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The dish is composed of a set of 10 inch by 12 foot curved mirrors, like the one seen here. The students easily mount the mirrors to the aluminum framework using simple hardware like washers and zip ties.  (Source: MIT)

The mirrors incredible power makes short work of a beam of wood, disintegrating it in flames and smoke. The focal point can melt steel.  (Source: MIT)
New solar dish from MIT concentrates sunlight intensely enough to melt steel

The solar industry is booming.  With waves of investment and grants, the solar power industry is for the first time becoming a serious business.  New power plants will soon be pumping power out to consumers, while other firms market to sell panels directly to the consumer, providing them with a more direct means of experiencing solar energy.

There are many forms of solar power technology.  Today the most dominant is photo-voltaics, which comprise the traditional solar panels that come to mind when one thinks of solar power.  However, there are other promising ways of capturing the sun's energy that are merely less developed.

Among these is a parabolic collector.  A parabolic collector consists of an array of mirrors focused on a singular point, which they heat to a high temperature.  By placing water or another liquid at the collector, energy can be stored in the form of a phase transformation, and later harvested through a turbine generator.

However, parabolic collectors are still a relatively new field of research.  Their true potential remains relatively unknown.  A glimpse of it was provided by a research team at MIT, which developed a new parabolic collector design, which will blow away current solar power designs in terms of efficiency.

The MIT team believes that their lightweight, inexpensive device holds the promise of revolutionizing the power industry and providing solar power to even remote regions.

The key piece is the 12-foot dish, which the team assembled in several weeks.  The design is exceedingly simple and inexpensive.  The frame is composed of aluminum tubing and mirrors are attached to it.

The results are staggering -- the completed mirror focuses enough solar energy at its focal point to melt solid steel.  The energy of typical sunlight is concentrated by a factor of 1,000.  This was showcased during a demonstration, in which a team member held up a board, which instantly and violently combusted, when brought within range of the focal point.

By directing the dish at a more practical target -- water piped through black tubing -- steam can be flash created, offering instant means of producing energy or providing heating. 

Spencer Ahrens, who just received his master's in mechanical engineering from MIT, was among the designers of the dish.  He and his fellow team members are serious about marketing it, and leveraging its cheap cost and easy production.  They have founded a company named RawSolar.  They say their design is easily mass producible and that they hope to be pumping out 1,000 of dishes in years to come.

The new dishes would return their costs in a mere couple years, unlike standard photo-voltaic installations which can take 10 years or more to return their costs.  This improvement is critical to providing practical economic justification for adoption.

The dish is based partly on components invented and patented by inventor Doug Wood.  He was so pleased with the team's work that he signed over rights to the components to the team.  He elates, "This is actually the most efficient solar collector in existence, and it was just completed.  They really have simplified this and made it user-friendly, so anybody can build it."

Wood says one of the keys to the success of the project is the smaller size.  Dishes are affected by the same weight dynamics that effect living organisms.  Much as large living organisms would need an inordinate amount of weight support and thus are not favored, larger dish designs fall short in that they require an exponentially greater amount of infrastructure.  For example, a dish the size of the RawSolar team's design costs only a third of what a larger dish would cost.

MIT Sloan School of Management lecturer David Pelly gave a guiding hand to the students and thinks the economic upsides of the technology are impressive.  He states, "I've looked for years at a variety of solar approaches, and this is the cheapest I've seen. And the key thing in scaling it globally is that all of the materials are inexpensive and accessible anywhere in the world.  I've looked all over for solar technology that could scale without subsidies. Almost nothing I've looked at has that potential. This does."

The ability to build unsubsidized, profitable, and easy to manufacture solar power will truly be something amazing.  This should be an exciting technology to follow as it is marketed and further developed.

Besides Ahrens, the other students primarily working on the project were Micah Sze (Sloan MBA '08), UC Berkeley graduate and Broad Institute engineer Eva Markiewicz, Olin College student Matt Ritter and MIT materials science student Anna Bershteyn.

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By Mitch101 on 6/21/2008 4:35:05 PM , Rating: 3
Looks like Mythbusters are going to have to revisit Archimedes killer mirrors again

RE: Mythbusters
By trajan on 6/21/2008 4:45:26 PM , Rating: 5
Nahh.. If I remember the myth of Archimedes, it was that he burned Persian ships out at sea from the shoreline. Building a parabolic mirror that can incinerate wood at a short distance is nothing new, but doing it at a range of half a kilometer or so -- that would be impressive. THEN, try doing it using bronze or other materials available to the ancient Greeks.

If the MIT device is novel, its only because its cheap to build and relatively high efficiency, both of which are very important for the future of solar energy.

RE: Mythbusters
By Goty on 6/21/2008 7:17:38 PM , Rating: 3
If the collecting area remains unchanged, all you have to do is change the focal point of the mirror.

RE: Mythbusters
By freeagle on 6/21/2008 7:49:16 PM , Rating: 3
but focusing several mirrors on a close-range focal point is way easier than focusing on something several hundreds meters away

RE: Mythbusters
By Goty on 6/21/2008 9:18:11 PM , Rating: 3
Well, yeah, it's easier, but that doesn't mean long-distance focusing isn't possible.

RE: Mythbusters
By Flunk on 6/21/2008 9:51:59 PM , Rating: 3
You forget, the technology to create curved mirrors did not exist so the point is mute.

