NANOWIRES: Such nanoscale structures might offer a new path to efficiently turn sunlight into electricity.
Image: Courtesy of Wallentin et al.
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Here's how to make a powerful solar cell from indium and phosphorus: First, arrange microscopic flecks of gold on a semiconductor background. Using the gold as seeds, grow precisely arranged wires roughly 1.5 micrometers tall out of chemically tweaked compounds of indium and phosphorus. Keep the nanowires in line by etching them clean with hydrochloric acid and confining their diameter to 180 nanometers. (A nanometer is one billionth of a meter.) Exposed to the sun, a solar cell employing such nanowires can turn nearly 14 percent of the incoming light into electricity—a new record that opens up more possibilities for cheap and effective solar power.
According to research published online in Science—and validated at Germany's Fraunhofer Institute for Solar Energy Systems—this novel nanowire configuration delivered nearly as much electricity as more traditional indium phosphide thin-film solar cells even though the nanowires themselves covered only 12 percent of the device's surface. That suggests such nanowire solar cells could prove cheaper—and more powerful—if the process could be industrialized, argues physicist Magnus Borgström of Lund University in Sweden, who led the effort.
The promise starts with the novel semiconductor—a combination of indium and phosphorus that absorbs much of the light from the sun (a property known as its band gap). "Now we absorb 71 percent of the light above the band gap and we can certainly increase that," Borgström says.
The key will be even finer control of the nanowires themselves as they grow as well as the chemical tweaking of the constituent compounds. At the same time the novel cells could be built into so-called multijunction solar cells—compound devices that incorporate several different types of semiconductor material in layers like a sandwich to absorb as much of the energy in sunlight as possible. Such multijunction cells have converted more than 43 percent of the energy in sunlight into electricity—currently, the highest efficiency photovoltaic devices in the world.
Such multijunction solar cells are also the most expensive type of photovoltaic, but they can be made cheaper by combining them with low-cost lenses to concentrate the sunlight onto smaller versions of the cells. Borgström, for one, suspects that nanowire solar cells will stand on their own once the production process can be simplified, such as growing the nanowires by applying simple heat and evaporation techniques in future. He explains: "Once large-area structures can be grown, concentration will not be necessary anymore."
Interactive by Krista Fuentes. Photo of photovoltaic array at Oberlin College courtesy of Robb Williamson
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81 Comments
Add CommentSo what happens with expansion & contraction acting on these nano structures, especially using lenses to concentrate the light? I see a few more hundred million dollars of waste. The aim should be dollar per unit of energy produced over the life of the device.
Reply | Report Abuse | Link to thisWell, good thing this isn't funded in dollars; the Germans use Euros! Please spare us your usual knee-jerk reaction against anything clean energy. No one has incorporated these nanostructures into a commercial device yet and even initial integrated testing is probably years away. However, an utterly cynical attitude like yours would preclude any innovation or risk taking like what is highlighted in this article.
Reply | Report Abuse | Link to thisWell it is certainly useful to see solar tech get better but basically I am locked into high density panels I have for the next couple of decades, so about then is when I will be interested in solar again.
Reply | Report Abuse | Link to thisWhen you say "high density" panels, do you mean crystalline Si or just rigid panels in general? Considering what solar PV tech looked like in 1993, I can't even imagine how advanced it will be in 2033 when you'll be looking at replacing those panels!
Reply | Report Abuse | Link to thisSo you know more about PVs than me? I built my first tracking platform with PVs in the early 1980s. When did your practical experience start exactly? I doubt you know more than me about anything unless perhaps it how to earn a taxpayer funded income.
Reply | Report Abuse | Link to thisAll PVs suffer a drop in efficiency with increased heat. These will be particularly vunerable.
There are some people who always throw in something bad "scientific" when you mention a promising new development. That is what Carlyle did. Screw him!
Reply | Report Abuse | Link to thisHans L
@sault
Reply | Report Abuse | Link to thisCarlyle is right, these cells with a dependency on nano structures will be sensitive to heat and mechanically damage. This doesn't mean that this is not worth while technology to pursue. However, that being said "clean" is a bit relative. Most solar cell production has highly toxic wastes as a byproduct. The reason we don't here about it is because a lot of manufacturing is done in China where they don't care about dumping arsenic. I doubt these cells well be any exception. I am not trying to belittle the accomplishment here, because I think this is a big stride forward; I am merely trying to interject a degree of realism. What will likely hold these new cells back is cost, and the inability to overcome the capacity factor. In Germany, however, with a cultural resistance to nuclear and no desire to increase coal power, the economics might be different than in the US. Even so solar is still not adequate for the base-load. Solar cells are close to if not competitive for providing the peak power.
When did your experience with nanotechnology in solar cells begin, exactly? I've worked on this stuff since 2006. You can take your foot out of your mouth anytime...
Reply | Report Abuse | Link to thisHave you seen the thermal stress data on this particular nanostructure? How do you know it is "a few more[sic] hundred million dollars of waste"? Working with tracking systems back in the 80's IN NO WAY qualifies you to make sweeping pronouncements on this breakthrough technology, especially since I KNOW you haven't seen ANY test data on it!
You have no evidence to say that they WILL damage under thermal cycling! I'll buy that they MAY damage, but what does the decay curve look like? Will the nanostructures get damaged through dislocations, mechanical separation, defect formation or a combination? What are the size of the defects formed and would they be the right size to jack with the sub-cell's bandgap or block absorption? It's WAAAAY to early to be making that call. Any engineer could tell you this.
Reply | Report Abuse | Link to thisClean energy cuts pollution by 90% compared to dirty energy generation as reported by this very magazine:
http://www.scientificamerican.com/article.cfm?id=solar-cells-prove-cleaner-way-to-produce-power
I agree, let's have more realism around here. Making hasty conclusions about a technology before you've seen the data is not being very realistic. Carlyle is not "right", they are just being a concern troll about anything related to clean energy!
Completely unfamiliar with the state of "solar PV",
Reply | Report Abuse | Link to thisI can't help but wonder, assuming that someday, this
technology is genuinely competitive with, or better
than, current energy sources, how in the world can
researchers protect the above kind of array from
simple contamination from particles/chemicals in
the air? Ie: the described array is ingenious,
and certainly could be a proto concept for later
innovation, but wouldn't its fine micro-geometry
be vulnerable to various kinds of 'erosion'.
