eSolar Receives Funding for 33MW Modular Solar Power Plants

From a 4/21 press release:

eSolar™, a producer of modular solar thermal power plants, announced (pdf) that is has closed $130 million in funding from Idealab, Google.org, Oak Investment Partners, and other investors for the construction and deployment of pre-fabricated power plants. Their distributed solar thermal plants achieve economies of scale at 33 MW, and are modularly scaled to fit the needs of large and small utilities.

"The eSolar™ power plant is based on mass manufactured components, and designed for rapid construction, uniform modularity, and unlimited scalability. Rather than over-engineering the solution, eSolar’s smart scalable solar architecture targets what we see as the four key business obstacles facing the sector: price, scalability, rapid deployment, and grid impact."

-- Asif Ansari, CEO of eSolar.

. . . Centering on eSolar’s 33 MW pre-fab form-factor, the company’s modular design translates to minimal land requirements. The company’s solar power plant solutions are tailored to fit local resources and produce a low environmental footprint, favoring a straightforward siting and permitting process.

. . . eSolar has secured land rights in the southwest United States to support the production and transmission of over 1 GW of power. eSolar will have a fully operational power plant later this year in southern California.

From their website:

The economic tipping point, for solar power, occurs when the capital cost of the solar field is less than the capital costs and fuel costs of the traditional system. To address this issue, eSolar has developed a modular power plant architecture designed to take advantage of mass manufactured components at every level.

eSolar has designed a solar field layout that minimizes installation time and cost. By employing a repeating structure and a revolutionary calibration system, eSolar plants come on line quickly . . . Utilizing very low wind profile heliostats, eSolar provides higher reliability in all wind conditions, lower risk of wind damage, and more power plant up-time.

Their power plants are structured on a 33 MW base modules, scalable to over 500 MW facilities, with energy prices that are competitive with fossil fuels, consisting of several thermal receiver towers, each with a field of heliostats. Each module is a complete power plant, consisting of several thermal receiver towers, each with a field of heliostat mirrors, and a central power block with steam turbine and generatore.

Solar heliostats were designed from the ground up to minimize every possible cost. Their heliostats are designed to fit efficiently into shipping containers to keep transportation costs low, and they are pre-assembled at the factory to minimize on-site labor.

If the statement that "prices that are competitive with fossil fuels" turns out to be true, than this is truly a breakthrough in solar technology. eSolar has provided no details about its technology and no specific information about "a fully operational power plant later this year in southern California," unless I have missed that announcement, I could find no reference to it on their website.

Comments

[unregistered]

I wonder what kind of footprint this 33 MW pre-fab form-factor unit requires. Real estate tends to be a premium at the same place where energy demand is.

[Cyril R.]

Real estate tends to be a premium at the same place where energy demand is.

Areas that receive more than 8 kWh per square meter per day ("desert") usually don't have high real estate costs. In fact, it's quite a non-cost. The cost of land preparation can be significant, so a compact design is still a big advantage.

The eSolar approach is interesting as it is very different from traditional power towers. I wonder how it would compare to the Ausra approach. It's too early to tell right now.

[Cyril R.]

There is of course the transmission cost. However, the economics of long distance transmission become excellent with larger amounts of electricity transmitted, so for the tens or hundreds or even more GWs it's a very modest cost. For now, smaller plants can be constructed close to demand centers in high solar direct beam locations. Places like Las Vegas might be a very good locations to commercialize these solar thermal technologies.

[bigTom]

Now we have claims from OptiSolar, a thin film outfit I had not heard of, for several solar farms including a 550MW one! http://venturebeat.com/2007/04/27/secretive-silicon-valley-company-optisolar-builds-largest-solar-farm/

[Kit P]

This a great idea. In fact this is how I would do it if someone gave me a bucket of money and a natural gas pipeline near by.

Of course this is just greenwashing. When the solar industry starts honestly providi

[Bob Wallace]

"Real estate tends to be a premium at the same place where energy demand is."

