

Storehouses for Solar Energy Can Step In When the Sun Goes Down - tokenadult
http://www.nytimes.com/2012/01/03/business/energy-environment/building-storehouses-for-the-suns-energy-for-use-after-dark.html

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philipmorg
"The water can be used to heat salt that stores the energy until later, when
the sun dips and households power up their appliances and air-conditioning at
peak demand hours in the summer."

Air-condition after sunset? Maybe, but that's an edge case for sure.

So if this thing actually costs $737MM to build, then the energy it stores
would have to be sold at around around $200/Megawatt to pay back the loan in
10 years. More, if you want to cover operating costs.

What's the catch? That's far above current market rates.

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Anechoic
> _Air-condition after sunset? Maybe, but that's an edge case for sure._

Not at all. Here in the northeast we run the A/C on occasion during the
evenings at times in July and August. I can imagine that humid areas in the
south run A/C at night far more often.

~~~
philipmorg
Good data point. Is that the primary component of off-peak demand, I wonder?

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ams6110
The "salt" they talk about is apparently not table salt. According to
Wikepedia[1] it's likely a mixture of sodium nitrate and potassium nitrate and
possibly some calcium nitrate.

Not only do I wonder about the cost and environmental impact of hundreds of
thousands of gallons of these chemicals, but observe that these are powerful
oxidizers and will be even more so if liquid-hot. This will require storage
tanks and piping that is not subject to oxidation, which will greatly add to
the expense of construction.

Not only that, these salts are prime ingredients for bomb-making, so such
plants will be potential terrorism targets, either as a source of bomb-making
ingredients, or for attempts to create a hellacious, non-extinguishable fire
by causing a massive release of the molten salt.

Edit: forgot reference...

[1]
[http://en.wikipedia.org/wiki/Solar_thermal_energy#Molten_sal...](http://en.wikipedia.org/wiki/Solar_thermal_energy#Molten_salt_storage)

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ori_b
Potassium Nitrate is primarily used as a fertilizer, as is calcium nitrate.
Sodium nitrate is also a component of fertilizers, but it's not as popular any
more.

If you're concerned about the impact of these being released into the
environment, you should realize that we're already doing it deliberately on
farms all over the country.

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danielharan
The article doesn't mention it, but these are known as concentrated (or
concentrating) solar power plants.

There's quite a bit of FUD about solar not being dispatchable (ready to
generate at a moment's notice). Massive heat sinks are just one solution; a
less capital intensive one is software that turns off electrical appliances
when needed.

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ams6110
My parents had a device installed that allowed the utility to cut off the air
conditioning for some short period of time (15 min?) during peak periods. They
got a discount whenever it was activated, but otherwise I can't see how it
really was a net savings, as the AC would only have to run that much longer
when it came back on. But I guess it does work to even out peaks.

~~~
danielharan
Having spare capacity to handle peaks is very, very expensive. Entire plants
sit idle 90% of the year.

