Compact Linear Fresnel Reflector Solar Power System Lower Cost Than Parabolic Trough Sytems, Ready Now

On Sept 10, Ausra Inc., the developer of utility-scale solar thermal power technology, announced that it has secured more than $40 million in funding from Silicon Valley venture capital firms Khosla Ventures and Kleiner, Perkins, Caufield & Byers (KPCB).

Ausra's power plants drive steam turbines with sunshine. Locally manufactured solar concentrators made of steel and glass focus sunlight to boil water, generating high-pressure steam that drives conventional turbine generators. New thermal energy storage systems using pressurized water and low cost materials will provide for on-demand generation day and night. Ausra's core technology, the Compact Linear Fresnel Reflector (CLFR) solar steam generation system, was originally conceived in the early 1990s by founder David Mills while at Sydney University. Mills later worked with Graham Morrison to develop the idea between 1995 and 2001.

Austra's innovation is that it uses commodity flat mirrors that sit low to the ground. The refectors concentrate sunlight on water-filled pipes that hang over the mirrors. As the water is heated up to 545 degrees fahrenheit (285 celsius) the resulting steam drives a standard turbine.

"We had been working on a wide range of alternatives and kept finding that simpler, cheaper approaches outperformed higher-temperature, more sophisticated designs," says Ausra Chairman David Mills.

The company claims that:

CLFR technology has significant advantages in cost, scalability and emissions profile.

Utility scale solar technology has traditionally been parabolic trough, but Ausra's less complex flat mirrors are much less costly.

Ausra's innovations in collector design dramatically reduce the cost of solar thermal generation equipment and bring solar power to prices directly competitive with fossil fuel power.

It can generate electricity for 10 cents/kWh now, under 8 cents/kWh in 3 yrs.

Ausra's zero-carbon power plants generate electricity at current market prices for fossil-fired power without the emissions caused by burning fuels. Low-cost thermal energy storage systems now under development by Ausra will allow solar electric power to be generated on demand, day and night.

Ausra's projects will include energy storage using hot water and other low-cost materials. Thermal energy storage puts the storage before the generator—heat is stored, not electric power. Storing heat is simpler, cheaper, and substantially more efficient than storing electric power. Thermal energy storage makes solar a firm, dispatchable resource.

In 2002, Mills and Morrison founded Solar Heat and Power Pty Ltd. in partnership with Ausra CEO Peter Le Lièvre, and SHP built a successful trial 1 megawatt system in 2004 for Macquarie Generation in New South Wales. A following 38 megawatt CLFR solar field is expected to be complete by 2009.

The company currently has a power project in the testing and commissioning phase in Australia, a project breaking ground this year in Portugal and a project in the permitting phase in central California. A significant number of large projects are being negotiated in other locations.

Ausra is developing a generation of plants in the 100-500 MW class.

Ausra is the successor company to Solar Heat & Power from Australia, in business since 2002.

Thanks for tip from After Gutenburg

Comments

[Ender]

If only our coal mining government would raise our Mandatory Renewable Energy Target from the pathetic 3% that it is now to 10% or more David Mills would not have to have gone offshore for funding.

As usual I guess we will have to buy it back at 4 times the price from some other country like Vanadium Batteries.

[Daniel Ferris]

Ecology Is Cheap? "Energy Crisis or Political Profiteering?" at
http://ezinearticles.com/?Energy-Crisis-or-Political-Profiteering?&id=725936 .

[Calamity]

Did someone rub my lamp, three times?

Right now, this is argueably the most promising utility scale CST power technology. It's superiour to troughs for at least a dozen reasons.

Unfortunately, the Howard administration is dominated by naivety and lack of geopolitical sense. Just look at the renewable energy grants issued. They throw a couple million $ at CLFR and expect a several hundred MW plant? Time to plug in to reality, hope they can still find the socket.

[David Stone]

Ender:

I completely agree with the spirit of what you are saying, but making these things mandatory is the wrong way to go.

This just makes it more complicated, as it would require governments to monitor and pick winners, making them
- open to critics saying they have no proof that it is better
- open to corruption by companies trying to influence them.

What is proven is that fossil fuels are bad. Therefore the government should penalise there use. It wouldn't even be necessary to fine their use; it would be enough to make those who use them pay the full price, including the damage using them causes.

If I like using ultrasound machines, should I only have to pay the price of the machine, or maybe also the price of all the windows I shatter?

This would make people go to the garanteed cheaper renewables, they would be developed by the companies satisfying the demand, price would come down to below what we are paying now per unit of energy or per mile, fresh REAL air could return.

[Bruce]

We don't have to mandate renewable energy use or penalize conventional energy use. All we have to do is make profits from selling equipment to produce electricity from renewable sources and selling electricity produced by this equipment tax free. People will swtch to renewable energy sources in droves with no force required. The govt wouldn't even have to give up that much revenue. The profits will make their way into income streams that are taxed.

