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December 14, 2007

Comments

Kit P

Cyril, sorry to break the news to you but Greenpeace is not an authority on making electricity or protecting the environment. Solar thermal has about the same as ghg emissions as nuclear. Solar thermal cooling systems have the same impact as any other thermal plant. So Cyril go ahead and testify in a hearing for the EIS of solar plant in the desert that places like Cramer Junction have no value.


However, what do others think in California?


A new report from California, Economic and Technology Advancement Advisory Committee (ETAAC) Report Discussion Draft – Released 12/21/07 has this to say about barriers to renewable energy project development.
Link - http://www.arb.ca.gov/cc/etaac/012508pubmeet/etaac_discussion_draft_12-21-07.pdf

“Many of these resource basins have a myriad of wildlife, archaeological and other siting
issues that must be addressed before development of these renewable resources can
proceed in earnest.”

Cyril R.

Kit P of course Greenpeace isn't any authority whatsoever, that's my point: if GREENPEACE - which nitpicks about pretty much everything - doesn't think solar thermal is an ecosystem killer, then people who do think it is an ecosystem killer, absolutely have to provide references.

The reference you provide makes a case for careful investigation, and that makes sense. Environmentally or other sensitive areas should be excluded, and in fact are already excluded from the resource potential in GIS etc. analysis already done.

Does that mean solar thermal annihilates ecosystems? No. Your reference doesn't even imply this. In stead it raises an important issue of project siting that deserves attention. It even provides possible solutions:

Possible Solutions: California could adopt a policy to identify and assess Competitive Renewable Energy Zones (CREZs) throughout the state and then develop a strategy for public agencies and other stakeholders to facilitate next generation build-out of these carbon free technologies. Supportive transmission infrastructure would be factored into this planning process. This policy should be coupled with a coordinated siting, environmental review and permitting process that is coordinated between the Federal, State and local agencies, similar to the CEC and BLM’s current joint National Environmental Policy Act (NEPA)/California Environmental Quality Act (CEQA) process for concentrating solar power plants. This new siting process will create common environmental documents and consolidated state and federal permits within one year. The program has a sunset date of January 1, 2012.

What gets me is people who are making bold statements about supposedly monstrous environmental impact without backing it up with references, and after that don't suggest any solutions to the problems at hand either.

steve

Kit I was just wondering what your background was? I have been reading many of your comments and I was wondering where you get your information. You stated that " Just because the best developers have failed to deliver a utility-scale solar thermal power plant does not mean the clueless are doomed to fail. " Any idea who these "best developers" are?? I would be curious why you consider Ausra "clueless"?

Another comment you made was something to the effect a cloud could knock you off the grid and blow up your turbine without storage. Well basically your your field and steam generator are your storage and a single small cloud is not going to knock you off the grid. I suspect if you knew much about steam systems you would know that turbines are designed to take themselves off the grid long before they damaged.

To be honest here I don't really have any idea if Ausra's system will work as promised. I do have some doubts myself but I do like their idea to make the design simple. I think I would agree with you that solar is not the "only" answer but we have to walk before we can run. From personal experience I can tell you it does work and the beauty of the system is that is produces the most when it is needed the most. In reality there has been very little done with solar thermal done until the last few years. It is my opinion that the more of these designs we try the better and cheaper they will become.

Cyril R.

Well Ausra has already proven their array design in a 40 MW coal reheater project in Australia. Which is working fine now, and array costs are well known. That's good news as arrays are the biggest solar thermal system cost, especially in the fully dispatchable load following plants that Ausra is shooting for.

The greatest design uncertainty will probably be their hot water underground storage system, which hasn't been tested yet. If it doesn't work they could probably make some other storage system work, it won't be as simple and cheap but then storage is a relatively small part of total costs.

DaveMart

Cyril, I was interested in your comment that 'storage is a relatively minor part of total costs' - I am not saying it isn't, but have not been able to locate any data to give an idea of what the costs are, other than the relatively fairly expensive batteries.
I wonder if you have a link?
Whilst we are talking about Ausra, it is also worth remembering that we also have people like e-solar, who the founders of Google have invested in, who are also making simple modular solar thermal systems.
2008 should be an exciting time, as by the end of the year we should have a much better idea of how the solar thermal ideas will pan out, as well as Nanosolar for PV

DaveMart

Ausra aren't going for 'hot water underground storage':
'The system will employ pressure and a steam accumulator to accomplish the trick. "You allow some of the steam to recondense," O'Donnell explains. "It flashes back to steam when you reduce the pressure just by opening the valve to the turbine."

Such long-term steam storage, however, is unproved. "Steam storage is currently feasible at small levels, for example, one hour or so," NREL's Mehos notes. "Due to large volumes and high pressures involved with steam storage, scaling up steam storage to baseload applications is very high risk."'
http://www.sciam.com/article.cfm?id=sunny-outlook-sunshine-provide-electricity&page=2
It also seems unlikely to me that Ausra plan this to be underground - they are going for a universal system, and taking out costs wherever possible, so presumably they would go for some sort of above ground pressurised vessel.
As you say, this is the most doubtful part of the system.

DaveMart

Hmm, Cyril, re-reading my last post 'recondensed steam' sounds an awful lot like hot water to me! So it sounds like you are right, but I don't know about underground.

Kit P

Steve I get my info by actually reading what these clowns say and checking for results. The question that needs to be asked is when is the environmental impact of solar worse than coal?

Interesting reading at Reports and Presentations by Ausra Experts on their web site:

“It uses less land than coal mining and transport.”

That is just not true. Here is a strip mine and power plant in Wyoming that I have seen.

http://www.panoramio.com/photo/3011029

While you are using something like google earth, look up one of my favorite mine-to-mouth power plants near Centralia Washington. The Mayor of Seattle likes to talk about how the city has a carbon free. Yes the city sold the power plant but it is still running. In an agreement with the State of Washington, the operators installed pollution controls and agreed to ship a million tons a year of coal. The following photos will help keep the environmental impact of coal mining: Let me present the largest polluter, nearby Mount St. Helens.

http://www.panoramio.com/photo/265668

This picture shows the railroad tracks from the semi-arid side of the Cascade Mountains.

http://www.panoramio.com/photo/1842048

The hydroelectric dams partial fills the scares caused by massive floods created by rupture of the ice dams that created Lake Missoula. The AGW folks do no have to worry about the glaciers returning to Washington State.


