Nevada Solar One Pictures

An aerial view of Nevada Solar One. The site takes up about 300 acres and contains 760 mirror arrays measuring about 100 meters each. Roughly 184,000 mirrors are installed at Solar One, a [64-megawatt] solar thermal plant that will go live next month in Boulder City, Nev. The mirrors direct sunlight on an oil-filled tube. The oil is then used to create steam, which turns a turbine.

Added 1:39 am, see previous post for details about the project.

People standing under one of the mirror arrays.

Comments

[Cervus]

So, what's the power output of this system? Has to be good for a few megawatts.

[cendrizzi]

According to wikipedia it is rated at 65MW

[Thomas Pedersen]

I think such solar troughs ought to have a second mirror (like large telescopes) above the receiver in order to utilize a much greater part of the circumference. This should also lower peak temperatures on the surface and thereby the longevity of the thermal oil.

On a different note, here is an interesting link to a study on the merits of solar tracking across Europe

[Kit P.]

Now imagine 200 of these. What is the environmental impact of building and maintaining them compared to one new nuke? Yucca Mountain is about 200 miles north of this site and the terrain is about the same. Every anti-nuke rants about spent fuel. Clearly the environmental impact of 2000 solar projects is huge compared to all of commercial nukes.

[Thomas Pedersen]

Kit P wrote:

Clearly the environmental impact of 2000 solar projects is huge compared to all of commercial nukes.

You need to explain that. Other than land use I fail to see the environmental impact. I do not regard "putting something made of steel on top of the desert" as environmental impact.

Due to the shade and cooling effect of the mirrors, conditions for vegetation may improve enough for plant growth to start?

If so, I propose employing goats/sheep as "lawnmowers" :-)

[Chad K]

What's the efficiency of this method vs regular tracking solar?

[Kit P.]

LCA per ISO 14000 is a systematic way to evaluate the cradle-to-grave environmental impact of doing something. There are large environmental impacts for manufacturing stuff, especially aluminum and concrete. Divide the impact by the amount of electricity produced by the solar system and comparisons can be made to other sources of making electricity.

I think this project is very cool and would judge the environmental impact acceptable if I lived in Nevada because I have studied that environment and know how the the electricity that will be offset is produced. However, place the same project in a different location and the environmental impact may be very unacceptable.

In general, large utility projects have the environmental impact carefully evaluated and monitored. Contrast that with someone who puts expensive solar PV panels on their roof to feel good about themselves. Like Thomas, they 'fail to see the environmental impact' because they are not trained to make very complex evaluations.

Let me inject some complexity. I agree with Thomas that land use is not an issue because the desert is ugly and useless. However, maybe the people in Boulder City think the desert is beautiful. The only reason they can live in Boulder City is that electricity is used to provide AC.

This solar project is not environmentally friendly but meets an acceptable standard. It will provide electricity to those who choose live in an environment with a low carrying capacity such that imported electricity and water are required.

[Nordic]

A very cool looking project. About half a section of land. I would be really interested in seeing how vegetation would be affected. The shade cast by the panels would increase available soil moisture, but I am sure much of the soil is compacted from construction activities, or access roads. The veg would have to be controlled. I am sure you wouldn't want a fire running through the site. I fight fires in this kind of terrain and environment - a cheatgrass fire when the winds are high and humidity low can really rip accross the landscape. Some vegetation, however would be nice if only to help keep the mirrors clean longer.

When I look at the top photo I can't help but think of a poor intern getting handed a squeegee and a bucket of water just after the sun falls behind the mountain.

[GreyFlcn]

And nuclear doesn't require tons of highly refined machining of metals and concrete?

Or massive strip mines to provide the materials, which have to be shipped halfway around the world, electroplated with gigawatts of electricity.

Just paying off the energy debt on nuclear takes decades.

Thinfilm solar panels can repay their energy debt in a few months.

_

Furthermore, these aren't even solar panels, these are mirrors.
Far less complex to manufacture.

