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September 13, 2007

Comments

Kit P

Calamity has again drawn the wrong conclusion based on 'very simple empirical evidence'.


What is the purpose of the small amount of thermal storage? Answer: to protect the turbine (pg 8)

Is the small amount of thermal storage, physically small? Answer: No, see picture on pg 10.

What Calamity lacks is a sense of scale. Each one of those 5 MWt storage tanks is about the same size of a 4000 MWt nuclear reactor. To produce the energy to maintain the plant 24/7 would require 8 times the solar collectors, and 120 storage tanks. Multiply that whole mess by 100 to get a 1000 MWe nuke plant.

Kit P

Some cool pictures of sustainable energy in Spain:

http://www.panoramio.com/photo/2309290


http://www.panoramio.com/photo/2922387

http://www.panoramio.com/photo/2922015


http://www.panoramio.com/photo/2328802

http://www.panoramio.com/photo/1642983


mds

I've been wondering why CST can't be combined with CPV of 35% efficiency in at least on case, using 40.8% PV cells. The CPV is likely to become even more efficient. Electricity from the CPV could be used for grid and excess could be used to cool water in cooing tank. Cold water is easier to store than warm water because the vapor pressure is lower, as long as you don't freeze it.
There is also a patented device that uses solar heat and gas expansion to drive a piston to push refrigerant through an aperature to provide enough cool to freeze ice. i.e. the thermal expansion drives the refrigeration. It has been a while since I read about this device. Not sure if it is still being sold. Patent for it will still be on record.

mds

I've been wondering why CST can't be combined with CPV of 35% efficiency in at least on case, using 40.8% PV cells. The CPV is likely to become even more efficient. Electricity from the CPV could be used for grid and excess could be used to cool water in cooing tank. Cold water is easier to store than warm water because the vapor pressure is lower, as long as you don't freeze it.
There is also a patented device that uses solar heat and gas expansion to drive a piston to push refrigerant through an aperature to provide enough cool to freeze ice. i.e. the thermal expansion drives the refrigeration. It has been a while since I read about this device. Not sure if it is still being sold. Patent for it will still be on record.

Paul Dietz

I've been wondering why CST can't be combined with CPV of 35% efficiency in at least on case, using 40.8% PV cells.

The cells will not operate well, or possibly even at all, at the temperature of the CST collector.

greg

There is the heat engine from Deluge Inc. that could be used. I think storing cold water would be a little like going backwards, at least in the case of CST. Concentrating light on PV cells might be dangerous, if the cooling/heat collection fails you could roast them.
I think the best aproach to CST would be (if not used already) 3 stages. Steam turbine, low temperature turbine (CO2 or freon?) and maybe the heat engine at the end. The stored heat could actuate the heat engine at night.

mds

Sorry for the double post.
No, CPV is already an existing approach. I was suggesting using both types of collectors near each other for the benefit of cooperative energy storage. One stores hot and the other cold. Integrating both CPV and CST in one collector is another level. I don't know you can assume the CST collectors are too hot for the PV cells. How do you know this is true? There are a number of CPV companies out there. Are you sure their collectors will all fail? They are using concetrated sun light so they must have to deal with a fair amount of heat.
http://thefraserdomain.typepad.com/energy/2007/03/delta_electroni.html (Delta Electronics – 35% eff. CPV panels using 40.7% eff. Cells from Spectrolab – March 2007)

greg

As far as I know, PV cells become very inneficient when they get hot. If they withstand the heat, in case the cooling system fails, without sustaining damage, it could be an idea. The only problem is that the operating temperature you would want for the cells is too low to be able to take advantage of the heat removed. Unless you used some refrigerant with a heat pump. I guess I'm just repeting your idea with different words.
There could be a mechanical safety device to rotate the cells in case of overheating. The thing would be to see how far you can push the cell output and the cooling system and still be economically viable.

Calamity

Kit P said: What Calamity lacks is a sense of scale. Each one of those 5 MWt storage tanks is about the same size of a 4000 MWt nuclear reactor.

What Kit P lacks is a sense of how much near-useless desert land there is on this planet. Death Valley didn't get it's name because the region is so useful and fertile.

Kit P said: To produce the energy to maintain the plant 24/7 would require 8 times the solar collectors, and 120 storage tanks.

More like 6x the solar collectors, even less in better locations. Which would also be the locations where space is not that much of an issue; desert land is dirt cheap if you pardon the pun.

As for storage, there are many options such as cavern storage, molten salts, caloria oil, thermal concrete/ceramics, metals, or even phase change materials. You can't even come up with one fundamental, inherent reason why the first option could never work.

Now, take another look at the proposed plant's figures:

http://solarheatpower.veritel.com.au/Eurosun240CLFRFinal2.pdf

I couldn't find much wrong with them, except perhaps the low discount rate which would add a small amount to the LEC.

greg

Has anybody come up with a reflective surface like aluminum or stainless steel sheets to replace expensive mirrors? Seems to me that the cost of the glass mirrors is a big part of the cost.
A metallic sheet, even if the reflection is not as perfect as a glass mirror, can be shaped better.

Nucbuddy

Calamity wrote: What Kit P lacks is

Please stop raping Energy Blog commenters.


Calamity wrote: how much near-useless desert land there is on this planet. Death Valley didn't get it's name because the region is so useful and fertile.

Death Valley derives its name from its reputation for killing unprepared human visitors.

The valley received its name in 1849 during the California Gold Rush by emigrants who sought to cross the valley on their way to the gold fields.


Calamity wrote: desert land is dirt cheap

Deserts are also complex biological-ecosystems.


