Also worth reviewing (again). Executive Summary: Assessment of Parabolic Trough and Power Tower Solar Technology Cost and Performance Forecasts - Sargent & Lundy LLC Consulting Group Chicago, Illinois

And people, the discussion is Solar Thermal. if ANYONE tries to drag this discussion off into solar PV .......

India has tremendous potential to make great strides in the area of cost-competitive renewable energy and especially concentrated solar thermal power (CSTP). Advances in high-temperature CSP (1000-deg C) can allow for the operation of externally-heated air turbine engines. India's aluminium industry can provide a mixture of bauxite and cryolite (molten eutectic compound) to store hihg-temperature thermal energy to continue operating the turbines until after sunset.

There is also potential for India to import CSP from the Saudi Arabian desert region at some time in the future, courtesy of an undersea power cable between Oman and the Gulf of Kutch. CSTP can also allow for solar air-cycle and solar-steam power plants to dump exhaust heat into desalination plants along the coast or at inland locations, dump the heat into solar towers (another air-cycle solar thermal technology).

CSP and CSTP definately have a future in India . . . . and especially with the cost of both expected to decline in the future.

We don't know if this is true or not.

So we are investigating.

http://www.prosefights.org/scriptpollute/chinasolar/outside/outside.htm

And we are submitting a proposal for funding of our work.

http://www.prosefights.org/scriptpollute/pnmproposal/pnmproposal.htm#collawn

Volts on the vertical axis and amps on the horizontal axis may equal power?

We are speculating, of course.

?

Let's see what happens.

Some 300 to 400 million Indians have no electric service what-so-ever, not even lighting. The other 800 million or so have mostly spotty service and industries frequently have to shut down and send people home for lack of electricity. If you are moneyed or absolutely need reliable service you buy your own diesel powered generator. Several hundred million cook their food using gathered twigs.

I don't have the latest figures at hand but my memory says over 80% of electricity is coal generated.

New coal mines are being opened up in India and India is buying coal mines(companies) in other countries. In recent months coal supplies at generating plants were at desperately low level, some a few days from forced shutdown.Coal usage continues to increase, new coal fired power plants are expected to burn more, not less, over at least the next sixty years.

India's excessive population is still growing, their ultimate impediment. Their population is expected to exceed China's in only a decade or so. Despite building many new coal burners, the cheapest and quickest way to get electricity to the population, it's been a losing battle,

So now they are going to be saved by more expensive solar power. Without anything close to baseload capacity or grid capacity. According to my childhood Mother Goose Book, "If wishes were horses beggars would ride." .

These threads are triggered by opinion. :-)

Ed

The other issue with large scale CSP concepts is the diurnal and seasonal variations in the collection of solar energy. The sun goes down every night so when the author lists the electrical output of a CSP plant it may be the peak output during the best hour of the year. As an approximate rule of thumb, the 24 hour average output, assuming the plant could run for 24 hours, would be about 25% of the peak value.

Not only are there diurnal variations in insolation, there are seasonal ones as well. A CSP plant in winter will only have about half of the output it has in the summer. How will this shortfall be overcome?

Finally, present designs are indeed turning to the use of molten salt compounds as the working heat transfer fluid. By storing some of this hot molten salt it may be able to shift some of the collected solar energy to more hours in the day, but at a comparable reduction in electrical output during the peak collection time periods. Figures like six hours extension in the time that the plants can put electricity on the grid are being talked about. However, this same salt heat tranfer fluid has a freezing point about the boiling point of water. Because of this, the salt fluid has to be drained each night and stored in an insultated structure and the whole system has to be refilled each following day.

Lastly, whenever the CSP plant is inoperable-each night- its dedicated transmission lines are also unused. This is an expensive way to operate a transmission grid system.

CSP plants may have a role to play in the future, but it could be a very limited one until the above problems are resolved and the resultant cost of electricity low enough to be competitive.

Herschel Specter mhspecter@verizon.net

"an ultimate heat sink" -- The obvious solution, though no developer thus far has determined it necessary, is to use a medium other than water (eg. any of several common refrigerants) in the turbine circuit to allow the condenser to operate efficiently at the higher temperature of ambient air, or to allow a large reservoir of standing salt water to absorb the heat effectively without needing to evaporate any high percentage of it, eg. low-rate replacement with a small pipeline from the ocean.

"A CSP plant in winter will only have about half of the output it has in the summer. How will this shortfall be overcome?" -- By the obvious means of providing low-cost thermal backup from fossil generation, either natural gas or coal. The lowest investment cost is direct-fired heating of the thermal transfer / storage medium during low-insolation periods, though more efficient no doubt would be the more capital-intensive use of a combustion turbine with the exhaust heat used to heat the thermal medium. All CSP plans, esp. those which in future may be targeted to baseload, provide for this variation in their economic models, and still work as advertised.

