Solar Juice, from Concentrate

Have you ever seen the trick where someone starts a fire using a magnifying glass to focus sunlight? Concentrated solar power is like that, just way bigger.

To the Flipboard! Let’s see what we’ve got in my “Sustainability” category……

Ooooooooohhhhhhh. Concentrated solar. I like concentrated solar.

What is it, you ask? Well, to answer that, let’s first say what it isn’t. Concentrated solar isn’t the same thing as photovoltaic solar panels. That’s a form of solar power where an individual panel is able to absorb the energy from the sun and directly convert that energy into electricity. That’s good technology too.

Concentrated solar is actually a lot more like conventional power plants. Whether coal fired, natural gas fired, or nuclear, power plants operate with the same basic principles. Step one: generate heat (burn coal, burn natural gas, or split an atom). Step two: boil water with that heat to create steam. Step three: use the steam to make a turbine spin, which results in kinetic energy that a generator can convert into electricity. Step four: send that electricity to your smart phone, toaster, night light, etc.

So can we get enough heat to boil water without cracking an atom open or lighting something on fire? It turns out we can. That’s what concentrated solar is.

Imagine a whole bunch of mirrors that can pivot to follow the movement of the sun (much like how these plants will turn and follow the sun). The mirrors all reflect the light back to one central point that can create a whole bunch of heat. Have you ever seen the trick where someone starts a fire using a magnifying glass to focus sunlight? It’s like that, just way bigger.

All of that heat, over 1,000 degrees Fahrenheit, is enough to melt salt. It turns out that molten salt is a convenient thing to have if you are trying to create electricity. Using a heat exchanger, the salt’s heat can be transferred to water to create the steam needed to turn turbines. And voilà, you have electricity. Cost effective electricity too, at least in locations where you have a lot of reliable sun (like a desert).

I’ve stumbled across two concentrated solar articles on Flipboard in the last several weeks, both from EcoWatch.com. Here’s the first one, which covers a concentrated solar plant in Dubai that will generate a gigawatt of electricity by 2020 and five gigawatts by 2030 (enough electricity to power 800,000 homes). And here’s the second one, discussing a Nevada-based concentrated solar plant that claims to be the world’s first 24/7 solar power plant.

How is that possible? The sun doesn’t shine round-the-clock after all. The answer is in the molten salt, which can act as a thermal battery. You can draw heat off of it even when the sun isn’t shining. And as we’ve discussed, when you have enough heat, you can create electricity.

With innovation like this, solar electricity’s future is bright (man do I love a terrible pun). See y’all next week!

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