[Angus]

Is it possible to have a windmill tower designed so as to collect solar energy in a simalar fashion to what is being done at Ausra? I'm wondering if existing towers could be modified to collect solar energy and turn it into electrcity in conjunction with wind?

Call me naive but we seem to be hammering the same old ideas with renewables-most of which don't hold much promise.

[David Stone]

Bruce:

making the profits of one technology tax free is again the government deciding which technology should be used.
Governments have a history of choosing badly and of bowing to pressure from others for favouring one.

And it wouldn't be 'conventional' energy being penalised, but 'harmful' energy. It is simply logical that the true cost is paid.

This isn't penalising.

If I damage your car while playing ball close to it, I am not penalised for playing ball if I have to pay to have your car fixed.
I have to pay the cost of the damage I cause to your car WHILE playing ball near your car.

It would be cheaper to build a fence around my playing area, than alway having to pay damages - unless of course I didn't have to pay you damages...

[Bruce]

David: I agree that the Govt shouldn't be picking renewable energy technologies. We don't need anymore corn ethanol boondogles. I was talking about all renewable energy technologies (solar, wind, hydoelectric, geothermal ...). I don't agree that "fossil" fuels are bad. Coal id dirty and coal power plants should be made to clean up there emissions. Natural gass is clean however, and it's use shouldn't be penalized.

[bigTom]

Bruce, pollution taxes would be a good way to get the market to solve these problems. Over here USA, political forces have unfortunately made the word TAX radioactive. So at least over here we need to use other economically less rational incentives.

Now I am not against research & development funds being given to promising startups. That has been a form of government spending which in the past has paid some pretty good alternatives.

Now can we go back to discussing the merits or lack thereof the the particular technology. This project makes some intersting claims about the ecomomics, and not just for peak power. It seems to me that CPV will likely be most effective for the later use, but if CPT can be used in a dispatchable manner, that covers a very important part of the need. Do those price claims seem reasonable?

[Angus]

It seems to me that this technology would be a prime canidate for cogeneration with geothermal energy. A geothermal plant would produce the electricity at a constant rate through out both day and night while the solar thermal plant would produce electricity during peek daytime demand when the grid is heavily loaded. That to me would elimanate the need for an expensive storage system and produce CO2 free electricity pretty much around the clock. when the clouds move in, the grid would draw from anothe source in the same manner as it does now.

[David Stone]

Bruce:

I understand what you are talking about, but others don't or don't want to. That is why, in such matters, the only way to look at these things is rationally and logically.

- Corn IS a renewable energy, just like your favored technologies. It is also very harmful for various reasons I won't go into now and should never have been supported. Real pricing would make it go away by itself.

- Coal is dirty, and even the cleanest coal is still dirty.

- Natural gas is not clean. It is one of the cleanest fossil fuel, but it is still releasing CO2. It is, after all, a hydrocarbon.

All fossil fuels are bad:

- they all release CO2 which stay where it is, and not in our atmosphere.
- emitting only CO2 is the cleanest they can get. But they also emit toxic gases. 1 in 4 people in Los Angeles suffer for related lung problems.
- burning up the raw materials of our planet is like driving a riverboat using parts of the deck to fuel the furnace - while filling the deck and all the passangers with smoke.

bigTom:

R&D funds would be great if the promising startups were involve in promising clean tech.

Unfortunately only a very small amount goes to this.
Most is spend on old, outdated and harmful processes.

The USA government spends billions on coal burning and, despite the unbelievably huge profits, it continues to subsidise the oil business.

[Bruce]

BigTom: I don't know enough about the technology to know if the prices are reasonable or not. I read this website to learn about interesting technologies for producing energy from non hydrocarbon sources. I think the market should decide which technology is best not the govt. I think using less energy to do the same work is a good idea in and of it self.

I don't think mankinds CO2 emissions are a problem. The only account for %3.4 (see http://www.junkscience.com/Greenhouse/index.html) of the total CO2 that goes into the atmosphere every year.

[Paul Dietz]

I don't think mankinds CO2 emissions are a problem. The only account for %3.4 (see http://www.junkscience.com/Greenhouse/index.html) of the total CO2 that goes into the atmosphere every year.

You are quoting a well-discredited bit of AGW denialist propaganda. The current increasing trend in atmospheric CO2 is entirely due to anthropogenic emissions. Indeed, the total increase in atmospheric CO2 each year is less than the total CO2 released by fossil fuel combustion, and this has been true for about a century. Were fossil fuel combustion to suddenly end, the CO2 concentration in the atmosphere would enter a long term decreasing trend.

Now, the total amount of CO2 cycled through the atmosphere each year is much larger, but this is irrelevant, since the inputs and output largely cancel out. The net increase is what's important, and human actions dominate that.

[JohnBo]

I love David Stone’s analogy to burning fossil fuels when he said…

- burning up the raw materials of our planet is like driving a riverboat using parts of the deck to fuel the furnace - while filling the deck and all the passengers with smoke.