If you look at a solar radiation map for the US you will see that the sunniest places in the winter include a lot of Nevada desert (close to the HVDC Pacific Intertie grid), a lot of southern Utah desert which gets the sites within reasonable reach of Utah/Colorado.

When you look east you see areas of South Carolina, Georgia, Mississippi,... where we're not talking Manhattan real estate prices.

Additionally, these projects can be set up on 'spoiled' land. Old industrial sites, brownfields, are good places to site solar farms. And there are probably sturdy grid ties already in place.

[Kit P]

“And there are probably sturdy grid ties already in place.”

You do not need a sturdy grid if you do not make much electricity.

[Luigi Aronson]

Kit P, did you ever post what your vision of how the world gets its energy in the near and distant future?

[Paul F. Dietz]

When you look east you see areas of South Carolina, Georgia, Mississippi,...
In the SE US, a large fraction of the insolation is diffused through clouds, so concentrating solar systems are less effective.

[Tom Nats]

When will they start making it so smaller businesses can purchase a system like this?

[Bob Wallace]

"When you look east you see areas of South Carolina, Georgia, Mississippi,...
In the SE US, a large fraction of the insolation is diffused through clouds, so concentrating solar systems are less effective."

In January you get 4 to 5 kWh per m2 per hour.

In July you get 5 to 6....

I'm betting that in January you have more wind and hydro and less AC demand.

[bigTom]

"In January you get 4 to 5 kWh per m2 per hour. In July you get 5 to 6..." Wow! Thats incredibly good, considering that the solar "constant" is about 1.35KW/M**2. And the standard accepted intensity at the earths surface is 1KW/M**2. So I figure youd have to move the earth to roughly the orbit of Mercury! I suspect it should have read -per day.

[Bob Wallace]

Well, I'm the first to admit that I'm operating in the shallow end of my knowledge pool. So please check this out.

I used this page...

http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/Table.html

I selected 'Average - January - Flat Plate Tilted Latitude + 15 Degrees' and 'Average - July - Flat Plate Tilted Latitude - 15 Degrees'.

Did I do something wrong?

Is the site incorrect?

I figured that since this page is put up by U.S. Department of Energy it ought to be halfway trustworthy....

--

Oops, took a closer look at my earlier post. Looks like it was me. I should have said "per day" rather than "per hour".

Anyway, aside from my typo, the point is that there does seem to be some usable sunlight in Mississippi in the winter.

Wasn't that the discussion at hand?

[Benjamin Cole]

The idea of standardization and buildability, whether for nuke plants, or solar, or wind, is brilliant.
Too many greenies act like their moral vision is enough. It is true, the external costs of fossil fuel consumption should be taxed.
But greenies need to make sure their ideas make money sense. I like this idea, and hope it works.

[Alex]

The design is based on the model of a classic Greek amphi-theatre: o.618 of the maximum radius is the stage radius.

[Cyril R.]

Well actually Paul Dietz is correct, CSP is not that good a plan for the SE US. But he is incorrect that concentrating solar in general being less effective in diffuse lighting conditions. Non-imaging designs, such as compound parabolic troughs, can capture diffuse radiation very well. These are low concentration though, and are mostly used for domestic hot water (solar boilers). Micro (perhaps Fresnel) photovoltaic concentrators can be designed for reasonably effective concentration of diffuse light.

But eSolar's system uses direct beam resource only, whereas flat plate PV uses both direct and diffuse radiation.

Not only is the direct beam resource in places like Florida much lower than in desert areas of the SW US, it is also much less consistent. Longer lasting, big clouds are common in the SE, and these increase thermal cycling stresses in the receiver as well as making the system unreliable in terms of guaranteed output. So then the thermal storage would have to be greatly oversized, which costs a lot, or a lot of extra natural gas has to be burned. No such problems in the SW: Nevada Solar One for example is contracted for 98% solar fraction, 2% natural gas.

The thing is, in the high GW range, it just makes more sense to build the plants in the best locations and use long distance transmission to get the power where it's needed.