RE: Mythbusters
By drank12quartsstrohsbeer on 6/21/2008 10:38:26 PM , Rating: 3
i think 'moot' is the word you are looking for. And how do you know that curved reflectors could not be produced? they most certainly had the technology to make a curved reflector.

RE: Mythbusters
By omnicronx on 6/27/2008 9:03:04 PM , Rating: 2
And how do you know that curved reflectors could not be produced?
Mirrors were not known to exist for 800 years after Archimedes 'apparently' created this death ray. Its pretty hard to believe that not only did he have something that did not exist(mirrors), but he also figured out how to curve the them. Seems pretty unlikely to me.

RE: Mythbusters
By masher2 on 6/21/2008 11:32:08 PM , Rating: 3
> "You forget, the technology to create curved mirrors did not exist so the point is mute"

You don't need a curved mirror to build a parabolic reflector; you simply need a large number of flat reflective segments, arranged on a parabolic surface...something which the Greeks certainly knew themselves.

RE: Mythbusters
By TheBaker on 6/22/2008 12:35:02 AM , Rating: 2
Yeah, but if you don't use curved mirrors you get a "stack" of flat panels of light, rather than a true parabolic reflector.

That is, the energy is focused into a (for example) 12" x 12" square rather than a 1" x1" (or smaller) area. The energy in the large square would make something really hot, while that same energy in the small square would be 144 times more powerful, and would burn things to a crisp. Make it a true parabola and the energy is condensed to a point source. Eventually, you get what these kids at MIT came up with.

They didn't do anything new, they just did it with more precision and efficiency than before.

RE: Mythbusters
By masher2 on 6/22/2008 12:46:14 PM , Rating: 5
Even a mathematically perfect parabolic reflector won't focus to a light to a single point. The minimum focus size is defined by many factors: aperture (size) of the reflector, wavelength of the reflected light, visual size of the sun or other psuedo-point source, etc.

So in reality, nothing is a "true"parabola. If a stacked mirror such as this contained, say, 1000 flat segments, the intensity at the focus could be as strong as 500X normal solar flux....certainly hot enough to ignite wood.

RE: Mythbusters
By blue7053 on 6/26/2008 6:48:06 PM , Rating: 2
The embarassing thing about this is the number of people who are amazed by it. 'The kids' at MIT didn't do it, some guy in Iowa did it and showed them where to buy 12' mirrors. There is absolutely nothing new here except the knowledge of the melting point of steel. Even there, they don't enumerate it. They just wave in the general direction.

RE: Mythbusters
By achintya on 6/22/2008 1:54:23 PM , Rating: 3
Yeah, but after a point, if you scale the piecemeal 'parabolic' mirror up it slowly starts achieving the shape of a true parabola. Basic geometry. Even a polygon with enough sides starts looking something like a circle. Think of a polygon with over 20 sides. Looks enough like a circle anyways. Most new large telescopes are made the same way by assembling many small straight pieces.

RE: Mythbusters
By someguy743 on 6/22/2008 3:39:16 PM , Rating: 2
Wow, this new solar thermal technology really could be revolutionary. I'd like to know what the "solar to grid conversion efficiency" number is for this solar thermal dish. Stirling Energy already makes a larger sized one that looks similar. It set the record for efficiency at 31.25%:

If Raw Solar's solar dish is a lot more efficient than Stirling Energy's AND it is a lot cheaper to manufacture and deploy in the field then these MIT guys might be sitting on a gold mine. Big Coal and the other fossil fuel industries won't like this one bit. :) It really could reach and exceed the price per kilowatt that coal is now. Now ... if only the solar thermal industry can get some really cheap energy storage technology to come out, they've got the world by the tail.

Cheaper energy storage and cheaper transmission lines are all that's standing in the way of solar thermal, photovoltaic and wind from becoming the dominant energy sources in the next 20 years ... in a super efficient and flexible "smart grid". I bet it's going to happen. The dream might soon be realized. Inexpensive, inexhaustible, non polluting clean energy that will NEVER run out and cannot be manipulated nearly as much by the Wall Street schemers and Big Oil, etc. :)

RE: Mythbusters
By masher2 on 6/22/2008 3:54:04 PM , Rating: 3
> "Stirling Energy already makes a larger sized one that looks similar. It set the record for efficiency at 31.25%:"

Concentrating solar cells already exist which have efficiencies in excess of 40%. They're still far more expensive than coal or nuclear.

RE: Mythbusters
By Denithor on 6/23/2008 9:00:44 AM , Rating: 2
Inexpensive, inexhaustible, non polluting clean energy that will NEVER run out and cannot be manipulated nearly as much by the Wall Street schemers and Big Oil, etc.

...which is exactly why it likely won't happen for several years.

RE: Mythbusters
By jskirwin on 6/27/2008 3:50:36 PM , Rating: 2
Inexpensive, inexhaustible, non polluting clean energy that will NEVER run out and cannot be manipulated nearly as much by the Wall Street schemers and Big Oil, etc.

Electricity gets manipulated all the time by Wall Street schemers (Is that what some call investors nowadays?) Enron did it to California in 2001.

RE: Mythbusters
By blue7053 on 6/26/2008 7:11:25 PM , Rating: 2
I don't know whether this is new or not, nevertheless I worked it out 20 years ago. Showed it to a country neighbor once, he said, "Oh yeah. I read about that in a magazine."