I also agree with Bruce’s comment that mankind’s CO2 emissions are not harmful. Man’s CO2 influence on the earth is about the same as an ant pushing a train. The earth’s temperature has been changing for millions of years and will continue to do so. It’s a dynamic process. Only a lawyer can make a case for mankind’s actions causing heating or cooling. People of reason call it nature.

Nevertheless, the renewable energy movement is good. Mankind needs to live on renewable energy and not the planks from the deck of the boat. Fossil fuels need to be preserved for future generations better uses. We should be good stewards of the earth. To me, the global warming hysteria is a joke, but it is having the benefit of leading us into a sustainable renewable energy life.

[Paul Dietz]

The earth’s temperature has been changing for millions of years and will continue to do so. It’s a dynamic process. Only a lawyer can make a case for mankind’s actions causing heating or cooling. People of reason call it nature.

People of reason call your argument nonsense (I am amused by the 'lawyer' line; was that deliberate self-parody?) It's not supported by evidence or logic. That the climate has changed in the past for natural reasons in no way implies that human actions cannot change it, or are not changing it now.

[Kit P]

Paul, that is an interesting theory you have. Of course Paul just claimed JohnBo's argument was unreasonable by completely misrepresenting it. JohnBo was suggesting that the magnitude of AGW is small compared to natural climate variations.

[Ken]

The best scientific assessments of climate change are saying it's "highly likely" that the current warming is due to human influences. Ignore the science if you so wish, but when every peak scientific body (except the American Association of Petroleum Geologists) says this science has a sound basis, I'd call it mistaken optimism to do so. Of course human influences overlay the natural ones as well as alter them and the best science on this issue is saying they aren't minor -less than the more extreme fluctuations in the distant past perhaps, yet on a more rapid timescale. Definitely not minor. I agree with Paul's point.

I hope Ausra's technology works as advertised - it looks to be essentially very simple. One clarifying point - my understanding is the mirrors begin as regular flat glass, but are flexed into a shallow curve, with the fresnels under the collector pipes concentrating the heat further - beginning with flat glass reduces the manufacturing costs significantly.

[Paul Dietz]

JohnBo was suggesting that the magnitude of AGW is small compared to natural climate variations.

The part I quoted does not argue the point you claim he is arguing.

But even the point you claim he argued is dubious. Human actions are causing changes in atmospheric CO2 concentrations of order unity, and are projected to cause even larger changes in the future. The projected rate of change in climate, and ultimate warming if CO2 increases continue, are beyond the usual natural climate variation.

[bigTom]

Ken:
I thought those mirrors looked like they might be curved on a single axis. It might not be too expensive to manufacture them as cyllinders. Otherwise they have to be under stress. Of course mirrors further from the
focal point should have a larger radius of curvature than the closer ones if perfect focus is required. The fact that the overall mirror surface isn't continuous might be sufficient to earn the fresnel name. One could of course stress cyllindrical mirrors as well, so as to either increase/decrease the curvature.

It would be interesting to see a hybrid system,
CPV, with the waste heat being used to power some sort of heat engine. I don't know if this makes economic sense, as the PV component needs relatively low temperatures, which significantly reduces the efficiency of the heat engine. In this configuration, at least on paper one could do even better than the raw efficiency of the PV component (approaching 40% for multi-junction cells), by getting additional usable energy from the heat.

[Calamity]

Of course mirrors further from the
focal point should have a larger radius of curvature than the closer ones if perfect focus is required.

Perfect focus - although nice to have - isn't that important for this technology, as the CLFR design uses a relatively wide receiver (for example, several small diameter pipes mounted in parallel to each other).

Low cost and simplicity are key words for this technology. The 10 cents/kwh cost estimate is rather high for a full scale plant with a small amount of storage. The interesting thing about CLFR is that the solar field, heat exchanger and thermal storage are rather cheap compared to the turbine. That implies more storage + more solar field = lower LEC.

It would be interesting to see a hybrid system, CPV, with the waste heat being used to power some sort of heat engine. I don't know if this makes economic sense, as the PV component needs relatively low temperatures, which significantly reduces the efficiency of the heat engine.

I recently suggested a CPV CLFR system. (Still not sure what to call it; CLFCPV or CLFRPV?) Combining it with a heat engine (e.g. free piston Stirling) may be a good idea if it improves economics, which is after all what CLFR is all about. The increase in heat might not be detrimental to the PV efficiency: GaAs cells are still very efficient under higher temperatures. Cell life may be diminished though. Not sure

When calculating multi generator system efficiency, be watchful not to simply add nominal percentages, but to multiply with the remaining fraction of the initial energy. Otherwise you might end up with over unity stuff. (50% generator 1 + 60% generator 2 = 110% should be 50% + 30% = 80%).

Ultimately it might be best to have an extremely efficient photonic converter, so that there simply is very little waste heat at all, but those devices do not yet exist unfortunately.