[Bob Wallace]

Cyril - Thanks very much for that post. Lots of good information presented in a courteous manner.

[Chien6372]

5-6KWh/day is the solar radiation received in surface of earth, while 1.35KWh is what solar panel can generate. You may get about 1.35KWh from 10-14KWh/day(highest solar radiation) multiple 13% (efficience).

[Al Fin]

Every region will be different in energy needs and energy solutions. Think local and regional.

The US desert SW is ideal for large scale solar thermal. Large sweeps of barren, sunny desert land cover the southwest. Solar thermal is far superior to photovoltaic due to load matching storage issues.

The US Southeast (Virginia to Texas) is ideal for bio-energy. Almost every square inch of soil is occupied by abundant life. Responsible management of biomass growth

We need to start looking at regional solutions instead of trying to solve national and world energy problems with one or two "magic bullet" technologies.

[Roger Brown]

But he is incorrect that concentrating solar in general being less effective in diffuse lighting conditions. Non-imaging designs, such as compound parabolic troughs, can capture diffuse radiation very well. These are low concentration though, and are mostly used for domestic hot water (solar boilers).

You are contradicting yourself here. CSP is less effective in diffuse sunlight, though not completely useless.

[Kit P]

“Nevada Solar One for example is contracted for 98% solar fraction, 2% natural gas.”

How much electricity is produced and when? It would only seem logical to know the answer to that question before you start building transmission lines “get the power where it's needed.”

I posted a link to this site a while back.

http://www.worldwater.com/pages/projects.html

At the time I was surprised by the 13% CF in New Jersey and the dismal 3-5% in California. Even more interesting is that the links to performance for California PV sites no long work but the one in New Jersey does.

People who make electricity love to brag about performance.

What the SE US has plenty of is humidity. If you folks in California can figure out how to make electricity out of it, I will proclaim your vision. What the SE has is lots of trees.

The best way to reduce electricity use in the summer is a shade tree and daylighted basement. The problem with shade trees and low humidity is the corresponding lack of common sense that is linked to it. Could be mercury BoB W, what do you think?

I watched the Oakland fire from my boat in Almeda. Generally hot weather in the central valley means great winds for sailing (The coldest winter I ever experienced was a summer in San Fransisco, SC, aka MT). That day, there was no true wind on the bay. The water was like glass. With the current, the apparent wind was enough to keep the sails full and have steerage. However, the Santa Anna types winds coming from the east turned the Oakland Hills into an inferno. The live oak and eucalyptus would literally explode.

[Vijayan Chomatil]

It is my absolute hope that they will soon make portable solar dynamic systems for single homeowners. One reason is that in places like Phoenix, solar dynamic systems aren't degraded by extreme heat like all photovotaic systems. Parhaps piezoelectric effect convert heat to vibrational energy.

[david foster]

Anyone have any insight as to just how effective the thermal storage with solar-thermal actually is? If I run the plant for a week of bright sunlight, storing all the energy, and then draw it down linearly over the next (cloudy & rainy) week, will that work?

[Al Fin]

A large solar thermal plant can only run on thermal storage a few hours after the sun goes down. That is enough to provide good load matching for most commercial and residential customers.

[Bob Wallace]

"The solar day is now 24 hours long, according to John O'Donnell, Ausra's executive vice president. He said Spanish solar thermal power station Andasol is currently running 24-7 and has a 16-hour storage reservoir."

http://peakenergy.blogspot.com/2008/03/solar-thermal-power-could-supply-most.html

As discussed here before (by someone more knowledgeable than I ;o) there's no reason why the storage limit could not exceed 16 hours.