And if they use recycled steel, which is quite common, since US steel has a higher recycling rate than an extraction rate, then that goes down as well.

And lastly, compared to normal solar panels, these are about double the effeciency.

_

I'd love to see an LCA comparison
But no, I'd doubt that it compared to nukes at all.

Especially within the first decade of operations.

[Peter Buck]

Could this be it (Google Earth, 35 degrees 48' 16.6" N, 114 degrees 38' 39.03" W)? Looks like when the picture was taken, one of four blocks had its mirrors on and the other three were in some stage of preparation -- some with the frames in place, some with just the landscaping done.

[Gregor]

I've mentioned this before but thought I would bring it up again. What if every house, building, etc. had a solar panel array on it thus contributing to the grid and their own usage. Would the enviromental impact be as great? If we are building a house or building anyway, why not make it an energy producing unit?

One way or another, whatever we do is going to have an impact on the environment, I guess it is a matter of trying to limit that impact as much as possible. How much impact is there in building solar panels?

[Paul Dietz]

And nuclear doesn't require tons of highly refined machining of metals and concrete?

It could be that it requires less. I don't have the numbers in front of me, but I suspect it does. Certainly nuclear displaces much less area from use by natural ecosystems in the plant itself.

[Harvey D.]

It is unbelievable to read that so many find ways to complaint against the cleanest power source, i.e. - SOLAR-.

Come on....let's be more reasonable.

[Thomas Foreman]

SOLARIZE

[Gerry Wolff]

Further information about concentrating solar power (CSP) may be found at:

http://www.trec-uk.org.uk/index.htm

and

http://www.trecers.net/index.html

and

http://www.trec.net.au/

[Thomas Pedersen]

I agree that roof-top solar panels is a more elegant solution than large arrays in the desert. A panel on every roof-top also diminishes the production cut when an odd cloud passes by.

Decentralized solar power production (again, roof-tops) does not require extra power lines to be built, but this cost may pale in comparison with installing power converters in every home. Although this latter cost may in the future be shared BEV charging...

However, solar thermal plants like this can potentially (I don't know whether this one does) store heat during daytime to drive steam turbines at night as well.

Economy of scale vs. decentralized flexibility. It's a tough call...

Here's an idea: Why not make concentrating photo voltaics (CPV) the same way - a cylindrical lens (as opposed to a spherical) with a "trough" of Spectrolab high efficiency cells in the centre line. This should result in a much simpler construction with only minor loss compared to two-axis tracking.

[J.C., Sr.]

Impact Shmimpact. C'mon it,s the desert. The only reason there is life out there is casinos and cathouses. Wait ;til the money comes rolling in. Is that all there is is 300 acres? When will wind turbines get rolling off the East coast? And they produce all night.

[Engineer-Poet]

I can just imagine soaring a hang glider in the thermal from the radiators.  Is that the black area in the foreground of the top picture, or are they part of the machinery further back?

[Dan]

Within the next 15 to 20 years, nanotechnology will provide society, smaller panels which can generate the same about of output as these larger panels.

Solar units of this type by that time, will be affordable for household usage and market-ready for widespread implementation. Along with this the creation of industrial electric storage facilities would surely make solar generation part of the every day grid.

About the same time technology will advance enough for widespread production of biomass and clean-coal generation. I'm afraid, however, all we have until then is coal & nuclear generation, and good old no-nonsense energy efficiency and conservation measures (the cheapest, most avaiable, and most affordable source of generation today!)

The question I have with this large array, is the cost v. the return. Anyone know those numbers?

Don't think vegetation will be any issue in that terrain.

Lastly, hopefully Nevada doesn't have baseball-size hail in its forecast. Then again global warming enthusiasts might seem to think so ;)

[Kit P.]

Roof top solar PV is not a very elegant idea at all, especially when the first decade is considered. That is because they do not work that long. Maybe someday.