Forming the Greek parabola:
Start with a 4x8 sheet of plywood, drive a nail in lower left corner of the long side.
Tie one end of an 8' string to the nail, double the string, (now 4') and put your pencil in the loop of the string.
Hold one end of the string at the nail and the other end with the pencil at the upper left side of the plywood.
Move the free end of the string along the bottom side of the plywood and the pencil to the right, maintaining a right triangle relationship between the nail, the pencil and the free end of the string.
As you move the pencil and the free end of the string to the right, you will be drawing a curved line describing the point of the opposite side and the hypotenuse. As the opposite side of the triangle moves away from the nail, the opposite side diminishes as the base and the hyoptenuse increase. The relationship amoung the sides remains constant.
When you end up with your 8' string at the lower right corner of the plywood, you will have half a parabola described across the sheet of plywood. The focal point is the nail.

RE: Mythbusters
By lco45 on 6/23/2008 4:07:22 AM , Rating: 2
A stack of flat mirrors is the same as one curved mirror, if you know your calculus.

A curve is just a bunch of straight lines, with the length of each line tending towards zero.

The greeks understood calculus, although not to the degree the Newtonians took it. Google "squaring the circle" for info on an early greek take on calculus.


RE: Mythbusters
By masher2 on 6/23/2008 11:24:17 AM , Rating: 2
More precisely, a curve can be considered a set of infinitely short line segments. There is a difference between a stack of flat mirrors and a curve...but that difference tends to zero as the size of the mirrors decreases.

And 'squaring the circle' isn't calculus. It's the equivalent problem to finding the area bounded by a curve, a problem which can also be solved by integral calculus..

RE: Mythbusters
By mpc7488 on 6/22/2008 12:16:18 AM , Rating: 4
Did you guys watch the actual show? They dealt with a lot of these questions after they had the first show, then invited MIT back for the re-visit.

It wasn't the distance itself that made it fail, it was the fact that the ship was moving. Even a slight shift brings it outside the focal point, which requires re-alignment (not trivial at all), in which time it's moved again, etc. It was pretty neat to watch them make the ship smoke though, even if they couldn't ignite it in flames.

RE: Mythbusters
By masher2 on 6/22/2008 12:37:22 PM , Rating: 2
> "It wasn't the distance itself that made it fail, it was the fact that the ship was moving"

But of course, in the time of the Persians, attacking ships would not have always been moving. In this day of motorboats and jet skis, people forget that ancient ships could not move against wind and tide. You couldn't simply sail (or even row) into any harbor whenever you wished; you needed conditions to be right.

The normal process was therefore to approach a harbor, then anchor until tide and/or wind was favorable for entry.

RE: Mythbusters
By tmouse on 6/24/2008 9:43:33 AM , Rating: 2
I guess you did not see the show. The MIT group tried and totally failed. The materials available at that time (bronze) was far inferior to silvered glass, the ship was rock steady in their tests in a calm bay slip, not the ocean; even bringing it in to 50 feet just got a slow smolder (this was a VERY dry old ship, not one that just made a voyage and would have been far damper). Add to this Syracuse faced east limiting the use of the weapon to the weaker morning rays and the availability of other more practical fire based methods and it seems very implausible. Even historically; it took 300 years to even mention that fire was used in the battle and the use of mirrors was never mentioned till 800 years later.

RE: Mythbusters
By mindless1 on 6/26/2008 6:16:57 PM , Rating: 2
Maybe they spent a great deal more time refining it than the basic mythbusters test did. Mythbusters is an interesting show but they try to take a know-it-all attitude instead of realizing they don't actually have all the variables resolved in their one-off tests.

RE: Mythbusters
By tmouse on 6/27/2008 8:21:10 AM , Rating: 2
Possibly but not likely; this is the second or third time they looked into it and the MIT group spent ALOT of time on it. Think about it; a defense like that would not likely disappear. Even though things like the formula for Greek fire are gone there are MANY independent references to it and most of the other colossal weapons developed during that age. There is only a single reference to the magic mirror, the rest are references to it.

RE: Mythbusters
By radializer on 6/24/2008 10:00:11 PM , Rating: 2
If the MIT device is novel, its only because its cheap to build and relatively high efficiency, both of which are very important for the future of solar energy.

Is it truly, though? Not much in the above write-up offers either figures for comparison or relative merits in terms of power concentration efficiency as compared to other existing schemes. I acknowledge the relevance of the MIT team's work but would prefer more numbers and analysis to proclaim that it is "revolutionary" indeed.

The single parabolic dish has the highest energy concentration efficiency - but this does not necessarily translate into gross efficiency since you cannot pack these dishes together as closely as you could a parabolic Trough system or a Fresnel Reflector system.

Also, unlike Troughs or Flat Mirror systems, parabolic dishes need dual-axis tracking (altitude & azimuth or RA and declination; pick your poison) which adds to the complexity of the tracking required. So it would be interesting and more valuable to compare these systems on the gross energy efficiency (energy produced per actual installation area with periphery included) or cost per kWh produced instead.

For reference on parabolic dishes; Sandia Labs has a dish-Sterling system made of laminated aluminum mirrors (82 of them) arranged in the shape of a dish on a steel frame (patented in 1990) that can achieve a net solar-to-electric conversion efficiency that reaches 30%.

For more on Trough and Tower designs, check out this study by the National Renewable Energy Labs

Just for fun, here's a parabolic reflector that they claim could achieve 8500 degrees (not sure what units but still pretty hot) ... check out the page scan from this March 1954 edition of Popular Science

RE: Mythbusters
By heeros1 on 6/22/2008 2:43:59 PM , Rating: 2
Looks like Mythbusters are going to have to revisit Archimedes killer mirrors again

That was the first thing that came to mind when I was reading this article.

