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Scott: This morning on Beyond Zero we're talking with Dr Craig S. Turchi, Senior Engineer at the USA's National Renewable Energy Laboratory, otherwise known as NREL. Craig originally joined NREL in 1990 working in the solar industrial program. He was detoxifying hazardous waste using solar ultra violet light. After leaving NREL he went to work as a principle investigator and program leader at ADA technologies. Craig is back with NREL now, he is helping with the Concentrated Solar Power project and he is working on systems analysis and the development and assessment of heat transfer fluids and thermal storage concepts. Craig is task leader for the Concentrated Solar Power programs market transformation activities. Craig joins us live from Colorado in the United States. Hello Craig and thanks for joining us.
Craig Turchi: Good Morning Scott or good afternoon from here.
Scott: Yes it is, it's afternoon of the Thursday so, and we're here Friday mornings. We’re getting used to these U.S. interviews at the moment with specialists from all around the world. I just wanted to plug that, you know, just to say what a great show we are!
Craig: Laughs.
Scott: Craig, I'd just like to ask, open by asking the question we ask a lot of our experts because it is quite interesting to hear how they became interested in the field of renewable energy and in your instance with solar power. Can you tell us how you kind of first came to the arena?
Craig: Sure, I’ve always been interested in environmental issues. In fact, when I was growing up we had a powerboat and my brothers were the ones that were always running around in the powerboat and I decided that wasn't good enough so I gravitated to a sailboat because I liked the renewable power source associated with that. And then when I went off to school I studied chemistry and chemical engineering and was really primarily interested in pollution control technologies. And in fact that's what I got my PhD in, was in using ultraviolet light for pollution control. And at the time my advisor, when I was at school, was doing some work for SERI which was the precursor to NREL, and he was advising a bunch of mechanical engineers on working in solar detox which involves a lot of chemistry and so he decided that they could really use a chemical engineer helping him out with some of these issues related to ultraviolet light and the breakdown of chemicals. He actually lined me up with an interview and I got to go out there and that's how I got started with SERI.
Scott: Ok, and so what was NREL called?
Craig: NREL was the Solar Energy Research Institute when it was first formed by Jimmy Carter in the late 1970's.
Scott: Ok, S-E-R-I. Ok, I got it. Well, thank you for informing us of that one. And can you tell us about the, you left NREL for a while and you came back, can you tell us about the work you're dong at the moment?
Craig: Well, the work I'm doing right now is in the Concentrating Solar Power program as you alluded to. This is often known as solar thermal, this differs from photovoltaics because we're using the heat energy in sunlight to generate steam and use that to generate electricity as opposed to the more familiar solar cells.
My particular role is helping in the development and testing of new thermal fluids. When we focus the sunlight onto the target of the receiver there is usually a liquid or gas flowing through that receiver and that's what’s absorbing all the heat and the properties of those fluids is extremely important to efficiency of the solar thermal process. So, that's one area I'm working in.
I'm also responsible for what we call market transformation which includes a lot of non technical areas - issues related to how much sunlight is at any given location. How much land the power plant uses. What impact the power plant has on the environment that it is located in.
Matthew: OK, and do you work with all power technologies, exclusively troughs, or troughs and towers and dishes or?
Craig: We work primarily with troughs and towers here at NREL. Our sister lab, Sandia National Laboratories also works with towers and dish engines systems. The two labs share the Department Of Energy's program in solar power.
Matthew: And we understand there's also some work on thermocline storage and are you involved in that also?
Craig: Yes, in fact that's a very good issue. Solar thermal technologies have the ability to store energy which is really rare for renewable energy technologies. Really only hydro power has a similar capability. But because we are creating heat we can actually stick that heat in a big tank, much like a large thermos, and then we can pull that heat back later on and use it to create steam and make electricity.
So, one of the large research areas is what we call thermal energy storage. Different ways to store heat that either use less space, cost less or are more efficient and the simplest way right now is actually a system which has just come online in Spain. It uses a molten salt, it's a nitrate salt and you heat the salt up and you stick it in a big tank then you pull it back out when you need it. And that works reasonably well but it's fairly expensive and it’s rather sensitive to the cost of these salts.
So, we are looking at one approach called a thermocline which allows you to use something much cheaper than salt just like rock or concrete in association with the salt to store the energy. So, you use rock to store some of the energy and you can use less salt and then the system as cheaper.
