Wells Fargo said today it has invested in Nevada Solar One, a $266 million, 64-megawatt solar power plant. The solar trough power station outside of Las Vegas was built by Spain’s Acciona Energy and will supply carbon-free electricity to two utilities. Northern Trust (NTRS) and JPMorgan Capital (JPM) joined Wells Fargo (WFC) in taking equity stakes in Nevada Solar One. The willingness of such heavy hitters to finance Big Solar is an encouraging sign for developers of other utility-scale solar power plants. While companies like Stirling Energy Systems and BrightSource Energy have scored deals with California utilities Southern California Edison (EIX), San Diego Gas & Electric (SRE) and PG&E (PCG) for massive solar power plants, obtaining financing to build the projects remains a big hurdle, particularly for technologies that have yet to be commercialized. That isn’t the case with Nevada Solar One. The plant’s solar trough design is a tried-and-true solar technology, which no doubt took some of the risk out of the banks’ risk assessments. In a solar trough plant sun-tracking parabolic mirrors heat tubes of synthetic oil to create steam and drive an electricity-generating turbine. Nine solar trough power plants built in the 1980s continue to operate in California’s Mojave Desert.
Big Banks Back Big Solar
August 16, 2007 by Todd Woody
Green Wombat 
It’s about time !
That’s what we need in North Florida. Let’s hope more banks will invest on commercial solar plants.
They are sure to lose their pants on subprime lending.
There is lots of hungry tax equity out there for renewable projects, and debt for solar trough plants is also extremely easy to get with one caveat. You have to have a contract that pays a price high enough to cover debt service at ~1.35 times and rent service, which is the payment to the tax equity, of ~1.15 times.
The difficult part is the contract, not the financing. 😉
The installed cost is about $4 per kW. The solar trough has been around a long time. Why is the cost still so high?
Any links to specs on this system? Unless Acciona has made some advances this “tried-and-true” technology will have the same old reliability issues and high operating costs – collector tube breakage and hose coupling leakage take down a significant number of troughs daily in existing systems, resulting in a lot less power being delivered than the advertised peak capacity.
Then there is the other issue – lots of water needed to run the turbines, a scarce commodity in the Nevada desert (unless it’s next door to Hoover dam).
Correction, that should be $4 per watt installed cost.
Geomark,
you raise very good questions which I am only beginning to understand. To answer your question regarding cost most simply: These troughs use a lot of raw materials. The steel or aluminum space frames themselves are expensive. Then you factor in the mirrors and collector tubes. These two items are specific to solar troughs, and there are only one or two suppliers for these items. Schott makes the tubes and as of this spring, the earliest you could get delivery of collector tubes was late 2009. There are a couple of other manufacturers who make the specially designed curved mirrors. You can’t just go to Home Depot, unfortunately. Also, projects in the US are competing with the solar gold rush taking place in Spain right now and having to contend with an extremely strong Euro. There are parties interested in building manufacturing plants in the US, however, that will not happen unless the regulatory framework (currently tax incentives) are given more certainty and longer terms. Having said all that, if the price has remained at $4/watt, it has decreased in real terms after taking into account inflation.
As to the technology, lots has been learned from the Kramer Junction projects. I believe the design being used by Acciona is called “Eurotrough” and is considered second generation technology. The couplings for the therminol have been improved, but there is still the problem of mirrors breaking and falling on collector tubes. Rule of thumb is that you have to replace 1.5% of the tubes each year, and for this reason you need a highly skilled welder on staff.
It is true that any power plant using a Rankine Cycle will use lots of cooling water, but wouldn’t you prefer the water to be used by a solar plant rather than a fossil plant?
Brent, that’s some good info.
I wouldn’t think that the structure is particularly expensive. Aside from the raw material cost it is just a lot of bending metal which should be pretty routine, especially for a large project with many identical pieces.
The severe curvature of the mirrors seems like a cost issue. The system I’m familiar with has mirrors with a very shallow curvature – easy to make and easy to handle during transport and installation. Does the trough need to be assembled at the factory and then shipped? Seems like a difficult and fragile assembly process.