[bigTom]

Calamity. Good post. Your point about proper accounting for efficiency is important, as some math challeneged people will get it wrong. I suspect the efficiencies are not so great though. Say 35% for PV (would require decent optics, and good multi-junction cells), then say 10% thermal for the stirling engine (I'm assuming pretty low collector temp) which would give .10*.65 or an additional 6.5%. I suspect getting above 50% overall is going to be really difficult, and probably not economic.

[JohnBo]

Sorry I stirred the pot regarding CO2 affects. Reading both sides; this is how I feel. It seems no one knows and you can build a case for either side on this CO2 affect.

Anyway…regarding the cost at 8 to 10 cents/kWh I have a question. I do not understand why coal plant power is cheaper. Comparing this system to a coal plant one would think a bunch of pipes and some mirrors would be cheaper to build and operate than a coal fired boiler. The boiler apparatus with all the coal handling equipment, cost of coal, maintenance on all the moving parts, etc. would seem to be much higher in cost compared to this nearly static heat gathering system.

I would also think this solar heat capture system would have a much longer service life compared to the coal boiler system. There isn’t much to wear out. So why is the cost of power 5 times that of a coal?

[Calamity]

I suspect the efficiencies are not so great though.

True, it is just a hypothetical example to show over-unity. In reality such figures do not exist of course. We probably won't run into this problem for a long time to come.

Been thinking that a pure solar thermal CLFR would be more useful generally, at least for now. There is no inexpensive storage available for PV, but storage for solar thermal is quite cheap and easy to scale up. The solar field and heat exchanger are also inexpensive, about 50 cents/Wp.

So why is the cost of power 5 times that of a coal?

That would make coal $0.02/kWh. That's only possible if you use unreasonably low discounting rates, and maybe if it uses no modern pullution controls etc. (which would be nasty).

Capacity factor is also very important. A coal fired plant with 75% capacity factor will be more competitive than one with 25% capacity factor (hypothetically), that requires no further elaboration. But it's also very true for CLFR plants. More storage, more solar field, better capacity factor, more competitive (and also more useful and reliable). Current cost optimum is for medium to high load CLFR plants (but not yet baseload).

Lastly, CLFR is a relatively new player in the CST area. Cost will likely come down with a few more improvements and when larger plants are built.

[Nucbuddy]

Calamity wrote: storage for solar thermal is quite cheap and easy to scale up.

Is storage for coal-thermal and nuclear-thermal not just as cheap and scalable?

[Kit P]

Let me provide some background on energy storage with respect to electricity.

I have been reading my state's energy plan and was surprised (only been here a year) to find that the largest capacity is pumped hydro. The foot print of these facilities are very popular recreation sites.

Many of the large nuke and coal plants in my region have built lakes to provide cooling water. The foot print of these facilities are very popular recreation sites. Looking at a satellite picture of one of these coal plants there is one huge ugly coal pile. A very cheap way to store energy.

The cheapest way to store energy is enriched uranium. The new fuel assemblies for a large city could be stored on three flat bed trucks.

Another good way to store energy is wood (aka biomass). I have my emergency winter heating supply stored next to the tool shed. While I enjoy heating with wood, I have stopped doing it full time because of the effect on indoor air quality. I choose to improve the efficiency of our electric heat pump because of summer air conditioning needs. In any case, 10% of the home heating is oil according to my state's energy plan which represents an opportunity for renewable energy to replace foreign oil.

There is a proposed coal/biomass hybrid under development at a reclaimed strip mine. The basic problem with wood as a sustainable energy source is the energy for transportation. The coal/biomass hybrid allows wood to be used at a facility that can also achieve economy of scale.

So to answer JohnBo's question, a 50 MWe thermal plant has the same number of shift supervisors, plant managers, plant operators, feed pumps, and turbines as a 500 MWe thermal plant.

So what is Calamity going to say when the first satellite picture of one of these 500 MWe CST plants published? If you live in some barren treeless tract of land, maybe CST will be an improvement.

The natural way to store energy is biomass. Passive solar is not to bas either because a certain about of concrete is needed in any dwelling to support the roof and walls. Concrete or heavy metal batteries are not environmentally friendly materials that can store renewable energy that is not not very environmentally to start with.

[bigTom]

Another good calamity response:

The argument for CPV is that peak power is more valuable than baseline power. So in this respect CPV, and CLFR would be complementary, with the former supplying an extra boost during peak power times, and the later (assuming significant thermal storage) baseline.

Using Nuclear and/or coal for energy storage has the following economic problem. The cost of plant&equipment is best amortized by running the plants flat out 24/7. Also the plants are slow to startup/shutdown. Gas turbines, using natural gas are cheaper per MWe, so using nearplant gas storage and using the gas turbines for periods of high demand makes more sense.

Eventually when PV becomes cheap enough to satisfy sunny-day daytime demands, baseline power should become more valuable than peak, but this is likely decades away.

[Nucbuddy]

bigTom,

The subject was thermal energy-storage. Is thermal energy-storage for coal-thermal and nuclear-thermal not just as cheap and scalable as Calamity claimed it is for solar-thermal?