About "dollar per unit energy over lifetime", I
suspect that if this had been the crucial bottle-
neck requirement throughout history (not to mention
the Pleistocene), that not much would have been
invented, let alone improved upon. We'd still
be up to our bellybuttons in piles of lithics
and deer sinew technology. :-)
would
As I was arguing on the other thread:
Reply | Report Abuse | Link to thishttp://blogs.scientificamerican.com/plugged-in/2013/01/16/guest-post-towards-a-distributed-intelligent-electric-grid/#comment-1306
the problem is, time is running out on global warming.
Gee-whiz announcements like this come every day, and have for the last 50 years. They act as a sort of tranquillizer, to dull peoples' senses to the realistic alternatives facing us.
On the technology of this announcement: solar is probably one of the less promising renewable alternatives. The further away from the equator you move the less viable it comes. Big improvements both in solar itself and in storage and transmission technology are essential before it can make a real difference to AGW. On storage in particular, it's fair to say, there's nothing even on the horizon.
Meanwhile, Germany, the home of the energy turnaround (Energiewende), is building new coal-plants.
An engineer can calculate what material he needs before he builds a bridge. Even if it is a radically new design. The same goes for most things. I am telling you, these cells will never be practical because they will not stand the thermal stresses. Even if all the other technical problems were to be economically resolved. It might take a few tens of millions, Euros or dollars, before they admit it but mark my words, they will never be practical because of straight out physics that could be calculated without building even one cell. If you think I am wrong, give me your engineering based arguments. How can such a devise with nano scale components & connections expand & contract virtually minute by minute, not evenly either, without tearing the connections apart. Temperatures vary across a surface. Towards the edges for example there are wider swings than in the middle. When these things fail through obvious shortcomings that were apparent at the outset, the esearchrs should have to reimburse the public purse. Not easily anticipated, fair enough. That is research. If I were on a grants approval board, I would insist that obvious shortcomings be proven surmountable first. This is such a situation. Even macro scale power lines have thermal failures, let alone structures of this scale & fragility. Then there are the mechanical forces like wind & vibration.
Reply | Report Abuse | Link to thisRemember, to be viable they must last thirty year without significant performance degradation. Would you bet you houses on it? Why should the taxpayer unless a feasible plan is first put forward to overcome the obvious concerns. Do that research first. Do not build the bridge without the foundations you know it must have.
Then at the end, what do we have anyway? An extremely expensive device that generates power for a few hours on a sunny day.
Of course sault will know everything about this too. Not.
Reply | Report Abuse | Link to thisJust as a matter of interest.
Back in then 60s 70s there were reports of people walking into a salt lake in Israel & receiving third degree burns. Turned out that the lake in question had some very unusual properties. It had three distinct strata. The main body of water had a very high salt content but above this there was a thin layer of fresh water. The three stayed in this stratified state unless stirred by wind. The result was that sunlight penetrated into & heated the salt water & the fresh water overlaying it acted in the same way as a sheet of glass would. Strangely, convective currents did not cross the barrier & the salt water reached near boiling point. These became known as solar ponds & experimental ponds were built in various parts of the world. A friend of mine, Dave Fredrickson, at the time I was pursuing other solar research, built quite a large on in Alice Springs:
2.3.5 Alice Springs solar Pond
Sherman and Imberger (1991) analyzed the performance of the 1600 square meter solar
pond in Alice Springs .See figures 2.4 and 2.5. Temperatures of the storage zone between
85 and 900C were consistently maintained and a solar to thermal efficiency of 12 to 15 %
was achieved when heat was extracted from late January to March 1989. Heat extraction
helped to maintain the storage zone temperature within the desired range. The pond was
used to supply heat to run a developmental 20 kW organic vapor screw expander Rankine
cycle engine and generator (Figure 2.5).
PDF file can be accessed from here: http://www.google.com.au/#hl=en&tbo=d&spell=1&q=Fredrickson%27s+solar+pond+Alice+Springs&sa=X&ei=HEL5UKLkOMOekwXmj4CIAw&sqi=2&ved=0CCwQBSgA&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.41248874,d.dGI&fp=145e449a990997f1&biw=1366&bih=613
Efficiencies are achieved when engineering mimics biology.
Reply | Report Abuse | Link to thisWRONG! Solar PV generates electricity at the point of load during peak usage times of the day. Therefore, it shaves peak demand, lowering stress on the grid and obviating the need for more inefficient and dirty "peaker" plants. Solar won't do it all, but if we were all as extremely pessimistic on the technology as you are, we would be denying ourselves a useful tool in combating climate change.
Reply | Report Abuse | Link to thisSeriously? You don't even know what you're talking about. I've run solar cells with nanostructures through thermal cycling much worse than what you are fear-mongering about and nothing of the sort happened. Quit being a concern troll.
Reply | Report Abuse | Link to thisSolar cells are usually hermetically sealed in glass and / or some kind of polymer. We've had solar arrays sitting out in the sun for decades without any of the problems you mention.
Reply | Report Abuse | Link to thisThe only reason why we forecast them to have a 20-year life is because some of the older adhesives caused the glass and polymer coatings to delaminate from the cells, allowing the adhesive to start to discolor, lowering the output of the cell.
With steadily-improving manufacturing techniques, I would be curious how cells manufactured in 1993 are faring compared to the cells made in the 70's and the 80's whose long-term performance the 20-year lifetime was calculated.
Experiments I conducted over 30 years ago taught me the downside of concentrating radiation onto PVs. We did not have the advantage of the internet in those days & no doubt were duplicating earlier work by others. Nothing has changed. This will apply to the new cells as well. On top of this will be the physical breakdown from mechanical failure of connections unless they are elastic. Another point is that 40% efficiency was achieved years ago in laboratory setting. So what is with 14%? Perhaps converting a wider spectrum of the radiation. still 14%?
Reply | Report Abuse | Link to thisI am not mocking the actual research by the way. Just the forecasts for its practical use in PVs. Who knows were experimental work like this could lead in other fields.
http://courses.ucsd.edu/rherz/mae221a/reports/Zauscher_221A_F06.pdf
Because solar PV panels interact with their environment and their _ref is so low, they passively absorb about 80% of the incoming solar irradiance as heat [9]. This would not be
such a problem if not for a 0.5% efficiency loss of the solar PV panels associated with a
1◦K increase of the cell temperature [3]. Because the highest temperatures of solar PV
panels recorded are about 70 ◦C [13], this efficiency loss can be very noticeable, especially
true for yesterday’s PV arrays that have such a low efficiency to begin with. Therefore,
heat transfer plays an important role in the actual output of PV arrays.
