Im a Pipefitter/welder that is working in Blythe at a differant design Thermal solar power plant.The one Im on uses mirrows to heat up oil at 800 degrees and it goes through a heat exchanger, flashes the water to steam and the steam turns a turbine. It covers 1800 acres of land and a new designed closed system cooling tower will save alot of water cooling the turbine. The tower type that you are talking about the bioler is on top of the tower,it heats sodium to 1200 degrees and that goes to the exchanger to make the steam. The exchanger, boiler and turpine are all in the tower. I dont know why but the higher the tower the more efficient the process. There are 20 or so solar plants on the books for the California,Nevada and Arziona region.
I have been on some of the largest clean coal power plants built in the last 10 years in the US, These are 850 MW and will be eating ALOT of coal for years, as said these plants are the backbone of the power grid in the US along with Nuclear. Big coal plants are at least 3 to 4 Billion dollar in total construction cost and will be eating ALOT of coal for years, Which isn't a bad thing, I like to have my lights on too. We all know the cost of a Nuclear plant but the fuel is small for the 800 to 1200 MW output but the fuel is very costly to get rid of. The small Natural gas peaking units are compined cycle meaning a HUGE jet engine turns a turpine the shaft is connected a generator and makes power there, then the hot exhaust gas goes through a boiler and makes steam to turn a turpine. Power companies like these units they can sit cold for weeks then when energy is in PEAK demand means most expensive they can turn them on is 20 minutes and keep the air cons on in the summer and the heaters in the morning in the winter. These units are 150 MW average, some are larger and have heard that these cost 175 Million per unit and are always built in pairs eather 2 or 4. They need a high pressure natural gas pipe line to keep them running.
The death of the old dirty coal burners in the coming years is due to the EPA rule for clean air, it's cheaper to build a peaking unit then to build a dry gas scrubber for the coal plant to clean the exhaust gas. The biggest enemy to the coal industry in the US is not the feds but is from fracking, the amount of cheap natural gas in the country is staggering.
Having read the facts of how power is made in the US the solar project im on cost 1 Billion dollars to build ,makes 250 MW, the owner will never need to spend money to purchase fuel but will take 15 years to turn a profit. After that its money in the pocket from the sun, long term smart, short term dump and wall street needs profit NOW to come up with the money to build. So uncle sam steps in to fund it, these solar units do work and the ones being built now are not experimental. I will also say this, the money from my pocket, from my pay check is a shot in the arm for the small town of Blythe. The local economy in these remote sites the units are built are very happy to see my money Lord knows they need it and the permanent jobs will be a happy site.
Hope this helps Dave