[cestith]

One of the goals with solar thermal is to store the heat in a thermal mass then use that to heat a closed loop steam or gas turbine at night. No fossil fuels are necessary if the system works well enough.

There's a recent proof of concept plant using bauxite particles instead of a liquid or gas as the thermal mass. It should help quite a bit in cost and reliability. Rather than a bunch of high-pressure tubing for liquid salts and such, it works with grain lifts.

One nice thing about using solar thermal for hydrolysis is that much hotter water is much easier to split with electricity. So if you use some of the heat mass to heat water steam to 600 or 700 C, you can use a lot less of the power post-conversion.

A CO2 heat loop might be more efficient than a water steam one, so if the plant isn't dedicated to hydrolysis it might end up with two generation loops.

[Retric]

The issue beyond direct costs is it’s concentrated solar thermal which stops working in cloudy weather or dirty reflectors. Which means you need some other way to generate heat our your randomly out both daytime solar and backup energy.

Net result, PV + batteries simply cost less for more reliable power unless you have backup fossil fuel for heat. If the goal was say 80% reduction of fossil fuels then concentrated solar is ok, it just doesn’t really work for a zero emissions grid because you need just as much storage somewhere else in the system.

[cestith]

Cleaning the reflectors may not be a trivial engineering task but neither does it seem insurmountable. Ultrasonic or electrostatic techniques come to mind. Maybe titanium dioxide plays a role as in self-cleaning window glass. If some sort of mechanical action is needed, it has a whole night to complete cleaning before the reflectors need to be ready again.

Heat mass plants provide storage as part of their electric generation process. That's the whole purpose of transferring the heat into the heat mass rather than directly to the turbine loop.

[Retric]

The problem is it isn’t free.

PV extracts more electrical energy per area of solar collector and it isn’t cost effective to clean them or currently to track the sun. Concentrating solar takes a larger hit when it skips either, which is just one of the reasons it’s not cost effective.