I am an engineer, and I work with micro-structures. Its never too early to assert that thermal cycling will induce damage eventually leading to degradation. It may take decades for that damage to manifest itself in efficiency loss. Dislocation and defect production are not typically thermal processes but their migrations are. These processes are mainly concerns with thermo-mechanical phenomena and high energy radiation damage. Typical defect production energies are several to tens of eV (ultraviolet) where as thermal energies are in the meV (infrared). Defects are not produced easily by photon excitation in semiconductors and metals due to momentum transfer. Thermo-mechanical forces are capable of producing energies in the range of MeV (gamma-rays). The degradation here, like other semiconductor technologies, can result from wearing down the connection between the semiconductors and wires. Due to the scale of the size of the wires, this technology will be sensitive to thermal expansion from cycling. The degradation process will be dependent on the micro-scale transport characteristics of the material (i.e. diffusion, thermal conductivity, nano-structure, lattice expansion). In extreme/dynamic environments nano-structured devices will eventually fail. Any engineer would agree. As to your other concern, yes the band gap will change over-time, but mostly at the junction between the wire and photo-absorber. This is caused by atomic diffusion at the interface. This does not really affect the absorption process, but it does cause a localized non-regular structures with increased scattering site density which hinders the electron transport across the interface.
Reply | Report Abuse | Link to thisThere is no existing micro-structured semi-conductor technology that does not eventually fail from environmental stresses. With concentrated solar energy this panels will be sensitive to thermo-mechanical stress as well as other micro-scale phenomena. Look neither Carlyle nor I said that these panels will degrade in a week, we simply said they will degrade. In that we are correct. Now whether that degradation happens over 20yrs or 50yrs is another question. The point remains, cycling concentrated solar energy on these panels, even in 24hr cycle lengths, will put the panels under thermal stress eventually causing development of microscopic deficiencies reducing performance. That said, these panels are not bad; in fact these panels seem to be better than current generation. Regardless of the any deficiencies these panels still are interesting and a worthwhile research endeavor.
Thanks for that assessment. When I was involved in solar research many years ago I used to become incensed at the waste of research money spent on things that had already had demonstration plants built elsewhere. That way, the so called researchers could make claims about what their project would demonstrate. They knew the results in advance. It was jobs for the boys. rarely was there any actual advance made. It is happening on an even grander scale today. some lobby group or politician decides to build something solar. They get a copy of what someone else ha done with no advancement. Someone has a bright Idea. Others copy it, even if the idea is a failure. Because it is always public money, no one is responsible for failure.
Reply | Report Abuse | Link to thisI know often times we jump the gun with the research. I've seen how research funding is not necessarily merit based but is often driven by the ideology of the organization funding the research. I've got some reservations about solar. I'm okay with using it to supplement the peak power, but I think often times lobby groups would prefer that it is used as the base-load for which it is ill-suited.
Reply | Report Abuse | Link to thisIf technology like that presented in this article is given a chance to be developed such that the cost can drop to competitive levels the efficiency benefits will be significant. The great irony in lobby groups is the best organization to drop the cost of such solar cells is the military. An organization which are typically abhorred by the people who support solar. Military bases and some facilities may wish to operate in remote locations or be mobile. For both of these applications photo-voltaic solar does well. The nice thing about the military is that they do not operate under the same economic laws as the free market; cost is secondary to functionality. As such the military is great for buying expensive new/revolutionary technology so that it can be developed to a point where it becomes affordable to private industry. There are countless examples of this happening, from computers to GPS.
Solar still is a worthwhile research area, and we have come a long way even in the last ten years. Maybe in the next ten years we can see even more progress to the point where solar is cheaper than some other alternatives. Until then we just need to create a highly competitive research environment that focuses completely on the merits of the science/engineering, not on idealism. As disappointing as is it is, politics has enter far too deeply into scientific research in a way where idealism has usurped pragmatism.
Research is fine & I support it when it is not simply duplication. What I do object to is spending huge sums on things that have already proven to be failures. PV farms are an incredible waste of resources usually duplicating an existing failure. On any measure they fail. Reliability regardless of day/night/season/weather $ per unit of energy produced. Ditto for wind/wave etc. The intermittent nature of these supplies can not be overcome economically except where other sources are even more impractical such as a remote Island or region where transport costs make conventional energy even more expensive. Germany is courting an economic disaster with its anti nuclear prejudice. Because of word count limit post continues below.
Reply | Report Abuse | Link to thisThe holy grail of energy efficiency is storage but what medium could exceed the energy density of fossil fuels? Synthetic fuel produced with off peak nuclear power is the only possible option that I can see apart from niche situations where hydro recycling is practical. What ever way you look at it, nuclear is the way. By the way, thermal energy storage will never work either for temperatures above the boiling point of water because of the practical problems associated with pumping things like molten salt & the recovery of the stored heat. Water stored below 100C (Over that it requires a pressurise storage tank multiple megga oil tanker in size for grid base load supply) & that is too low for efficient thermal to mechanical/electrical conversion, There is no way around the Carnot Cycle. The theoretically possible efficiency of a heat engine operating on 100C temperature differential input to output is only 25%. In practice much less through thermal & friction losses.
Reply | Report Abuse | Link to thisIf your energy’s stored at 90C & ambient temperature is 20C you have 70C differential. Theoretically possible is only 17.5 percent energy conversion. In practice more like 10%. When you consider the initial cost of generating & storing your thermal energy, ignoring thermal loses along the way during pumping & storage, to get such a small return demonstrates the absurdity yet engineers who understand these things sign off on projects that must fail. They should have their papers cancelled.
These are inconvenient truths. I did not make the rules but they are immutable. You might as well rale against gravity.
As an engineer I know you understand these things & the above is written for others who are genuinely interested in the science. Many prefer to believe in things like warp drive rather than reality.
The Carnot cycle: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/carnot.html
Enter your own temperature differentials in the graphic. Top box for your hot input & bottom cold output. Absolute zero Kelvin is -273.15 C. The freezing point of water is 273.15k. Boiling point 373.15K
Well, here in Europe we don't get much sun on winter mornings and evenings, when domestic demand peaks. You must let me know in what blissful land you live, where you get a sun that shines strongly at those times.