[Calamity]

Nucbuddy said: Is storage for coal-thermal and nuclear-thermal not just as cheap and scalable?

What are you trying to say here? Want to use thermal energy storage for coal and nukes? Nothing wrong with that. In fact if it's economical then why not? However your assumption behind this question appears that coal and nuclear are better than CST and should be used instead of CST. Why?

CST has no proliferation issues. CST has no highly toxic or radiotoxic waste issues. CST has almost no NIMBY. CST is a more politically sound choice than nuclear fission, both foreign and domestic. CST has little potential for catastrophe of any kind. CST has no market related fuel problems.

CST does not produce much lifetime GHG emissions compared to coal, it's even less than most nukes. Even if 90% of the coal plant's CO2 is sequestered, CST still has less lifetime CO2 emissions than coal. CST produces almost no nox, particulates, sulfur and heavy metals. Even the cleanest coal can't beat that.

Moreover, thermal storage is not as important for coal and nukes as it is for CST.

And I would feel a lot better if Iran had built a couple hundred square miles of CLFR (they have plenty of desert) in stead of thousands of uranium enrichment centrifuges. But maybe that's just me.

[Nucbuddy]

Calamity wrote: your assumption behind this question appears that coal and nuclear are better than CST and should be used instead of CST. Why?

Coal and nuclear cost less, meaning they have superior risk profiles.

Calamity wrote: thermal storage is not as important for coal and nukes as it is for CST.

Thermal storage will never have any importance for solar-thermal-energy, because solar-thermal-energy will never be able to be produced competitively.

The at-least-theoretical cost items you list are irrelevant partly because they have not been priced so high by the market that nuclear and coal have become uncompetitive, e.g. riskier. If you think they should have certain prices, you can improve their relevance to this discussion by at-least listing those prices -- and beyond-that by showing your math. Claiming, without showing any evidence or method of reasoning, that a given price -- or list of prices -- causes a given item to cost more is an unfalsifiable argument, and therefore constitutes fallacious reasoning.

It would be uncompetitive to apply thermal-energy-storage to solar-thermal-energy, if it could just-as-inexpensively be applied to the less-expensive alternatives coal-thermal and nuclear-thermal. Is your goal the mass-adoption of uncompetitive, e.g. high-risk, energy paths? Uncompetitiveness, e.g. riskiness, is not everyone's -- nor every society's -- goal.

[bigTom]

Nucbuddy: I can only answer for myself, and not Calamity. I can give a cost estimate for coal, which is the cost of coal with carbon, capture and sequestration, which I believe will add about $.03KWhr. I believe we should be vigorously supporting the development of CCS technology. I also like Nuclear, but don't think it can grow its portion of the power supply pie. This is mainly due to a poor choice of nuclear fuel cyle, which buries something like 98% of the potential energy as waste, and therefore seriously limits the supply. Uranium is already being bid up in price, significant expansion is not feasible without the development of greatly more efficient fuel cycle. That would be very expensive, and time consuming, and likely politically impossible. It is unfortunate that nuclear draws such severe opposition from environmental activists, that clearly adds an unnecesary risk premium to it.

I don't know enough about solar thermal to estimate the cost. Early small to medium scale projects are likely to be more expensive than later mature technology applied to large scale systems. The only major counter to that statement is that the early projects are likley to be in more favorable sites. Clearly the cost per KWhr from solar will be higher in New England, than in the Mojave.

All investment in solar technologies carries a risk. The competition may not neccesarily be the cost of current (or future) fossil plants, but other solar technologies as well.

[Nucbuddy]

bigTom wrote: Nuclear [...] don't think it can grow its portion of the power supply pie. This is mainly due to a poor choice of nuclear fuel cyle, which buries something like 98% of the potential energy as waste, and therefore seriously limits the supply.

How did you reach that conclusion? The earth's crust contains enough fissionable heavy-metal to produce electricity at today's rates for, on the order of, half a trillion years. If they are average, every square meter of land under your feet right now contains $100 million worth of fissionable heavy-metal.

bigTom wrote: Uranium is already being bid up in price

Correlation does not imply causation.

[Nucbuddy]

Math for the $100 million in heavy-metal/meter^2:
gristmill.grist.org/story/2007/9/2/21234/97899#comment38

The half-a-trillion-years nuclear-fuel supply refers to fuel for the degree of electrical power presently produced by nuclear powerplants only. Producing all of today's electrical power would reduce the size of that supply to some 80-billion years worth.

[bigTom]

If I could access all the material from under my feet to the center of the earth, I could also access the 10,000degree F core temperature. The only viable sources of any material, are the few high concentration sources near the surface. I am pretty sure the current supply/demand situation is out of balance, how far supply can be increased over time I don't know. If in fact Uranium supplies can be made to meet any likely future demand, I'd like to know that. Interestingly 10% (or is it 20%) of the current nuclear fuel we are consuming was recycled from Soviet era Nuke weapons. Unfortunately this source is due to dry up in the near future.

