Concentrating Solar Power Ready to Replace Fossil Fuels - CO ratepayers

[jpak]

http://home.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20060818005485&newsLang=en

DENVER--(BUSINESS WIRE)--Aug. 18, 2006--For the first time ever, utility ratepayers in Colorado have asked that incentives to burn coal for electric power be replaced with solar power. Concentrating solar power (CSP) produces steam with mirrors that gather sunlight. By storing some of the heat, CSP runs generating plants day and night. A new form of CSP that is directly cost-competitive with fossil fuel combustion is now entering commercial deployment, according to the testimony submitted Friday at the Colorado Public Utilities Commission (PUC).

"The southwestern United States has superb solar resources, with more energy than Saudi Arabia waiting to be tapped," said John S. O'Donnell, the expert witness who submitted the testimony on Concentrating solar power. "This solar power can directly replace the burning of fossil fuels to heat water and produce steam," said O'Donnell.

Dan Friedlander, an individual in the Colorado PUC case, said, "We all need to be concerned about future costs of coal and carbon regulations because ratepayers will be footing the bill, especially here in Colorado. Coal burning exposes us to rate increases and the dangers of planetary heating. Generating our power with sunlight instead of coal is the safest, soundest, and cheapest choice."

Alison Burchell, a geologist and spokesperson for Ratepayers United of Colorado, said, "We talk about carbon capture as if it's a ready solution to critical planetary warming. But trying to bury the massive amounts of CO2 emitted from coal plants is like burying a mountain range - it will be difficult and, at the least, very expensive. If we build CSP plants instead, we avoid paying for the coal and its transportation and the monumental back-end costs to bury its exhaust."

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[JohnWxy]

1. THis is an important post. recommended.

this is worth repeating:

"We talk about carbon capture as if it's a ready solution to critical planetary warming. But trying to bury the massive amounts of CO2 emitted from coal plants is like burying a mountain range - it will be difficult and, at the least, very expensive. If we build CSP plants instead, we avoid paying for the coal and its transportation and the monumental back-end costs to bury its exhaust."

[bananas]

2. Great quote: "more energy than Saudi Arabia waiting to be tapped"

"The southwestern United States has superb solar resources, with more energy than Saudi Arabia waiting to be tapped," said John S. O'Donnell, the expert witness who submitted the testimony on Concentrating solar power.

[hankthecrank]

3. I think this is the right way to go for now

It seems that we can get the heat out of sunlight better than we can convert it to electricity.

On a smaller scale how about using one of these

http://www.whispergen.com/

It uses a Stirling engine but instead of burning fuel as a heat source use heat from sunlight. You could put sunlight onto expansion coil from a/c unit and use freon to transfer the heat to the stirling. The stirling works on the heat difference to move a generator.

After staying in Vegas one night with the temp gauge showing 118 degrees we sure should be able to extract some of that energy.

[Viking12]

4. Stirling solar is also going large scale...

http://www.stirlingenergy.com/breaking_news.htm

[skids]

5. Just to link this up...

Here's something I posted a bit back in another thread that can fill people in on the various projects going on in this field.

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=60395&mesg_id=60408

[RedEarth]

6. K&R

[Dems Will Win]

7. Actually, Stirling Engine's SDGE plant never went in

Windstorms kept ripping up their tracking.

It will never work the way it's designed.



The Concentrating PHOTOVOLTAIC design pictured above is 4 times more efficient, 39.4%, and cannot be damaged by wind because it is flat to the ground and short focal length.

The technology above is a superior and far simpler and cheaper design than a Stirling, which uses steam and is primitve in comparison.

[Duppers]

8. this "Concentrating PHOTOVOLTAIC design"

Is that technology currently in use by consumers or a prototype?

Link for more info? Thanks.

[skids]

10. The only direct-to-consumer ones I've seen are tracking.

Sunball and MicroPV sell two tracking-based systems -- both would have a bad wind profile for very windy areas, but would be doable anyway because the lower panel size means you can compensate with a strudier design, which in the case of SunBall/SunCube is built in, and in the case of microPV you choose the heliostat to mount it on if I guess right.

