Nevada 64MW solar thermoelectric plant starts build in 2007

[skids]

Solargenix recently announced the approval of amendments to their Power Purchase Agreements with Nevada Power Company and Sierra Pacific Power Company by the Public Utility Commission of Nevada (PUCN). This approval by the PUCN will allow Solargenix to complete the development of Nevada Solar One, the largest solar electric power plant to be built globally in the past 14 years and the third largest solar power plant in the world. This project will make Nevada one of the largest generators of solar energy in the United States.

According to published information from DOE through its national laboratories, the parabolic trough technology used in this plant represents one of the major renewable energy success stories of the past two decades and has a near-term potential to compete directly with conventional fossil fuel powered technologies.

In addition, DOE has issued a report that identifies suitable land and solar resources in Nevada that could produce more than 600,000 megawatts (MW) of power generation using concentrating solar technologies. Currently, Nevada's electricity consumption is less than 3 percent of this resource capacity. The same report claims that the economic benefits far exceed the cost to develop this clean renewable energy source.

http://www.earthtoys.com/news.php?section=view&id=994

Solar thermoelectric has an advantage over direct solar photovoltaics in that there is no "preferred band" of sunlight -- all frequencies of sunlight contribute to heating the working fluid (in this case a synthetic oil that can be heated to high temperatures.) Depending on the efficiency of the second stage (thermoelectric conversion) such projects have acheived higher total conversion efficiencies than current direct photovoltaic systems -- with no solid-state technologies involved.



Solar troughs are very efficient systems in areas where direct light is plentiful, as they trade off the ultra-high temperatures of a two-axis concentrator for simplicity of construction. Horizontal tracking is effectively provided by the shape of the collector itself, with only a bit of waste at the very ends when incident light is at an angle.

A good starting point for studying the underlying concept can be found here:

http://www.nrel.gov/csp/

Concentrator systems are less apt for overcast environments, though solar thermal systems based on glazed plates have been known to work for low-level omnidirectional solar thermal collection even in these environments, and some technologies (thermophotovoltaics and concentrating flourescents) in development aim to bring both wide-band and omnidirectional advantages to photovoltaics -- though if they don't hurry they may find themselves competing with new and improved solid-state thermoelectrics, MEMs heat engines, and thermoharmonics.

So many options.... the future of this industry is sure going to be interesting. :popcorn:

[sam sarrha]

1. Clinton funded a national program would produce 72% of daylight energy need...

with 3 units 10 miles square.. Bu$h canceled the project his first week in office

[NNadir]

2. According to the news link at Solargenix, their Arizona plant, which

presumably is finished, a one megawatt unit, will produce power at $0.12/kw-hr.

http://www.solargenix.com/news_details.cfm?id=9

This is not cheap in direct costs, but when external costs are factored in, that's not too bad. It almost borders on the realm of an acceptable cost, although its 6 times of the wholesale cost of other forms of electricity and is "only" 9 times as expensive as the power production costs at the Palo Verde nuclear station in Arizona, which produces power at $0.013 kilowatt-hour.

http://www.nei.org/documents/Economic_Benefits_Palo_Verde.pdf

The Arizona plant 1MW cost 5 to 6 million dollars to build.

Solargenix, a unit of the large corporation, Duke Energy, does not say how much the Nevada plant will cost, or whether any economies of scale will be realized. One imagines that a full sized solar trough plant at 1000 MWe (peak) could be built for a few billion dollars. That's not too bad, given what it does. Solar thermal units ought to be taken seriously. They are excellent peak load devices in areas with dry, sunny, hot climates, where air conditioning is a big part of the peak demand.

[phantom power]

3. Do these things boil water, or expand a gas, or what?

[NNadir]

4. Usually the turbines are driven by good old fashioned steam.

Molten salts are sometimes used as heat transfer agents.

This is, to my knowledge, one of the few forms of solar energy which is able to produce process heat, wherein the heat is available to produce chemical reactions.

I am not familiar with the technical details of this new plant.

Several of these plants have operated in California for years, even though the company that built them, Luz, went bankrupt. The companies acquiring the plants them found them economical to operate, once the capital costs were discharged.

http://www.eia.doe.gov/cneaf/solar.renewables/renewable.energy.annual/backgrnd/chap11h.htm

[skids]

5. This company uses a Rankin turbine.

The hot mineral oil is put through a heat exchanger, vaporizing another working fluid -- probably propane or something like that. The vapor drives a turbine, and then is condensed and fed back through the loop.

My one concern with this is they seem to have to use water cooling to condense the vapor. The heat release is no big deal -- but I hope in the desert they are using a closed-loop system air-cooling the water, rather than depleting the local water supply.

[NNadir]

6. Propane as a working fluid? That's a new one for me.

It sounds rather risky to me, especially around hot metals, but who am I to say? I'm not saying that it wouldn't work, but I really can't see why one would choose a flammable gas, albeit one that is easily liquifiable, as a working fluid.

I see no reason that they couldn't use steam turbines. I have understood that these devices provide some fairly high temperatures.

[phantom power]

7. these linear-collectors have lower temps than "focal point" collectors.

How much lower, I don't know. Using a working fluid/gas that has a lower boiling point, and lower heat of condensation, would be beneficial, although it's hard to beat water for ease of use and environmental friendliness. Although water's heat of condensation is awfully high.