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Comment by deepnotderp | Hacker News Reader

Thermal storage has very poor discharge rates unfortunately (usually slower than a day), as well as surprisingly high cost once you factor in inefficiencies and turbine cost

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As was repeatedly explained in that other thread, thermal storage of the kind described there is inherently a long term storage technology, and this drives the design to minimize capex, not maximize round trip efficiency. The focus on efficiency is fundamentally misplaced there, as it becomes orders of magnitude less important compared to diurnal storage (which batteries appear to be well on their way to dominating.)

Long term storage and diurnal storage are complementary technologies, sort of like the different levels of cache and main memory in a computer memory hierarchy. Combining them appropriately reduces cost vs. using just one of them.

Anyway, the technology as described would produce heat at 600 C for as little as $3/GJ, which nuclear would have a hard time competing with.

$3/GJ is $108/MWH which any large scale fission buildout would easily beat for thermal energy costs

You misplaced a decimal point. A MWH is 3.6 GJ, so it's $10.8/MWH.

$3/GJ is about the current Henry Hub price for natural gas, and as you should know cheap natural gas like this is what killed the "nuclear renaissance" in the US.

Oh my bad, you’re right

Re: Nat gas, agreed, it’s not solar though, storage is much more expensive

Thermal energy still needs to drive a turbine to generate electricity

Sure. 600 C is about the temperature of steam in a coal fired power plant, so one of the use cases here is to take an old coal plant and replace the heat source. It's much higher temperature than the steam in a LWR, so the turbine can be smaller and cheaper. Also, no steam generator is needed as in a PWR.

Yes but one of the reasons that coal is being replaced by gas is because of the capex of the steam turbine

Yes? That doesn't mean the capex of a steam turbine for this application would be unaffordable, or that this wouldn't have superior economics to nuclear (which also has a steam turbine, and a more expensive one).

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