Reply | Report Abuse | Link to thisAs an indication of the dishonesty or brute ignorance that prevails when renewables and being discussed: a serious paper in Germany announced last winter that solar had saved the day when the peak energy demand came at 5 o'clock in the afternoon in January.
Industry needs a constant and reliable energy supply also: see how German industry is having to install emergency generation equipment:
http://www.spiegel.de/spiegel/print/d-87737177.html
and work out how much carbon these generators will spill out.
Sorry, the above post was a response to Sault #16
Reply | Report Abuse | Link to thisDollar, Euro, Pound or any other currency / efficiency doesn't come into it.
Reply | Report Abuse | Link to thisEverything is expensive to start with, and complaining about costs with everything would have left us in the Stone Age.
Remember that CPUs once had a 90% or higher failure rate straight from the wafer, now it is normal to expect 90% minimum success.
The same goes for RAM, which cost £30 per Megabyte when I first bought a PC, now we talk in Gigabytes, and the price we pay is incomparable.
If multi level PV can be 46% efficient, and this tech can be added or perfected in another way, then mass produced, the only ones to complain will be nations who produce nothing but oil.
Comparative cost is absolutely relevant. You would not burn diamonds to fire a steel furnace would you? They are carbon you know. The comparison with CPUs etc is not relevant. They can be miniaturised & still perform as well or better than their ancestors. PVs are limited no matter how they are designed. Ultimately, the total amount of solar radiation falling on one square metre directly aimed at the sun in good conditions is 1kw.
Reply | Report Abuse | Link to thisThe maximum theoretically possible conversion efficiency for sunlight is 86% due to the Carnot limit, given the temperature of the photons emitted by the sun's surface. [6]See an excellent explanation:http://www.scientificamerican.com/article.cfm?id=nanowire-solar-photovoltaic-cell-achieves-record-efficiency&posted=1#comments
In laboratory conditions using concentrating optics about 43% has been achieved so if it were possible to achieve 100% of the possible the efficiency could be doubled whereas the efficiency of CUs has been repeatedly doubled.
Link error in post above. Should be: Comparative cost is absolutely relevant. You would not burn diamonds to fire a steel furnace would you? They are carbon you know. The comparison with CPUs etc is not relevant. They can be miniaturised & still perform as well or better than their ancestors. PVs are limited no matter how they are designed. Ultimately, the total amount of solar radiation falling on one square metre directly aimed at the sun in good conditions is 1kw.
Reply | Report Abuse | Link to thisThe maximum theoretically possible conversion efficiency for sunlight is 86% due to the Carnot limit, given the temperature of the photons emitted by the sun's surface. [6]See an excellent explanation: http://en.wikipedia.org/wiki/Solar_cell_efficiency
In laboratory conditions using concentrating optics about 43% has been achieved so if it were possible to achieve 100% of the possible the efficiency could be doubled whereas the efficiency of CUs has been repeatedly doubled.
How is 14 % efficiency a record if thin film cells work at 19 % ? As for peak power demand some people mentioned: locally it is in winter, on weekdays between 6 and 9 pm. Definitely after sunset.
Reply | Report Abuse | Link to thisThanks for the explanation. My main objection was that Carlyle dismisses this technology out of hand and is adamant that the research dollars on it are a waste. They do this without seeing ANY test data on the cells and I know for a fact that the test data that could conclusively prove what the degradation curves of these cells looks like doesn't even exist yet at this early stage of development. I'm just sick of Carlyle's knee-jerk reaction against anything that doesn't burn or fission to produce energy.
Reply | Report Abuse | Link to thisRun the numbers. Even with CURRENT PV efficiency, all you would need to power the USA's ENTIRE energy need is a square solar farm 100 miles on a side. We've got plenty of desert areas where nothing much else goes on besides the sun heating up and blowing sand around.
Reply | Report Abuse | Link to thisWhile this is not practical, 10,000 square miles can be divided up over the country's roof spaces, south-facing building facades, parking lots, and some open space. Since we waste around half the energy used in this country for no good reason, cut that down to 5,000 square miles. Throw in wind, wave, geothermal, etc., natural gas and a little bit of nuclear power (can't bulldoze all those plants we already built, they were really expensive!) and maybe you cut that down to 2,000 or 3,000 square miles!
Ole Sault is at it again. With his laughable claim of a BS and MS in engineering, he continues to spew.
Reply | Report Abuse | Link to thisAccording to the NREL if all the rooftops in the US were covered with solar cells less than 5% of the countries energy needs would be met even at the current 60 cent a kwh all in cost.
There is no way to store solar even overnight much less winter summer or over a rare 2 month rainy weather interval at less than a buck a kwh.
The CPU reference is relevant.
Reply | Report Abuse | Link to thisMiniaturisation is one thing, but the bit fight was to create the ICs in quantity, reliably, and with a good yield ratio, put that together with the quest to make them more stable, and it's easy to see an analogy.
The article refers to the need to make the system mass-producible, stable and reliable.
These are the things that are a constant struggle in all tech areas. Miniaturisation is just a way to make more transistors fit in a smaller space, whatever the end aim.
This tech has only just started. To dismiss it because it isn't going to be 100% efficient, or in it's present form an end product is daft.
I & others have frequently told you why PVs are not practical even with a suitable storage system if such a thing were possible. New advances can not eliminate the inherent problems & are diverting attention from making hard choices. It is like alternative medicine advising people against surgery. They have a softer choice. Problem is, without surgery, your going to die. You tell them that & they say, no we have just developed a new herbal treatment. It’s almost ready. Surgery will be a thing of the past. We just need more money. Patient dies.
Reply | Report Abuse | Link to thisO.k. compare the progress made since the 60s in gains with the two. How many times has each doubled its performance? Or do you think PVs are something new? Which technology has received billions in public funding support?
Reply | Report Abuse | Link to thisYou don't even listen. I admitted 100% pv isn't practical. You and seth constantly use this unrealistic scenario to argue that solar power also needs storage when nothing could be farther from the truth. The constant strawman arguments you use give away the fact that you haven't really looked into this issue like you claim. Sure, installing PV or whatever in the 80's is all well and good, but the industry has moved on from then a great deal.