By Howard on 6/21/2008 7:07:22 PM , Rating: 2
Tell me again how this is revolutionary?

RE: Subject
By CloudFire on 6/21/2008 8:07:42 PM , Rating: 1
because no one has ever thought of this idea before? it might be simple as the concept is the same as magnifying glasses used to burn ants, but they took it and expanded it.

the greatest ideas often times can be the simplest.

RE: Subject
By tanishalfelven on 6/21/08, Rating: -1
RE: Subject
By Doormat on 6/22/2008 1:41:23 AM , Rating: 2
Well #1 is the standard solar power question. Problem #3 is easy - you just angle the dish away from the direction of the hail, wind, etc.

#2 is an excellent problem - its probably the biggest problem with this type of solar concentrator. Yea it can concentrate a ton of heat onto one point, however the problem then is how do you mount whatever device you want at that point to do something with that heat.

You cant really put a fluid tube like a traditional solar thermal concentrator (NV Solar one) because for this device to work it has to be on a two axis tracker, and you'd need a flexible pipe to convey the thermal transfer fluid form one dish to the next to get heated up. Its not practical for it to be flexible and withstand the heat.

What you really have to put out at the focal point is a sterling engine or steam engine, and thats heavy because of the structure needed to hold the device in place.

RE: Subject
By masher2 on 6/22/08, Rating: 0
RE: Subject
By ahdlm on 6/23/2008 2:05:10 PM , Rating: 2
"And how does one do that,"

we seem to manage to keep all of our TV sattelite dishes from blowing away or being beaten to a pulp by hail. why would this be any different?

angling the dish to track the sun is easily automated.

and, why don't you pick the most inappropriate use of the technology as a reason why it won't work. on sailboats? that's akin to suggesting the use of a nuclear reactor on a moped.

RE: Subject
By elpresidente2075 on 6/23/2008 4:53:04 PM , Rating: 2
we seem to manage to keep all of our TV sattelite dishes from blowing away or being beaten to a pulp by hail. why would this be any different?

Because those aren't made of curved glass. A TV satellite dish is made usually of some sort of metal mesh, and often covered with a fiberglass protective coating, neither of which has "Light Reflectivity" as it's purpose. With a system based on mirrors, you need to keep the surfaces relatively clean and damage free for the system to continue working.

That said, just build a dome with one big (flat) glass window on it and just clean that big one. Then just enable the whole structure to rotate into a protective shell-type covering when dangerous weather approaches. Sure, you'll lose a bit of the solar energy, but you could put transparent PV cells in there (the window) to perhaps utilize some of the other wavelengths of light that would otherwise be wasted.

If the problem with a technology is only the fact that it is too expensive to implement efficiently, I am of the opinion that it is only a matter of time until it (or something based on it) becomes a standard and efficient way of doing that which it is designed to do.

RE: Subject
By G2cool on 6/24/2008 12:52:32 PM , Rating: 2
Too easy! Bring in the Chinese to shoot down the weather!

RE: Subject
By ahdlm on 6/23/2008 2:00:48 PM , Rating: 2
plenty of flexible, reinforced steam tubing and articulated pressure / heat rated fittings available if steam is the desired product. the apparatus at the focus doesn't need to be flexible, just where it all needs to rotate in tracking the sun. probably somewhere under the dish.

RE: Subject
By FredEx on 6/23/2008 4:48:00 AM , Rating: 2
Depends on the cloud cover. It can still work up to a point.

Keeping the dish aimed is not real difficult.

You can make the reflective surface something other than a glass mirror. A mirror polished metal for example.

Back in the 70's when I was in tech school a teacher read an article in a magazine about using a parabolic dish to heat water. We split our class in to 2 groups, he did that with all his classes. In all there were 6 groups. He set some parameters and told us to do our best. He wanted us to fashion a 12" parabolic dish with a 3" focal point and it had to track the sun. It was supposed to heat water. My group, rather than make a dish made a parabolic reflector, but only on one axis. My roommate worked at a machine shop and we made a framework out of aluminum. We had the CNC machine cut a parabolic shaped groove in each end. Just for a temporary thing we slid sheet metal into the grooves which flexed it into a parabolic curve that was 12" by 12" with a 3" focal point. Doing that we had a long focal point across the reflector that we put .5" copper tubing painted flat black across. We went to Radio Shack and got various sensors and found a photo transistor that worked best. 2 for vertical and 2 for horizontal adjustment. Each pair ran into a comparator circuit we designed to control our axis motors. We were running out of time and money, so we bought some aquarium mirror mylar to fasten to the sheet metal for the reflector. We had wanted to get a curved piece of aluminum polished or a curved piece of metal chromed for the reflector. There was a lot more to it, such as a Z80 based microprocessor controller, but I've rambled enough. Basically we ended up with a device where we could track the sun and we could pump water in at one end of the copper pipe at a slow rate and we had steam coming out at the other end. That was on that small set-up. Something larger would have been down right dangerous.

We never completed it for class, we all went far beyond what the teacher thought we would in the time given. He never thought we'd get beyond the planning and circuit schematics. We all had varying degrees of a working unit. Ours worked the best, but we didn't do a dish, we did a curved parabolic reflector. They hit us on that. The others were way off on the 12" dish and the 3" focal point. They had done very rough dishes, but they were typically around 2' to 3'. We had proven our tracking worked though, the only ones that worked reliably, but we hadn't finished the programming for resetting back to the east for the next day of tracking. He gave us all A's, in all the groups.

