I am saying that the size of the infrastructure we would need is a whole lot bigger than what you must imagine if you think that renewables can produce 99% of the world's energy.

You just vastly underestimate the problem. Saying "look, I went from selling 10 devices last year to 100 this year, so this proves that in 10 years I will be selling 1000000000000 devices per year" is the kind of reasoning you use in a startup when talking to a VC. But when you're being serious about solving a problem, it doesn't work like that.

Let me repeat it one last time: we will go away from fossil fuels, it's not a choice (they are limited in nature). We will need as much fission and renewables as we can get to compensate for as much as we can, but that won't remotely be enough (again, think about a real big merchant boat and tell me how it travels around the world without fossil fuels - not the startup way, but with a real solution).

So on top of fission and renewables, we need sobriety. A ton of it. And it means clever engineering across the board. So instead of wasting talents doing AI or polluting more with SpaceX, they should work on solving the actual problems we have for tomorrow.


3% of the worlds electricity per year isn’t several orders of magnitude from solving the problem. When I say that’s on pace to hit 100% carbon free grid before 2050 I’m not assuming crazy growth in anything.

We’re past the crazy exponentials. Global demand is still increasing every year by ~2.2% but that already includes the EV and Heat pump transition.

350GW last year, 356GW in 2024, 362GW in 2025 etc and before you know it we are done. Except 2024 is on pace to massively exceed that estimate, ~500GW looks more likely.


Again it's all startup talk. I never mentioned orders of magnitude, I mentioned complexity. You keep focusing on what already uses electricity, ignoring the fact that 80% of the energy we use is NOT electricity.

And you still haven't answered my question: how do you power a big merchant boat with electricity? Do you realize it doesn't work with batteries, or not? And do you realize that the merchant boats ARE globalization? We don't have a technical solution for that, not even as a proof of concept. And most certainly not with renewables.


> 80% of the energy we use is NOT electricity

99% of the energy used by mankind is sunlight, but obviously we aren’t aiming for accuracy here.

Your 80% as fossil fuels is half (coal, natural gas) which are mostly used to make electricity and therefore goes away on a renewable grid on its own. In essence you are double counting the inefficiency of fossil fuels as if it was somehow a positive. People do use some natural gas for heating and cooking, but there’s direct swap in replacements that use electricity.

https://en.wikipedia.org/wiki/World_energy_supply_and_consum....

“40%” is oil though again that’s what’s pumped out of the ground not what’s actually used as fuel. Subtract EV’s and year really talk about 10% “of the worlds energy” used in boats and aircraft.

> big merchant boat with electricity.

New boats can run 100% hydrogen out of the gate.

Container ships don’t actually last that long, but you can also retrofit existing engines to run 85% on hydrogen fairly easily.


I think the idea is more that the potential profit or the need for energy to prevent limiting this profitable venture will drive more capital into fusion projects. It's not clear that they will hit the man-month problem since it seems like there's dozens of fusion startups trying slightly different variants. Of course that doesn't mean it will solve the problem faster.


> It's not clear that they will hit the man-month problem since it seems like there's dozens of fusion startups trying slightly different variants.

I read: "it's not clear that parallelization will not help, because they are parallelizing", which doesn't really make sense. Ok, it's not clear that parallelization will not help (just because it's hard to prove). But we have to acknowledge that fusion energy is not a new thing, and it's currently unsolved. So let's not bet our future on the hope that it will be solved in the next 10 years in such a revolutionary way that it will beat all our expectations by orders of magnitudes, shall we?


The Man Month essay describes a breakdown in work throughput because of the exponential increase in communication channels and complexity of administration. Parallel startups do not communicate with each other. It appears from the outside that fusion does not have a known critical path to completion so increasing the number of bites at the apple seems like a logical way to scale attempting to solve it.

I agree we should not count on fusion (or wide spread carbon capture) to solve our problems and pretend we can continue as if there aren't any limits. Unfortunately unrealized miracle solutions are presented all the time to problems and since a lot of tech revolves around startup culture, our industry is prone to believing in them.




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