Concentrated Solar Thermal (CST) converts sunlight into heat which can then be used to generate electricity via steam generation and/or stored for several days. If stored the heat can be used at night, on cloudy days, or to meet peak energy needs. Think of it as putting something hot in a giant thermos bottle and efficiency runs at about 40%. Putting CST plants in variety of locations further reduces problems with intermittent sunlight; the sun is always shinning somewhere. The best locations for CST in the U.S are toward the south and west. This isn't ideal for meeting the energy needs of the entire nation, but by using high efficiency direct current power transmission lines this issue can be minimized. CST is an established and well understood technology, currently generating many gigawatts of electricity in the U.S. and around the world and new plants are being planned or are under construction world wide. Compared to nuclear, coal, or natural gas, CST plants are comparatively inexpensive and quick to construct and do not generate green house gases or nuclear waste. CST is not a cure-all, it will not fix all our problems. No single answer can do that, but CST can be a very large part of the practical, workable, economical, and environmentally friendly solution that we need.

The "negawatt" and cogeneration proposal says,in effect, " Go ahead and burn coal,( or oil or NG ) just burn less.". How about cogeneration with "distributed nuclear power"?
Consider the SSTAR https://www.llnl.gov/str/JulAug04/Smith.html It is small enough to be delivered almost anywhere. It will run for 30 years without refuling, after which it will be shipped back for recycling. It will be very economical; factory made by the hundreds. But not in a USA factory. It will join the VCR and Flat Screen TV as a brilliant American inovation to be manufactured by other nations!!