About 31 years later I wonder if my roommate still has that set-up. We let him take it, since he'd popped for the aluminum and worked at the machine shop. I had all the circuitry since we did it on my Heathkit breadboard.

RE: Subject
By vapore0n on 6/23/2008 9:08:01 AM , Rating: 2
most closed minded comment ive seen yet

Solar energy does not work when its cloudy, or at night. That is a given and other energy methods needs to be used.
Or how about store the excess energy to use at night?

the angle might need to be readjusted through out the day. The whole panel needs to move so that it keeps the sun at the best angle. You would think they would use flexible glass or movable panels.

hail, wind, etc, all part of nature. A site survey would take care of that so that a solar panel plant does get installed in the best place possible.

Solar is not about complete replacement to current energy methods, its about complementing them.

Imagine cutting coal use by 30-40% per day.

RE: Subject
By Curelom on 6/23/2008 12:03:55 PM , Rating: 2
You shouldn't need flexible glass. Even though the sun moves across the sky, it's distance is the same, you just need a mechanism that keeps it pointed at the sun.

Of course Solar doesn't work at night. No energy production method is perfect. Solar can take a big bite out of energy consumption as it works during the day when most of the electricity is used anyway, especially on hot summer days. Energy usage drops at night and you can use other means to complement.

RE: Subject
By vapore0n on 6/23/2008 2:39:59 PM , Rating: 2
i wonder why I got rated down?
don't see anyone disagreeing.

Just like hybrids, solar/wind/wave power is to complement other major power sources, not to replace.

Guess people get butt hurt when reality kicks in

RE: Subject
By ahdlm on 6/23/2008 1:55:48 PM , Rating: 2
on cloudy days? have a field of such reflectors focused on a mass of molten sodium to retain the heat and generate electricity even at night.

constant adjustment is not so hard.

wind rain hail etc could all hurt your car or home, but that doesn't stop anyone from owning them. something gets damaged: you fix it.

RE: Subject
By jimbojimbo on 6/23/2008 2:51:55 PM , Rating: 2
Popular Science likes to publish old covers they had sometimes and one of them was from the early 1900s of the exact same idea. Not a new idea, just new reflective materials.

RE: Subject
By ahdlm on 6/23/2008 1:51:00 PM , Rating: 2
no one thought of it before??

and the first link is using a home made turbine to generate electricity. or, if you aren't too mechanically inclined, buy one here:

RE: Subject
By JediJeb on 6/23/2008 2:48:36 PM , Rating: 2
I actually thought of something like this about 10 years ago, when the DirecTV dishes came out and there were a lot of old large tv dishes sitting around. I never had the money or time to try it out, but just think of all the power you could generate with adding mirrored surfaces to the old dishes not being used now. Just need a sideral tracking motor to keep it aligned on the sun and a way to put a small water tank at the focus where the LNB used to be. Use aluminum roof flashing to line the dish, polish it and your done, cheap and easy. Man if I had been able to perfect it back the I could be rich now.

RE: Subject
By Doormat on 6/21/2008 8:24:26 PM , Rating: 2
Thats what I'm trying to figure out - Nevada Solar One and many other Solar Thermal plants use parabolic troughs with glass pipe and a specially formulated oil for boiling water and turning turbines.

RE: Subject
By winterspan on 6/21/2008 8:51:30 PM , Rating: 2
Yea, I understand this is hardly a new idea, but why isn't this already widely deployed all over the world, especially in developing countries? Also, I think the novelty here is how cheap they can mass produce the components, and how simple it can be to setup.

How efficient is the electricity generation of concentrated solar energy -> steam -> turbine?

Could it possibly be more efficient to instead concentrate the solar energy onto a small patch of an otherwise expensive high-efficiency photovoltaic material?

Are there PV materials that can handle the high temperatures of concentrated sunlight?

If not, would that be more/less/same efficiency than shining the same amount of light (non-concentrated) onto a larger surface of the same photovoltaic material so it doesn't melt?

Ah! questions..questions.. Time to go back to college! thermodynamics FTW!

RE: Subject
By Rike on 6/21/2008 9:15:36 PM , Rating: 2
Could it possibly be more efficient to instead concentrate the solar energy onto a small patch of an otherwise expensive high-efficiency photovoltaic material?

I don't know the efficiency of this mirror solution, but work in concentrated light and photovoltaics is long since under way.

Here's just one example from the U.S. DOE.

You'll get lots of hits if you search "concentrated photovoltaic."

RE: Subject
By TreeLuvBurdpu on 6/22/2008 3:06:00 PM , Rating: 2
This is what I wondered. The article, oddly, says nothing about it's efficiency of producing Watts or something. Only at burning a stick, which of course, has been done.

RE: Subject
By Dobs on 6/24/2008 10:53:01 PM , Rating: 2
Are there PV materials that can handle the high temperatures of concentrated sunlight?

Solar Systems (Australia) have been using a concentrated PV on their thingy's for years.


I think this story was very poorly writen as it doen't explain why it is revolutionary at all.

RE: Subject
By piroroadkill on 6/22/2008 6:57:49 AM , Rating: 2
I agree - all they did was take the time to build a well focused array of mirrors, I don't think there's a person out there who doesn't understand why this works

RE: Subject
By aKarma on 6/22/2008 12:46:40 PM , Rating: 2
While the concepts are by no means revolutionary, from an engineering point of view this may be a great improvement.

