Why America Is Choking Under An Everything Shortage

[Eacaraxe]

What is solar thermal?

Long story short, think the Archimedes death ray except used for power generation. Basically, the solar power plant in New Vegas (which was based on a real plant near Primm).

Long story not-so-short, concentrating solar power via trough mirrors, parabolic dish mirrors, or heliostat arrays to provide heat to a central location. A medium is pumped through that location, absorbing the heat and being carried through mechanical action, convection, or conduction, to turbines which then generate electricity. Pressurized water can be the medium at baseline, but given concentrated solar plants under the right conditions can achieve temperatures in excess of 7,000 degrees Fahrenheit (in other words, way beyond high-temp gas-cooled reactors), water represents the low end of potential media in both thermal conductivity and capacity, with gas turbines and even molten salt or metal turbines in the realm of possibility.

The best thing is, they work at night or in suboptimal weather, and better in latitudes with poor solar insolation than photovoltaic: excess heat gets stored in thermal batteries, as opposed to convert that heat to electricity for storage in electrical batteries which is a less-efficient storage method.

The technology's actually over a century old, solar steam engines were first introduced in the 1860's and working designs for commercial solar power plants were created in the 1910's.

 

[Satinavian]

What is solar thermal?

Instead of using solar cells to convert sunlight directly into electricity, it uses it to convert into heat, usually with collectors.

It hardly works on cloudy days with diffuse radiation and is very dependend on good weather. There are ways to mitigate that, so called flat collectors, but those are either not very efficient or really expensive.

Solar thermal installations can be made far more resilient. That is why most of the "use solar in deserts" projects rely on them. Of course you still to make some extra efforts and there was at least one big solar thermal desert project that utterly failed because it wasn't sand-proof. But they are basically designed to resist vast temperature differences and hold up far better there.

It is generally less efficient then PV but cheaper. It is especially worse at producing electricity because you already lose energy when producing heat and then again for converting to electricity. Which is why the most common use for solar thermal in the world is providing warm water and for heating. But for this it suffers a bit from heating and warm water being mostly needed in the winter. In fact most installations are optimized for winter use but it is still when they are weakest. An alternative are seasonal storage systems which work well but are expensive and would need to be built when the house is built.

Generally installing solar thermal for water and heating into existing homes is more difficult than installing PV. Which is one of the main reasons holding it back.

Main user so far is China but it is also quite popular in Germany and in Turkey. It is also one of the techologies where China still imports from Germany a lot while it is the other way around with PV, mostly due to rare materials.


US and UK have basically ignored it for some reason. Maybe not fancy enough.

 

[Eacaraxe]

It hardly works on cloudy days with diffuse radiation and is very dependend on good weather. There are ways to mitigate that, so called flat collectors, but those are either not very efficient or really expensive.

It's far more effective in suboptimal weather conditions than current commercially-available PV, especially with thermal energy storage solutions. Flat collectors are really only used for temperature control and water heating, which I'll get to.

Solar thermal installations can be made far more resilient. That is why most of the "use solar in deserts" projects rely on them.

With notable exceptions, but the benefit is solar thermal is one hell of a lot more versatile in design and function than PV.

Of course you still to make some extra efforts and there was at least one big solar thermal desert project that utterly failed because it wasn't sand-proof. But they are basically designed to resist vast temperature differences and hold up far better there.

If you're referring to the Mojave heliostat plant projects, those were giant bureaucratic, mismanagement-laden, FUBAR's that overpromised and underdelivered, one of them going offline before the startup that built it could begin running in the black. As it turns out, computer-operated flat-panel heliostats with electric motors generate a little bit of a parasitic drain on your own plant -- especially when it takes months to melt your medium so that it begins generating power.

It is generally less efficient then PV but cheaper. It is especially worse at producing electricity because you already lose energy when producing heat and then again for converting to electricity.

It's actually more efficient. The best commercially-available PV panels, last I read, top out at about 23% efficiency (and the higher end are still concentrated solar photovoltaics). Your absolute worst case scenario for solar thermal is a collector that converts solar energy to heat at 70% efficiency, coupled with a steam turbine that operates at 40% efficiency converting mechanical to electricity: so, 28% efficient in converting solar energy to electricity. And when I say "worst case" I mean it: that's the efficiency of solar thermal generators using century-old technology: parabolic dish collectors heating water, which drives a single-stage turbine.

The bonus of solar thermal is, that like nuclear, efficiency increases as the medium's temperature does. Which is why the holy grail for the technology are molten salt and metal thermal batteries; that means efficiency than photovoltaic will have in its current state, simply because energy doesn't have to be converted to electricity before storage, and that means dispatchable high-efficiency power.

Which is why the most common use for solar thermal in the world is providing warm water and for heating.

That's the best feature of solar thermal, versatility.

US and UK have basically ignored it for some reason. Maybe not fancy enough.

Insert rant about aforementioned fad-chaser, low-info, liberals and political grift here. The marriage between fossil fuels and the GOP is one of wide-scale but low-grade stupidity, but the marriage between green energy grifters and the Democrats is one of small-scale but weapons-grade stupidity. Because Democrats keep shoveling money into green energy donors' pockets to push some of the dumbest fucking dead-on-arrival initiatives that are clearly scams to get federal funding and run.

Hell, remember when Jay Inslee ran for president, and that whole thing came out about Washington state's 100% renewable energy plan came to light? The one they passed in 2015, if I remember right. Where the state legislature had initially made an exception for hydroelectric as a renewable energy source, to funnel grants and credits to photovoltaic companies to build solar plants...in the state with the worst insolation in the country...because state legislators were getting kickbacks from PV companies, or had stock in them?