Now back to the clueless Ausra Experts:

“The solar multiple is the ratio of actual array size to the minimum size required to run a turbine at full capacity at solar noon in mid-summer.”

The idea here is to add more solar panels and thermal storage so the plant can run the other 16 yours a day.

And then there is this, “at the unacceptable price of increased vulnerability to terrorism,
according to a major MIT study.” Where have we heard that before?

My point is that Ausra Experts are clueless is that they should should spend more time discussing Cyril' statement, “Well Ausra has already proven their array design in a 40 MW coal reheater project in Australia.”

Cyril R.

Kit, the point about the coal reheater project is that:

1. The array itself is proven. It is working right now feeding the reheat line of a big coal plant in Australia.
2. Ausra has built it and since it actually works, they can't be completely clueless. Vinod Khosla has been known to lie a bit now and then though. I can live with that as long as he puts his own money in the projects :)

Still, building a standalone solar thermal plant must be quite challenging for Ausra, with little experience in the field and especially since they have to get it online in just several months.

Cyril R.

Dave, in some of the sources on Ausra's website a reference is made to underground thermal energy storage. Or cavern storage they call it. Because they're too lazy to pronounce it in full, and not American enough to use the abbreviation UTES :)

Anyway, it's supposed to be hot water (at that temperature it should be liquid under workable pressures) stored in metal lined (steel or alloy plating?) caverns 200 meters and (or?) 400 meters deep. Maybe, as in a conventional ore or coal mine with one vertical shaft and multiple horizontal shafts. I'm curious about the details, and have lots of questions about it but the Tanner reference (who researched it) was not available.

There's nothing wrong with the idea itself. Hot water is cheap (just commodity demineralized feed water) contains tremendous amounts of energy so not that much cavern space would be needed. And containing it with a couple hundred meters of rock seems very clever:

* Very little extra surface space required
* Very safe (couple hundred meters of rock could easily contain such low pressures)
* Excellent heat retainment (rocks and sediments are really good insulators)
* Environmentally friendly (just pure hydro and it's deep underground)
* Should last a LONG time.

Whether they could turn this idea into a practical design would be the main question.

Cyril R.

What's fascinating is that they claim this thermal storage system would cost $3 per kWh thermal so that's maybe $10 per kWh electrical.

That would make it by far the cheapest form of electricity storage. Even if it turns out to be 100% more expensive then planned, that won't change the picture at all. Still extremely cheap, much cheaper even than lead acid (which won't last as long, won't be as efficient and contains toxic chemicals as well).

Cyril R.

On the Ausra website, this reference gives a storage cost of their cavern system: $68/kWe. That's less then 7 cents a Watt! Almost a non-cost compared to the total costs. Array costs are by far the biggest, so it's good to know that they have that real 40 MW project already operating as a realistic reference.

steve

Kit thanks for answering basically none of the questions I asked you. Still waiting for who the best minds were who have failed at solar thermal and I am guessing you are not an engineer. Great thing about Google is that you can almost always find something to support your argument.

Ok in the interest of fairness I work in the solar-thermal industry but not for Ausra. I am also a very big fan of nuclear power and see it as one of our best options for breaking our dependence on foreign oil and gas any time soon. I do feel that solar has a great future but I don’t believe we will be running our country on just it. I think one of the things that frustrates me the most on here is reading the all or nothing approach that many take.

Ok here are some of my opinions and not necessarily those of my employer. As far as environmental damage to the Mojave desert where most of these would probably be built. There are impacts but lets face it there is a huge amount of land out there and not a lot out there. There is plenty of land to set aside to let the tortoises, foxes, snakes and rabbits live. There are environmental trade offs in everything you do but I feel that most Americans would be willing to live with this one. Our biggest problems are lack of cooling water and transmission lines.

As far as heat storage I really don’t feel it is a huge issue. Being able to extend our the plants day a few hours would be a great thing but being able to run at full load all night is not really necessary at this time. Solar’s greatest benefit at this time is its ability to produce the most when it is needed that most. We have to walk before we can run. Again not an all or nothing approach.

Well to me the terrorism argument seems to be stretching a little bit but really all power systems are vulnerable to it. Sure a nuke plant would be almost impossible to get inside and blow up but very easy to cut a tower and stop the flow of electricity. I mean what is a terrorist going to do to a solar plant? Smash a few pipes and spill a little water? Blowing up the power block would be the same for any type of power plant and I don’t really see any difference between that and a coal fired plant.

DaveMart

Thanks for the link Cyril - you must be a better Googler than I!
I did find this link though, which although much of it is above my head, and anyway tends to be rather US specific, gives some idea of the complexity of comparing costs from different generating strategies:
http://gristmill.grist.org/story/2007/11/7/112038/471

DaveMart

Steve, good post.
I am no professional in the power industry, but I would agree that many seem to see things too much in an either/or fashion.
There is just so much exaggeration going on - GW seems highly plausible, but the IPCC's 'estimate' of 95% likelihood is ludicrous, and charges that those who disagree are 'deniers' brings rightly to mind religious fundamentalism rather than rational debate.
Still, it is probably a good idea to minimise CO2 emissions as far as possible, and there are a lot of good ideas around for doing so.
The risks of using nuclear fuels are grossly exaggerated, and the waste issue is chiefly relevant if one ignores all possible solutions - for instance reprocessing it to make more fuel.
Britain recently said that they cold produce 60% of the electricity they need for thenext 60years simply by reprocessing stockpiles to hand, without considering going to fast breeder reactors, which would stretch the fuel loads further.
The risks associated with this would be orders of magnitude lower with the new reactors than the present already low risks we have from the current generation of reactors, which only provide around 20% of current needs.
That to me is a good thing, not a bad thing.
One of the most cogent critiques of the civil nuclear program came from one of the guys who helped design the early navy reactors - the civil program was rushed into production far too early.
We should not make the same mistakes with renewables, nor do we need to.
Gas supplies are too tight for it to be the next big thing, and if we take GW at all seriously then coal is in trouble, as all the sequestration proposals are at least as difficult to implement as renewables.
Even in the case of coal though it should be noted for instance that new stations produce a fraction of the pollutants of older ones, and so CO2 aside many of the current problems with this source will be minimised, that CO2 sequestration may be possible and that the use of advanced technologies like Direct Carbon fuel cells would revolutionise the industry.
Without excessive costly rush a lot of the renewable technologies are either ready or will within the next few years be ready to audition for the big time.

