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November 17, 2006

Comments

amazingdrx

This would seem to be well suited to solar trough collectors. For double the power from the same PV cell area.

And that is double the power at 39% efficiency (according to NERL tests)if the concentration reaches 10 suns. And of course at 10 sun concentration about 1/7nth the normal amount of PV cells used in a flat plate collector are needed.

This bifacial PV cell would put that around 1/14nth the cell area. That is the way to cut solar electric costs without relying on silicon prices coming down.

Cost is added for the concentrating collectors, but they are inexpensive anyway, fabricated from sheet metal.

Nucbuddy

Dr. X wrote: This would seem to be well suited to solar trough collectors. For double the power from the same PV cell area.

The solar trough only concentrates on one side. A bifacial cell, if it would even work at all with a concentrator without failing, might increase the power by only 1%.


Dr. X wrote: And that is double the power at 39% efficiency (according to NERL tests)if the concentration reaches 10 suns.

What does that mean?

amazingdrx

http://www.worldchanging.com/archives/003127.html

"At the conference, NREL announced a new record efficiency of 37.9 percent at 10 suns, a measure of concentrated sunlight."

Actually I have in mind a special kind of concentrating collector that uses a compound parabolic design. It could supply both sides of the cell with 10 suns.

This design can cogenerate heat (while cooling the PV cells)as well to boost total efficiency (it looks like maybe 65%% from wide spectrum PV cells that operate at 55% in flat plate collectors as well as an extra 20% for the heat collected), heating hot water or providing heat energy to power adsorption cooling for air conditioning or refrigeration.

The higher efficiency and more hours that this type of collector can operate (it concentrates diffuse cloud light as well as morning and evening light), will result in many more kwh per year with a fraction of the PV cell area needed in a flat plate collector.

At over 75% total efficiency (elerctricity and heat energy)using maybe 1/10nth the PV cell area these systems would power the world from rooftops and over parking lots and highways. No additional land area need be used.

Compare that to the huge area used by nuclear and fossil fuel power. Oil wells, pipelines, power plants, mines, fuel processing plants, nuclear waste and disposal facilities, reactors, and 1000s of square miles of ground and surface water contamination.

Nucbuddy

Dr. X wrote: "At the conference, NREL announced a new record efficiency of 37.9 percent at 10 suns, a measure of concentrated sunlight."

Does that mean that they were producing 379 watts of DC power per square meter?

Nucbuddy

Dr. X wrote: At over 75% total efficiency (elerctricity and heat energy)using maybe 1/10nth the PV cell area these systems would power the world from rooftops and over parking lots and highways.

At 1000 watts per square meter, 100% solar-conversion-to-AC efficiency, and 100% efficient storage that takes up zero space and can store long enough to overcome seasonal variations, how much land would be needed to provide the electrical needs of the United States?

amazingdrx

I'm not claiming solar power could provide enough energy to replace the current gas guzzling, wasteful mess we have with present energy policy.

Only with geothermal heat pump heating and cooling, energy efficient homes and appliances that use solar heat from cogeneration, mass transit revival, bike trails, serial battery electric plugin hybrid vehicles, heat pumps for industrial processes, and biofuel from algae in solar collectors.

I would not like to try this right now without massive wind machines and wave/wind power platforms offshore. These are great transitional sources. How would nuclear power provide for a transition, with 1000s of new plants needed to replace current sources, and only enough fuel to last 6 years if nuclear was relied on to power the world?

As efficiencies increase and once room temperature superconduction is possible, even the wind and wave machines could be retired and recycled, using renewable energy of course.

How would nuclear power provide for a transition, with 1000s of new plants needed to replace current sources, and only enough fuel to last 6 years if nuclear was relied on to power the world?

Nukes. Don't need 'em and their characteristic danger from accidents, astronomical cost, waste and contamination, and danger from nuclear proliferation and the warring over that proliferation. The current leaders in the White House are planning a preemptive attack on iran over nuclear proliferation enabled by nuclear power.

