Oregon Public Broadcasting

The best uses of solar thermal energy are, in my opinion, those which displace high energy consumers for large infrastructure needs, especially those where power intermittency matter less or none. Namely: 1. HVAC for large building spaces such as malls, warehouses, retail shopping centers, etcetera, using absorption chillers driven by solar thermal concentrators. Store excess energy in hot water Dewar tanks. Works best in Southwestern US and less well in humid Southeast. 2. Pumping of irrigation water, especially in remote or rural farm and farm community areas. 3. Pumping and sanitizing of sewer and potable water for large municipal water treatment plants, especially for large urban, suburban, and exurban needs. 4. Pre-heating of shower water for large apartment complexes (preheat everyone's incoming water line.) I've identified these especially because they are needs which serve the broader societal needs and where solar intermittency does not matter as much. They can be coupled with wind energy too quite well, especially the pumping applications. Rather than converting solar thermal energy to electricity to pump, I envision a direct pumping mechanism, for instance the use of a Stirling pump. Finally, identify which needs *require* energy storage/buffer for cloudy areas. In those cases, the energy can be stored hydraulically by raising water up vertically into a reservoir. It can be a fully enclosed reservoir or an earthen-bermed reservoir. In my opinion, this is a more efficient means of energy storage than pneumatic which has high pumping losses on both sides of the storage input/output. However, in some cases where there is no practical provision or lack of land, pneumatic may work. In closing, I think the *intermittency* of renewables such as wind and solar is overstated and used as a blanket excuse for simply not trying anything. We have become so attached to old conventions that it's beginning to harm our society and world. In many cases, intermittency matters little or none. The primary requirement for successful integration of renewables into our existing infrastructure is to build smart capacity, e.g. match the power source to the load requirements and perform as few conversions as possible. Use direct thermal energy and isothemal fluids pumping where possible. Obey thermodynamics and stop trying to fight it. Electricity is NOT the only valid form of energy.

— Posted by nicklockard