DaveMart

Steve, any thoughts 'from the horse's mouth' on the relative advantages of different storage strategies.
How does Underground hot water storage sound to you?

steve

Dave I agree some of the hysteria surrounding global warming seems a little exaggerated to me also on both sides. It has taken on somewhat of a religious zealot feel. Because this is such an divisive issue this will probably be my last comment on it. I feel it is happening and going to continue. I also feel there may be very little we can do about it with the rise of China and India. They are looking for cheap fuel and it is pretty hard to tell them not to do the same things we did. That does not mean we can not be trying to develop technology that would help the world minimize its affects. I also feel that coal will continue to be used in the United States and there are some technologies that can greatly minimize its affects. Coal gasification for one. It is not ready to use now but shows some promise.

As far as storage, I just don’t see why long term storage is necessary right now. We are a very long ways from being able to run the country on just solar. Until we develop economic ways of storing electricity we will never be able to do it. Pumped hydro storage shows some promise but the best numbers I have seen are only about 80% efficient. Sometimes, even in the Mojave, we don’t get sun for four or five days at a time. It is very rare but it does happen. You would have to be able to store enough heat for all that time and in the winter be able to do it in 8 or 9 hours a day. Being able to store for a couple of extra hours of run time would be a great help. We could bring the plant up a little earlier and operate it longer to follow peak load. Being able to run at night, even at a greatly reduced load, would help wear and tear on the plant too but really we need the most load during the day.

As far as heat storage the three most mentioned are molten salt, hot oil, and hot water. Like I said before I am not in any way an expert on Ausra’s design. I am very knowledgeable on Solel’s design and the way steam plants work in general. I am guessing hot water storage would just be another way of storing steam. In a typical steam plant the water is well over 400f before it is ever made into steam. All you have to do is keep pressure on it. Solel’s design uses dry or superheated steam. Ausra’s design calls for wet steam and to be honest with you something I have never dealt with but this is the way a nuke operates. I have no doubt running 24 hours can be done but we need to develop and raise the efficiency of the plants before we worry about that.

DaveMart

Steve, I agree that the debate about GW has got a bit hysterical - on both sides.
As I said, I think man-made GW is probably happening, but don't think we know enough at the moment to be sure of by how much or it's importance.
Just the same, it seems to me that it is worthwhile and practicable to reduce CO2 emissions.
That is where I perhaps differ to some extent from you.
In spite of the huge increase implicit in the growth of India and China, we can perhaps greatly reduce emissions over a period of time, although not immediately.
There is no silver bullet, but a combination of a lot of different technologies should make the problem containable.
Solar thermal's day is coming, although as you say probably not 24hour in all seasons as yet.
PV is also getting there, within 10years seems probable, even if Nanosolar's technology disappoints.
Wind is viable already in some places, and should high-altitude wind work out, that alone could supply all electricity needs, as could nuclear.
Agrichar could also theoretically capture all CO2 emissions, whilst simultaneously greatly enhancing agricultural productivity.
If we were dependent on one technology, we would probably screw up, but there are a lot of alternatives out there!

Nucbuddy

DaveMart wrote: the waste issue is chiefly relevant if one ignores all possible solutions - for instance reprocessing it to make more fuel.

To what could nuclear-fuel reprocessing be a solution?
google.com/search?q=richard+garwin+gnep+cost

Cyril R.

As far as storage, I just don’t see why long term storage is necessary right now.

It's not strictly necessary right now, that's why Ausra's first plant will only have a tiny amount of storage. However it does actually makes sense to develop inexpensive long term storage concepts ASAP because:

* Power utilities will like fully dispatchable plants better than occasionally unreliable plants, so they will be more interested in these plants. With sufficient storage, solar thermal can make use of it's high correlation with demand to make it load-following. With emergency NG heaters (which are very cheap and the US already has an extensive NG network) it will be truly dispatchable and reliable. That means it doesn't require any backup whatsoever. A significant grid benefit. NG should only be used during periods of long lasting cloud events or dust storms though, and in the future we'll probably want to use bio-energy instead. Thermal storage can take care of daily energy storage, with emergency heaters dealing with the occasional week or two of bad weather during the year.

* Having such inexpensive storage means lowering the cost per kWh as there is less power block per kWh and power block costs are higher than Ausra's proposed storage system. Array costs rise proportionally so won't increase the per kWh cost. As a result, net kWh costs will be lower in a higher capacity plant. In this way, storage can actually decrease the cost of solar thermal electricity. Which will make it more attractive as well.

So you see there really are good reasons to go after daily storage in the near-term.

Cyril R.

Sometimes, even in the Mojave, we don’t get sun for four or five days at a time. It is very rare but it does happen. You would have to be able to store enough heat for all that time

No, for such occasions there would be the emergency heaters. It's more economical to use a smaller amount of thermal storage for day/night and install emergency heaters for longer interruptions.

and in the winter be able to do it in 8 or 9 hours a day

Total national electric demand is lower in winter and in a good solar location you'd still get plenty of sunshine during the winter months. You can see the graphs and correlations in the Ausra reports (on their website).

100% solar thermal is, at least in principle, very much possible. I don't think it's likely at all, not in my lifetime at least, nor that it's a good idea to focus too much on any one technology, but it's certainly possible.

steve

Cyril you certainly seem to have Ausra’s stats down. You wouldn’t happen to work for them would you? One thing you need to remember my friend is Ausra is in business to make money and as such you need to question everything. I think they show great promise but being in the industry I have some serious doubts about some of their claims. Let them build a plant or two and I might change my mind.

Yes you would save money by not having to build a bigger power block but you are going to spend more money building a storage system. You also going to have some loss in any storage system. Right now we already have base load plants that are plenty capable of producing power at night but what we need now is a plant capable of producing power during the day and early evening. Being able to run at night would reduce maintenance on the plant but you have to reduce the amount of power you produce in the day when it is most valuable.