I was reading a story about a California developer putting solar panels on 4000 square foot, $600 k, homes. The first thing I noticed was large windows and small overhangs. This is also a poor area for solar resources. The local PUD is a leader in solar PV. They have already figured out that roof top solar is a bad idea. I worked for this utility many years ago. They never published that the solar panels they installed stopped working. They also do not brag about their present output.

[Paul Dietz]

Roof top solar PV is not a very elegant idea at all,

It would also likely lead to a great many deaths and injuries, compared to nuclear. Working on roofs is very hazardous.

[J.C., Sr.]

Hey Kit P. In my lifetime I've had a dozen cars stop working for me. It never stopped me from running out and buying another. And don't even count the unrenewable carbon I've dumped into the tank and atmosphere. Maybe that solar project the power company took on was just another PR gone sour. They are married to the coal and oil industries.

[David Delcor]

I would like to know how does the desert dust affect the efficiency of this technology. If there is any automatic cleaning system and if there is any company specialized in providing this kind of solutions. I would also like to know which comapny provides the mirrors.

Besides I would recomend (in fact it should in my opinion be obligaatory) to allways give numbers, units and references. Specially so that nobody would make coments like:
"It could be that it requires less. I don't have the numbers in front of me, but I suspect it does. Certainly nuclear displaces much less area from use by natural ecosystems in the plant itself".

If there is not unit don't post it.
nonumbernopost.blogspot.com

One last thing Gregor, I have homework for you:

- Find the economical and energy costs of a Nuclear Plant:
-Construction
-Mantainance
-Comissioning
-Decomissioning
-Mineral mining
-Processing of uranium
-Disposal of the residuals
-Transport of materials
-Security
-water usage

[Kit P.]

I am an advocate of a PTC to for solar. I am not complaining about solar that works like Nevada Solar One. It is solar that does not work that gripes me.

Funny thing too, unlike JC, expect my cars to keep running too. I expect my new Corolla to last 30 years. I have two low end Fords with over 500,000 miles on them. The purpose of a car is transportation not a big status symbols. The purpose of a power plant is to make electricity. After your favorite boutique generator makes electricity, we can debate if it is cleaner than coal.

[Nabloid]

We have to learn how to crawl before we can walk, and walk before we can run.

This is just another step in the right direction.

Where does all energy on this planet come from? I'm just glad we are starting to go direct to the source of energy we have access to.

[Ken]

A decade of working life is not typical of PV. 20 and 25yr warranties are normal for major brand solar panels (usually warranted to put out 80% or better of their original rated output). There are a lot of people living off-grid around here (rural Australia) - they may complain that the panels are expensive, but not that they've proven unreliable or short-lived. IIRC the failures for silicon PV are mostly due to failures of the glues and resins used and the subsequent deterioration of electrical junctions from moisture not failure of the cells themselves, but major brands do use quality materials and have long service life. New types (CIGS for example) are being claimed to have similar durability and Sliver cells (much thinner silicon) ought to last quite well.

[Kit P.]

“A decade of working life is not typical of PV.”

Ken, oh really!!! Warranties aside, I would like to see the data for electrical generation for 10 year old PV solar systems. I am sure off-grid applications like rural Australia can be kept running but what is the costs and the environmental impact.

I have no problem with people living the way they want to. Please spare me about how you are protecting the environment. This solar project is a result of government polices to protect the environment which it fails to do. Rural Australia is not the American southwest.

Now Ken, multiple your PV solar system by a a million. I want to hear your plan to keep them all working for 10 years. How many technicians and truck will you need? Zero!!! It only takes one year of electricity production to figure they are not worth repairing.

[Mick]

Is it just me, or was the last post from our friend in Australia completely non-sensical? Not to mention hypocritical. You want to talk about protecting the environment? Australia has the highest rate of land clearing in the world. Australia has the highest per-capita greenhouse gas emissions of any country in the world. Australia is the only other industrial country besides the US to refuse to sign Kyoto...why? Because your country is completely beholden to coal.