Is Schott the only source of collector tubes? A single source for the critical component is a risk area. Plus only one company to count on for improvements. And that lead time, ouch.
I wasn’t aware of the mirror breakage problem. Is that from thermal stress, or from handling/washing? When a collector tube is broken it takes down a whole row of troughs since they are connected in series, at least in prior trough systems. So the impact on power output is more significant that what a single collector would produce. The availability numbers would be interesting to see.
Yes, I definitely prefer solar as the heat source in a Rankine cycle. The problem is the scarcity of water where the solar power plant has to be installed. That can be an intractable problem or really expensive.
The Week in Cleantech (Aug. 12 to Aug. 18) – Bubble or Biggest Investment Opportunity of the Century?
On Sunday, Dan Lewis at AEI wondered what we could re-weight the dollar exposure of alternative energy into. An interesting take on global monetary policy and alternative energy investing. On Monday, Kevin Bullis at Technology Review informed us that n…
The cost of the structure is not insignificant. Besides the tons of raw materials required, there is some amount of proprietary engineering involved. The amount of flex on the collector tube has to be within incredibly tight tolerances, as do the mirror parabola. Additionally, the structure must be able to withstand high winds. The wind issue, as well as hail damage are usually what breaks mirrors. When mirrors break, collector tubes are sometimes collateral damage. When a collector tube is broken, it takes down one line, which is not terribly significant given the number of lines in a project such as Nevada Solar One, and the relative speed with which it can be prepared. One side effect is that you spill therminol, which is somewhat nasty stuff. You are correct, however, that once the crew installing the structures does one or two, the rest go up like Legos very quickly. The Solargenix demonstration project I visited on site at an APS peaker plant was actually color coded for ease of installation. Mirrors and tubes are shipped, and the troughs are assembled and tuned on site with partially pre-fabricated steel space frames.
Flagsol is the only supplier of the curved mirrors used in solar trough technology, although R&D is being done on polymer mirrors, rather than glass, which should improve this situation from a technology, durability and cost stand point. Schott and Solel are the only suppliers of collector tubes. The flatter mirrors you are talking about are likely a compact linear fresnel reflector “CLFR” design. This is an interesting design due to it’s cost savings and ability to use parts which are “off the shelf”. The shortfall is lower operating temperatures which mean a less efficient Rankine Cycle.
We applaud PG&E for being one the best IOU in Renewable Energy Procurement. However, despite these folks who speak against.
In due respect to all piers, inclusive thereof Brent, Geomark, et al, please note of the followings:
We cannot disclose trade secrets, however can elaborate (considering the facts that our copyrights and pending registration patents are in place) on the “Supper System” to be implemented by Solar MW Energy, Inc.
Also, we applaud Mr. Todd Woody, for his viable comments. (There was a wrong link to one of our affiliates, however did not apply to our affiliate. It was another person/entity, who did not like PG&E.
Please note, that we strongly believe that PG&E is the leader in the procurement of Renewable Energy, as well as one of the best utility (IOU)
The “Supper System”:
(Please note that the Copyright’s Laws protects the “Entire design system embodied into one mass”, and Patents covers “Individual Components”)
– Parabolic trough technology was invented around 1860 by Mr. Mouchot, (Copyright has expired some 62 years ago), implemented in a utility scale by LUZ, as weal as the “Dish-Tower” (some decade ago) implemented by Stirling.
– In 2005, two inventor’s(confidential names) perfected the tried-and-true parabolic trough technology’s design of Mr. Mouchet, that was utilized by SEGS over a decade and half ago and subsequently and recently by Nevada Solar One, (not a LUZ II / BrightSource) including few small pilot projects in between (also known as Concentrated Solar Power CSP), as follows:
+ Instead of one parabola collector (mirrors), will utilize “Twin Parabolic Collectors” (mirrors), which do not break (designed to withstand over 80 mph wind force and up to 7.6 earthquake magnitude, on single gear axis.
Said Twin Parabolic Collectors (TPC) are of rigid structural integrity thermoplastic mirrors (manufactured in China – confidential Mfgs).