The array appears both light and of low cost, meaning it can be easily rotated to match the sun by only small motors. The assembly also seems sufficiently simple it could be done by semi-skilled workers, and with low materials cost, so is ideal for countries developing infrastructure. The frame also means it would be physically small for transportation.

RE: Subject
By lco45 on 6/23/2008 4:16:01 AM , Rating: 2
It's not really revolutionary, they are definitely hamming this up.

I suppose they are saying that the revolution is that they can make a dish cheaper than before?

Either way, shining more light onto the same solar panel is cheaper than buying another panel. All other variables remain the same of course, such as cost of the panels, sunlight strength at your lat/long, cloud cover, night storage of energy, and so on (and on).


That's insane!
By Spivonious on 6/21/2008 3:52:27 PM , Rating: 4
Just wait until a supervillain gets ahold of this and it gets mounted on a satellite and starts burning places off the map.

RE: That's insane!
By GeneralJohnson on 6/21/2008 4:29:44 PM , Rating: 1
hehe we should use this to melt any one that try's to fight us

p.s. us=USA

RE: That's insane!
By James Wood Carter on 6/21/2008 6:42:33 PM , Rating: 1
why does everything have to be a weapon ?
I see this technology a potential energy saver. This could be a step closer towards energy independence.

RE: That's insane!
By codeThug on 6/21/2008 7:32:49 PM , Rating: 5
No problem, it's dual use.

Think positive; we can fry everybody we don't like AND be energy independent.

RE: That's insane!
By chiadog on 6/23/2008 10:01:33 AM , Rating: 2
Or just an energy efficient way to barbeque someone :o~

RE: That's insane!
By spluurfg on 6/22/2008 2:13:42 PM , Rating: 2
Nothing has to be a weapon, but it just turns out that way. Nobel thought dynamite would revolutionize construction, which it did. It just revolutionized warfare as well.

RE: That's insane!
By EntreHoras on 6/21/2008 5:43:16 PM , Rating: 2
That's the plot of 007's Die Another Day.

RE: That's insane!
By Stevenking on 6/21/2008 8:20:55 PM , Rating: 5
This story is completely untrue!!

Rosie O'Donell already told me that you can't melt steel!!!

RE: That's insane!
By feraltoad on 6/21/2008 10:47:13 PM , Rating: 2
But she said you could cook up a ginormous mess of hotdogs. Weiner!

RE: That's insane!
By feraltoad on 6/21/2008 10:45:26 PM , Rating: 3
The Sun is a weapon of mass destruction, and we must take this power out the hands of the Solar Jihadis.

RE: That's insane!
By feraltoad on 6/21/2008 10:48:20 PM , Rating: 3
I don't support Sun control; it violates my natural rights.

Too hot to be practical?
By Diesel Donkey on 6/21/2008 8:29:58 PM , Rating: 3
By directing the dish at a more practical target -- water piped through black tubing -- steam can be flash created, offering instant means of producing energy or providing heating.

If this thing melts steel, then how is black tubing going to hold up to the heat? It would have to transfer that heat to the water might quickly before it melted, it seems.

RE: Too hot to be practical?
By Chaotic42 on 6/21/2008 9:27:52 PM , Rating: 2
If this thing melts steel, then how is black tubing going to hold up to the heat? It would have to transfer that heat to the water might quickly before it melted, it seems.

Tungsten, Titanium, and any other of the several materials that can withstand the heat without melting. What would be cool is if they could get photovoltaics to be hearty enough to withstand this kind of heat, then aim mirrors at them. I wonder if that kind of setup could ever be more efficient than just heating water.

RE: Too hot to be practical?
By drank12quartsstrohsbeer on 6/21/2008 10:42:26 PM , Rating: 2
Put a larger diameter pipe inward from the focal point. Same light over a larger area = no melting.

RE: Too hot to be practical?
By Hare on 6/22/2008 3:16:14 AM , Rating: 2
... or concentrate the light to a larger surface area. Sounds simpler.

The fact that this thing can burn metal just shows that it can collect quite a lot of power from sun rays and focus it to a single point (well designed and built). It doesn't need to do that to be of great use.

Btw. Isn't this a paraboloid mirror since all edges are curved?

RE: Too hot to be practical?
By ahdlm on 6/23/2008 2:08:16 PM , Rating: 2
simply adjust the distance from the focus to a location where the temperature is apropriate for the material being used. if you want to melt sodium, keep it in a high temp container at the focus. if you want steam, keep it farther away from the focus and as a bonus get more "illuminated area" at that temp at the same time.

RE: Too hot to be practical?
By robg64 on 6/22/2008 11:58:18 PM , Rating: 2
If the mirror was focussed on a coil with a coolant such as water running through it, the drain of energy from the water being converted to steam should prevent the steel pipe from ever getting hot enough to melt.

Making the coil from a more expensive metal would defeat the point of the exercise - making a cheap collector.


RE: Too hot to be practical?
By lco45 on 6/23/2008 4:03:31 AM , Rating: 2
Hi Diesel,

Because the steel contains water, and the energy is going into boiling the water, the temperature can't really get above the boiling point of water (so long as the water stays topped up).

It's the same as a rice cooker, they switch off automatically once all the water's gone, because once the water's gone the temperate starts to rise over 100C and a thermal sensor cuts the power.