Reply | Report Abuse | Link to this@sault, what you are hearing from Carlyle and the other denier trolls is panic. The world is changing and moving ahead without them. They are obsolete but instead of trying to keep up they lie to themselves and everyone else that despite the fact that they have done no research and have no qualifications, that they are right and everyone else is wrong. We should trust them because after all, who is more trust-worthy a scientist with evidence, published in a peer review journal or a troll with delusions, ranting in the comment section of a news article? Must be sad to suddenly find yourself worthless, fighting for the wrong side and so mired in political dogma that you don't know which side is up until Glenn Beck tells you.
Reply | Report Abuse | Link to thisNew developments have added how many hours of sunlight exactly. How many hours less dependant on back up? By how much has the extensive roll out reduced people’s power bills? Discounting the subsidised buy backs, carbon credits of course & all associated government subsidies? In fact power costs in countries like Germany have skyrocketed due to alternatives, particularly solar. I know your livelihood is tied to solar, but that applied to tulip growers & traders years ago before the bust. Just as surely there will be an alternative energy bust.
Reply | Report Abuse | Link to thisThe amount the market declined from peak to bottom: This number is difficult to calculate, but, we can tell you that at the peak of the market, a person could trade a single tulip for an entire estate, and, at the bottom, one tulip was the price of a common onion.
Read more: http://www.investopedia.com/features/crashes/crashes2.asp#ixzz2ITQpS4Kl
.
So your area of expertise again? Oh. Denigrating those with whom you disagree without offering any original contributions. sault I do not hold it against you that this intellectual pygmy likes to associate himself with your side of the debate. There are some equally moronic people nominally on my side of the debate. Though they do seem to be fewer :)
Reply | Report Abuse | Link to this@Carlyle, if you were capable of rational thought I would have a rational argument with you. As I've said many times before, the issue isn't a different interpretation of the facts, the issue is intentional misrepresentation of the facts and blatant lies. So the real issue is the low moral character of people such as yourself who are agenda driven rather than evidence driven.
Reply | Report Abuse | Link to thisNo one knows what the future of this technology will be. That is why we are doing the research. To suggest that past limitations apply in the case without looking at any of the engineering specs or participating in the science is nothing more than idiotic. Ultimately, this is only one piece of a many part puzzle so imposing constraints that would not have been addressed in this very targeted study is also idiotic. Saying that you know how this is all going to turn out and that, if they know what is good for them, they should abandon it post haste is revealing. What kind of person suggests that scientists should assume the answers and not bother to do research? A Luddite, a shill, someone who is afraid of the answers. I don't address people just because I don't agree with them, I call out people who attack science and the scientific process and have the audacity to do it here. You are the antithesis of a scientist. Why waste your time here?
So I would suggest you deal with your own insecurities instead of demanding the world slow down to accommodate your limitations?
@sethdayal, "There is no way to store solar even overnight much less winter summer or over a rare 2 month rainy weather interval at less than a buck a kwh." don't take this personally but you are either a liar or an ignoramus. You choose. You aren't limited to just one. First, solar panels still generate electricity on cloudy days. Second, solar panels generate electricity in winter. There are a number of storage options which are getting better all the time. Also, solar panels can be located closer to their consumers so less energy is lost during transmission. Finally, these numbers are all artificial. What happens when you factor in real costs. Take away the subsidies. Take away the environmental and healthcare costs. What you are left with is the fact that fossil fuels are not sustainable. Furthermore, the fact that you would talk about lowest output as though it were average output once again demonstrates that you are driven by ideology and not the facts. We have a new discovery and you and the other trolls are saying it won't work because of what things are like now or how they were. You don't seem to understand what science is about but then again why would you? You aren't a scientists, you are a right wing fanatic who wants to maintain the status-quo. You have nothing to contribute here but your ignorance.
Reply | Report Abuse | Link to thisYou & sault know each other; work in the same facility & claim intimate knowledge of this new development? Interesting. So you are not janitors because you both say you are scientists. With your intimate knowledge, dispense with the generalities & explain exactly how this new nano scale technology is designed to be impervious to thermal damage, particularly when utilised in conjunction with concentrating collectors.
Reply | Report Abuse | Link to thisWhen you have explained that, tell us about the improve storage developments.
@Carlyle, "Which technology has received billions in public funding support?". Fossil Fuels & Nuclear.
Reply | Report Abuse | Link to this@Carlyle, "explain exactly how this new nano scale technology is designed to be impervious to thermal damage", so let me get this straight, you can make the claim that this technology will fail, without looking at the technical specs, without conducting your own research, after having done nothing more than browsed a 1000ish word summary of the work and based on nothing more than that declare this project a failure and waste of money, but when you are challenged, it is everyone else's responsibility to prove you wrong. In other words, yours is always the default hypothesis. While you are looking up dunning-kruger please also look-up delusions-of-grandeur.
Reply | Report Abuse | Link to thisIf you read what I said, and I know you don't trouble yourself with reading things you disagree with, you'll note I said, no one knows how this will turn out, pointing out, that is the whole reason for doing the science. What you are claiming is that you already know everything about how this will turn out so it is a complete waste of time doing any science, if only they had come to you, the scientists who work in solar energy would have gotten the lesson in thermodynamics they so desperately needed.
You are obligated to prove your hypothesis. It is that simple. When you have done that, then I will be glad to read your paper. In the meantime I will consider the possibilities open for this technology despite what fanatical climate deniers think about it.
I am not obliged to prove my hypothesis, those seeking or spending public money should explain how they intend to overcome obvious problems facing their project when they make application. Mostly they do not.
Reply | Report Abuse | Link to thisif solar power continues on its exponential growth then it will power the world in about ten years.
Reply | Report Abuse | Link to thisPosting irrelevant links does not make up for the fact that EVERY CLAIM YOU HAVE MADE is totally unfounded. Please show me some "storage" built for solar power! You seem to be so familiar with it, you should have some just sitting in your backyard!
Reply | Report Abuse | Link to thisIf you want to do a full cost accounting of different energy sources, why do you consistently ignore the $100B - $500B in negative externalities that coal power ALONE causes in the USA EVERY YEAR?
http://pubs.aeaweb.org/doi/pdfplus/10.1257/aer.101.5.1649
http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2010.05890.x/abstract
Lets add up the historical subsidies that fossil fuels have enjoyed for over a century while we're at it! What about all the interest payments on stranded debt and nuclear industry bailouts too?