Ok as for my opinion on emergency heaters producing electricity, they are complete crap. They are not something new that Ausra came up with and are only designed to very inefficiently meet a contract. You basically take a heater that is capable of 30% efficiency (could be a little off here but close) and replace combined cycle gas turbine that is close to 60% efficient. Now Solel’s design does require the use of an emergency heater to keep the HTF (heat transfer fluid) warm in periods of extended clouds but is rarely needed. HTF freezes at a fairly high temperature. The Nevada 1 plant outside of Vegas went this route only putting in a very small freeze protection heater.

Ok one last comment about Ausra’s claim to make power during the winter months. Yes less power is needed during the winter but not the more than 50% a solar thermal plant is going to produce. You not only have much shorter days but you have a much different sun angle. I believe Ausra’s design, much like Solel’s, does not have a way to chase the sun as it moves towards the south. The solar tube is fixed but in the winter as the sun angle changes, so does its focal point. One reason why I believe the solar towers may end up being a better system in the end. They look to me it would be easier to get the most out of the sun year around.

Kit P

Steve, still working on the answers to some of your questions. Before than maybe answer a few questions. What do you call workers sprayed with HTF? What do call dirt when HTF is spilled on it?

steve

Hmm Kit do you have a point with your little riddle? :) Well beings as you asked so nicely I will try and answer to the best of my ability. To tell you the truth I have no idea what you would call someone who has been sprayed with HTF or what to call soil that has HTF spilled on it. I think the point you are trying to make is that HTF is not exactly the greatest stuff in the world. Now if someone gets sprayed with it, especially in the eyes, you are going to want to get it off as soon as you can. It burns like hell. You definitely should avoid breathing it and one of its more nasty components is benzene. Benzene is also in gasoline and a reason you should avoid breathing it also. I suspect you googled this as soon as I wrote about it and already knew the answer.

As to soil it has been spill on it depends on how much has been spilled. Small amounts are picked up and placed on a concrete slab. The sun breaks it down and it evaporates. Large spills would need to be dug up and sent offsite. The truth is the companies do everything they can to keep from spilling it and are really pretty good about cleaning it up when there is a spill.

Now for some reason those “clueless” folks at Ausra decided not to use HTF and I could be wrong but I don’t believe Bright Source is going to use it in their towers either.

Now come on Kit I answered your questions. Why can’t you answer mine? Are you still so sure about your statements? You always seemed so sure you were the only intelligent one on here.

Cyril R.

Cyril you certainly seem to have Ausra’s stats down. You wouldn’t happen to work for them would you?

No but I hear they're hiring :) I don't want to propagandise how wonderful Ausra is or whatever, but you'll have to admit their design and design philosophy sounds very good. That is, of course, no guarantee to succes. As you said, let them build a plant or two. We don't have to wait long, they want to get a plant online by april.

Yes you would save money by not having to build a bigger power block but you are going to spend more money building a storage system.

OK I'll repeat myself one more time:

Having such inexpensive storage means lowering the cost per kWh as there is less power block per kWh and power block costs are higher than Ausra's proposed storage system. Array costs rise proportionally so won't increase the per kWh cost. As a result, net kWh costs will be lower in a higher capacity plant. In this way, storage can actually decrease the cost of solar thermal electricity.

Cyril R.

You also going to have some loss in any storage system.

Yes, fundamental thermodynamics. However, what matters is HOW MUCH losses. Which in case of thermal storage are very low, only about 2 to 7 percent.

And Ausra's proposed final system - granted that they can actually build it - doesn't use any heat exchangers, so it should be on the lower end of that scale. It uses an organic Rankine cycle turbine where the pressurised water from storage is flashed to steam directly, regulated by flow controllers. They can do this because their system can operate on wet steam, allowing cheaper nuclear turbines to be used. They also use dry cooling so it's a closed loop system and there is very little water use, just some for cleaning the mirrors every now and then.

Cyril R.

Ok as for my opinion on emergency heaters producing electricity, they are complete crap. They are not something new that Ausra came up with and are only designed to very inefficiently meet a contract.

I didn't say Ausra came up with it nor does that have any relevance. If you use the emergency heater during regular operation, then they are crap yes. But you shouldn't as they are called emergency heaters. With sufficient thermal storage you wouldn't need them >90% of the year.

You basically take a heater that is capable of 30% efficiency (could be a little off here but close) and replace combined cycle gas turbine that is close to 60% efficient.

Industrial heaters are actually >95% efficient. It's the turbine that is lossy. Your 30% figure may be right overall.

So why do I propose emergency heaters rather than combined cycles? Simple. Cost. What do you think the latest ~60% efficient combined cycle gas turbines cost? They are very expensive compared to simple industrial methane heaters. And, as I've said, with sufficient storage you wouldn't use all that much gas so less efficiency is not that big a deal and because you would not use the backup GTCC most of the time there's no way you could recoup the extra investment anyway.

One thing that may be interesting though, is using efficient SOFC's as additional peaking and backup as well, with the waste heat powering the plant's original turbine. SOFC's are coming down in price and going up in reliability so it may be an option pretty soon. Just an idea.

Cyril R.

Now Solel’s design does require the use of an emergency heater to keep the HTF (heat transfer fluid) warm in periods of extended clouds but is rarely needed. HTF freezes at a fairly high temperature.

Ausra uses water as HTF. And as working fluid. And as storage. All in one cycle, no heat exchangers needed. Water doesn't freeze easily considering they have a well insulated system. Water also has low toxicity, so I think that solves Steve's and Kit's concerns about leakage and safety. This would not necessarily be any more dangerous than a coal fired plant which also uses water and steam.

Cyril R.

Ok one last comment about Ausra’s claim to make power during the winter months. Yes less power is needed during the winter but not the more than 50% a solar thermal plant is going to produce.

Take a look at the graphs here. Correlation of 96 percent with US demand. The rest could be provided by emergency heaters or other clean power sources, which could also deal with occasional climatic irregularities. Not that I think it's likely that solar thermal will be that big, but that's not the point. Just a hypothetical analysis how far we could really go with this. It' probably a bad idea to get too close to that correlation with solar thermal, but let's say 80-90% should be doable. That way there's some room for compensating extreme weather.