Matthew: And how much less salt do you use in a system with that?
Craig: You can use about one third of the total amount of salt that you would need in the more conventional system. So, you can replace almost two thirds or so of the total mass with an inexpensive sand or rock mixture.
Matthew: And yes so are you saying there is a significant cost reduction there and obviously making it heaps more commercially viable?
Craig: That's exactly right. The catch is it's a more complicated system to operate so no one's built a full scale one yet. We've got some pilots and small scale systems that have been tested and we're doing more work and more computer modeling along those lines.
Matthew: And do you have any interest expressed by any of the big players like your Solar Millenium's or your Abengoa's or so forth?
Craig: Definitely. Yes we work very closely with the industry – a couple of the one's that you mentioned - and they are extremely interested in lower cost ways of doing thermal storage. The utilities here in the United States really like thermal storage because it makes the solar power plant look more like something they're used to. If you've got thermal storage incorporated in the plant the operators of the grid can rely on that plant to deliver power for the next two hours whether clouds come across or not. So, that's an important factor. And the solar companies like Abengoa are doing their own research and they're doing some work that we actually help fund them with and then we're working cooperatively with them on these models.
Scott: Now Craig, with the thermocline tank, the single storage tank, obviously the aim is it will significantly reduce costs from a two tank system. Currently with a two tank system people are starting to talk about baseload solar, even though despatchable power is more important, but they're talking about storage for about 16 hours or so that can be can pretty much run all through the night, especially during summer. With a thermocline, single storage tank I assume you're likely to get the same amount of storage in number of hours?
Craig: Yes. You can design the tank to have the same number of hours as you would have in the two tank, ordinary molten salt system. The goal is just to be able to do that less expensively.
Matthew: So, if you go for one thin, tall tank, does that cost more than two short fat tanks? Like some things cost more and some things cost less, obviously you're saving money on the salt and the raw material but you've got to build a big, thin tank?
Craig: Exactly, a very good question. The ideal case for a thermocline would be a tall, skinny tank and that's clearly not practical when you get above a certain length. So, we're looking at options for either putting a bunch of tanks in series. So you have a series of tall, skinny tanks that are linked together so that they act like one big tall skinny tank. We're also looking at some other ways of designing the tank itself that would be more amenable to work a thermocline system.
Matthew: So, effectively what we should have is a system that costs like 50 % less or 70% less than a current system.
Craig: That's what we're shooting for, yes. The other aspect of the cost is that the cost of the solar field is actually very important when you start adding thermal storage because you have to put in additional solar fields to capture the additional energy you are going to stick into the storage tank. So, at the same time we have continuing research on bringing down the cost of the trough mirrors and the heliostat mirrors and the other elements of the solar field.
Matthew: Yes, now talking about that, you're talking about the actual working fluids and you’re working in those heat transfer fluid areas, can you tell us what work's going on there? Now, we understand from talking to Rainer Aringhoff from Solar Millenium that the current system uses oil throughout the field and then that's heat exchanged into the molten salt to store the heat and then again they need to pull the heat out of the salt and flash it to water so that they can run the turbines. Can you tell us how this is done in the systems that you're researching?
Craig: Well, that is right. You've described the current design with the oil and exchange to molten salt. We and others are looking at a number of heat transfer fluids.
Probably the most commom one is what's referred to is direct steam generation where instead of having a heat transfer oil you're making steam directly either in the troughs or in the power tower. We like that because you can then send the steam directly to the power turbine and you don't have to have a bank of heat exchangers in there so that's more efficient.
The catch is that the direct steam systems run at higher pressures so you have to have heavier pipes and it's more difficult to incorporate storage into direct steam generation systems. A simple molten salt storage mechanism does not work very well with steam generation. So, we are researching other storage approaches that are more compatible with direct steam generation.
One of other interesting areas that is being looked at a little bit longer range is referred to as nano fluids where you take like the standard heat transfer oil and perhaps you add a little bit of this magic pixie dust to it that's a nano particulate material that's designed to enhance the thermal properties of the fluid. It's kind of analogous to making a graphite composite tennis racquet or something where you put a little bit of these carbon nano tubes or small nano material into the fibreglass and its gives you a much stronger racquet. The same type of approach we're looking at for the heat transfer fluid. The nano materials are very expensive so you have to be able to get by with just a small amount.