[steve]

Well first off Kit I the interest of keeping you from your famous fact twisting can you please explain how you get only a 3-5% capacity factor in California with the website you provided? Yes one in San Diego may seem to imply that but never really clarifies what they mean. The DT Locke Ranch would imply a 24 hour cf of around 20%. With a 38 kw system producing an average 179 KWH of electricity a day. Another Edison project would have a cf of around 14% by your same website. Also it is just more of your little fact twisting to compare PV with solar thermal anyway. If you were in anyway honest you would have to admit that California is a very big and diverse state. Trying to compare say Humboldt County with say San Bernardino would be one hell of a stretch in both distance and climate.

Kit I have to laugh at your pathetic attempts to make yourself seem important. I really have no idea what that whole last post was about other than trying to impress everyone with all the places you have lived. Still don’t really remember you posting the state you live in now but have to admit I don’t read all your posts. And beings as you would have done this to any other person on the board (along with calling them an idiot) please don’t butcher quotes from one of my favorite authors. Mark Twain never made that quote. Another thing is Santa Anna winds occur in Southern California and not in the Bay Area

[Paul F. Dietz]

I thought it was clear I was talking about high concentration designs of the kind the original message was talking about, but I should have been explicit. Yes, non-imaging concentrators (and fluorescent concentrators) can work with diffuse light, but achieve only low concentration.

[Kit P]

Well Steve, please feel; free to provide some data for any solar plant you would like. How much electricity is produced in a year. Then you can calculate the capacity factor.

“Another thing is Santa Anna winds occur in Southern California and not in the Bay Area”

That is correct Steve. Try to improve your reading skills. I said, “Santa Anna types winds”

Bob Wallace you may want to spend a little more time doing some research be for you post. It will save me the trouble of pointing out your dishonesty. Andasol does not have an operating record yet if it is even running. The design does look interesting. It has 7.7 hours of storage. Approximately, 10% of the solar energy is lost in the process. They claim a 38% capacity factor.

So the claim that “solar day is now 24 hours long” is only a marketing claim and not a fact.

[Cyril R.]

You are contradicting yourself here. CSP is less effective in diffuse sunlight, though not completely useless

I tried to make clear that it depends on the design. CSP includes low concentration compound parabolic troughs solar hot water systems, and these work very well under diffuse lighting conditions. The reason they are less effective is simply because of the lower energy available when the light is diffused compared to perfect unobscured direct beam conditions; clouds reflect and block much of the sun's energy. The heliostat design employed by eSolar only works with direct beam insolation, so are actually quite useless under strongly diffused conditions.

Yes, non-imaging concentrators (and fluorescent concentrators) can work with diffuse light, but achieve only low concentration.

It is possible to get higher concentration with non-imaging. Small parabolic dishes integrated into a flat plate, with the dishes covered with tiny reflective flat Fresnels, could do quite well under diffuse light. It's important that they are very small to lower optical losses over distance incurred by the diffused conditions. This would be suitable for concentrating photovoltaics.

[Clee]

Kit P. writes
http://www.worldwater.com/pages/projects.html
...the dismal 3-5% in California. Even more interesting is that the links to performance for California PV sites no long work

Or maybe their webpage maintainer isn't so great. I'm calculating 17% lifetime capacity factor at the Idyllwild, CA water district.
http://view2.fatspaniel.net/FST/Portal/WorldWater/idyll/HostedAdminView.html

[Paul F. Dietz]

It is possible to get higher concentration with non-imaging.

Non-imaging systems can achieve higher concentration on diffuse light than imaging systems can, but the maximum concentration is still fairly low. If this were not the case -- if non-imaging systems could achieve the high concentrations achievable with direct sunlight -- then one could violate the second law of thermodynamics.

[Cyril R.]

Non-imaging systems can achieve higher concentration on diffuse light than imaging systems can, but the maximum concentration is still fairly low. If this were not the case -- if non-imaging systems could achieve the high concentrations achievable with direct sunlight -- then one could violate the second law of thermodynamics.