As for PV degradation rates with time, there is a lot of information available, if you cared to look it up. Typical degradation over 10 years is 5%
http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/8468/26685/01190878.pdf

As for all the talk about PV, the Nevada Solar One project cannot be directly compared to PV. The technologies are completely different scales. The Nevada project will be 64 MW. The largest PV plant in the world is 12 MW (http://www.pvresources.com/en/top50pv.php).
You can't (yet) cost-effectively supply utility-scale power with PV. PV is fundamentally a distributed generation technology.

The Nevada project will supply enough power for 40,000 homes. The project cost is approximately $240M (http://www.reuk.co.uk/Nevada-Solar-One.htm). Care to calculate how much it would cost to power 40,000 homes with PV? Assuming a 3 kW system in California for every home, at a rough installed cost (after rebates) of $5.50/Watt, you get 3 kW x 1000 W/kW x $5.50 x 40,000 = $660M. This is very roughly 3x higher than the Nevada project cost.

Moreover, although the Nevada plant does not incorporate thermal energy storage, similar new plants in Spain will. This allows the plant to produce electricity after the sun goes down. This allows the plant to provide both base load and peak load power, which makes it a far more useful renewable technology than wind, which only produces when the wind blows, and for which there is no effective energy storage technology.

As for the asinine remark about nuclear power near the beginning of this blog chain, a new nuclear plant might be 1200 MW. Future parabolic trough solar plants might be 100-200 MW in size. Let's say 100 MW. So yes, you would need 12 plants to have the same capacity as one new nuclear plant. Not 200 plants. And the environmental impacts? Have you heard about radioactive waste? The biggest environmental impacts of a concentrating solar power plant are water consumption (of course rates are much higher for nuclear), land utilization (of course, solar doesn't require strip mines to produce uranium), and endangered species issues. These pale in comparison to radioactive waste management and disposal, plant decommissioning, and strip mine remediation.

Nuclear will almost certainly have a place in the future world energy mix, but don't delude yourself or mislead others into thinking that the environmental impacts of nuclear are minimal, or somehow trivial compared to a concentrating solar power plant.

Regarding the post about washing the mirrors, yes, dust will affect the performance of the mirrors. There is a requirement for regular power washing of the mirrors. The company that supplies most of the mirrors for parabolic trough plants is Flabeg GmbH in Germany.

[Kit P.]

Mick, you may want check your calculation. This time take into account capacity factor or solar.

LCA of nuclear and solar get about the same results. My delusions are based on reading peer reviewed LCA. If you go back and read my post on this topic, you will notice that I have objectively discussed the pros and cons. I can also see pros of PV if they are maintained.

[Mick]

Kit,Yes my error regarding capacity factor. I assume you are talking about my comparison of CSP to nuclear. A typical nuclear plant has a 90% capacity factor. A CSP plant with thermal storage (such as the ones being built in Spain) have approx 40% capacity factor. So if you had a 1200 MW nuclear plant with 90% capacity factor you get 1200 * 8760 hr/year * 90% = 9,460,800 MWh/yr.

To get the same production from CSP you would need 27 x 100 MW CSP plants with thermal storage based on 9,460,800 / (8760*.40) = 2700 MW.

So yes, my mistake on the number of plants. Should be 27 CSP plants to equal one nuclear plant. Still not 200 as you state above.

I disagree with your supposition that PV requires a significant maintenance effort to keep it working. Besides annual washing of the panels, and replacement of the inverter every 7-10 years, there is almost no maintenance required.

Please send link to LCA evaluation of nuclear vs. solar.

[john]

It puzzles me that very few (if any) of the comments above reflect awareness that this is not a new technology. Two 50MW and two 80MW plants, of an even more advanced design located in the Mojave about 90 west of LA, have been supplying reliable and clean power for almost 20 years now. The two larger plants owned and operated by a partnership of which Florida Power and Electric Co. is the majority holder.

So the real question is not “will these plants work?” but, in twenty years, why hasn’t our government supported the environmental studies, technology improvements and project financing which by now would have made the US the undisputed world wide leader in this technology, which has the potential of being a very major factor in slowing or reversing the growth-rate of green house gas emissions.