Links here. There are plenty in the works, but some are only sold to large turnkey project buyers and some are still on the bench.

http://www.dailykos.com/storyonly/2006/3/7/114711/9242

I like the energy innovations one because it's active tracking and looks very wind-immune, but that company has been very slow to commercialize (and very quiet lately.)

This is the first I've heard about there being problems with the SDG&E stirling dishes -- both companies' websites have no articles I could find saying there were any setbacks.

[BrightKnight]

11. A Fresnel lens would eliminate the need for tracking.

THe lens would focus light from the entire sky.

A fresnel lens can be as cheap and easy as an extruded plastic film with ridges stretched between two bent wire supports.

[phantom power]

14. Huh? Fresnel lenses require parallel rays like any other focusing optics.

[BrightKnight]

16. "line-focus" Fresnel lens concentrator:

http://www.stretchedlensarray.com/TheProject.htm

"NASA and ENTECH developed a new "line-focus" Fresnel lens concentrator. It was easier to make and more cost-effective than the mini-dome lens concentrator. In 1994, ABLE joined the refractive concentrator team and led the development of the SCARLET (Solar Concentrator Array using Refractive Linear Element Technology) solar array. SCARLET used a silicone Fresnel lens to focus sunlight at 8X concentration onto triple-junction solar cells. When NASA/JPL launched the Deep Space One spacecraft in October 1998, the SCARLET array powered both the spacecraft's electronics and the ion engine. "

The focal point is always the same regardless of the position of the sun. The lens is essentially focusing an image of the sky.

This was designed for PV. I don't see why it couldn't be adapted to generate heat for a Starling engine. stretched film would probably be a lot more cost effective than mirrors.

[skids]

19. Line focus isn't good for stirling.

Stirlings prefer spot-focus because the way they are built they really like as high a temperature as you can get them. Rankin engines and others are used in systems where a liquid transfers the heat to the engine, as is done in line focus. Troughs are great for collecting a whole lot of low-delta-T heat energy, whereas dishes are good at collecting smaller quantities of high-delta-T heat energy.

As far as collecting light from the entire sky, fresnel lenses do not do that very well -- they focus parrallel light beams, and are not good onmidirectional receiviers. There are optical arrangements that do ("non-imaging optics") -- in basic optics the compound concave parabolic mirror arrangement does it, and in the advanced "holographic" systems under development it is done with very cleverly designed gradient transitions. Some of these systems have a large cone/angle of acceptance, others simply have a cone of acceptance big enough to permit a cheaper and less precise heliostat.

[phantom power]

20. Then would you classify the gadget posted by BK as non-imaging?

It seems to be not a true fresnel lense, but maybe based on a similar optic design. Either way, it seems as though it at least has the advantage of not requiring tracking motors.

[skids]

21. Imaging in one dimension...

In the other dimension it is non-imaging.

Here's a breakdown:

Pyron solar is 2D semi-imaging with a non-imaging back-end
(fresnel + reflective fresnel + second-stage omni receiver) needs tracking.

Sunball/Suncube are imaging 2D fresnels from what I can tell. Tracking built in.

Energyinnovations SunFlower 250 is 2D imaging reflective + non-imaging compound concave parabolic second stage. Tracking is built in. The shelved SunPod design is imaging 1D fresnel and requires course 1D tracking.

Daystar's concentraTIR is 1D, and non-imaging in that dimension. Fancy graded polymer optics. 5-10 suns. Not sure about tracking needs.

Prism solar's is very similar to Daystar's.

MicroPV is probably non-imaging. I don't know what to make of it -- they say they have managed a 6 degree admittance angle at 3 suns insolation to the cell, but then say they don't need any tracker, even though it looks like a 2D system. There's not enough information to go on -- but they are one of the only companies actually selling product.