It seems to me the best way to overcome these limitations is to change to a more efficient fuel cycle. I hesitate to say we are wastinga precious resource, because future residents could decide to mine our nuclear waste sites to access the interred materials.

[Tony]

I also wanted to point out that the mirrors are not flat; it is likely they have a small spherical curve. I wonder how they bend the glass. Do they use a hot steel form? Do they silver the glass themselves? What does the ray diagram look like? Does the array have a north-south orientation or an east-west orientation, or does that depend on the latitude?

[Nucbuddy]

bigTom wrote: If I could access all the material from under my feet to the center of the earth

The $100-million/meter^2 of fissionable heavy-metal is near the surface of the earth's crust. Because of uranium's and thorium's peculiar chemistries, they are concentrated in the continents, there is very little of them in the mantle, and there is even less of them in the core. If you can mine a mile or two down, you've basically got all of it.

By the way, the 4.5 billion tons of fissionable heavy-metal floating in the oceans is not much in comparison -- just a half-million years' worth -- but it is easy $100/pound pickings with the help of polyethylene adsorbtive strips.

[Nucbuddy]

Tony wrote: I also wanted to point out that the mirrors are not flat; it is likely they have a small spherical curve. I wonder how they bend the glass.

Please read the original post, Tony:

"Austra's innovation is that it uses commodity flat mirrors"

[Nucbuddy]

Sorry about that last comment, Tony. I did a little googling just now and stand corrected:

DR DAVID MILLS, CHAIRMAN, AUSRA INC.: We use flat reflectors. The other competing technologies, such as parabolic trough, have to use reflectors which are actually slightly melted and formed into the correct shape, which is much, much more expensive. We just bend our...flat glass into the correct shape, and...only slightly. All of these kinds of things have been put together to get the cost as low as possible.

[bigTom]

Nucbuddy, if the Uranium supply can indeed to sufficient, and you can solve the political difficulties, that would be great. If increasing nuclear could take out a significant slice of future energy needs, that would make our future prospects considerably brighter. My personal opinion is that the PR battle for nuclear is nearly hopeless. There are too many people who are irrationally terrified of it.
I'm sure you are tired as heck of running into them.

I once worked in fusion research, so I am familiar with theoretically nearly unlimited but nearly hopeless energy sources.

[Paul Dietz]

Sorry I stirred the pot regarding CO2 affects. Reading both sides; this is how I feel. It seems no one knows and you can build a case for either side on this CO2 affect.

There you go, promoting falsehoods again. The evidence, both observational and theoretical, does not support your assertion here. This is why the scientific consensus (not unanimous, but it never is) is that AGW is a serious concern.

The case against AGW is a pretty clear example of 'lawyer science', where the arguments are more like those of a defense attourney than actual scientific arguments. If you have a predisposition to not want to believe the other side, these arguments can sound convincing. But drill down and they fall apart.

[Calamity]

Nucbuddy wrote: Coal and nuclear cost less, meaning they have superior risk profiles.

Cost/kWh is not by far the only variable in risk assessment. In fact if the cost is known beforehand it is not a risk at all, as uncertainty is a fundamental element of risk. Moreover, you are not counting various externalities in that cost. Which are difficult if not impossible to quantify. How do you internalise runaway global warming in the cost/kWh of coal fired plants? Adding the cost of CSST in the LEC. How do you internalise the global security risks posed by worldwide nuclear power, whether directly or indirectly, in the cost/kWh of nukes? A bit more difficult.

What's more, CST is on a downward price trend, from 30 cents/kWh to 20 cents/kWh and 10 cents/kWh now. It would be interesting to see how far this can be pushed down.

Nucbuddy said: Thermal storage will never have any importance for solar-thermal-energy, because solar-thermal-energy will never be able to be produced competitively.

This is an unfalsifiable argument, and therefore constitutes fallacious reasoning.

Nucbuddy you are a hypocrite, and likely to be wrong as the price trend for CST is downwards (see above) and doesn't appear to be grinding to a halt @ 10 cents/kWh.

My assertion there was that

thermal storage is not as important for coal and nukes as it is for CST.

Coal and nukes already have their storage built into the fuel; they are already dispatchable. Why would you want to add large amounts of thermal storage to an already dispatchable power source? The idea for CST is to increase capacity factor wich has amortisation benefits.

Adding a small amount of thermal storage for buffering etc. may or may not be good for coal and/or nuclear, but the benefit will at best be marginal. Think about it. Increasing the capacity factor of a 92% CF nuke to 97% (hypothetical figures, pick others if you like) will not create a major cost advantage, but with a 20% CF CST plant there is so much more to improve. A coal fired plant might benefit more than a nuke but not nearly as much as CST.

One other reason why thermal storage would be desirable for coal/nuclear is higher thermodynamic (i.e. peak) efficiency. However, this will be (partially) negated by the fact that this storage itself will have a round-trip efficiency of less than 100%. Thus making the benifit very small at best.