One answer:

Plants such as Solar One are a great big threat to the nuclear power industry – an industry dominated by the giant construction firms such as Bechtel. It takes a Bechtel to build a nuke, whereas any competent mid-sized power plant contractor can easily build a solar power plant, and you know they will underbid and outperform a Bechtel every time!

So, look out for opposition from the nuke industry posing as citizens genuinely concerned about the relative environmental merits between solar power plants and nukes. This is a red herring (and laughable).

[kit p]

FPL is the leading US producer of solar electricity using this technology. It is also the US leader using wind power. Unfortunately, their web site does not provide any info on performance although it would appear they use advanced predictive maintenance methods.

FPL is also a major player in operation and development of nuclear plants.

So apparently John is mistaken. It will be the nuclear industry that develops wind and solar to its potential. Solar wind and nuclear are not competing technologies and it takes the same skill set to manage high capital cost, low fuel cost assets. Every project requires discussing the relative environmental merits between solar power plants and nukes. This is a legal requirement.

[kit p]

Mick, nice response, sorry I did not see it sooner. Now consider that a new nuke will be 1600 MWe (with the same foot print of a 1200 MWe nuke plant), with a 95% capacity factor (by design). The CSP is a 64 MWe thermal plant just like the nuke. The nuke plant will have one thermal cycle a year while portions of the CSP will have 365 cycles. The size cooling pond and water usage for 1600 MWe of thermal generation is the same regardless of the heat source. These factors will result in significant maintenance and the associated

This site www.worldwater.com provides some real time PV data. Three locations in California at capacity factors if 4%, 5%, and 18%. One NJ site had 13%. Mick may be right about PV maintainability. Thermal cycling of electronic stuff is not my thing.

[Jezz]

Energy Payback
http://www.feasta.org/documents/wells/contents.html?two/wellselliott.html

http://www.hydroquebec.com/sustainable-development/environnement/pdf/rendement_investissement.pdf

Including Plant construction, fuel Mining, Fuel transport, operation, waste disposal, decommissioning, Estimated Energy Payback Periods (yrs) are
Coal 3.3
Fission 2.5
Wind 1.1
(Based on 1998 Document Used by UK guv)

There are extensive (biased) claims on UK energy sites with regards to LCA. Can't remember which ones. Must harass lecturer.

[funkyoldude]

Google Earth:

35 48' 09.47"N 114 58' 34.28"W

About half completed, very impressive at 5 Km altitude.

[Dan]

Not sure if the 1st image shows the installation under construction but this is the final thing:

http://www.german-renewable-energy.com/Renewables/Navigation/Deutsch/
Solarenergie/fallstudien,did=144890,page=1.html

[Tmorgan]

Nevada just opened the first tourist center run 100% on solar an wind energy. See the blog for details or visit www.nevadasilvertrails.com to plan a trip to see it. It's in Tonopah

[Tmorgan]

Nevada just opened the first tourist center run 100% on solar an wind energy. See the blog for details or visit www.nevadasilvertrails.com to plan a trip to see it. It's in Tonopah

[Tmorgan]

Nevada just opened the first tourist center run 100% on solar an wind energy. See the blog for details or visit www.nevadasilvertrails.com to plan a trip to see it. It's in Tonopah

[Tmorgan]

Nevada just opened the first tourist center run 100% on solar an wind energy. See the blog for details or visit www.nevadasilvertrails.com to plan a trip to see it. It's in Tonopah

[jimt]

how many acre feet of water/ year, does a 1000 acre/ 200 MW development require ?

[LG3]

Could you calculate how much energy would be generated yearly if you had one solar panel on every rooftop in the country?

I'm sure someone has thought of this. You can use the satellite view in Google Maps to estimate the combined square footage of every rooftop in the country. Then using weather data from any year to figure out cloud cover.

Understandably, It would be a very rough estimate but It would illustrate solar power's effectiveness.