RE: Too hot to be practical?
By mindless1 on 6/26/2008 8:05:06 PM , Rating: 2
That is incorrect. The steel MUST be hotter than the boiling point of water in order to make the water inside boil. Thermal gradients at work here, while the water does keep the metal from getting nearly as hot there is still easily the possiblity of melting metal even when there is water around it.

Hint- Underwater welding

RE: Too hot to be practical?
By Jimbo1234 on 6/23/2008 1:44:51 PM , Rating: 2 running water through the pipe. The water will absorb the heat as it passes through keeping the temperature of the pipe at a desired constant. It's a simple heat exchanger.

And they call wind turbines bird-killers?!
By Captain Orgazmo on 6/21/2008 5:59:35 PM , Rating: 2
What would happen if a bird flew in front of that? Mmm... roasted duck.

By freeagle on 6/21/2008 7:52:14 PM , Rating: 5
I doubt it can convert ANY bird to a roasted DUCK :)

RE: And they call wind turbines bird-killers?!
By nvalhalla on 6/21/2008 7:57:14 PM , Rating: 2
And that's exactly why they'll try and stop this too...

RE: And they call wind turbines bird-killers?!
By Ringold on 6/22/2008 4:51:05 AM , Rating: 2
Slightly more legitimate concern: If there a lots of little fields of these around the country, what do they look like from above? Ie, 500ft and higher.

Pilots can't exactly help but to look at the ground, and if it's really right at that distance, well.. you don't have to look directly at the sun to be hindered by it.

Not that its a show stopper.. if it's cheap and highly efficient, then perhaps it would just be something indicated on aeronautical maps as a navigational hazard. Again, if its a concern at all.

By wien on 6/22/2008 9:14:10 AM , Rating: 2
One would assume the point is to aim these at some medium on the ground to extract energy, meaning if a pilot got the sun in his eyes they're doing it wrong.

melt steel?
By TonyB on 6/21/2008 4:22:07 PM , Rating: 2
topic is misleading, they didnt melt steel instead they burned a wooden board.

RE: melt steel?
By Diesel Donkey on 6/21/2008 8:26:34 PM , Rating: 2
No, the article is not misleading. It says that the dish could melt steel because its focal point becomes hot enough. It does not say anywhere that the melting of steel was actually demonstrated.

RE: melt steel?
By BruceLeet on 6/21/2008 10:09:52 PM , Rating: 2
A sustained source of ambient heat would be required to melt steel. Not probable with their current method outdoors.

RE: melt steel?
By lco45 on 6/23/2008 4:22:23 AM , Rating: 3
You could melt steel with this, certainly at some stage a reflector would be able to melt anything if it was big enough (and accurate enough).

If you're going to pick holes in the article, what about the line "costs 1/3 of a larger dish"? I can't think of a less meaningless line! You could say "costs 0.0001% of a larger dish" if that larger dish were the size of Australia.


RE: melt steel?
By paydirt on 6/23/2008 9:53:41 AM , Rating: 1
If you don't "get" this article, then just go back into your cave, man.

RE: melt steel?
By ahdlm on 6/23/2008 2:20:00 PM , Rating: 2

the entire operation doesn't necessarily have to be out doors.
just the reflectors and concentrator. the focus could extend into an enclosure. it is possible. its more than probable because it has been done.

By GlassHouse69 on 6/21/2008 4:33:27 PM , Rating: 2

Anyone remember this episode on the roof? Both him and Robin were about to be grilled by the sun. The episode ended with this cliff hanger.

how is this groundbreaking?

RE: na-na-na-na-na-na-na
By JustTom on 6/21/2008 7:30:49 PM , Rating: 2
It is not.

RE: na-na-na-na-na-na-na
By ahdlm on 6/23/2008 2:25:37 PM , Rating: 2
it certainly does reinforce the "don't let this fall into the wrong hands" category though...


Im making a 4' diameter fresnel reflector at home using some reflective mylar and masonite on a wood frame. the reflector part is easy. its the generating steam part that's got me. I don't know anything about steam plumbing and that can get someone hurt.

RE: na-na-na-na-na-na-na
By blue7053 on 6/26/2008 9:37:14 PM , Rating: 2
You are absolutely right.
For this reason, the parabolic trough should be used. The temperature only gets to 200 or 300 degrees, leaks are easily managed at this low pressure, and the system still generates enough energy to be useful as well as safe around a household or neighborhood of people and kids.
Parabolic with their thousands of degrees of generated termperature are systems that are incredibly unforgiving of error.

By excelsium on 6/21/2008 9:32:21 PM , Rating: 2
Does this work on overcast days? This thing gives at least free hot water for life for anyone who buys one of these which is a big deal.. at least in summer time.. or longer?

RE: Overcast
By lco45 on 6/23/2008 4:09:12 AM , Rating: 2
Works OK on overcast days, but not nearly as well.

It works OK because most of the light is still getting through, but not as well because the light is approaching the mirror at a variety of angles, so a lot of reflection misses the focal point.


RE: Overcast
By mindless1 on 6/26/2008 8:10:25 PM , Rating: 2
On an overcast day "most" of the light is not getting through. The angle doesn't change very much, because the cloud cover effectively prevents light from traveling at much on an angle through more clouds and they are high enough up to be relatively in line with the sun for what light does pass through.

Can't get something for nothing
By Chernobyl68 on 6/22/2008 4:04:22 AM , Rating: 2
it may be concentrating the light energy, but it's not getting more energy is it? I really don't see how this improves anything.