Nucbuddy said: It would be uncompetitive to apply thermal-energy-storage to solar-thermal-energy, if it could just-as-inexpensively be applied to the less-expensive alternatives coal-thermal and nuclear-thermal.

Paul Dietz' comment applies to you as well Nucbuddy. 'Lawyer science' indeed! Hammering on semantics and methodology and in so doing you try to cover up the fact that your initial statement has little relevance. Thermal storage is simply not as useful for coal and nukes i.e. it will at best be a marginal improvement in the cost/kWh. Which makes your argument moot altogether.

You want figures? Thermal storage is already proven at <$25/kWh (it might be as low as $3/kWh but that remains to be seen)and the solar field and heat exchanger of CLFR are ~$500/kWh. I have provided you and others with these sources already, but I doubt you could find them so here is a list:

http://solar1.mech.unsw.edu.au/glm/papers/Mills_projectproposal_newcastle.pdf

http://solar1.mech.unsw.edu.au/glm/papers/clfr-canberra-1997.pdf

http://solar1.mech.unsw.edu.au/glm/papers/Morrison%20Aus_China2006.pdf

http://solar1.mech.unsw.edu.au/glm/papers/Reynolds_newcastle2002.pdf

http://solar1.mech.unsw.edu.au/glm/papers/ISEC2003_Mills.pdf

http://solar1.mech.unsw.edu.au/glm/CLFR/stanwell_clfr.pdf

[Calamity]

bigTom said: My personal opinion is that the PR battle for nuclear is nearly hopeless. There are too many people who are irrationally terrified of it.

An objective assessment of the risk management capabilities of the IAEA et al, leading to the very basic conclusion that there is a discrepancy between these capabilities and the actual requirements for risk management themselves in a world powerd by nuclear fission plants?

Is that irrationally terrified? Take a look at "Too hot too handle? The future of civil nuclear power" by the Oxford Research Group.

Notice again how the nuclear advocates cannot expand the scope of their thoughts realistically into the future and onto the entire world. It appears to be a concept they cannot grasp.

Now, this thread is about CLFR. Let's at least try to limit the discussion to CST shall we?

[Calamity]

Apologies for the typos.

[Greg Woulf]

I'd like to see the NREL or Argonne do a study on flat to curved mirrors. Somewhere there's a cost to efficiency curve that would show where parabolic pays for itself if it ever does.

It seems logically that it would have to. You get more energy out of parabolic for sure.

It would be a good study to roll up manufacturing costs of flat, partly curved all the way to full parabolic so we could pick the best overall technology.

[Kit P]

Calamity, thanks for the interesting links documenting the beneficial effect of adding solar thermal to a fossil plant rather than adding tons of thermal storage to a stand alone solar thermal.

BigTom, in the US the nuclear PR battle has already been won. I have seen it. Go to a public meeting for a proposed new plant in a town that already knows the benefits and risks by having several reactors operating for 30 years. Community support is overwhelming. The utility does not have to defend the plant. Community civic leaders will step up and speak to every issue that a that arm waving anti-nukes like Calamity brings up. In such a forum, what do bused in irrational fear mongers sound like? Answer: bused in irrational fear mongers.

[Calamity]

Kit P said: Calamity, thanks for the interesting links documenting the beneficial effect of adding solar thermal to a fossil plant rather than adding tons of thermal storage to a stand alone solar thermal.

It comes as no surprise to me that your small mind was unable to comprehend the information I provided you.

The strategy for coal fired reheaters is a low risk approach to commercialise solar thermal electric generation, while saving GHG emissions at the same time.

And of course you didn't get all the comments about the potential for standalone solar thermal electricity plants.

Wait... Did you even read all of the files?

[Calamity]

Kit P said: Community civic leaders will step up and speak to every issue that a that arm waving anti-nukes like Calamity brings up.

Kit P don't you know that GHG emissions are a global problem? What good is it to have nuclear in the US while many other countries still emit vast amounts of GHG's?

Very little of course as the problem is not solved. All of the world needs to be powered by nuclear for it to work. Besides the simple fact that that is a completely unplausible scenario in the first place, this brings me to a reiteration:

An objective assessment of the risk management capabilities of the IAEA et al, leading to the very basic conclusion that there is a discrepancy between these capabilities and the actual requirements for risk management itself in a world powered by nuclear fission plants?

Is that irrationally terrified? Take a look at "Too hot too handle? The future of civil nuclear power" by the Oxford Research Group.

Notice again how the nuclear advocates cannot expand the scope of their thoughts realistically into the future and onto the entire world. It appears to be a concept they cannot grasp.

Now I really do wonder how a "community civic leader" would speak to that. But enough about nuclear. It's busted, get over it. Let's talk about CLFR.

