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A Tower of Molten Salt Will Deliver Solar Power After Sunset (ieee.org)
schwit1 sends this report from IEEE Spectrum: Solar power projects intended to turn solar heat into steam to generate electricity have struggled to compete amid tumbling prices for solar energy from solid-state photovoltaic (PV) panels. But the first commercial-scale implementation of an innovative solar thermal design could turn the tide. Engineered from the ground up to store some of its solar energy, the 110-megawatt plant is nearing completion in the Crescent Dunes near Tonopah, Nev. It aims to simultaneously produce the cheapest solar thermal power and to dispatch that power for up to 10 hours after the setting sun has idled photovoltaics. ... [The system] heats a molten mixture of nitrate salts that can be stored in insulated tanks and withdrawn on demand to run the plant’s steam generators and turbine when electricity is most valuable. ... Eliminating the heat exchange between oil and salts trims energy storage losses from about 7 percent to just 2 percent. The tower also heats its molten salt to 566 degrees C, whereas oil-based plants top out at 400 degrees C.
Previously such thermal solar tower designs have caught a lot of flak for a number of reasons, including their ability to light passing birds on fire ('streamers'), their maintenance-intensive nature (lots of mirrors and associated electronics to clean and maintain), the risk of massive arrays of mirrors reflecting light for passing pilots, as well as their relatively low power density.
The article reads more like a fluff PR piece instead of providing any credible reason for why we should get about yet another one of these plants.
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... and many more will, this is an old design, already in use.
Personally my favorite solar thermal concept is the compact linear fresnel reflector. They're much more dense (land area used per unit power generated) than pretty much all other solar tracking methods. Also, they only require single-axis tracking in long linear rows - but unlike other single-axis tracking methods like parabolic troughs, you don't need a receiver (heat pipe) running through the middle of every reflector; a reflector is *just* a reflector. The alternation of directions in which light gets reflected reduces blocking between reflectors, and thus increases how close you can space them. And the high density means less distance for the hot water to flow, and thus less heat loss, further increasing the power generation per unit area.
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We will eventually have 11 billion people consuming power at US levels - likely before the end of this century. Smart meters won't fix that. Solar is the only thing that scales (unless fusion finally stops being "just 20 years away"). Efficient PV panels and Tesla batteries are very high-tech solutions, and it's unclear that they could be available cheaply at that scale. Solar thermal, though, is quite straightforward.
This plant isn't good enough to be more than an experiment, and useful to hedge against a steep rise in fuel prices, but it's an incremental step. There seem to be many more incremental steps available for various approaches to solar thermal (I'm not the biggest fan of this exact design, but the power storage aspect is nice). Solar thermal just isn't a hyper-optimized mature field grasping for 1% improvements - there's lots of headroom here.
We're going to need a power generation solution that scales over 10x current world generation, and we're likely to need it in the lifetime of some /.ers. A solution with no exotic toolchain requirements, and no raw material requirements that won't scale, and that works for base load doesn't leave many options. (Obviously, solar isn't good for high latitudes, and gas generation isn't going away, but we're going to need something new for base load until fusion finally shows up).
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I like seeing things like this. I'm not excited about the solar power aspect, I actually think that is a fool's errand. I'm excited about seeing people research molten salt power transfer systems and high temperature power generation.
One big problem holding up research in molten salt fission reactors is that the power generation systems it relies upon for much of its efficiency gains have not been tested fully. If we can prove to the powers that be, like the US Department of Energy, that we can handle molten salts safely then we can get that much closer to getting a molten salt reactor built.
Looking into how these concentrated solar power plants work I had to ask myself, what do they do when the sun doesn't shine enough to keep the salt molten? They claim ten hours of storage capability, that might get them through the night I suppose. What if the morning sun is obstructed by clouds? Well, I found my answer when looking at the Ivanpah Solar Power Facility.
https://en.wikipedia.org/wiki/...
To get these things started in the morning takes a lot of natural gas. I understand the need for a power plant, any power plant, to have backup power on site in the case of the need to shut down the primary electric generation when there is loss of a connection to the grid. But the need to do this every morning does sound a bit counter productive. This is a plant that is supposed to reduce our reliance on fossil fuels. That's what I thought the whole point of solar power was supposed to be.
Perhaps, after we prove molten salt solar can work when the weather agrees, then we can put a small modular thorium reactor on the site to warm up the salt in the morning and provide a base load of power for when the sun doesn't shine. Of course, once you can show that small modular reactors of about 100MW capacity can keep the solar power plant running then people will begin to wonder why they bother with the large expensive solar tower when the reactor keeps running regardless of the weather. At some point they'll tear down the tower to make room for more reactors.
That's the whole point to me, moving towards small modular thorium reactors. Of all the technologies we have out there right now I see that as the one true solution. We'll still see wind, solar, hydro, geothermal, and so on in the times and places where it is cheap but small thorium molten salt reactors can be used in so many places. Make them on an assembly line like a Boeing airliner and we should see a new one built every month. In twenty years we should see the grid powered by more than 50% nuclear fission.
I still think that nuclear fusion will prove viable within my lifetime, but only when done on a multi-gigawatt scale. That is going to be very expensive to build initially but once built it should run for a long time using common elements as fuel. Until we have a leap in technology like that we have three choices:
- Nuclear fission
- Continued fossil fuel use, with all its pros and cons
- Expensive unreliable wind and solar
So, go build your concentrated solar power plants, those would make great sites for a future thorium fission power plant.
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