Turning Glare Into Watts

[OKIsItJustMe]

http://www.nytimes.com/2008/03/06/business/06solar.html?ref=business

March 6, 2008
The Energy Challenge

Turning Glare Into Watts

By MATTHEW L. WALD

BOULDER CITY, Nev. — At first, as he adjusted pumps and checked temperatures, Aaron Boucher looked like any technician in the control room of an electrical plant. Then he rushed to the window and scanned the sky, to check his fuel supply.

Mr. Boucher was battling clouds, timing the operations of his power plant to get the most out of patchy sunshine. It is a skill that may soon be in greater demand, for the world appears to be on the verge of a boom in a little-known but promising type of solar power.

...

The technology is not new, but it is suddenly in high demand. As prices rise for fossil fuels and worries grow about their contribution to global warming, solar thermal plants are being viewed as a renewable power source with huge potential.

After a decade of no activity, two prototype solar thermal plants were recently opened in the United States, with a capacity that could power several big hotels, neon included, on the Las Vegas Strip, about 20 miles north of here. Another 10 power plants are in advanced planning in California, Arizona and Nevada.

...

[gristy]

1. I do like solar thermal power

http://en.wikipedia.org/wiki/Solar_power#Solar_thermal



A parabolic dish or dish/engine system consists of a stand-alone parabolic reflector that concentrates light onto a receiver positioned at the reflector's focal point. The reflector tracks the sun along two axes. A working fluid (hydrogen, helium, air or water) flows through the receiver where it is heated to 1000 °C before transferring its heat to a Stirling engine for power generation. Parabolic dish systems display the highest solar-to-electric efficiency among CST technologies and their modular nature offers scalability. The Stirling Energy Systems (SES) and Science Applications International Corporation (SAIC) dishes at UNLV and the Big Dish in Canberra, Australia, are representatives of this technology.

Note: CST == Concentrating Solar Thermal. Though I can't back it up, I am willing to bet that CST is more efficient than photovoltaics and has a lower capital and energy investment.

[OKIsItJustMe]

2. CST is currently more efficient than PV in converting sunlight into power

On the other hand, I believe EROI for CST is currently lower for CST than for PV.

[RC]

3. Can you translate into English please?

Just because you know what something means does not mean anyone else does.

[OKIsItJustMe]

5. Sorry about that

EROI - Energy Return on Investment (AKA EROEI)
CST - Concentrating Solar Thermal (AKA CSP)
PV - Photovoltaic



Okay, so why would the efficiency be higher for CST while the EROI is lower? Well, consider the typical "solar panel." Basically, you put it on your roof in the sun, and it puts out electricity. It's solid state, very low maintenance.

Now, consider the most efficient concentrating solar thermal unit (a parabolic reflector with a stirling engine at its focus, which is tied to a generator.) Okay, you've got a bunch of moving parts involved here. Clearly, even if it were cheaper to build (which I don't believe it is) its going to take a good deal more maintenance. (Right?)

[gristy]

4. Because the CSTcapital investment is higher?

That does not sound right to me. Silicon cheaper than mirrors? Is the CST powerplant the deciding factor?