Stellaris uses a non-imaging compound concave parabolic 1D design that has a very high admittance angle for the angle perpendicular to the trough. Doesn't need tracking, 3 suns.

Solfocus is using a 2D non-imaging Cassegrain-like dual mirror arrangment, Requires tracking -- probably rather precise tracking. Very high concentration in the hundreds of suns range, onto extremely small triple junction cells.

[Ezlivin]

24. Pryon's system is pretty damned neat

As you noted, it does require tracking, but the way that it has solved it is pretty ingenious. They float the collectors on a thin layer of water allowing for a nearly frictionless tracking system that requires very little power to use.

They also store excess power by generating hydrogen which is used at night to power a generator.

http://www.pyronsolar.com/US/index.htm

[phantom power]

25. wow, a hundred suns seems like it would fry the PV cell.

[Gold Metal Flake]

17. Fresnel lenses are earier to make than you might think.

Cast from molds with clear silicone. That is a major factor in the new low cost concentrator systems. Now that you have cheap focused light at 300-400 suns or so, you can use small multi-junction GaAs space cells. Normally, these cells cost big bucks at two per wafer, but for concentrators they are only about 1cm square and you get many per wafer. The Green & Gold systems work this way (early versions were silicon). http://www.greenandgoldenergy.com.au/

One utility is using full-sized GaAs cells under concentration with mirrors. I posted about it a few days ago and it's repeated below.


Boeing to Supply Terrestrial Solar Cells for Australia

http://www.boeing.com/news/releases/2006/q3/060815b_nr....

ST. LOUIS, Aug. 15, 2006 -- The Boeing Company today announced it has signed a multi-million dollar contract to supply concentrator photovoltaic (CPV) cell assemblies to an Australian company that produces renewable solar energy.

<snip>

The solar cell assemblies will be capable of generating more than 11 megawatts of electricity -- enough to power 3,500 average-sized homes.

"For the past 50 years, Spectrolab has been a leader in space-based solar cells," said Dr. David Lillington, president of Spectrolab, the world's leading producer of space and terrestrial concentrating solar cells. "We have leveraged our expertise in space photovoltaic products and created terrestrial concentrating solar cells with record-breaking efficiencies averaging above 35 percent. We are now partnering with the best of industry and making great strides in reducing the cost of solar energy to homes and businesses worldwide."

This contract with Solar Systems continues an earlier relationship between the two companies. In April, Spectrolab and Solar Systems brought the world's first full-scale ultra high efficiency 35-kilowatt solar generator online in Australia. The system created a new benchmark for solar concentrator systems both in system efficiency and cost, and showed great promise for the future of renewable energy.


Edit to add lonk and fix spelling and to remove jab at employer.

[skids]

18. Apparently not easy enough...

...this product got shelved in the industrial engineering stage because the lense part could not be mass manufactured cheaply enough, according to the company.



http://www.energyinnovations.com

[Gold Metal Flake]

22. You think they are the only ones?

:-)

[skids]

23. ?

Your question is vague. The above company tried different manufacturers of UV hardened plastic transparencies. Or, if you mean do I think this company is the only one doing fresnels, no of course not, but the question there is of those companies, what is their price target / peak watt?

[IDemo]

13. Stirlings do not use steam

While some concentrating solar power technologies do use steam to power turbines, Stirlings rely on a sealed "working gas", generally hydrogen. One thing Stirlings can provide that no PV can: the ability to continue supplying energy at nighttime or on cloudy days, using landfill methane or natural gas.

http://www.stmpower.com/Technology/Technology.asp

[immoderate]

9. Some years ago I did a back of the envelope calculation.

Fermi math, for those familiar. Anyway I estimated that the energy demands of the United States were roughly equal to the output of photovoltaic cells covering an area equal to all the roof tops in the US. and they are more efficient now.

--IMM

[OneBlueSky]

12. the reason solar hasn't advanced faster is simple . . .

they can't charge you for the fuel . . .

[suziedemocrat]

15. EXACTLY!!!!!!