Oh, and this is the BEST! How in the world is this "power costs in countries like Germany have skyrocketed due to alternatives, particularly solar."????
"Power for 2014 delivery in Germany and France dropped to records as rising solar output is expected to cut demand for other electricity sources."
http://www.bloomberg.com/news/2013-01-16/european-power-for-february-rises-on-freezing-weather-forecasts.html
Time to get in step with reality, Carlyle!!!!
You obviously have no idea ho logic, arguments or even the Scientific Method works, do you?
Reply | Report Abuse | Link to thisYou are the one making claims, Carlyle. You have to back them up with evidence to have any credibility! We just want to know WHAT EVIDENCE you used to come to the conclusion that this technology won't work, or that clean energy in general won't "work". Where are you getting this information? As an engineer with a background and intense interest in clean energy, any concrete data you could provide to me would be very helpful.
Thermally toughened safety glass coefficient of expansion:
Reply | Report Abuse | Link to this- The linear heat expansion coefficient is 9 x 10-6 K-
A rule of thumb: An increase of temperature by100°C causes an expansion of approx. 1,0 mm/m
Now they are talking about using concentrating collectors. Other laboratory tests using concentrating collectors used over 400 to one concentration. Now you & sault being scientists will have no trouble calculating what temperature range this will impose on the glass from a subzero night temperature to clear sunshine concentrated by 400 times on a calm 20C ambient temperature day. With these figures & the known structure of the cells you can tell us how much the structure will be stretched between the nano spaced elements by the glass. Of course they will have expansion & contraction forces of their own to cope with also. Just start with the glass.
To claim that it is impossible to calculate these forces is ridiculous. In any case these figures would be known from conventional cells. Now tell me my contention is wrong that nano scale structures will be torn apart by these thermal forces. If I am wrong, show me where & I will conceed my mistake.
Sault #32 "to power the USA's ENTIRE energy need(ed) is a square solar farm 100 miles on a side."
Reply | Report Abuse | Link to thisWhere do get that figure from? MacKay, page 236 of the book (http://www.withouthotair.com/ he's one of the biggest experts in the game) gives 360 miles on a side (600km).
And this doesn't even take the storage problem into account, for which there is no solution.
"How is 14 % efficiency a record if thin film cells work at 19 % ? As for peak power demand some people mentioned: locally it is in winter, on weekdays between 6 and 9 pm. Definitely after sunset."
Reply | Report Abuse | Link to thisIt's a record for nanowire solar, not solar in general.
"I am not obliged to prove my hypothesis"
Reply | Report Abuse | Link to thisWithout taking sides in the overall debate, you are actually obliged to prove it. If one comes up with a hypothesis, that person is the one responsible for doing the research to back it up and turn it into a theory. Otherwise, it's just a collection of words.
sault, just how restricted is your knowledge of what is or has been done around the world. Even things that at least on the surface, lend support to your arguments, seem to have passed right under your radar. you asked me for proof of solar thermal power systems. There are plenty of them. See: ‘Power towers’ and storage
Reply | Report Abuse | Link to thisAttention is now focused on the recently completed German solar (pronounced ‘hemasolar’) Solar Tres project near Seville, also in the south. Solar Tres is the first commercial CST plant of ‘power tower’ design to have salt storage – some 15 h worth. The tower configuration allows the plant to achieve higher operating heat and efficiencies. The salt will be heated to ~565°C, meaning greater energy storage and greater thermal efficiency than for a trough plant. At these temperatures, each megawatt hour (MWh) of energy generated requires ~25 tonnes of salt. Plants operating at lower temperatures require proportionally more salt per unit of energy stored. Trough plants have an upper temperature of 400°C and store energy at the ratio of 1 MWh per 75 tonnes of salt. http://www.ecosmagazine.com/paper/EC10095.htm
Obtaining actual performance, reliability & costing figures has defeated all my efforts. Perhaps someone can supply authentic actual figures rather than projections.
It is those who put forward this system who have to prove it is viable. If you go to buy a car, it is up to the salesman to satisfy you about its performance. If you tell the salesman that you are dubious about the performance claimed, it is up to the seller to allay your concerns, not the buyer to prove his question is valid. I have asked a question & provided some hard data about the methods that can be used to answer my question. See my post No.50. What have I got in return except excuses, prevarication & criticism for daring to ask a perfectly valid question & expressing doubts?
Reply | Report Abuse | Link to this@Carlyle, "It is those who put forward this system who have to prove it is viable." Show me where it says that. You are like a child who is so obsessed with winning that he thinks he can change the rules of the game to favor himself whenever he likes. "If you go to buy a car" no one is trying to sell you anything. They are trying to make solar cells more efficient. That is it. They have no obligation to prove that solar technology meets your definition of financially viable. This is a science site but you and your denier friends use it as a platform to advance your agenda. That makes you a troll. Why should anyone respect what you have to say?
Reply | Report Abuse | Link to thisConcentrating pv usually has heat sinks / radiators thermally coupled to the cells. Again, here you go, cherry-picking worst case scenarios and ignoring key facts in a blatant attempt to justify your clear prejudice against clean energy.
Reply | Report Abuse | Link to thisYou're either obfuscating by intentionally changing the subject or you have no idea what you're talking about. We're talking about SOLAR PV here, not solar thermal. You DO know the difference, right? Solar thermal needs direct sunlight to collect heat. Having a little bit of storage helps these plants keep steady production going when a cloud rolls overhead. Having hours and hours of storage allows a solar thermal plant to be dispatchable and act more like a baseload plant.
Reply | Report Abuse | Link to thisSolar PV generates on sunny or cloudy days. While output is lower on less sunny days, it is still a decent percentage of the array's full output (depends on the type of cell). PV acts like a negative load when it is producing, cancelling out a portion of demand wherever it happens to be installed. It doesn't need storage unless you're off the grid, living in some cabin in the woods.
Why you would confuse this and solar thermal power is beyond be.
#48, sault, power costs have gone up considerably in Germany. Apart from that you can choose to buy "oekostrom" ecological power in Germany, it costs more than ordinary power. Btw, the nuclear power stations they are closing down are being replaced by lignite powered station, but if they are more then 50% efficient their output is considered "oekostrom". A lot of houses have PV panels on their roofs, and feed in tariffs are Euro 0.5, but some interest groups are pushing to double them. And that in a country that is rather unsuitable for both wind and solar. Somebody has to pay for that. But I am an optimist and hope this technology brings the breakthrough we are looking for. Which still leaves us then with the problem of finding a storage medium.