Matthew: And can you tell us a bit about the storage technology you're working with that works with steam. Because we understand the difference between steam and molten salt, conventionally thinking is, you've got water that's quite dense but once it turns to a gas it involves high pressures and it’s not very dense for a given volume. Can you tell us how you're working with that?
Craig: Yes. The issue with storage in steam really comes around to that phase change where you're converting the liquid water into steam in the collector field and most of the energy is actually stored in that phase change element. It's referred to as latent heat related to the phase change. The key part is that that always happens at a constant temperature. So, if you want to store that energy into something else you can't store the steam because as you said its density is so low that you would have enormous pressure tanks and that would be prohibitively expensive.
So, you want to exchange that energy into something that's got more energy density and the most likely approach is to use another phase change, but instead of a gas to liquid phase change what's being looked at is liquid to solid phase changes. So again, the storage material might be a salt but where you would incorporate it with the steam is you would melt and freeze the salt with the evaporating or condensing steam. So, you can match up those temperatures and actually come up with an effective heat transfer to get the energy back and forth out of storage.
Scott Now, we're speaking to Dr Craig S.Turchi. He's a Senior Engineer at the USA's National Renewable Energy Laboratory…
Matthew: …We've been talking about solar thermal storage options. That's of course, if you've just joined us, that's solar power at night effectively. Like solar power when the sun doesn't shine . You can store that and you keep running your power plant all night long so we don't need coal and gas plants any more because now we've got dispatchable solar power.
Scott And Craig, look do you ever have dreams of finding a single heat transfer fluid that doesn't need to be pressurised, it's cheap, it's easy to run? Surely that's the ultimate dream?
Craig: That's exactly right! That's the thing we fantasize about, maybe to stretch it a little bit.
The reason that it seems like it's just beyond reach is that these salts are made up of very common materials. There are nitrate salts, you could use chloride salts and there's almost an infinite variety of mixtures that you can put together and the salts behave very differently when you start to create these mixtures.
So, we actually have some work going on with a company out in the San Francisco area and they are doing what we refer to as combinatorial research. They're blending thousands of different combinations of these salts together in tiny little amounts and then they're testing the properties of that to see if they hit upon one that actually is the magic recipe that will work for us. So, that's bit of a holy grail. It's something we've been searching for for a while and will continue to go on because there are so many combinations possible.
Matthew: Is that company called Terrafor?
Craig: That company’s called Symyx. It's spelt S-Y-M-Y-X, I think.
Matthew: Fantastic. We'll have to look into that.
Now, in terms of commercialisation you've been obviously working on these thermocline systems . Is there any sort of timeframe you can give that you think that solar thermal trough and power plants could be using the new thermocline systems and one-third of the raw materials in terms of the salt?
Craig: The thermoclines are not fundable right now. The banks consider them to be too risky for a full scale system to be built. So ,we'll have to go through probably 2 or 3 years of pilot testing and demonstration scale testing on these systems before anybody would be willing to fund a large full scale system. So, probably you're talking kind of the second round of CSP plants to go in, maybe in the 2015 timeframe might involve thermoclines.
Matthew: And you definitely think that's probably where it's moving given the availability of the raw materials.
Craig: Thermoclines are certainly and attractive option. The folks in Germany that we work with at the research institute there, the DLR, are very keen on concrete storage. Concrete is also a very inexpensive material and it's basically sensible storage within the concrete. So, you heat up the concrete and then pull the heat back out. They're doing some pilot testing in that already so that could easily be full scale in the same kind of timeframe.
Scott Craig, we'd also like to ask you about your expertise in current grid integration and transmission because I read that that's something you’re also working on. Could you basically explain that to the audience and talk about the area that you're concentrating on at the moment?
Craig: Sure. One of the attributes of Concentrating Solar Power in the United States and in most places around throughout the world, is that it's located in areas where you have very good sunshine, which for us is our South West. The population centres may or may not be adjacent to that area. It happens in the States, we have some good population centres out there; we have Phoenix and Los Angeles. But if you really want to start to make a significant dent in the nation's energy needs, you gonna need to move that power out of the South West into other parts of the country.
And in order to do that you’ve gotta have extensive transmission line capabilities. And so sighting the transmission lines, getting them installed, is at least as important as installing the power plants themselves because if you can't get the power out of the location where it exists it's not going to do us much good.