That's the theory, but there are practical limits to concentration ratios with imaging optics:

In principle, the second law of thermodynamics permits an optical device to concentrate the solar flux to obtain temperatures at the Earth's surface not exceeding the Sun's surface temperature. In practice, conventional means for flux concentration fall short of this maximum because imaging optical designs are inefficient at delivering maximum concentration. Non-imaging light-gathering devices can improve on focusing designs by a factor of four or more, and approach the thermodynamic limit. We have used a non-imaging design to concentrate terrestrial sunlight by a factor of 56,000, producing an irradiance that could exceed that of the solar surface.

56,000x concentration is not what I would call "fairly low". Of course, the design Gleckman et al created may not be suitable for commercial solar energy applications. But a Fresnel micro point focus concentrator might be suitable for CPV.

[steve]

Kit you are correct you did say “types” so I will apologize and admit I was wrong. You also said that California had a 3-5% cf and New Jersey had a 13% one and posted a website to prove your point. I am just wondering how you came up with your conclusion. Remember I am not an engineer like you and sometimes I get a little confused with my math. All I am asking for is for your to explain yourself without trying to throw up a bunch of mud hoping I will forget. I never made the capacity factor claims, you did. Really it seems pretty easy to me. Explain yourself, admit you may have been mistaken or admit you may have stretched the truth a little.

Now Kit I told you I was going to call you out. I am going to continue to do so. Kit I am going to assume you are not a complete idiot. Since I assumed that, then I am also going to have assume you know that most of the solar projects in California will be built where the solar radiation is higher than New Jersey. Because of this I would have to assume you were intentionally making misleading statements. If you were not intentionally making misleading statements then I would have to assume my first assumption about you was wrong. Have a nice day Kit.

[Cyril R.]

Steve, there's no need to rebut Kit P's lies, it's not like anyone is really listening to him anyway.

Kit P is just here for some entertainment, and is best left alone in his Wonderland. I do pity Alice though for having to keep up with him.

[Roger Brown]

"Anyone have any insight as to just how effective the thermal storage with solar-thermal actually is?"

I have read that nitrate salt thermal storage systems have energy losses of 1% per day, which would mskr multi-day storage time possible. However, there may be an issue of capital costs. I also read that nitrate salt storage may cost $35/KWh. At one cycle per day it would take 10 years (and even longer if you add on the cost of interest) to reduce the storage cost of delivered electricy to $0.01 per kWh. If the cycle time went to 10 days then 100 years would be required to reduce storage costs to $0.01/kWh.

[Bob Wallace]

Looking for a discussion forum:

Someplace with a similar focus as this one.

Someplace with a better format.
Easier navigation - not having to page through multiple posts to get to the current ones.
Threaded discussions - the ability to have slightly off topic/different aspects of the topic within the same thread.
Member initiated topics - not dependent on the site admin to initiate topics.

And a place where there is an enforced requirement of civil behavior. I've watched some knowledgeable people leave this site in disgust.

Any ideas? (I've emailed Jim and have received no indication that he intends to change the situation here.)

[Al Fin]

If any solar thermal plant has extended its thermal storage beyond 6 hours +- 2, that would be the first I've heard of it. Within the next few years I expect thermal storage to provide 24 hour capacity--once the thermal energy corps start making the big money.

Even at 6 hours of storage, load matching for most regional markets should be fairly good.

[Cyril R.]

I have read that nitrate salt thermal storage systems have energy losses of 1% per day, which would mskr multi-day storage time possible.

The thermal losses over time would depend mostly on three things:

* Quality and quantity of insulation
* Ratio of surface area to storage volume (big storage tank has relatively less surface area per volume stored so has less losses per thermal energy stored over time)
* Ambient temperature (atmospheric or underground)

So a large well insulated storage volume deep underground could have very low losses.

Still, the issue of capital costs will probably make long term thermal storage a bad idea. Considering how well solar with diurnal storage correlates with the load, long term storage would only be needed in case of an emergency, such as a week or two of bad weather. A bit of natural gas or biogas comes in handy then. The extra system costs should be low; mostly existing NG infrastructure can be used, or onsite tanks, and the industrial heaters are cheap.

[Bob Wallace]

I'll post again since the previous copy is lost on a previous page...