[Kit P.]

Yes, the answer is zero. Solar panels do not work at night.

A good utility scale PV project in the right location may achieve 19% capacity factor of rated. Solar on roofs of homes most likely will do much worst.

[W.C.L.]

Hubbard's Peak calculations did not pretain to natural gas. Natural gas is found all over the world in abundance and in area with little oil. The world's known main deposits are in Russia, North America and Australia. There are very large accumulations in the continental shelf regions all over the world and in the form of methane nodules on the ocean floors. Also, we still do not know for sure that methane on earth has a biogenic origin. It could be a juvenile gas like Jupriter's atmosphere. The big oil companies are "Black Oil" companies and they don't like "messing" with natural gas. Pipelines for natural gas force them to deal with local and national government entities that they generally can avoid with black oil operations (transported by truck or ship). New more efficient Gas to Liquid (GTL) technologies can be used convert methane to a cleaner diesel and gasoline for use in transportation.

[killer]

Anyone who can't see the benefits of solar, is a caveman

[tumara baap]

maaderchod tumahri vajaha se hamare 15 rs barbad ho gaye to maaderchod iski working tumahara baap batayaga jo bhi ise padhe uski maa ki chood

[pandreson]

Over 120,000 people are expected to attend Solar Home Tours nationwide this year. This is 13th year for the National Solar Tour, and the third for southern Nevada. It's a great way to meet people and get good, practical ideas on using renewable energy.
---------------------------
pandreson
Nevada Drug Addiction

[Atomictoad]

There will be no plants left when these are all built. All mirror systems reuire 100 percent destruction of biodiversity on the site. Plants store carbon, desert plant do it very well. Google CAM plants. Scraping up deserts will ultimately make the earth hotter by releasing more carbon in the athmosphere adding to the green house effect. It is not green to scarpe up the desert. It will kill a lot of species. Roof top is the real "green" energy. Read below:

DOI: 10.1126/science.320.5882.1409

News of the Week

ECOSYSTEMS:

Have Desert Researchers Discovered a Hidden Loop in the

Carbon Cycle?

Richard Stone

URUMQI, CHINA--When Li Yan began measuring

carbon dioxide (CO2) in western China's

Gubantonggut Desert in 2005, he thought his

equipment had malfunctioned. Li, plant

ecophysiologist with the Chinese Academy of

Sciences'Xinjiang Institute of Ecology and

Geography in Urumqi, discovered that his plot was

soaking up CO2 at night. His team ruled out the sparse

vegetation as the CO2 sink. Li came to a surprising

conclusion: The alkaline soil of Gubantonggut is

socking away large quantities of CO2 in an inorganic

form. A CO2-gulping desert in a remote corner of

China may not be an isolated phenomenon. Halfway around the world, researchers have

found that Nevada's Mojave Desert, square meter for square meter, absorbs about the

same amount of CO2 as some temperate forests. The two sets of findings suggest that

deserts are unsung players in the global carbon cycle. "Deserts are a larger sink for

carbon dioxide than had previously been assumed," says Lynn Fenstermaker, a remote

sensing ecologist at the Desert Research Institute (DRI) in Las Vegas, Nevada, and a coauthor

of a paper on the Mojave findings published online last April in Global Change

Biology.

The effect could be huge: About 35% of Earth's land surface, or 5.2 billion hectares, is

desert and semiarid ecosystems. If the Mojave readings represent an average CO2 uptake,

then deserts and semiarid regions may be absorbing up to 5.2 billion tons of carbon a

year--roughly half the amount emitted globally by burning fossil fuels, says John "Jay"

Arnone, an ecologist in DRI's Reno lab and a co-author of the Mojave paper. But others

point out that CO2 fluxes are notoriously difficult to measure and that it is necessary to

take readings in other arid and semiarid regions to determine whether the Mojave and

Gubantonggut findings are representative or anomalous.

Waiting to exhale? CO2 flux readings suggest

that the Mojave Desert in Nevada is gulping

carbon at the rate of a temperate forest.