Reply | Report Abuse | Link to thisHe was talking about solar power in England which doesn't get as much sun a the U.S. southwest. He also assumed 10% efficient solar panels, which is an antiquated assumption in a market where 15% efficiency is the baseline and manufacturers are going from there.
Reply | Report Abuse | Link to thisGerman electricity rates have gone up mostly because utilities have increased their profit margin from 1.1% to 8.2%:
Reply | Report Abuse | Link to this"Yep, just as solar boomed, driving down the wholesale cost of electricity on many a day (or even turning it negative), and wind boomed, driving down the wholesale price of electricity on many a night, utility companies’ profits boomed!
Admittedly, the retail power rate in Germany (which is not set by the government, but rather by the market; any household in Germany can switch to any power provider) has risen by around 20 percent since 2007. But an analysis by Germany’s Network Agency, which regulates gas networks and power grids, also recently found that the profits of power firms rose during that time from a profit margin of 1.1 to 8.2 percent. The Agency says that the net rate for power could have even dropped since 2009 had power firms passed on the lower cost of wholesale power to consumers; but unfortunately, only the factors that increased prices were passed on."
http://cleantechnica.com/2012/09/03/german-electricity-prices-rise-as-utilities-increase-their-profit-margin-from-1-1-to-8-2/
Wow. What profiteering. Just imagine. 8.2% profit. Who would invest in infrastructure with margins like that. Or maintenance come to that.
Reply | Report Abuse | Link to thisWell, the German power providers were doing just fine with 1.1% margins! It's disingenuous fossil fuel shills that try to blame higher power prices on clean energy instead of the German utilities taking higher profit margins that actually caused the rate increases! And on top of that, the utilities aren't passing on the savings from lower wholesale electricity prices that clean energy provides to their customers!
Reply | Report Abuse | Link to thisLook, you can't ignore the fact that clean energy works, especially when a coherent energy policy like Germany's is put in place. They can install solar at half the price that the USA can because a lot of the red tape and market barriers have been streamlined or removed there. All that baloney you hear coming (directly or indirectly) from fossil fuel companies is just meant to obscure this truth from you.
After reading many of the posts here it seems as though there may be a confusion between efficiency in regards to PV. Efficiency is the measure of maximum power output divided by effective light power incident on the panel. This number can range from 3% to up to 40% and is a fixed performance value for the panel with little to no connection to its use. This fixed number depends on the manufacturing and properties of the materials used to absorb light.
Reply | Report Abuse | Link to thisThere is another value often confused with efficiency called the capacity factor. The capacity factor of any power system is the ratio of the average power output to the rated power output. The rated output is the amount of power the system is capable of producing. For solar cells this value is between 10% and 25%. In comparison to other systems; nuclear 90%, or coal 60%. The reasons for the low capacity factor is that the sun rises and set, and clouds can block sunlight in some locations. Until efficient and economical power storage is found solar will continue to perform on average at less than 1/4 its rated capacity. The maximum capacity factor for PV that can be achieved without storage is somewhere roughly between 25% and 33%.
Its easy to get efficiency and capacity factor confused, but it is important to make the distinction. Without this distinction it is difficult to distinguish what is an intrinsic and environmental impacts on PV performance.
(In the following post I will explain the issues with using solar for peak power)
So many of you have heard that solar can be used for peak power. This is true but solar also has some disadvantages for this use in the current electric grid. PV does not provide a consistent output (depending on location) and tends to oscillate throughout the day. Now the issue with this is that the power output is not oscillating with demand, such that sometimes the power is overabundant and sometimes in shorter supply. To provide a power supply consistent with demand the base-load providers such as coal, gas, and nuclear would have to compensate for the oscillations in solar. The issue with this is that ramping up and down in power puts strain on the equipment and the plant. This causes equipment to wear down faster and have to be replaced more often. Replacing equipment costs money which is reflected in the cost of power.
Reply | Report Abuse | Link to thisNow the good news is that solar is not a large part of the grid (<1%) so this issue is not significant yet; however, it is a reality that utilities are looking at when considering the expansion of solar and wind. With a push towards "green" energy one of the solutions has been adopting small module reactors (SMR). These nuclear reactors provide power comparable to small coal units and can be ramped up and down in power more quickly than traditional nuclear plants but still have the issue of equipment strain. Other solutions may involve the smart grid currently under R&D.
Overall PV will need to be able to better stabilize its power output as it becomes an increasingly important source of electricity. Stabilizing the power will mean the ability to prevent spikes in power output, a problem less significant in areas with few clouds. Different groups are already underway to determine how to best effectively use PV, especially in those areas where sunlight is not consistent throughout the day.
sault #59
Reply | Report Abuse | Link to this"...he was talking about ...England.."
I'm sorry but that's just not correct: the 360 mile square is shown right on the southernmost part of the USA, where's there's most sun obviously.
As for increased efficiency of solar, if even we accept your figure that it's now 50% more efficient (which I strongly doubt) that still gives a square side of 250 miles against your 100 miles.
So you were only out by x5, instead of x10! Don't worry though, a discrepancy like that is well within range for a greenie.
The increased profit margin in Germany cannot account for more that a fraction of the cost to consumers. It's only in a communist system that a firm is long-term viable with a 1% profit margin: it's far too close to negative values for comfort.
engineer238 : there's also capacity credit to consider, which admittedly is not easy, but is very important. It has to do with so-called dispatchability, i.e getting the power when you need it.
In Europe power produced by renewables is often effectively dumped, because it's not needed when it comes. They try to hide this problem by forcing utilities to take renewable power in preference to other power sources even when it's not economic. The result is that the baseload power facilities have to run at reduced thermal efficiency, further increasing carbon output.
So how come taxpayers around the world are being compelled to pay for these PV systems when these basic foundation stones have not even been quarried yet let alone put in place. It is nothing short of scandalous.
Reply | Report Abuse | Link to thisFortunately, innovation will continue even past the time when alternative energy becomes economical.
Reply | Report Abuse | Link to thisThere doesn't seem to be any other choice to stop the pollution then to innovate our way out of the problem.