"The solar day is now 24 hours long, according to John O'Donnell, Ausra's executive vice president. He said Spanish solar thermal power station Andasol is currently running 24-7 and has a 16-hour storage reservoir."

Rainer Aringhoff of Solar Millenium, which operates Andasol, apparently made the same statement at the WIREC conference in early March.

Now, one of two things are happening here:

1) Ausra is running 24- 7 and has a 16 hour storage reserve, or...

2) John O'Donnell is lying (or being misquoted).

What I can find on line says that their plant began construction some time back and is scheduled to be hooked to the gird this summer. That leads me to suspect that the plant is currently running in test mode.

[Cyril R.]

Roger Brown, one more thing, adding diurnal storage costs a lot of money, but usually not as much as the marginal cost of powerblock and cooling system, which is displaced - they just get higher capacity factor.

As long as the marginal cost of storage is lower than the marginal cost of powerblock+condenser, actual levelized costs per kWh are slightly lower than for a non-storage plant. In practice, adding storage may be even more interesting to investors, as the plant would be more flexible and dispatchable so can deliver power when it's worth the most.

That's just for daily storage though, longer than that is unlikely to be economic.

[Al Fin]

Bob Wallace: Nice research, thanks.

I suspect, as you suggest, that Ausra is running in test mode which means that John O'Donnell is misleading although not outright lying. The scale of production makes all the difference in the world as to cost of storage. 24 hour test operation at 10 kw is a lot different than 24 hour operation at 500 Megawatts.

When Ausra does finally start providing usable power to the grid, how much capacity will they be able to maintain through the dark hours?

Don't hold your breath until O'Donnell provides specifics. ;-)

[Bob Wallace]

Al, I don't get how you can interpret O'Donnell's statement as misleading (assuming that what he said is correct).

He said that it's "currently running".

You seem to be adding a qualifier to the effect that if the plant isn't feeding the grid it "isn't running".

Furthermore, I don't believe that Andasol is designed to pump maximum power 24/7. But that's a total guess on my part. I would guess that the operators will maximize their income by selling to the grid when profits are highest. Remember the CAES paper linked a few days back?

For example, it might make more sense to store afternoon heat and use it to make early morning electricity rather than middle of the night electricity.

Now, let me underline. The above two paragraphs are pure speculation on my part. Not something stated by any of the parties involved.

[Al Fin]

Here's the problem, Bob. If a company is running a test plant at 1/100th scale, and achieves a benchmark of 24 hour production, does that mean when the plant comes online at full 100% scale that it will automatically achieve 24 hour production?

Obviously not. The differences in storage costs between 24 hour production at 50 kw test and 24 hour production at 100 MW online involves a considerable difference in storage expense.

It is not an academic question.

[Clee]

Ausra is not Andasol. Ausra's John O'Donnell isn't quoted as saying that Ausra has done any of these things. He's claiming Andasol in Spain has. Ausra is not involved in the Andasol project. I think he's lying or misquoted or misquoting.

Andasol was designed to have "molten salt storage for 7 full load hours" according to the company that designed it.
http://www.flagsol.com/andasol_projects.htm

Funny thing is, it's John O'Connell that made the claim that "Rainer Aringhoff of Solar Millenium, which operates Andasol, said at the WIREC ... that Andasol operates 24x7 in the summer months"
http://media.cleantech.com/2570/ausra-and-solar-thermal-electricity

which, while similar, is not at all the same. During summer months, they don't need 16 hour storage, and there's no indication that Andasol ever claimed to have 16 hour storage.

[Paul F. Dietz]

Cyril: what you quoted there in no way contradicts what I wrote. The 56,000x concentration was for a non-imaging optical system that works with direct sunlight. The solid angle of acceptance of that system is quite small. Non-imaging optical systems with 2pi steradian acceptance (same as a flat plate) could not achieve anywhere close to 56,000x concentration. It's easy to see that if this were not the case, you could violate the second law.