Biology

Habitat varies from saltpan 282 feet (86 m) below sea level to the sub-alpine conditions found on the summit of Telescope Peak, which rises to 11,049 feet (3368 m). Vegetation zones include Creosote Bush, Desert Holly, and mesquite at the lower elevations and sage up through shadscale, blackbrush, Joshua Tree, pinyon-juniper, to Limber Pine and Bristlecone Pine woodlands.

[...] where water is available, an abundance of vegetation is usually present.

These zones and the adjacent desert support a variety of wildlife species, including 51 species of native mammals, 307 species of birds, 36 species of reptiles, three species of amphibians, and two species of native fish.

Small mammals are more numerous than large mammals, such as Bighorn Sheep, Coyotes, Bobcats, Kit Foxes, Cougars, and Mule Deer. Mule Deer are present in the pinyon/juniper associations of the Grapevine, Cottonwood, and Panamint ranges. Bighorn Sheep are a rare species of mountain sheep that exist in isolated bands in the Sierra and in Death Valley. These are highly adaptable animals and can eat almost any plant. They have no known predators, but humans and burros compete for habitat.
[...]
Death Valley [...] is home to over 1,040 species of plants, and 23 species are endemic—found nowhere else in the world. Adaptation to the dry environment is key. For example, creosote bush and mesquite have tap-root systems that can extend 50 feet (15 m) down in order to take advantage of a year-round supply of ground water. The diversity of Death Valley's plant communities results partly from the region's location in a transition zone between the Mojave Desert, the Great Basin Desert and the Sonoran Desert. This location, combined with the great relief found within the Park, supports vegetation typical of three biotic life zones:

  • the lower Sonoran,
  • the Canadian, and
  • the Arctic/Alpine
in portions of the Panamint Range.
Based on the Munz and Keck (1968) classifications, seven plant communities can be categorized within these life zones, each characterized by dominant vegetation and representative of three vegetation types: scrub, desert woodland, and coniferous forest. Microhabitats further subdivide some communities into zones, especially on the valley floor.

Unlike many locations across the Mojave Desert, many of the water-dependent Death Valley habitats possess a diversity of plant and animal species that are not found anywhere else in the world. The existence of these species is due largely to a unique geologic history and the process of evolution that has progressed in habitats that have been isolated from one another since the Pleistocene epoch.


Introduce an ecosystem-killing technology -- such as solar-power -- into a delicate ancient ecosystem such as Death Valley, and you kill the latter.

greg

Good point, even deserts have life in it. I don't think man hasn't built over any part of the world that didn't already have an eco-system and we should tread lightly. That is why it would be best if we used already existing construction (roofs) for solar power. Wouldn't it be a better world if we could do away with centralized power generation and all those ugly and costly power lines that clutter the view?

Of course that might take a while. In the mean time, I'd vote for thermal solar in areas where the impact on nature is minimum, and I think a small portion of desert used for a solar thermal plant that doesn't polute, is not going to endanger the wildlife.

Kit P

Nucbuddy, nice post except for the rape comment. I have a thick skin and can handle insults. Discussing energy with Calamity is like talking to someone on a merry-go-round, they keep coming back so dizzy they forgot what you said last time.

I have seen nuke plants, windmills, solar panels, and coal mines. Environmentalist obsess about stripping coal off of mountain tops and replanting trees. Then they call covering the tops of the same mountains with windmills sustainable.

I have my favorite spot to hike in the desert. A small springs creates a few trees for shade perfect for a few hours of solitude reading. I do understand why those who travel from LA to Las Vegas think of the desert a waste land and want solar panels to power their slot machines. They do not understand statistics or the environment.

Setting aside a certain amount of the desert to produce electricity is okay with me just spare the sustainability claims.

A. Martin

This technology was jointly developed from the early 1990’s by both Morrison and Mills. Your article regarding the origin of this technology in Australia is quite incorrect. Why does your account fail to acknowledge the other original founder, Morrison? Mills developed the optical design of the concentrator while Morrison developed the thermal design of the absorber and system operation.

Cyril R.

Nucbuddy is evidently a propagandist for nuclear absolutism. Small wonder Kit likes him.

A very strange bunch, they are. Seem to have lost all reason.

Back on topic, the Ausra guys have got a plant operating. 5 MWe for 15 million, that's 3000 per kWe. Going to much larger scale will result in at least a 50% increase in power generation (1.5x turbine efficiency). So that alone lowers it to 2000 per kWe. Add in the fact that larger steam cycles themselves are cheaper per kWe as well, and the fact that larger plants have lower overhead and installation costs, it looks like the capital costs can be about halved just by plant scale-up.

A.non

Shockingly, last month Kit P announced that Ausra plant opening without any snide comments despite it being in California!
http://thefraserdomain.typepad.com/energy/2007/12/ausra-building/comments/page/3/

Kit P

@A.non

I thought readers here would be interested in Ausra accomplishment. If you watch carefully I treat folks with respect. My snide remarks are reserved for those who make wild leaps of logic and only then when the call me a racist because I do not subscribe to their infinite wisdom. Being negative with negative people is just a sign of respect.

Making electricity with solar is interesting. Saving the world by erecting glass/metal in the desert or on the roof is absurd.

A.non

There's the snide remark! Knew it was in you.

Francis Chetcuti

Dear Sirs,
We are interested in you solar power collectors.
Can you help.
Thank you.
Regards.
F.Chetcuti.
Director.

Tony

people we've got to start some where, any where!

sildenafil

a greater loss but has had the rock, lyrics miss his talent and infected us with a rage of others, wish you were his art and his talent here with us the man was alone on their own ..

hot water heater systems

Solar Energy is the most easily available and free source of energy. It is the most important out of non-conventional sources of energy too, it is non polluting, available for all and convenient source therefore helps in lessening the greenhouse effect.

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