Can solar energy be used to spin turbines?

Q&ACategory: QuestionsCan solar energy be used to spin turbines?
1 Answers
AvatarAdmin answered 3 years ago
I think your answer is already in hand from others.

However, I blame the French! Carnot ( Nicolas Léonard Sadi Carnot ) conceptualized the processes that go into (and out of) heat engines and teaches us that lower temperature differences have lower amounts of extractable work. And the temperatures available to solar concentrators is relatively low so turbines driven by them are doomed by both the theoretical limits (thanks Nicolas!) and the practical mechanical losses that come from imperfections in machines.

In solar collection there is another accursed Frenchman: Fresnel! He lays out the loss mechanisms that interject themselves when light moves between media. Along with his namesake lens form (the rough, sawtoothed lenses) he shows that any wavefront moving from, say the air to glass, will be reflected in part back to the source. Clearly, a French conspiration!

So you can spin turbines with solar energy… However, the low energy density of solar, the conversion losses in heat engines, and transmission losses (even at the light stage) mean it is generally a “mauvais plan.”

That said, there are some concentrator schemes that do aim for high temperatures (to push up the high side the Carnot curve) and store the heat in molten salts for dispatch later in the day. This energy is more valuable since it can be delivered approximately at will, and in the later hours of the evening – high load periods in the developed world. Those watts, while compromised by losses in collection, storage and heat engine losses might still be valuable enough. The jury is still out. The scale of these collector sites is huge (instructively so.)



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