[Bob Wallace]

Clee - correct. O'Connell might have "misspoken" when he quoted Aringhoff.

[steve]

Esolar’s concept is interesting but they are going slightly against current wisdom with how they plan on building plants. Most of the projects now being built are getting larger to try and bring down costs. I would also bet my retirement that they have no chance of actually getting a plant online by the end of the year. It may be possible for them to start but even that would be a stretch. I do like the concept of keeping things simple as long as they don’t give up too much efficiency.

Now as far as solar storage, there are two projects right now that I feel have a very good chance of being built. One is a 280 MW Plant in Gila Bend Arizona and another is a 250 MW plant in California City California. The one in Gila Bend plans on using limited heat storage and the one in California City does not. We are a very long ways from 24/7 storage but a limited amount would be great. It would allow you to follow load more evenly and give a couple of extra hours full load production during the early evening hours when everyone is getting home. I do know the company that is building the plant in California City is interested in the technology but does not quite feel comfortable tying to implement it right now

Some of the reasons I don’t feel that solar-thermal needs to be 24/7 right now are is there is just no demand for late night, early morning power right now. Also utilities can pay a premium for power produced when solar is at its best. They are not going to want to pay the extra at say midnight.

There is advantage to being able to run all night and that is stress on plant equipment. Currently the plants are cycled everyday. When they are brought up in the morning there is about a 5 minute time from steam being introduced to the turbine and being on the grid. Now any of you who have been around steam plants would know that is a pretty brutal startup. All things considered they hold up to it pretty well but being able to stay on the grid all night would definitely help with wear and tear. Now trying to run at too low of a load can cause problems with wet steam beating up your turbine too so you have to find a happy medium.

As far a Ausra I have to agree with Al here. They have not gotten permission from the California Energy Commission, to build the plant, so I am sure they have not even started on construction. Unless I have missed something, the new plant they have planned for California will not even have heat storage. I know they are using a low pressure turbine so they plan on just storing hot water and flashing it to steam. This is an interesting concept and I hope it works out for them some day. I am pretty skeptical of some of Ausra’s claims but think they do have some very good ideas. The important thing to remember is they are trying to sell a project and that there are far more projects proposed than ever get built.

[Kit P]

Steve & Clee, I found what I wrote some time ago when I first found this interesting site.

“This site www.worldwater.com provides some real time data. Three locations in California at capacity factors if 4%, 5%, and 18%. One NJ site had 13%.”

It is an interesting coincidence that the link that no longer work.

The reason to discuss CF is it is a measure of performance. It is found by dividing the actual amount of electricity generation by the nameplate generation. Another important factor is Availability Factor. For example, a 4 MWe PV may be designed to produce 4 MWe every hour between 9 and 3 during the summer. The occasional cloud may result in a 99% Availability Factor.

The generating company that Steve works for is going to be doing a root cause analysis when performance is not what is expected. The utility that I worked for in California did not care if the PV panels produced electricity. The purpose of PV was public relations.

When discussing energy, readers should be alert to the difference marketing and engineering performance. When I looked on the web for the Andasol in Spain, I had no trouble finding engineering data from the engineering company. Clearly the company marketing solar equipment is engaged in marketing. This is not lying, it's marketing.

[Cyril R.]

Cyril: what you quoted there in no way contradicts what I wrote. The 56,000x concentration was for a non-imaging optical system that works with direct sunlight. Non-imaging optical systems with 2pi steradian acceptance (same as a flat plate) could not achieve anywhere close to 56,000x concentration. It's easy to see that if this were not the case, you could violate the second law.

Yeah, the way you wrote that confused me a bit. It's off-topic anyway, what I talked about is to get a fairly high concentration ratio with small parabolic dishes with the reflective area divided up in flat facets. Of course the concentration ratio couldn't be anywhere near 56.000x but it could be high enough for high efficiency commercial CPV. I think it would be possible to do a lot better than the single digit concentration ratios that most designs get for concentrating diffused light. What do you think?

[poetryman69]

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