Chemical Engineer <cheme...@gmail.com> wrote:
> Some numbers based upon most efficient claimed CSP plant: (approx 2 to 3 > times more efficient than PV but much more expensive) > They are not much more expensive, and by the time you build one that is 100 miles to the side, they would be the cheapest source of electricity. It would not actually all be put in one place. > 350,000 mirrors (assuming they are clean) > Generates power ~10 hours/day > The number of mirrors depends on how big they are. The trough mirrors in existing CSP plants are pretty big. > To cover peak US demand of 768,000 MW you would need 781 MILLION mirrors > that only cover you 10 hours per day. > Those must be small mirrors, since you need 2 or 3 per person in the U.S. The trough mirrors generate much more than one person can consume. With thermal storage you would need to more than double the area if you > wanted to store during the day and generate at night, taking up > 60% of > the Mohave. > Not really. Demand at night is far lower than day. > You also need to develop weather technology to keep all clouds out of the > desert... > Nonsense! When there are clouds or rain, demand falls in that part of the country. You would not actually put the entire facility in one place. > Also, your "Robots" will need to clean 781 million mirrors per month > (monthly cleaning cycle) in the heat and sand of the desert. > So what? Use 100,000 robots. Do not be afraid of large numbers. Think of how many railroad cars it takes to haul the coal now used in electric power generation, or the number of long-haul trucks in use (a million or so, I think). > Plus where will you get the water to clean them or power for your army of > hundreds of thousands of robots? > It does not take much water. With some techniques it takes none at all. The power is right there! It is a tiny fraction of the total output. Energy overhead -- including the power needed for robot maintenance -- is far lower than for other types of generators. > If you cannot clean 781 MILLION mirrors per month you will need more, > less efficient dirty mirrors and more space > Why would you not be able to clean them? I do not understand this comment. Robots are highly reliable and this application is ideal for them. I do not know if they need to be cleaned once a month, but in any case, the amount of cleaning, the energy and equipment needed to clean is tiny compared to the overall energy output. - Jed