Cyril R.

One reason why I believe the solar towers may end up being a better system in the end.

I also believe point-focus systems will eventually win out. High tech could one day beat the low tech low cost approaches, but not now. Low tech is probably our best bet for now.

MTSA has particularly interested me. But it would be way too costly to build one right now; in fact not all the required technology is reliable yet. Such approaches can be seen as a long term R&D target. If they turn out to be better than the lower cost designs then that will be great, if not we'll be fine.

Solar thermal can only get cheaper.

DaveMart

Nucbuddy, sorry for the delay in replying to your post:'To what would reprocessing be a solution?'
Thanks also for providing references - that is the reason I participate in this blog, to have informed debate.
I take your point that reprocessing many be unnecessary/uneconomic, my point was rather that it should not be dismissed out of hand when it might have the potential to provide a lot of power.
That, at any rate is the opinion of the Chief Scientific advisor to the British Government:
http://www.guardian.co.uk/science/2007/dec/23/scienceofclimatechange.climatechange
What seems to me a fair assessment of the current state of play is given here:
http://www.spectrum.ieee.org/feb07/4891
The plain fact is that with some 900 designs of reactors, and many different fuel cycles possible, there is no way I can judge between the technologies, lacking expert knowledge and considering that even the experts disagree.
I don't think we should dismiss nuclear out of hand though, as it is a much more compact heat source than anything else, and does not have the carbon issues of coal or the land use and possibly cost issues of solar.

DaveMart

To expand a little on my above post:
To minimise costs I think it is a good idea to avoid rolling out technologies ahead of when they are ready.
So we should build a new fast reactor to see if we can improve the technology, as SuperPhoenix was the last one, and technology has moved on since that.
The reason it is difficult to evaluate at the moment the need and costs of fast reactors are that:
We have not got precise models of greenhouse
gas emissions effects on global warming - we don't know how much it warms the climate, if it warms it, and hence don't know how much we should be prepared to spend to minimise CO2 emissions.
We don't know how well we will be able to introduce renewables, or how much they will cost, and so can't properly compare them with nuclear - they are changing rapidly.
As we can't sort out the above, we don't know how great the demand for nuclear will be, as reprocessing is more attractive at higher nuclear levels.
Lastly, we don't know how much it would cost to dig more uranium/thorium and so can't compare it to the cost of reprocessing and fast breeder reactors.
Nucbuddy's links have led me to realise that reprocessing is more closely associated with fast breeder reactor technology than I had realised though, and that the benefit of producing MOX in more limited reprocessing may be less than I had thought - I am making the assumption here that Britain's Chief Scientific Advisor is hypothecating fast breeder reactors in his recent press release in favour of reprocessing.
Sorry if this is a bit OT for this thread! - I always try to reply to points put to me

steve

Cyril I agree with you that the simplicity of the design is Ausra’s strong point and I am not try to beat them up. It is very likely that I will be dealing with one of their plants in the next few year. I just have to admit I don’t buy everything they are selling. Since you are taking a very pro Ausra view I will take point out some of the problems I have with some of their claims. This is not meant to disrespect you but most of these views are ones I have developed from personal experience.

I think we have both made our views known on storage. I feel, at present time, a limited amount of storage would be great but that long term storage is really not needed. If we were ever able to cover the desert with these type of plants then I guess I would agree with your view that long term storage is good but just for now I consider it a step that we don’t have to take.

Ok as you might have guessed my pet peeve is taking a clean energy source like solar thermal and backing it up with a very inefficient source like industrial heaters. You can quote 95% efficiency but the real test is gas in and MW’s out. Basically it is just a feel good approach that makes us think we are doing something good. Now if you feel you need backup and presumably you have built 5 or 600 MW’s worth of solar thermal then why wouldn’t you build a combined cycle peaking gas plant. They do make them. Yes it is expensive but much more efficient and you will be using it a lot more than Ausra claims. I will talk more about that later. The beauty of doing this is you would not necessarily have to have it on the same site. It could be placed anywhere on the system, presumably where water or other resources are more available.

Ok as for the dry cooling system they plan to use. Sounds great but in practice I have my doubts. For those who don’t know it is just basically a giant radiator, much like a car. I have never worked around one so I will relate a conversation I had the other day with a friend who has. Basically he said they don’t work very well, especially as large as a 170 MW plant would require. They are complicated and expensive which seems to fly in the face of Ausra’s design. He quoted an average loss of efficiency of 10 to 20% especially in the summer. As I am sure you know in this type of system as temperature goes up, efficiency goes down pretty dramatically. Maybe someone with personal experience can chime in here.

Ok as for the graphs you quoted on Ausra’s website. Really they are nothing new and I am sorry but there is no way you are going to stay within 96% of demand unless you are producing 150% of demand in the summer. Ausra has already admitted that their system is less efficient than Solel ( to be made up with lower operating cost) but in many ways pretty similar in the way they gather heat. I think a much more accurate measure would be how much one of Solel’s designs is able to produce in the summer (less any gas backup) and how much they produce in the winter on average. I can tell you from personal experience it is less than 50% and one of the main reasons you would have to use natural gas backup much more in the winter if you were relying heavily on just solar. Edison may even give out the information on how much solar they purchase in any given month. I did notice that you really didn’t comment much my winter sun angle statement. There may be sun available in the winter but not really that useful if the design is not capable of efficiently collecting it.

Cyril one of my problems I have with many of your statements is that you just quote directly from Ausra’s stat sheet. You have to remember they are in the business of selling a product and as such they are only going to put things in it that help them do it.

steve

Ok and as much as I hate to google I found this link about dry cooling towers.
http://www.epa.gov/waterscience/316b/phase1/technical/ch4.pdf

Kit P

What do you call workers sprayed with HTF? Torch

What do call dirt when HTF is spilled on it? Hazardous waste.

So Steve, you are going to figure out that I have a lot more time working at steam generating stations. Steve neglected to tell us what HTF is, why? All power pl;ant must follow environmental and safety regulations. One of my pet peeves is banning PCBs as a HTF without a better alternative. The clueless seem to think they will get a pass because they are renewable energy and not that awful coal or nuclear.