Credit: Desert Research Institute, Nevada

For now, some experts doubt that the world's most barren ecosystems are the longsought

missing carbon sink. "I'd be hugely surprised if this were the missing sink. If deserts are

taking up a lot of carbon, it ought to be obvious," says William Schlesinger, a

biogeochemist at the Cary Institute of Ecosystem Studies in Millbrook, New York, who

in the 1980s was among the first to examine carbon flux in deserts. Nevertheless, he says,

both sets of findings are intriguing and "must be followed up."

Scientists have long struggled to balance Earth's carbon books. While atmospheric CO2

levels are rising rapidly, our planet absorbs more CO2 than can be accounted for.

Researchers have searched high and low for this missing sink. It doesn't appear to be the

oceans or forests--although the capacity of boreal forests to absorb CO2 was long

underestimated. Deserts might be the least likely candidate. "You would think that

seemingly lifeless places must be carbon neutral, or carbon sources," says Mojave coauthor

Georg Wohlfahrt, an ecologist at the University of Innsbruck in Austria.

About 20 kilometers north of Urumqi, clusters of shanties are huddled next to fields of

hops, cotton, and grapes. Soon after the Communist victory over the Nationalists in 1949,

soldiers released from active duty were dispatched across rural China, including vast

Xinjiang Province, to farm the land. At the edge of the sprawling "222" soldier farm,

which is home to hundreds of families, oasis fields end where the Gubantonggut begins.

The Fukang Station of Desert Ecology, which Li directs, is situated at this transition

between ecosystems.

In recent years, average precipitation has increased in the Gubantonggut, and the

dominant Tamarix shrubs are thriving. Li set out to measure the difference in CO2

absorption between oasis and desert soil. An automated flux chamber measured CO2

depletion a few centimeters above the soil in 24-hour intervals on select days in the

growing season (from May to October) in 2005 and in 2006. The desert readings ranged

from 62 to 622 grams of carbon per square meter per year. Li assumed that Tamarix and a

biotic crust of lichen, moss, and cyanobacteria up to 5 centimeters thick are responsible

for part of the uptake. To rule out an organic process in the soil, Li's team put several

kilograms in a pressure steam chamber to kill off any life forms and enzymes. CO2

absorption held steady, according to their report, posted online earlier this year in

Environmental Geology.

"The sterilization treatment was impressive," says biogeochemist Pieter Tans, a climate

change expert with the U.S. National Oceanic and Atmospheric Administration in

Boulder, Colorado. "They may have found a significant effect, previously neglected, but I

would like to see more evidence." Indeed, the high end of the Urumqi CO2 flux estimates

are off the charts. "That's more carbon uptake than our fastest growing southern forests.

It's a huge number. I find it extremely hard to believe," says Schlesinger, who nonetheless

says the Chinese team's methodology looks

sound.

Missing sink? Tamarix shrubs are thriving in

China's Gubantonggut Desert, but the soil

itself may be socking away far more CO2 at

night. Credit: M. Stone

At first, Li was flummoxed. Then, he says, he realized that deserts are "like a dry ocean."

The pH of oceans is falling gradually as they absorb CO2, forming carbonic acid. "I

thought, 'Why wouldn't this also happen in the soil?' " Whereas the ocean has a single

surface for gas exchange, Li says, soil is a porous medium with a huge reactive surface

area. One question, Tans notes, is why the desert soils would remain alkaline as they

absorb CO2. Li suggests that ongoing salinization drives pH in the opposite direction,

allowing for continual CO2 absorption. But where the carbon goes--whether it is stowed

largely as calcium carbonate or other salts--is unknown, Li says. Schlesinger too is

stumped: "It takes a long time for carbonate to build up in the soil," he says. At the

apparent rate of absorption in China, he says, "we'd be up to our ankles in carbon."

