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CA's First Molten Salt Energy Plant Approved
An anonymous reader writes "This year we've seen molten salt power plants start to pick up steam around the world, and now the technology is heating up stateside — California just approved its first molten salt energy plant. Designed by SolarReserve, the plant uses heliostats to focus thermal energy on a power tower filled with salt, which is able to reach very high temperatures (over 1000 degrees Fahrenheit) and can hold heat for an extraordinary length of time. Heat from this reserve of molten salt can then be pumped through a steam generator to provide on-demand energy long after the sun has set."
810.777 Kelvin .... nuff said.
http://en.wikipedia.org/wiki/Solar_power_plants_in_the_Mojave_Desert
Only if you ignore Solar II that ran from 1996 to 1999....
---In a time of Chimpanzees I was a Monkey.
They didn't have the desert sun pouring onto a thousand large mirrors perfectly aligned on something for hours on end. Their test was more about the ability to align all of these mirrors without technology. These kind of things are dependent on energy going in vs energy going out. A thin sail surrounded by cool damp sea air only being shone upon from one side is going to have a lot less energy going in, and a lot more energy going out than a desert solar array.
Besides that it is also a "trivial geometry" case. If you assume the collector constant the more obtuse the angle of reflection requires a bigger mirror. If the receiver is low, you end up with an obtuse angle out of necessity. The higher it is, the easier to obtain that magic 90 degrees that minimises the mirror size and from there cost and everything else.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
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It takes several days and nights of little to no sunlight for the salt to cool down enough to no longer be molten and useful.
It doesn't have anything to do with the amount of heat loss. That just affects sizing. Heat pump efficiency depends on the temperature differential between outside and inside.
And I'm including the efficiency of electricity generation via fossil fuels in my statement. That should be obvious, since the thermodynamic efficiency of the heat pump alone can be upwards of 400%. Also, comparing the efficiency of renewable energy generation to fossil fuels is pointless.
"I assumed blithely that there were no elves out there in the darkness"
1 horsepower isn't enough to run a house. And smaller heat engines are inherently less efficient than larger ones. And a smaller reservoir will loose heat faster than a larger one that has proportionally less surface area.
You still don't want the thermal mass in or near your house. A thousand degrees is enough to make paper and wood instantly catch fire. It is enough to melt aluminum and damage commercial bricks and concrete. It is enough to cause 3rd degree burns in seconds.
Looks like saltpeter (sodium nitrate and potassium nitrate) with a bit of calcium nitrate mixed in is the currently preferred mix with a ~220C melting point.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.