The solar power plants are trickier than the conventional power plants because in general they only work when the sun is out. Now if we can add thermal storage into these systems we avoid some of that issue and by doing that allows you to use that transmission line for more of the day so you're using it more efficiently and more effectively and it's more cost effective to install it.
But the whole balancing of the grid, taking into account when wind turbines are turning and when the sun is out, that's done in the States usually by someone we call an Independent System Operator, or I.S.O., and they're responsible for making sure that the entire grid stays balanced and being able to dispatch the solar power when they want it is a key element that we look to model.
Matthew: Now, if you were imagining a zero carbon grid, and we've heard the Federal Energy Regulation Chairman, John Wellinghoff in the United States, say that he thinks that wind will be the cheapest dispatch or the cheapest energy to put out there first, do you see the Solar Thermal Plants with storage as offering that firming power that secures the network supply and then as much wind as possible dispatches first?
Craig: Yes, we do. We think that there is complimentary value between wind and solar, in general. Here in the States, as a general rule, the wind blows more at night and the sun obviously shines more during the day. So, there is nice balancing between the two technologies in that regard.
Solar thermal with storage is also easier to integrate into the grid because you do have knowledge of a certain buffer of stored energy that you can always rely upon. Wind is cheaper right now but we think solar thermal is going to come down in price and it has these other features that make it a nice mix.
Matthew: And now talking about price, I was doing some research and there was a report for the NREL commissioned by the US DOE by a group called Sargent and Lundy and they're a power industry assessor, an engineering firm, of power plant projects for banks and things like that. Now, they are actually talking about tower systems using molten salt as costing potentially, you know, electricity for 3.2 to 5 cents a kilowatt hour. Is that trajectory still in play? Obviously not as many solar thermal plants are being built as what they predicted to date, but I am wondering what your thoughts are there?
Craig: The study you're referring to I think came out in 2003 and it's actually being updated right now by the same company. Sargent and Lundy is coming out with an update, probably by the end of the year.
The costs have shifted a large amount due to commodity prices. Prices of concrete and steel and glass have risen more than anticipated, particularly in the last few years. But the fundamentals are still correct, we believe. Power towers systems, we think, are going to come down significantly in price. They have some nice advantages versus the trough systems but they haven't been demonstrated yet.
So, we think when the first power towers come online, the operating experience and the scale of manufacturing is going to let them realize some significant reductions in their overall costs and ultimately probably be the cheapest of the solar thermal technologies.
Matthew: Now, there's two companies pursuing towers with the molten salt as a working fluid. There's Torrasol, owned by SENER in Spain and there's also an American equivalent, Solar Reserve. Is there any sort of difference to those company’s technologies and approach?
Craig: I'm not familiar with the Spanish company. Solar Reserve, I know fairly well. The major difference we see between the power towers is those using molten salt and those using direct steam generation and in the US, as you indicated, Solar Reserve is in the molten salt camp. They generally have larger heliostats, the mirror systems tend to be bigger for each rotating mirror.
In contrast, there are companies like Bright Source and eSolar who use smaller mirror fields and direct steam generation and their big challenge is gonna be integrating storage into their technologies.
But the smaller heliostat fields have some nice advantages in that they're easier to maintain, they have less wind loading because they are physically smaller and some of the advances in controls and software allows them to control these heliostat fields because the smaller ones of course have many more heliostats but the advances in software and control? allowing them to control those fields and those may ultimately win out. The market place will tell.
Matthew: Now the heliostats or course, for listeners, are the mirrors that surround the giant tower that sends the light up to the tower receiver then creates the heat. Now, just asking about that, is it possible those molten salt systems like the Solar Reserve or the Torrasol one could use the smaller heliostats from those companies like eSolar and Bright Source? You know, the ones that are using the really small one metre by one metre heliostats? Could they be combined with the molten salt technology?
Craig: Sure. Yes, the ability to put the sun on target doesn't particularly care what the fluid is you're heating up. In some cases, with the phase change steam, it's more important to have that a little more accurately perhaps than in the molten salt case. But you could easily pair up a molten salt tower with the smaller heliostat field.