"the salt fluid has to be drained each night " -- of course it does, and that is now being done at all the sites which Sargent and Lundy's evaluated in coming up with their analysis referenced above.

Honestly, in your entire criticism there is not a single point which can possibly have any novelty to anyone like NREL or Sargent and Lundy's engineering, who've determined that your conclusions are simply wrong.

The only energy that can be used to do work is that which is above the available sink temperature. (Power plants generally have a better e in the winter.) The thermal efficiency, e, of a condensing turbine depends on the pressure (vacuum) of the exhaust which is fixed by the condensing temperature. A condenser temperature of 100 F corresponds to an exhaust pressure of 1 psia. Less, an inch of Hg is better.

Obviously daylight desert air is frequently over 100 F so even an infinitely large air condenser cannot provide us low exhaust pressures. Maybe at some point we might hear that the sun is free so let the e slide?

So no matter how it's done the sink (environment) has to take all the rejected heat. I roughed out that If water is the cooling medium about 8 or 9 pounds of water has to be evaporated (lost) per kWh generated. This is what you see rising and causing plumes rom cooling towers on buildings and power plants.

Use of a "refridgerant" would not eliminate the heat sink problem. I can't see how it could do anything but make it woarse.and consume energy, with even more heat to get rid of.

A large salt water pond would would have to lose not only the 8 or 9 pounds of water/kwh through evapoation but have enough additional evaporation to keep from gaining temperature from sunshine. If the water added to the pound was salt water you would soon have youself a salt flat

i have been careless about the word desert. What we are talking about here is a special kind of desert - the kind like the Sahara, not the kind like much of Antarctica.

Obviously a cooling pond would need to be shaded, perhaps best by solar collectors plus some auxiliary means. Development of the salt flat would be an expected design feature.

So I drug (hillbilly for dragged) out my first edition Keenan and Keys, The thermodynamic Properties of Steam, and made a better estimate. To use some real numbers I used 600 psia 740 F super heated steam with 1 psia exhaust (@101.74 F) You are welcome to choose your conditions, but not valid for dual cycle or super critical - not likely in a hot desert anyway.) I have been trying to think of a power plant I have seen or oil refineries I have serviced that was not on a river or large body of water. I starter a catalytic cracker at Zarka, Hashimite Kingdom of Jordan. But this plant had no large turbines and did not generate electricity.

it was in Jordan that I first heard the joke about Moses wandering in the desert for.forty years only to pick out the only place in the area without oil.

Now I say 6.2 pounds of water per kWh generated in a Rankine cycle plant. A bodacious number in a hot desert. For a 200 meg plant that would mean 13,144/(8.33*60)=16,000 gpm. (I'd size the makeup line at 8 inches.)

My wife says nobody will read this post. Let's see.

So capital costs of the standby system are now the problem? I wouldn't expect that, since (last I heard) simple cycle turbine generating plants cost "in the range of" $600 / kw, whereas the solar generation is at now likely costing "in the range of" $4,500 / kw and dropping (eg. S&L / NREL's present-day $0.125 / kwh). I would expect that direct gas firing of the thermal fluid should cost significantly less than turbine generators if gas turbines with exhaust heat recovery are too costly.

Transmission of electricity (large amounts, HVDC, > 300 km) and Natural Gas are approx. comparably costly per kwh of electricity delivered at the destination, though its too bad we've made such large sunk investments in gas transmission. If you're planning to depend on shale gas resources into the distant future, you should get the delivery guarantees in writing, with penalty clauses. Some are quite sceptical, particularly regarding extremely rapid depletion rates of shale gas wells, apparently averaging only 1 or 2 years to uneconomic. Present market is likely an extreme anamoly. Last estimate I saw, ABB was ballparking 2 GW HVDC for 300 km at $325 million. So lets assume a 2 GW solar installation 325 km inland from LA, costing $7 billion capital + $1.4 billion in construction interest, to construct. The transmission will cost $1.06 billion. Given an 83% availability, with an average wholesale price of electricity at $0.07 / kwh, with 10% of capital per year in O&M, and an 8% interest payment on capital, 4.6% transmission losses, (and a whole lot of other quite reasonable assumptions), the system will retire its capital loans in 10.5 years. Of course we must then add the cost of pumping cooling water from either the ocean or some more useful location, but not likely significant.

Today 20,000 children died from diarrhea and tomorrow another 20,000 will die because they didn't put a few drops of bleach in their drinking water at a cost of mere cents. And you ask about the cost of pumping sea water hundreds of miles to a power plant not needed. it is an easy calculation, but how fatuous.

So what, when we are headed for a die-off that makes anything experienced in the past look like a mere walk in the park. Sorry, numbers have no conscience.