One possibility, DRI soil chemist Giles Marion speculates, is that at night, CO2 reacts

with moisture in the soil and perhaps with dew to form carbonic acid, which dissolves

calcium carbonate--a reaction that warmer temperatures would drive in reverse, releasing

the CO2 again during the day. (Unlike most minerals, carbonates become more soluble at

lower temperatures.) In that case, Marion says, Li's nighttime absorption would tell only

half the story: "I would expect that over a year, there would be no significant increase in

soil storage due to this process," he says, as the dynamic of carbon sequestration in the

soil would vary from season to season. Li agrees that this scenario is plausible but notes

that his daytime measurements of CO2 flux did not negate the nighttime uptake.

In any case, other researchers say, absorption alone cannot explain the substantial uptake

in the Mojave. Wohlfahrt and his colleagues measured CO2 flux above the loamy sands

of the Nevada Test Site, where the United States once tested its nuclear arsenal. From

March 2005 to February 2007, the desert biome absorbed on average roughly 100 grams

of carbon per square meter per year--comparable to temperate forests and grassland

ecosystems--the team reported in its Global Change Biology paper.

Three processes are probably involved in CO2 absorption, Wohlfahrt says: biotic crusts,

alkaline soils, and expanded shrub cover due to increased average precipitation. "We

currently do not have the data to say where exactly the carbon is going," he says. Like the

Urumqi team, Wohlfahrt and his colleagues observed CO2 absorption at night that cannot

be attributed to photosynthesis. "I hope we can corroborate the Chinese findings in the

Mojave," he says. Arnone and others, however, believe that carbon storage in soil is

minimal.

Wohlfahrt suspects biotic crusts play a key role. "People have almost completely

neglected what's going on with the crusts," he says. Others are not so sure. "I'm mystified

by the Mojave work. There is no way that all the CO2 absorption observed in these

studies is due to biological crusts, as there are not enough of them active long enough to

account for such a large sink," says Jayne Belnap of the U.S. Geological Survey's

Canyonlands Research Station in Moab, Utah. She and her colleagues have studied

carbon uptake in the southern Utah desert, which has similar crust species. "We do not

see any such results," she says.

Provided the surprising CO2 sink in the deserts is not a mirage, it may yet prove

ephemeral. "We don't want to say that these ecosystems will continue to gain carbon at

this rate forever," Wohlfahrt says. The unexpected CO2 absorption may be due to a

recent uptick in precipitation in many deserts that has fueled a visible surge in vegetation.

If average annual rainfall levels in those deserts were to abate, that could release the

stored carbon and lead to a more rapid buildup of atmospheric CO2--and possibly

accelerate global warming.

Science. ISSN 0036-8075 (print), 1095-9203 (online)

[fireofenergy]

CSP can sustain total global populations complete with electric cars. So could PV if only battery tech could last the lifetime of the project... In reality, batteries only last about 1/6th of this timespan, at most! To have a solid state (non moving parts) grid, supercapacitors have to become about 100 times more energy dense (and about 100 times cheaper, along with the disillusion of PV priporitary issues). Supercapacitors hold that promise though, since, theoritically, they contain unlimited electrons per quantum spacetime! In the meantime, thousands of square miles of mirrors, heat resevoirs and nuclear class steam generators (1990's tech) must suffice!

If that isn't good enough for purists, then there is advanced geothermal systems which will be capable (after further development) of supporting thousands of such global populations!

But first, we must go against economics (because it is cheaper to utilize $2 per gallon gas, again) and build all them millions of mirrors because if we wait, fossil fuel prices will skyrocket (again) to the point where it will be impossible to afford the energy required to build such massive capital!

When it is time to decommission the "mirrors", it is best to point them flatly skyward, as to reflect the sun and reduce negative albedo (this only helps if all countries have already built thousands of sq mi of such by that time).

With mirrors, there will be a STOP to GW and a STOP to economic woes...

[Account Deleted]

I would like to know what is the collector's efficiency, i.e. how big is the potion of solar rediation being transferred away by the fluid, what kind of fluid is used?
Can anyone give me some idea about that?