Scott: Ok, and now Craig I think we're getting nearer to the end, so I like to just kind of go back to the big picture a bit. You talked about solar being quite compatible with wind power because wind power comes onto the grid constantly (ie: can't be controlled) and you can't really store it and stuff like that. It's quite hard. Whereas with solar you have that dispatchable, stored power that can meet the supply and smooth it out. Apparently, with base load coal that doesn't seem to work so well with wind. Can you describe that to me, like what the weakness is there?
Craig: With base load coal providing firming power to wind? Is that what your question is?
Scott: Yes, in that it can't be ramped up and ramped down quickly.
Craig: That's true. Nuclear and coal plants don't like to be ramped up and down. The complexity of those plants, and all the associated feeders and then the coal-side, pollution control elements just don't like to be changed.
So, here in the States at least, most of the ramping and intermediate control is done with combined cycle, gas-fired power plants. And those are very good at ramping things up and down, but gas prices also are very good at going up and down. So, running those plants is a little bit dicey depending on the cost of gas.
Scott: So, in the future as fossil fuel prices are gonna probably continue to go higher and also, as you say, the uncertainty in them, it makes logical sense to transfer away from coal power ultimately, and the gas power, and just use big thermal solar plants to firm up the wind power.
Craig: That's exactly right. We have tremendous resource in solar power here in the States and also down in Australia and it's really a shame to be wasting, to be burning coal and natural gas which are wonderful resources and can be used for a lot of other things, but just to burn them and make electricity seems like a waste when there are other ways to do it that are cleaner.
Matthew: Now, one more thing. If you build a solar thermal plant with storage and you compare that to gas, the gas requires an offshore drilling field or gas site with oil rigs and a processing plant and then it involves a pipeline and then it involves your combined cycle plant. So, there’s those three components.
You're really replacing that with a solar thermal plant and if you cost all those together wouldn't they be a similar price - you know, the rig that pulls the gas out of the ground plus the pipeline infrastructure and they got to process the carbon dioxide out of it if it's too high and finally the gas plant? Wouldn't that be more costly than a solar thermal plant?
Craig: Well, it goes up and down. Last year it was. But all those prices that you refer to are incorporated into what you pay for your natural gas when you buy it at the end of the pipeline. So, those prices are included in the gas cost but gas prices are very volatile. So, last year when they went up by 4 or 5 fold the solar plants that were running in California, were doing better than the natural gas plants. And if you want to add in things like carbon taxes or cap and trade systems those prices could go up even higher. That said, there's still little doubt we need to do a job and get the prices of the solar technologies to come down even more.
Scott: And we're certainly looking forward to that. We're already very excited on the show because we've interviewed so many people about their solar expertise and we can really see now how this solar (technology) is going to skyrocket and really take a big part of the market share. Thank you very much Craig for informing us about your work there.
Craig: My pleasure. Glad I could help.
Scott: And we'd love to speak to you soon.
Craig: Sure that'd be fine.
Scott: We've just been speaking to Dr Craig Turchi. He is a Senior Engineer at the USA's National Renewable Energy Laboratory and he gave us some great little snippets of information there which we'll certainly be using in our zero carbon plans, etcetera. If you want to learn more about Craig's work at NREL, and the rest of the guys at NREL obviously, because we've interviewed a few guys there, Greg Glatzmaier and Mark Wanlass, amazing people, you can visit www.nrel.gov and you can also go to their Concentrated Solar Power area directly via www.nrel.gov/csp.
Transcription by Kevin.