"The Republic of Trinidad and Tobago is using desalination to free up more of the island's water supply for drinking purposes. The desalination facility, opened in March 2003, is considered to be the first of its kind. It is the largest desalination facility in the Americas and will process 28.8 million gallons of water a day and sell water at the price of $2.67 per 1,000 gallons[52]." Ionics to build $120M desalination plant in Trinidad - Boston Business Journal

Looks like Isreal's plants are running at about $2.75 / 1,000 litres, perhaps a more reasonable figure. Wiki - costs of Isreali desal plants

Could an RO desalination facility be combined with cooling the condensers of a solar-thermal generating plant using seawater pumped inland, a very high brine concentration (RO desal plant --> solar thermal condensers stage 1 --> open pond w/agitators for evap cooling --> solar thermal condensers stage 2 --> salt production ponds) ?

Regarding your concern on population, the only ethical means at hand to address the problem is to improve the standard of living, education and personal freedoms of everyone in the world, so we'd all best get ourselves busy.

Too bad, but I guess it shows that water in the southwest US is clearly not close to being scarce yet.

Despite the very low costs of agricultual water you cited the supply situation is marginal to desperate in many places. I understand that watering a lawn in Phoenix or Tucson is a capital offense, or ought to be.

Reverse osmosis is a desperate measure to supply drinking and sanitary water. I pay $ 0.85 / 1000 gallons for potable water delivered under pressure. The reverse osmosis figure you cite are $ 10.41 /1000 gal, over 12 times more costly but cheaper than distillation.

As for condensing turbine exhaust in the desert I can't conceive of a scheme that is both feasible and thermodynamically efficient. For thermal efficiency a very low pressure is required at the last stage (bladed wheel) of the turbine. We want almost zero pressure drop through the lines and condenser, even one psi drop hurts. All the "surface condensers" I've seen put the steam through the shell side and the cooling water through the tubes.

World Population. I believe we have already passed the point where our civilization can survive without a die-off, not merely of tens of millions as we experienced in the USSR and W.W.II and the Holocaust ,etc. but billions. As recently as about 1927 we could have at least in theory saved ourselves by zero population growth staring then, at 2 billion. Today we are 7 billion and growing. From the Dawn of Man unlit a thousand years ago world population had never been over 0.3 billion. Alas, ethics has nothing to do with it.

At he time of W.W.II the literacy rate in Japan was higher than the US. The Germans were the most sophisticated and literate in the world. Only Iowa had a better literacy rate than Japan.

Yet the almost unbelievable and sickening atrocities of the Japanese military against Koreans, Chinese, Filipinos, Americans (the Batton Death march one of the most egregious episodes in all history) has faded. Now they presume to lecture us on ethics.

Education. We have become dumber, far dumber. My grandchildren and later children know far less than I did at their age and get praised. They get A's. I got C's. . .

As to previous comments on California/Arizona water supply. I ran across a 2008 rating of cities as to the sustainablity of their water supply. At the tail of the list, that is,those most at risk were ten cities:. 4 in CA, 3 in AZ, one each in CO, NM an NV.

As far as power plant cooling is concerned, there are power plants that use sea water mechanical-draft cooling towers. However, makes more sense to just use once-thru sea water cooling because it is more economical. Saltwater cooling towers also end up putting salt spray all over the area around the plant (drift from towers).

Combined-cycle power plants with air cooled condensers are a good fit for desert locations, provided there is access to natural gas. However, generally also need inlet air evaporative coolers for the gas turbines, so some water is needed. Inlet air coolers using chilled water from a refrigeration plant can also be used to reduce, but not eliminate, water use.

India might want to consider turning coal into substitute natural gas through coal gasification for use with combined-cycle plants and general use. However, mid-sized supercritical pulverized coal pants are undoubtedly the lowest cost solution, if coal is available. On the down side, my experience is that Indian coal is not very good. Circulating fluid bed boilers might be a better but more expensive solution (CFB's can burn pretty much anything).

As far as using solar with a combined-cycle plant (basically solar heat creates steam used with the plant’s steam turbine), the increased plant output is pretty small while the capital cost of the solar trough array (or tower) is pretty high. The economics are not very good and has only a limited ability to solve India's basic problem of not enough power.

If it were me, I would greatly accelerate the Indian nuclear program and use coal gasification to provide for the basic energy supply, while using some solar photovoltaic for villages with limited power needs and limited access to power lines. Ultimately, India needs to greatly expand the transmission and distribution system so power can be moved more easily throughout the country.

PS As far as using reverse osmosis (RO) in California for drinking water - the environmental lobby and mind-numbing, massive state bureaucracy continue to stymie that. Power plants, however, routinely use RO for water make-up to cooling towers.