Turning a solar power system into its own backup | Hacker News Reader

Turning a solar power system into its own backup

arstechnica.com

62 pointsPaulHoule26 comments

We can break the 5500K temperature limit with passive elements and some clever engineering.

https://en.wikipedia.org/wiki/Solar-pumped_laser

https://ieeexplore.ieee.org/document/1553831

While heating something that hot using “passive” components (is a laser really passive?) is awesome, is it really useful? 5500K is considerably hotter that, say, the combustion chamber of a rocket, and those chambers need active cooling. And even 1500K is plenty hot that the Carnot efficiency of the heat engine part will be high.

Also, a solar pumped laser needs cooling, just like a heat engine! Just from first principles, you can’t have a gadget at thermal equilibrium that magically produces an excess of light at its output frequency — this would violate the second law of thermodynamics.

And if you imagine a model three-level laser, exposing all three transitions to bright light will pump the nonlasing intermediate transition (overfilling level 2, thus reducing the population inversion in a laser lasing on the 3 -> 2 transition, or pumping useful level 2 atoms back up to level 3 in a laser lasing on 2 -> 1) and will actively un-pump the lasing transition in any variety of laser (because light in the wrong mode will cause a population-inverted transition to emit into that same wrong mode by simulated emission).

Maybe I missed it somewhere in the write up but in what way is the solar system its own backup? It seemed like the battery was just subbed for a combustion system using stored heat?

It's a weird way to phrase it. It's a solar generator that shares it's turbines with a conventional generator.

I was picturing a solar-charged battery running a light above the panel overnight

Not quite. It's a solar thermal (heat generator) that feeds a heat storage facility via an air-flow heat exchanger. That exchanger can alternatively be fed hot air generated using any other technology, including burning fossil fuels.

So, the heat storage facility is "source neutral". In addition, precisely how the stored heat is used "downstream" is also not a central part of the design, but turbines etc. are a likely option.

In the way that that will make you click the link.

Tangential: a non-parabolic curved mirror setup can be used for DIY solar thermal concentration to get more energy without motors and working better under clouds:

https://youtube.com/watch?v=8zlAI32MSsQ

REAL TLDR: Just Slap some gas generators onto the bad design and it'll work this time(tm)

How is this different from Ivanpah?

I guess that they're using multiple smaller towers? This does reduce the complexity of the tracking and alignment systems.

Uhm, so if the cost of generating energy (LCOE) of PV + BESS is cheaper than this tech and cleaner (no fossil involved) why should we promote this?

I’m very sceptical about its potential for generating electricity cheaper than PV + BESS but for process heat it seems plausibly more efficient since CSP is 50-90% efficient for thermal transfer (without the electricity generation step.)

TLDR: it's a concentrated solar plant (field of mirrors shine light on a tower to boil water) with a backup system that boils the water by burning stuff.

"The first installation will be"

It also hasn't been built yet. Let me know when they have one working prototype. Until then, it is just a concept on a drawing board.

If I understand the article correctly, there is no boiling water, it uses hot air only. It says the concentrated solar generates air up to nearly 1000 degrees, and that's used to heat up compressed air to run through a turbine, with the eziting air at around 250 degrees. Burning fuel would replace the initial source of hot air. Burning fossil fuels to get hot air and then dumping 250 degree air to the environment doesn't seem very efficient, but the article doesn't mention anything about the efficiency of the process with either source.

Does say the hot air at the end can be used for industrial processes, so it might not be completely lost

Not quite right.

The 1000 degree air is not used directly to drive turbines, but instead to deliver heat to a heat storage unit via a heat exchanger. The solar-heated air, after flowing through the heat exchanger, is still around 250 degrees and the article mentions some possible uses of that heated air (again, not generation).

Generation occurs using heat coming from the heat storage unit, not using the solar-heated hot air. Since the heat storage unit can also be fed by hot air heated via other means, this makes the heat storage unit "source neutral" - it can be heated by solar or fossil fuel combustion (or whatever).

The turbines are "downstream" of the heat storage unit.

Advanced new power generation technique!

Look inside, it’s boiling water to spin turbines.

There's actually no mention of the technology used by the turbines. This article is about how you heat up a heat storage facility that is then used (somehow) to drive turbines. Might be water, might not be.

Have we discovered any way to directly generate a stream of electrons without any mechanical movement?

Solar panels

doh

I'm dumb, but I meant, anything else and similarly magical?

I guess there's the ATP stuff used by all lifeforms..

Probably those radioisotope thermoelectric generators used in space probes?

Not really the thing you want sitting between your legs.

You don't know me

Antennas and the peltier/seebeck/TEC should also count.

> to boil water

Brayton cycle so no water needed. It seems as if the concept has not changed since https://www.rostinternational.com/wp-content/uploads/2019/10...

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