[Calamity]

And for what it's worth, thermal storage doesn't have to be concrete or molten salts if that's a problem, it can simply be demineralized water - the heat transfer fluid itself, just a hell of lot more of it. This may yet prove to be the least expensive option and perhaps also the most environmentally friendly one, as the water can be demineralised using some of the waste heat from the CLFR, or some of the generated electricity itself (e.g. very efficient reverse osmosis membrame technology) making the entire system more self sufficient.

This PDF hints at the potential of CLFR, including the benefit of inexpensive thermal storage to increase the capacity factor on the LEC:

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

Conclusions: The potential cost advantage gained by low temperature operation derives from an unusual combination of large low cost low temperature turbines developed for the Design of a 240 MWe Solar Thermal Power Plant Mills Eurosun 2004 Conference nuclear industry, and an inexpensive storage concept which suits that particular temperature range. Should both options be applicable, then this is likely to be the most cost-effective and simple solar thermal electricity development path, using simple solar collector technology already being installed, and a proven turbine from the nuclear industry. Cavern storage cannot be taken higher than about 360°C and still has some developmental uncertainty ahead of it, but two reports have now identified it as potentially the lowest cost storage concept. Recent discussions that the authors have had with geologists and mining companies suggest the concept is in the realm of current mining technology and can be widely applied; suitable rock structures are common. If suitable geological structures are not available, Caloria oil storage with a CLFR array is a low risk option available for a cost which is still below the trough collector systems. Environmentally, however, cavern storage would be safer than either molten salt or oil solutions. The electricity wholesale cost for the unoptimised CLFR/cavern in 2010 (the earliest that one can be finished is about 2009) at 68% capacity factor, without the use of any Green support mechanisms, is comparable to the cost of some current conventional pulverised coal-fired (PC) generation in the USA. The cost advantage of coal appears at high capacity factor, but even at a coal CF of 90%, the advantage is only about US$5 per MWhe. The CLFR/cavern approach is unoptimised and may benefit from slightly higher operational temperatures should a suitable turbine be available. Such turbines may be available in the USA or Europe. The coal fired plant referenced also has a larger turbine than the solar 240 MWe. According to NREL, 2003, a 400 MWe power block should be 25% cheaper per kWh delivered than a 240 MWe equivalent, which reduces cost by about US$3 per MWhe. Furthermore, David and Herzog (2003) suggest that pulverised coal plants could incur an additional cost of US$30 per MWhe for long term cost carbon sequestration.

This brief discussion needs extensive elaboration and more detailed work within the scope of a real project structure. The authors have begun site investigations for a 240 MWe plant of the type described, assisted by Australia’s largest utility.

Overly optimistic? Maybe, but certainly worth a shot.

[Kit P]

What a hoot Calamity. As any mechanical engineer specializing in the steam cycle (like me) will tell you water turns to steam without a lot of energy input. So what is the plan to store energy?

“Cavern storage involves storage of water under pressure in deep metal
lined caverns where the pressure is contained by the rock and the overburden weight.”

[Calamity]

You do not appear to be a real steam cycle engineer otherwise you would have shown that you know about the most basic thermodynamic concepts of enthalpy and entropy. Higher pressure, water remains liquid under elevated temperatures. With an added entropy bonus on top of that, a few tonnes of water under pressure can contain a heck of a lot of energy. There are very simple graphs and tables for this.

Water turns to steam without a lot of energy input? That is just flat out false. You first have to get the water to the operating temperature. Which means sinking energy into the water, which not only has very high specific heat capacity but also a very high latent heat of fusion. Ever try to boil a kettle of water until it's completely evaporated? It takes a long time. Also, water is very cheap, so vast amounts could be used and the environmental impact would be small; processing and recycling could be done in a more or less self sufficient manner. Lastly, dry condensers might be used if necessary as someone recently mentioned to me.

Now, there is very simple empirical evidence here; there is a plant in Spain that uses water as thermal storage (in tanks) which already gives a considerable amount of storage, and it's just a relatively small storage system, designed to compensate for cloud cover etc:

http://ec.europa.eu/energy/res/sectors/doc/csp/ps10_final_report.pdf

For cloudy transient periods, the plant has a saturated water thermal storage system
with a thermal capacity of 20 MWh, equivalent to an effective operational capacity of 50 minutes at 50% turbine workload. The system is composed by 4 tanks that are sequentially operated in relation to their charge status. During full load operation of the plant, part of steam produced by receiver at 250ºC-40bar will be employed to load the thermal storage system. When energy is needed to cover a transient period, energy from saturated water will be recovered at variable pressure, from 40bar to minimum pressure allowed by the system to run the turbine at a 50% partial load.

As it just so happens to be, the CLFR design can - and does - use saturated wet steam. And it is more simple and cheaper than central receiver designs. It also has a higher MW/area so less land would be needed.

The pressure and heat requirements are relatively low so very conventional off the shelf equipment could be used in stead of cavern storage if it doesn't prove feasible or scalable or whatever.

You were going to say something about cavern storage?

[Calamity]

One more thing Kit P. Do you know what Delta T is?