June 7, 2007 12:50 PM PDT

Solar thermal energy making a comeback

Solar thermal technology, dormant for about 16 years, is waking up fast.

Nevada Solar One, a 64-megawatt power plant outside of Las Vegas, has begun to supply electric power to the grid, Acciona Solar Power, which owns and built the plant, said on Wednesday.

Photos: Nevada Solar One

The plant, which covers 400 acres, will generate 134 million kilowatt-hours of power a year. That's enough to power 15,000 households annually. (Sixty-four megawatts refers to the maximum power the plant can generate at any given time. Kilowatt-hours effectively refers to how much power gets delivered when measured over time.)

Acciona will sell electricity from the plant to Nevada Power Company and Sierra Pacific Power Company under long-term, fixed-rate contracts.

Nevada Solar One is the first thermal power plant built in the world in 16 years. Other companies, however, are constructing similar and larger plants in California's Mojave Desert, where an existing solar thermal plant has been cranking out electricity for over 20 years, and elsewhere. Acciona has a project under way in its home country of Spain.

Solar thermal plants, also called concentrated solar power plants, harvest heat from the sun with highly polished mirrors. The mirrors concentrate the heat on a tube filled with liquid or gas. Pressure builds inside the tube, and the pressure is then exploited to crank a turbine.

Heat is harvested by the mirrors. What can't be economically converted to electricity at the time it's obtained can be stored in molten salts at these plants. Thus, solar thermal plants are capable of generating electricity at night.

By contrast, solar panels essentially harvest electrons from sunlight.

Although solar thermal plants aren't cheap and take years to complete--Nevada Solar One's budget ran to $250 million--many believe that the technology is capable of delivering electricity for a price comparable to more traditional plants. The trick is to build massive plants providing close to a gigawatt, or 1,000 megawatts, of power, and building the plants close to urban areas.

Because of its smaller size, Nevada Solar One won't likely provide electricity at rates on par with regular grid power for several years, said executives from Schott, a German company that supplied components to the project.

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Please check my math
Based on the numbers provided, the plant will operate at a
capacity factor of 24%.

A $250 million loan at 8% would generate $20 million per year.
If the plant sells 124 million kilowatt-hours of electricity, it will
have to sell that electricity at 16 US dollar cents per kilowatt-
hour to generate $20 million per year.

Does anyone have any idea what the O&M costs for the plant will
be?
Posted by Rod Adams (74 comments )
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Real cost of alternatives
Chances are, it qualifies for government subsidies and they will be able to sell it for less. Whether that is good economics depends on a number of assumptions about future energy costs and the R&D required to develop alternatives. It also depends on the the cost of defending our current foreign energy supplies, which are huge, and raises the real cost of energy much higher than is charged to the customer now (in effect it is subsidized now).
Posted by Jim1900 (821 comments )
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Math 101
1. Solar field capacity factor 24%
2. From MS storage tanks capacity factor 19%
3. From co-fired ng-gas-assist (25%) allowed capacity factor add-on 14%

Total capacity factor: 57% x 365x24x64MW=319,565 mWh/y at say $69./mWh+$19/PTC a total of $88./mWh/y = $28,127,720 (-) O&M 11%=$25 million
(Fully amortized $250M @ 8% = $25M/y payments = break even. That is why needs Wartsila 24 gas engines (add-on of 197 MW) to have min. net profit of 7%.
Whereas: 197x365x24x.49%=845,600 mWh/y at $69./mWh (no $19)=$58M (less gas MMBTU $13M)=$45M
Cost of Wartsila 24 engines: 24 x8.2=197MW at $500K/MW=$98M Loan on $98M at 8%=$10M
NET REVENUE: $35M (LESS O&M $10m)= NET PROFIT OF $25M on total costs of $350M (7%)to the IPP.
Posted by ecosystemsolar (2 comments )
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About
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 affiliate, 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 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, over a decade and half ago, as weal as the "Dish-Tower" (some decade ago) implemented by Stirling.

- In 2005, two inventors(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 - they have another (own system of one of the best functional design) 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 in parabolic shape 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 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 the plant can start in less than 9 minutes and develop for less than 9.2 cents levelized costs, with insignificant O&M's 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"
Posted by ecosystemsolar (2 comments )
Link Flag
Please I need help with:
what factors determine the capacity factor of a STPP, and for a 20MW how could you determine the capacity factor. Is it a design parameter that the engineer decides on his own or what?
we can do more discussions at: gafopoku@yahoo.com
Posted by gafopoku (1 comment )
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gafopoku,

Capacity factor is basically the percentage of time that a power plant is producing power at full rated capacity. It is the ratio between the actual energy production and the theoretical maximum. This plant is rated for 64MW. If it was making power at 64MW 24/7 all year long it would make 560.64 million kWh of electricity. The article states, however, that it will only produce 134 million kWh/year. Dividing these two numbers (134/560.64) gets us 0.239 or 24%. Hope this helps
Posted by lute146 (1 comment )
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