Nucbuddy

Dr. X wrote: I'm not claiming solar power could provide enough energy to replace the current gas

I did not say "gasoline needs". I said "electrical needs". The US currently has an installed base of ~500 gigawatts of electrical capacity.

You asked me to compare the land area needed by "75% efficient" solar PV to the land area needed by nuclear. I asked you for the land area that would be needed by 100% AC-efficient solar if we assume insolation of 1000 watts per square. Assume a 25% insolation factor, or 6 kwh/square-meter-day.

amazingdrx

Current energy wasting electrical use is deceptive. It loads the question.

I am not going to claim any other source than large scale wind/wave power floating offshore could provide the present waste level power needs without pollution and at low cost.

For instance: Air conditioning load alone is a huge use that could dissapear almost completely with solar panels that block overheating on buildings, energy efficient design, and geothermal cooling.

Industrial energy use could change radically too. If energy intensive processes like distillation and refining could be done much more efficiently using heat pumps.

amazingdrx

A leading question for you buddy. How much roof space, space over parking lots and highways, and suitable other industrial locations for collecting solar energy are there in the US?

Enough to power an energy redesigned US economy? At an affordable cost? Sometime soon i think that will happen, but meanwhile I propose using large scale wind and wave power for a transition to distributed renewable generation and storage.

That means closing down nuclear and fossil power plants and going to wind/wave all the way to mainly solar.

Nucbuddy

Dr. X wrote: How much roof space, space over parking lots and highways, and suitable other industrial locations for collecting solar energy are there in the US?

None of those areas are designed to host solar-mining fixtures, so the answer is "zero".

Nucbuddy

Regarding building over freeways, I found this exchange:

Q: Jimmy of Tosa - Larry- How come we don't make better use of the space over the freeway, like the Courthouse garage does over I-43? These roads gouge through our downtown, and still do little to alleviate parking woes. Large lots downtown only serve to further dilute the density of our downtown. Why not make better use of the dead space above our sunken freeways?

A: Larry Sandler - This would probably be a better question for my colleague, urban landscape writer Whitney Gould. I think the short answer is that it's not easy or cheap to build over freeways, and there are some engineering and maintenance issues. Note that the Courthouse Annex has deteriorated and will be knocked down, and that county workers previously had to knock off chunks of it so they wouldn't come loose and fall to the freeway below.


amazingdrx

Ok nuc, hehey. Go right ahead with those 1000s of nuclear power plants instead. Good luck with that.

Nucbuddy

Apparently, building over freeways and garages, etc. (which, in turn, are termed "low-intensity land uses"), is more-generally termed air rights development.
google.com/search?q=%22air+rights+development%22


Some discussion.

Cotuit Oct 26 2005, 10:07 PM

Air-rights development (building over highways) is very expensive. The reason we are seeing air-rights development in Boston is becuase downtown and Back Bay are pretty much built out. The only remaining large parcels are in the Seaport (which has height restrictions because of it's proximity to Logan) and over the highways.

In Providence we still have plenty of regular parcels downtown so taking on the expense of an air-rights development is not necessary. If Providence keeps growing, the air-rights over route 95 will become attractive eventually, but we're looking at decades, not years to see that happen.


Calamity

One of the problems with bifacial modules is that they are no good during high sun at noon (although that does makes them great for high latitudes).

There is a very easy solution though: place mirrors on the ground in parallel with the bifacial solar modules, on both sides; tilted under such an angle towards the modules that they act as a booster mirror at noon.

That should get almost the same yield as dual axis trackers, without the downsides.

sean  Norris

I would like to know the complications on building a prisim of glass. The prisim would stand many feet tall. This is for an art project. The hight would be one or two stories tall. Who could pore it and shape it?

workplace accidents

There are lots of industries working all over the world but good to see there are lot of blogs also who are sharing industrial information. Great job keep this work up!

 solar  collectors

wow this is so interesting. i just love the new technology.

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