(Can assemble this super pre-assembled system in less than 3 months per 100 MW solar plant, at total costs mfg+assembly of less than 1.5 cents of levelized costs)
+ The Twin Parabolic Collectors are not mounted on “labor intensive and costly aluminum space frame. Instead, such are mounted on Super Rigid Thermoplastic Structural Integrity System. (Again, manufactured in China – confidential Mfgs.) Can also assemble this super pre-assembled system, in 3 months for costs of less than 1 cent of levelized costs)
+ Instead of single pipe receivers (pipe in glass (vacuum) pipe, the Super System will utilize “Twin Parabolic Receivers – one for each of the Twin Parabolic Collectors, designed to be a bent carbon steel tube, primed with best carbon coating (trade secret coating), which will heat the Heat Transfer Fluid (HTF) to over 400 degree Celsius. These receivers do not brake, nor leak. A Clamp system (can remove one only without the rest in series) with Super Connection System – Triplex Leg Tube-Pipe System.
+ It is a know fact that the solar alone capacity factor may not exceed 33%, even in Zone 9 Solar Iradiaion, being where the solar plants will be. (Just a hint – in the Mojave Desert, close to the Kramer Substation, Kramer Junction, Cluster 7, CAISO Zone SP-15).
Therefore, that is why the second tube in the twin parabolic collector’s system is implemented, to collect the HTF during sunlight and directly go to the storage of the MS (underground -trade secret system) Storage Tanks (Hot & Cold), to be utilized during off-peak (7 hours duration), increasing the capacity factor by 29%, to a cumulative for the solar field of up to 62%.
+ Renewable Portfolio Standards for California allows up to 25% use of natural gas-assist’s system for Qualifying Facility (QF) under PURPA. Such QF’s receive another substantial incentive – called Production Credit (dollar amount per mWh is confidential to disclose).
+ Utilizing the “Super Combined Cycle System” (SCCS), that includes Wartsila reciprocating natural gas-fired engines from Finland, each at Nominal 8.2 MW, which uses only 1 gallon/h of water and have Oxidation Catalyst / Ultra Low Emission System (near-zero pollution), the capacity factor is improved by another 24%, to a cumulative of 86% capacity factor.
+ The hot exhaust plumes from the Wartsila’s engines, instead of going to be wasted and released to the air, are re-directed to: System 1 to the MS Hot Underground Storage Tank, and System 2 to the Waste Heat Recovery System (WHRS), thus increasing the capacity factor by another 11%, to an aggregate of 97% capacity factor.
This Supper System can be integrated, and can be Supper-peak, base load and/or anything in between, and for less than 9.2 cents levelized costs.
With the carbon fiasco, fossil fuel plant will soon reach 10 cents levelized costs, and therefore not only the IOUs will be thrilled, but the ratepayers, when such Super System Solar Thermal Hybrid Powers Plants – Utility Scale are develop and operational.
And the sooner, the better, if the Financial Community also accept, at least 101 Educational Course. Some already see the “Green Base Load – Production Incentive Driven Fix Income” and are questioning……….
This Supper System of the two inventors falls under the Copyrights Laws, construed as “Design Embodied Into one Mass System”
Brent, more great info, thanks.
I see, the stringent rigidity requirements of the structure to minimize flex of the collector tubes makes the structure dimensional control a significant issue, which means cost of course. That would be especially challenging in high wind conditions. Hail, ouch, that’s tough. Even in the desert I suppose they get it once in a while. Do they rotate the troughs to a safe stowage position to minimize damage?
Actually, the flatter mirrors I’m talking about are not for a trough system but for a parabolic dish. Multiple mirror segments are mounted on the structure to form the reflector. The mirrors have a longer focal length and shallower rim angle than the troughs. So the mirrors have curvature, but it’s not severe and they are easy to pack, ship, uncrate and install. The structure is not nearly so sensitive to flex either. The mirrors are mounted on strain relief pads and small errors in focusing don’t affect performance since the collector area is large enough to allow for small misalignments. Wind and hail are always an issue but there is no fragile and expensive collector that will get broken, just the mirrors. And the system continues to operate with multiple broken mirrors, just at a lower efficiency.
Ok, I’ll stop side tracking this topic, which is troughs. I’m just very interested in comparing the issues I’m familiar with to those of trough systems.