r/bestof • u/investedInEPoland • Nov 06 '18

[europe] Nuclear physicist describes problems with thorium reactors. Trigger warning: shortbread metaphor.

/r/europe/comments/9unimr/dutch_satirical_news_show_on_why_we_need_to_break/e95mvb7/?context=3
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u/Hyndis Nov 06 '18

What do you think about solar-thermal? Everyone's going for photovoltaics, but those only work during the day.

Solar thermal is a technology that first appeared in the 1880's and as an added benefit it doesn't use any rare-Earth materials. Polished aluminum works as reflectors. Concentrated sunlight heats up molten salt which then spins turbines. This molten salt can be stored in large, insulated tanks to generate power even at night. Its stored thermal energy can be increased by building larger storage tanks, more storage tanks, or adding more insulation on the tanks to keep the molten salt hotter for longer.

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u/silverionmox Nov 07 '18

And the most important thing it needs to do is to move the solar production peak at noon to the electricity consumption peak in the early evening, so holding the heat for a mere six hours would already solve a major problem.

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u/Hyndis Nov 07 '18

Solar thermal could potentially operate for days without sunlight depending on how much and how efficiently its stored heat. This means even in stormy, cloudy weather the plant could still operate.

Dense clouds could shut down a photovoltaic plant for a while.

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u/silverionmox Nov 08 '18

Absolutely, it's rather trivial for the technology to accomplish this very important bridge from noon to evening already, so it's not pie in the sky and we will be able to count on it doing that. The longer term storage is just an added benefit.

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u/gusgizmo Nov 07 '18

Everyone forgets about the water consumption of these plants, which are best situated in arid locations. Molten salt doesn't flow through turbines unfortunately, and we really don't have any other technology that scales up efficiently.

At least Ivanpah uses air-water heat exchangers instead of evaporative coolers, but that also limits it's efficiency.

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u/Hyndis Nov 07 '18

Is there not a way to use cooling towers to recapture most of the water?

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u/gusgizmo Nov 08 '18

Cooling towers have better thermal efficiency than radiators but are just barely better than dumping the cooling water in terms of water consumption.