I cheer the scientists and engineers who are working toward feasible solutions. I also applaud the scientific press that publishes articles on scientific advances. These publications make new technology known to other innovators.
It's because the governments see them as an investment. Solar is not all bad, but it is still an emergent technology as far as economics go. I wouldn't go as far as to call it scandalous but I do not necessarily agree with subsidizing any power source. Those foundations aren't necessary but they will help dramatically. As I said as long as solar and wind stay less than maybe 3-5% of the total grid there won't be dramatic problems. The capacity factor problem is one that has limits simply due to the solar cycle. As of right now the economics still favor gas, coal and nuclear as the heavy hitters on the grid. The increasing price of coal is partly artificially created by increasing regulation.
Reply | Report Abuse | Link to thisIs it 14% 71% 43%? I realize these are in reference to different things, but it gets really confusing when the difference isn't really explained, and if you're not reading really, really carefully.
Reply | Report Abuse | Link to this- 14% is the intensity of light captured and transformed into electricity in the semiconductor compared to the total intensity of the light incident on the panel. This figure is the measure of the net performance of the cell. It tells you how much power in electricity you will get for a given amount of power of the suns light shining on it. The power of the sunlight incident on the cell can be controlled by having reflectors that re-direct sunlight onto the cell. The downside to pointing more light on the cell is that it heats up and may not generate electricity as effectively (see 43%).
Reply | Report Abuse | Link to this- 71% is the fraction of the frequencies of light with energies greater than the band gap that are absorbed. The band gap for indium phosphide is around 1.3eV. The frequencies with energy greater than the band gap are the high end of infrared and upward through visible light and UV. To figure out how this translate to performance you need to know the exact frequencies absorbed and the intensity of each of those frequencies from the sun on the earth's surface. In this case the number is presented more as a point to impress the reader than an actually usable quantity.
- 43% is the fraction of the energy of incoming light that is converted to electricity in the cell. This percentage has to do with the ability of electrons excited by light to move freely through the semi-conductor. When electrons are excited by light in a semi-conductor they may move around between atoms or they can loss energy and be 'trapped' by scattering with defects and grain boundaries or with atoms causing vibrations in the crystal structure of the semi-conductor. This process of atom-electron scattering is called electron-phonon scattering. Higher temperatures causes the number of equilibrium defects and vibrations (phonons) in the semi-conductor to increase resulting in increased electron-phonon scattering and defect scattering. This increase in scattering further inhibits the movement of electrons decreasing the efficiency with which the solar cell converts light into electricity.
57. sault in reply to Carlyle 01:12 PM 1/20/13 You claim that solar PVs generate power even in cloudy conditions. The output is compromised depending on how diffuse the incoming radiation is & how much impacts the collector. Part of this article discusses concentrating collectors. Just try concentrating diffuse light & see how you go whether it be concentrating for thermal or PV. You have a very expensive piece of equipment generating nothing.
Reply | Report Abuse | Link to thissolar energy is more than doubling every two years. It is called exponential growth. if it continues growing at this rate, and cost per watt continue dropping, then solar power will be cost competitive with other energy sources in less than 10 years. i believe combination of solar, wind, and nuclear power are the future. can i get an amen?
Reply | Report Abuse | Link to thishttp://www.theequitykicker.com/2012/09/25/solar-powera-case-study-in-exponential-growth/
That is what people were saying back in the 1980s.
Reply | Report Abuse | Link to thisCarlyle, did we ruffle your feathers here? MY, my, but you do seem to be tweaked.
Reply | Report Abuse | Link to thisWe need to start making solar panels by the square mile and not keep waiting for maximum efficiencies to come out of the lab.
Reply | Report Abuse | Link to thisMaximum efficiency instead of maximum energy return per dollar should in fact be the aim. We do not need Ferrari PVs. Who cares it's only tax payers money.
Reply | Report Abuse | Link to thisTried finding hundreds of square miles yet that are not already serving a good purpose. Must also be close to infrastructure, free of flooding or dust storms & definitely not endangering the five legged thingamy that has not been discovered yet. Good luck with that.
Dear Carlyle,
Reply | Report Abuse | Link to thisEfficiency and price per watt go hand in hand. in the 1980's solar power was around $27/watt. Solar is now less than a $1/watt. Gas prices in the 80's were a little over $1 per gallon. Now they are over $3 per gallon. Soon gas will be over $5 per gallon and solar will be less than $.25 per watt. Solar energy is very similar to Moore's Law aka the Law of Accelerating returns.
Well it's certainly been an interesting discussion between the protagonists, however I feel I should make one point.
Reply | Report Abuse | Link to thisIt's doesn't matter how much more recoverable fossil fuels are discovered, the planets atmosphere already has nearly 400ppm CO2 plus many other even more harmful green house gases. The few courageous souls, especially here in the USA, doing their best to develop the best solar and other renewable energy sources need to be encouraged. So what if there are numerous problems and obstacles to making these systems efficient and usable in everyday applications.
Even from an airborne pollutant perspective, forgetting about global warming, the planet desperately needs these technologies and a forum like this should acknowledge this.
Everytime I see a new development in solar, I really smile, as for me it's only a matter of time before these systems take off. I'm all for freedom of expression guys, however from my perspective many of the comments have been petty and just plain argumentative.
A huge transition is in progress, start paddling in the right direction.
Everytime I see a new development in solar, I really smile, as for me it's only a matter of time before these systems take off.
Reply | Report Abuse | Link to thisI smile too. Especially at the claim of solar at $1 per watt. What about installed cost? What about the back up cost? What about depreciation & maintenance? What about the cost of land, roads, water, transmission lines & infrastructure? Solar will NEVER be a base load reliable, economic supplier. The sun will not be delivering more energy per meter than it is now & except for short periods at the poles, not 24/7 either.
A local to me coal fired power station generates 1.8 Gig 24/7.
Reply | Report Abuse | Link to thisThe recently completed tracking PV installation:
http://www.army.mil/article/94468/Corps_of_Engineers_completes_Army_s_largest_solar_array_installation/
can generate a little over .1 of a Gig during ideal conditions. The figures are all there. See how much per watt it cost. By the way the generating capacity is not net either. Does not cover parasitic losses.
That was per square mile by the way. To match my local power station that plant would cover 16.3 square miles & even then only for a few hours per day at that output level. Efficiency is raised by tracking but so is cost & maintenance.
Reply | Report Abuse | Link to this