Now for old questions:

Steve wrote,

“From personal experience I can tell you it does work and the beauty of the system is that is produces the most when it is needed the most.”

If this was true steve would be able to identify successful developers of utility scale solar thermal plants that demonstrate they have a clue. None exist at this time. Be careful steve, I will probably ask for some indicator of performance.

For example, Nevada Solar One announced six months ago when they first tied to the grid that they would be commercial in a week. Clueless!! Still waiting for them to meet contractual requirements to be a commercial plant. However, to be fair, 6 months is not very long to work out the bugs of a thermal plant even if it is only 60 MWe.

Solar thermal plants does not produce electricity when it is needed most without storage or using natural gas. Steve has danced around this question but form satellite views it sure looks like there is CCGT in the middle of those solar plants. Nothing wrong with that except failure to disclose the non-PC secrets of solar.

Steve wrote,

“I suspect if you knew much about steam systems you would know that turbines are designed to take themselves off the grid long before they damaged.”

If Steve had personal experience he would know that the turbine is not connected to the grid, the generator is. The issues with a sudden lost of the sun are discussed in a report on one of the solar towers in Spain. The dynamics of steam system were not discussed in detail except the need for storage to protect equipment. A system using saturated steam/water as a HTF will experience different dynamics than HTF that steve did not tell us what it was. Carryover, water hammer, and feed heaters flashing comes to mind as issues. The design feature of navy saturated steam systems was the operator. Been there, did that, got a white hat.

Steve wrote,

“Any idea who these "best developers" are?? I would be curious why you consider Ausra "clueless"?


Duke, FPL, and PP&L would be examples of the best of developers of steam plants. PG&E and SMUD are not on my list. The good maintain a low key. They do not make outlandish public announcements or run down other choices. Duke, FPL, and PP&L have all demonstrated the ability to move their expertize outside of their traditional market. Duke created the model for building CCGT but failed to make solar thermal a business line. FPL has taken failed solar and nuke projects and made them profitable.

For PV, I think Constellation and Tucson Electric Power (Springerville Generating Station: http://www.greenwatts.com/pages/SolarOutput.asp ) are doing interesting things.

DaveMart

Steve, I would agree that initially at least solar thermal would be primarily peak rate in hot climates, perhaps extended a bit with some storage.
That gives you a big enough market for solar thermal at utility scale to expand as fast as it practicably can for some years before you have to worry too much about lots of storage anyway, and by then the options may have changed.

Kit P

We will never have too worry about storage since wind and solar will never be more than 1% of US generation. This is based on the practical limitations of project development and maintenance.

Let me suggest an experiment. Get your hourly wage in pennies and drop them on the floor. Now pick them up one at time bending over each time. Now try the same experiment with dollar bills. Think about hard you would have to work to provide firewood to 100 homes but a coal or nuke plant operator can heat 1000 homes.

DaveMart

Kit,
You seem to feel that wind power in the US will differ from the EU, where that alone without solar already exceeds 1%, being around 3.3% of energy generated:
http://en.wikipedia.org/wiki/Wind_power_in_the_European_Union
The US has better on-shore resources than the EU.
You may be right, or at least maybe you should be right if the least-cost option is followed, but there is no guarantee that will be the case, and your blanket statement is too strong.
Please substantiate your comment.
Secondly I would agree that nuclear power is an excellent option, providing as you say a very compact power source, but there is no indication that building more of it in the West is going to be a viable political option for a very long time, and even should opinions change then it would take some time to increase build capacity to make a substantial difference as it has been so run down.
It is also true that most nuclear projects have vastly overrun their initial costings, critical for projects where the costs are upfront.
The third option you mention, coal, is entirely dependent on how you feel about carbon dioxide emissions.
I am also not entirely convinced that man-made GW is happening, and if it is it is not clear what it's contribution is.
Just the same it is apparent that there are valid grounds for concern.
It is also clear that coal already does not pay the full costs for it's emissions other than CO2 - in effect, a subsidy, from health costs to electric bills.
I really feel that you have a lot to offer to the debate, a contrarian voice is always to be welcomed, but do wish that you would do it in the form of reasoned arguments, with references, rather than ex cathedra statements and analogies.
Your post previous to the one I am here referring to was an excellent one, and shows the qualities I would hope you would more often bring to the forum.
Regards,

steve

Kit in reading your comments I pretty much get you are always right, everyone else is stupid, and if anyone wants to know why just ask you. If anyone dares ask you to support any statement you make you start with the personal attacks and bullying but you really don’t bring much to the table to support what you say. I am not an expert in all things and I can’t guarantee solar-thermal will be the next big thing. I do have opinions and knowledge of the current system most often used and steam turbines in general. I will give you credit, that while trying to attack me, you did bring up some interesting points and problems with the current system and I will give “my” opinions.

Ok you seem to have latched on to HTF. In an earlier post I referred to HTF as “heat transfer fluid” which is exactly what it is. The oil is heated to around 700f and is run threw a heat exchanger to produce steam in the plant. I also stated in another post that it was not exactly the greatest stuff in the world. Not really sure what I was trying to hide there. I will let you on in a little secret. I am not a big fan of the stuff and don’t know anyone who is. One of the reasons Ausra’s design interests me so much. The original Segs designs called for one of the future plants to be operated as a direct steam plant also but was never built.

Ok you also said I was trying to hide the fact that NG is sometimes used to power the plants. When I said I had personal experience with the heaters and was bashing them I would think most people would assume that I was talking about the solar plants. Now since you are saying I am trying to hide something I will explain a few things to you. I don’t agree with the use of heaters but because of the contract the plants work under it is necessary. Ok here is a little school about the definition of a solar thermal plant in California. By definition it is allowed to create 25% of its total BTU’s with NG. Not only that it must demonstrate that it is capable of running the 6 peak hours (noon to 6pm) that it is capable of never going below its rated nameplate. That is if it is a 35 mw plant it can never go below that number and it is watched. If it does it risks losing its contract. It also must produce at least 80% (try for 100%) of its “peak” contract or risk voiding the contract. The peak months are June-September. Now I hope we don’t use this blueprint for any future contracts or affordable solar is doomed to fail. Basically these are left over Carter era policies and don’t make a lot of sense. Of course a plant is going to use gas when it needs a little extra. It makes huge economic sense to do so and maybe even plant survival. The Nevada 1 plant is just paid by what solar they produce and I think that makes a lot more sense than paying premium money to burn gas.