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It is well known that the advantage of solar energy is that the fuel is free, abundant and inexhaustible. In the face of global warming, solar projects are proving increasingly valuable cutting the use of energy and greenhouse gas emission. Sjöberg said Siemens solar turbines are sold in the US, Spain, Algeria and Egypt and they are keen to open the market to more places that are suitable for solar energy development such as Asia, Africa and Latin America.Their products include SST-700 DRH, ISCCS or SST-900 and SST-600 steam turbine for solar power plants. Solar power technologiesOne type of solar technique is to use mirror to focus the sunlight on to a tower and the heat will be transferred into a steam cycle or other kind of heat-receiving medium, such as liquid sodium. The linear Fresnel concept uses flat mirrors close to the ground to reflect and concentrate sunlight on water-refilled pipes that hang over the mirrors. In a parabolic trough plant, sunlight is focused onto a receiver tube filled with thermal oil in the center of the parabolic mirror collectors, the heat being transferred via heat exchangers to the steam turbine, which generates electrical power. In all cycles, surplus heat can be stored in large storage tanks and used to extend the running hours of the steam turbine during times without sun radiation.Siemens turbine technology can fit all of these concentrated solar power (CSP) concepts. EfficiencyFor a typical Spain solar steam turbine, investment can reach 260 to 300 million Euros. But steam turbine only accounts for 5-8% of total investment. The solar field can be approximately 80 football fields in size. Thermal storage can be up to 6-7 hours of full operation. In order to justify the high investment cost for a CSP plant, which will not be run 24 hours per day, high demands for efficiency and increasing economic returns are imposed on the steam turbine used in the process. Siemens has cooperated closely with leading solar thermal EPC companies to develop and finetune the SST-700 DRH(dual-casing reheat) steam turbine, now optimized for solar steam cycles and capable of generating up to 175 MW in CSP applications. This highly efficient turbine with its high-speed, high pressure module enables a smaller solar mirror collector field with associated reduction in investment cost for generation of the required electrical power output. Alternatively, the surplus heat can be put into thermal storage to extend the production time for the plant. The reheat solution improves efficiency and reduces problems with erosion/corrosion and moisture in the LP turbine, according to Mr. Sjöberg. Excellent daily-cycling capacity When focusing on annual power production, the short start-up times the turbine can provide are of great benefit to the CSP plant owner. Daily cycling and temperature variations require special attention. The SST-700 DRH, with its low-mass rotors and casings, is ideal for daily cycling and has a low minimum load, enabling maximum running hours per day for plants without heat storage. The cycle has also been optimized for stand-still at night and rapid restart in the mornings. The SST-700 DRH uses high quality materials specially chosen for long and trouble free operation in a solar plant, bearing in mind the potential wear and tear of the special cycle conditions. In Southern Spain, due largely to government-granted price surplus for solar-produced power from units less than 50 MW, the 50-MW size has proved to have the optimal fit and flexibility for single or multiple units.Advantages of the solution is flexibility, long lifetime, high availability and reliability, short start up time, fast and easy assembly, lower installation cost, high efficiency and savings on the solar field,Sjöberg claimed that Siemens' solar thermal experience is best in class and the solidity and reach of the Siemens global network is an advantage in terms of security of investment, supply and after-sales service. "Our experience shows that customers still want the best product even if the price is a bit higher," said Sjöberg confidently. ISCCS-integrated Solar Combined-Cycle SystemFor excellent performance and attractive emission reduction, parabolic troughs can be effectively integrated with a conventional combined-cycle plant as well as a steam-cycle plant. The Siemens ISCSS (integrated Solar Combined-Cycle System) is a single-casing high pressure non-reheat unit, suited to demands of the combined cycle. This SST-900 can be used with any gas turbine or in combination with one or more Siemens 47 MW SGT-800 gas turbines, as in a pioneering ISCCS in Morocco.This configuration is doubly effective. It not only minimizes the investment associated with the solar field by sharing components with the combined cycle, it also reduces the CO2 emissions associated with a conventional plant. The integration maximizes operation efficiency even though solar energy intensity varies according to the weather and time of the day. Peak thermal-to-electric efficiency can exceed 70% for an ISCCS plant compared to 50/55% for a conventional gas-fired combined cycle plant.Although the SST-700DRH turbine configuration is the most used on the market, all Siemens steam turbines have the potential for solar applications. Demonstration tests are currently underway with leading institutions in Spain and Germany to test both the lower end of the industrial turbine range-around 1.5 MW and also the mid-range around 20 MW-in solar tower applications. One commercial order has been placed for a 19 MW SST-600 steam turbine for the solar tower project Solar Tres in southern Spain. Sjöberg said market trends indicate that solar power will increase up to 20 fold in the midterm future. The benefits of solar power are compelling: environmental protection, economic growth, job creation, diversity of fuel supply and rapid deployment technology transfer and innovation.Solar thermal technology undoubtedly has a large global potential. Where there is sun there is heat, where there is heat, there is power-clean and renewable power. And the Siemens industrial turbine ensures that customer confidence is not misplaced, said Sjöberg. By Xuefei Chen, People's Daily Online, Stockholm.
ACCIONA opens its first CSP plant in Spain, in Extremadura Tuesday, Jul 28, 2009