I almost forgot about this one. You really didn’t make too much of an attempt to name the best companies who failed at solar thermal and I gave you a pretty big opening. There really are very few people who have tried so pretty hard to say who failed. Not a lot of projects out there right now. You could have said LUZ and you would have been mostly right. They went bankrupt building the Segs project. Now the truth of their failure had more to do with mismanagement bordering on being criminal. They had great contracts and many of my friends worked building them. They have some pretty interesting stories to tell. They were also successful because the design has worked profitably for many years. Admittedly having a good contract helps

Ok as for performance. I don’t have the performance figures at hand for any of the plants and even if I did I would not post it. I reliability (availability) of the plants is in the high 90’s but can’t really remember exactly what they are. Pretty much the same as most any steam plant. Because of how the contracts were written performance had been going down over the years. Gas was cheap and it made more economic since to burn extra gas than keep the solar field in top shape. Now with most of the plants under one ownership and gas prices spiking things are changing dramatically. The plants now have common ownership that is dedicated to making solar work. Solel’s twenty year old tube design has been dramatically improved and most of the tubes (at great expense) are being replaced. In the plants that have already had tubes replaced the improvement has been impressive. The smaller ones are pretty much able to make the contract without gas most all the time. I suspect the larger plants will have similar results also. High gas prices have pretty much eliminated burning NG during anytime but the summer peak months.

Ok Kit you got me when I said trip the turbine off the grid. You are technically right. The generator trips off the grid but when a plant comes down for the night an operator trips the turbine, which immediately trips the generator. Conversely if for any reason the generator trips the turbine trips also. It is also pretty common to hear an operator use the slang trip the turbine off the grid.

I apologize to everyone for the length of this post. Didn’t want Kit to say I was ducking any questions. I am sure I forgot something but I am sure he will remind me.

Kit P

DaveMart, with all due respect, you are not expecting me to provide a reference for my opinion about the future? I did provide the basis for that opinion.

With respect to the EU, incentives were in place earlier for renewable energy except for a few states like Texas when Governor Bush provided the leadership that was lacking on the national level. I would be surprised if many countries in the EU have built as much wind power as Texas.

As a generality, the amount of alternatives to coal in any country is based on the amount of coal they do not have.

Kit P

DaveMart, with all due respect, you are not expecting me to provide a reference for my opinion about the future? I did provide the basis for that opinion.

With respect to the EU, incentives were in place earlier for renewable energy except for a few states like Texas when Governor Bush provided the leadership that was lacking on the national level. I would be surprised if many countries in the EU have built as much wind power as Texas.

As a generality, the amount of alternatives to coal in any country is based on the amount of coal they do not have.

DaveMart

Kit, I really can't understand the basis on which you expect to have a rational discussion.
You said:
'DaveMart, with all due respect, you are not expecting me to provide a reference for my opinion about the future? I did provide the basis for that opinion.'
In reference to this comment of yours:
'We will never have too worry about storage since wind and solar will never be more than 1% of US generation. This is based on the practical limitations of project development and maintenance.'
I noted that actual generation in watt hours in the EU is around 3.3%, and gave a referenced source for this.
So how can you possibly feel that it is unreasonable to ask you on what grounds you make your assertion?
Can't the US manage 'project development and maintenance' at the rate of a third of that of the EU?
You also say 'As a generality, the amount of alternatives to coal in any country is based on the amount of coal they do not have.'
FYI, Germany has plenty of coal, albeit somewhat expensive and dirty, and is probably the leader in going for alternatives.

Cyril R.

Hmm. The problem about Steve's reasoning appears to be that he bases his arguments on what is available now. Being an insider that makes sense as he can evaluate what is currently working. It's good to hear an insider's opinion. However, Solel doesn't have plants with large amounts of storage. Storage really changes everything, because the system cost of solar heat in Ausra's system (ie in a high CF plant with a reasonably cheap array) is less than the system cost of natural gas, and the latter will only increase in price whereas the former will decrease. With much less natural gas needed (e.g. 90% solar fraction and 10% natural gas fraction), having a CCGT as backup just isn't worth the extra investment. Now I'm repeating myself again, I already answered most of these issues in previous posts. The advantage you name of not having the CCGT on site is very marginal and still doesn't justify the extra cost when the solar fraction is very high. Efficient gas burning is nice but if the economics aren't justifiable it's not going to work on a large scale.

I think you're confused about this because Solel's array is rather expensive so it will be more economical to use larger amounts of natural gas rather than storage with more array. So then, yes, building CCGT's will make more sense. But Ausra's design just has different economics.

Regarding dry cooling, yes these systems are more expensive and a bit less efficient. However it is not so much as to make the per kWh cost suddenly unaffordably high. And dry cooling systems work very well, yes actually. The Cramer Junction plants employ dry cooling and it's working quite well. Don't forget, saving a lot of water is important in the desert! So I don't think there is any choice between dry or wet cooling. Wet cooling condensing towers are also more visually impeding; they're bigger and taller than dry cooling systems. Besides, dry cooling technology could no doubt be improved in the future, especially in terms of being more efficient for larger plants.

As for land efficiency, that is just plain wrong. Ausra's 177 MW plant occupies about one square mile. Solel's 553 MW plant is about nine square miles. That's maybe 62 MW per square mile. So that's 62/177 = 35% of Ausra's output. To be fair, some of that may have to do with some amount of storage and thus higher array field per nominal output. And perhaps quality of location may have something to do with it. Or poor site geometry. Even then, Ausra has better land efficiency, one of the more important reasons for this is that troughs have to be spaced apart quite a bit to avoid mutual shading. I'm sure you realise this.

There simply is no inherent reason why Ausra's design won't work out, that is my point. Sure, politics, bad managment or poor execution and operation of the design in reality can ruin things, but it's impossible to determine how that will go, and any company could suffer from this anyhow. Their managment team and production crew looks pretty capable. The array is already working so that's like >70% of project costs. The only thing I've put a small questionmark behind is their cavern storage, but again not inherently a problem as it's technically just very simple.

Cyril R.

The thing about true land efficiency is that you can't just take the solar to electric efficiency and say that's it. Sure, some point-focus designs have 40% solar to electric efficiency. That does not take into account the fraction of the available beam reaching the entire site. Often, in point-focus systems, less than 20% of the available beam is captured due to large mandatory mirror spacing. So then it'll be 40%*20% = 8%. That's optimistic mind you, and still worse then Ausra's system, and more expensive and complicated too. MTSA or similar design would solve this but it's not commercially viable at this point.

Cyril R.

One more thing about dry cooling I just realized: in a high CF plant, you have less power block per kWh but also less dry cooling system per kWh. That lowers the cost of dry cooling per kWh.

This also implies that more expensive, higher efficiency turbines would likely be preferable. Because while they are a much smaller part of the cost of high CF solar thermal plants, they are very important when it comes to kWh yield, so it will often make sense to have more expensive but more efficient turbines. That also lowers land area required, not that I think that's a real problem.

DaveMart

Cyril and Steve, thanks for some great posts - it's been really interesting and informative, and as Cyril said it is a rare treat to get insights from an industry insider.
I somehow think you are going to be a bit busy before long, Steve!:
http://www.renewableenergyaccess.com/rea/news/story?id=50977
The 533MW Solel should give a lot of valuable experience, as it will use their latest and greatest!
Just a comment on land use intensity, Cyril - I don't think low density is necessarily a disadvantage - to obtain permits on environmental grounds, then surely indicating that a lot of the land will remain free strengthens the case?

Cyril R.

I don't think low density is necessarily a disadvantage - to obtain permits on environmental grounds, then surely indicating that a lot of the land will remain free strengthens the case?

Good point Dave. Having less mirror coverage would indeed leave a bit more room for the environment.

But then, you're forgetting that you'd need more total land area to provide the same amount of kWh's. So that will have a bit more impact.

The question then is what's the net environmental effect?

In either case I'd say it's trivial. I have yet to see a reference that states that solar thermal plants of any design have destructive impacts on local ecology.

Still, a more compact design would no doubt have an economic efficiency benefit. I think it's an interesting time for solar thermal with so much happening right now after basically decades of slumbering.

Good luck Steve! Keep us informed on progress if you can spare the time.

DaveMart

Cyril said:
'But then, you're forgetting that you'd need more total land area to provide the same amount of kWh's. So that will have a bit more impact.'
I didn't forget, Cyril, I just got into my advocate mode! ;-)
If I were arguing with the planners on behalf of Solel, I would certainly make much of the low density of the mirrors enabling preservation of much of the environment which might otherwise be threatened, and if I could find a snake or something that liked the shade cast by the mirrors, would major on that!
I agree though, in desert environments environmental impact should be easy to minimise - I am not so sure about covering up perfectly good farmland in Germany and so on - stick it on roofs and so on in that environment, I say.

Clee

Is misspelling contagious? It's Kramer Junction, not Cramer Junction.

steve

Cyril I will concede a couple of points to you and argue a couple. They always say start with the good so here goes. You have a great point that in land efficiency Ausra’s design will probably win out. While I was technically correct in saying Solel’s trough is more efficient, the thing that matters most is the amount of MW’s you can get out of a given area of land and most importantly the cost in doing so. While land does not seem like a big thing in the vast Mojave it is. Most of it is owned by the Government and not always easy or cheap to obtain. Really this should be easy to remedy but with anything the Government deals with probably not going to be. Also you need to set aside at least one and usually two acres of land for every one you use.

I also like the high density approach because even in a lower density approach there any wildlife allowed to live on site. You just can’t allow brush to grow between the mirrors and basically the land is cleared anyway. I am really not a big fan of encouraging snakes or other critters to be in my workplace anyway. In the original Segs projects they had people who’s only job it was to protect and relocate tortoises

You also have some good point with lowering cost through long storage but then again I don’t believe that making power at 2am is necessary at the present time. The current contracts the plants work under do not even allow it. Also most utilities will pay more for electricity at peak times than they will at super off peak times, when the already have enough. But then again it all depends on the contract the company writes with the utilities.

Ok as to where I don’t agree with you. Kramer Junctions power plants do not use a dry cooling system. You many be confusing the closed cooling system cooling system all plants have for plant and generator cooling. It uses a heat exchanger but also draws water out of the cooling tower. Really the amount of water it uses is a non issue. I agree a dry system sounds like a great idea but after talking to a very knowledgeable person I know about a month ago, I just don’t think it will ever be practical in the Mojave. The majority of the plant water usage is for the condenser. Ok in the Mojave the summer temperatures regularly go over 110f in the summer and over 100f most days in the summer. A dry system will never be able to reduce temperatures of the water below ambient temps. Now all the plants are a little different but I pick the larger ones. They are designed for a 80f inlet temp and a delta of 18f or 98f outlet temperature in the condenser. On a hot day in the summer a dry system would have a very hard time getting the inlet temperature below 120 and use a huge amount of parasitic fan electricity doing so. The plant will not only be very inefficient at this temperature it simply will not stay online. I admit a saturated steam system is different than superheated one and I don’t really know how it would be affected but I am going to assume it will be similar.

Not sure where you get the 9 miles for 533 MW’s using the Solel system but I am going to assume it is a misprint. Right now Segs 3-9 have a little less than 4 square miles of field for 310 MW rating. If you were to build the field today it would be more efficient and have a higher rating. If I remember right the large Segs solar fields are on about 480 acres or ¾ of a square mile. If built today the field would be rated at least 100 MW’s because of efficiency increases in the tubes. I am pretty sure you could get at least a 130 MW rated field out of a square mile. Still less than that claimed for Ausra.

I guess I have a problem with saying we can sacrifice efficiency for this and that. Lets face it solar is expensive at the present time. 2 or 3 percent here and 10 percent there add up very quickly. I agree with using efficient turbine as the cost compared to the total cost of the system is low. I also am happy that two of the first places Ausra has decided to build, Florida and the Central Valley of California, are not exactly ideal. If they can make it work there then it will definitely work in the Desert Southwest.

Dave yes I am very excited at the present time for everything going on. Both Ausra and Solel’s designs excite me and hope some others will jump in the fray. Efficiency can only get better and cost can only come down.

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