RE: Can't get something for nothing
By excelsium on 6/22/2008 4:11:00 AM , Rating: 2
It takes less time to collect a given amount of energy with this.

By excelsium on 6/22/2008 4:14:47 AM , Rating: 2
So you do get more energy out of it over the course of e.g. a day.

By frumiousbobsyeruncle on 6/22/2008 4:31:08 PM , Rating: 2
someone mentioned how hard it would be to keep something in the focal point; make the focal point the tracking pivot point. someone raised the worry about aviators being blinded by the light reflected; there is no reason the focal point must be directly over top of the parabolic reflector. direct it downward and slightly change/oblong the overall shape of the reflector. someone asked about whether it would work on a cloudy day; as long as it was still aimed at the sun it would work to its maximum allowable efficiency due to the cloud cover.

RE: How?
By lco45 on 6/23/2008 4:25:20 AM , Rating: 2
All correct.

Besides, you'll be wanting to do something more useful with the focal point than positioning it into ducks' flight paths.


RE: How?
By ahdlm on 6/23/2008 2:28:35 PM , Rating: 2
I don't know...

a sufficiently fast tracking device and you could have some fun with that...


By mjcutri on 6/21/2008 6:51:04 PM , Rating: 5
For example, a dish the size of the RawSolar team's design costs only a third of water a larger dish would cost.

Dailytech needs to get some better (any?) proofreaders.

10 more years...
By Duwelon on 6/21/08, Rating: 0
RE: 10 more years...
By JohnnyCNote on 6/21/2008 6:57:10 PM , Rating: 1
Till enviornmentalists will admit the sun is hot.

And what do you say when these "environmentalists" talk about global warming?

RE: 10 more years...
By lco45 on 6/23/2008 4:33:30 AM , Rating: 3
Forget global warming, I'm more interested in running out of power.

Sustainable energy is important because it's sustainable. I ran out of fuel in my Jeep Grand Cherokee the other day (first time ever) and man was I annoyed. Magnify that feeling by 7 billion people and I say let's start looking for other power sources.

Nuclear fission for the next 80 years, nuclear fusion after that. Solar and wind both great, but tiny amount of power for a helluva lot of effort, and very variable supply.

Nuclear has a rock solid supply, and the raw materials are fron Canada #1 and Australia #2, both countries that are pretty easy to do business with.


By GotDiesel on 6/23/2008 10:09:05 AM , Rating: 2
jeez.. it took a masters to re-invent a centuries old concept..

what do they teach at these colleges today??

By ahdlm on 6/23/2008 2:33:49 PM , Rating: 2
Now, now.

Remember: nothing is true or reliable until Science says it is.


There is nothing at all revolutionary about this.
By 91TTZ on 6/23/2008 10:45:27 AM , Rating: 2
Please stop with the sensationalist headlines.

There is nothing at all revolutionary about this. They took an old idea and slightly improved upon it. It wasn't even a major improvement since they didn't do anything else that hasn't been done before. Hell, you can buy kits that pretty much do what they're demonstrating.

By Icelight on 6/23/2008 11:31:30 AM , Rating: 2
It wouldn't be DailyTech without a hearty helping of sensationalism.

A wonderful breakthrough
By anthonydalekuhn on 6/23/2008 12:09:38 PM , Rating: 2
An affordable DIY solar concentrator that can generate huge quantities of electricity via steam generation is just what we need. It's not terribly huge, but can do mighty work and wouldn't look out of place in any 'green energy' lover's back/front yard. I can't wait to see the price on this innovation! Thanks for your coverage, DailyTech!

RE: A wonderful breakthrough
By 91TTZ on 6/23/2008 1:14:04 PM , Rating: 2
It's a "breakthrough"? They did not develop this technology. It's been around for decades.

MIT's solar project looks very familiar
By texassolarcookers on 6/23/2008 2:58:06 PM , Rating: 2
If anyone should know how to use the 'Net for research, you'd think it would be MIT students. Funny how they would miss something like this:

By samron on 6/24/2008 3:36:33 PM , Rating: 2
Hey Guys,

This is not revolutionary! Do a google search on Spain (the country) green energies. They are already using these mirrors focused to a tower for collection and refocusing the energy to create steam for power. They are currently generating megawatts of electricity by using these mirrors and are working to bring additional systems on line as I write this. They are placing these systems in an arid region of their country where the weather is clear a great percentage of the time. We are not using this technology in this country yet do to the failed or non-existent Energy policies of our government the last 35 years that I am aware of!

By owyheewine on 6/22/2008 11:08:45 AM , Rating: 3
So what is the efficiency? Heat level doesn't matter as much as total energy captured. Looks like a high tech water heater and windfoil.

By excelsium on 6/23/2008 5:22:36 AM , Rating: 3
Is this one of those things that's too good to be allowed to be productized e.g. no/little recurring revenues?

How novel
By Suntan on 6/23/2008 1:39:08 PM , Rating: 3
Jeez, now if only someone could think of a way to make this large scale....

Come on, this isn't novel. It not even that difficult. How about writing an article about the technical merits of making this system "cost efficient" (as was mentioned breifly) instead of fictionally hyping it up to be a group of students that invented a new method of solar collection.

I have no doubt that the people in this article had significant challenges to develop a low cost system that is viable for resedential use (assuming that this is), and that would make a good, truthful story. However, it wouldn't be nearly as sensational as saying they built a "revolutionary" new dish.


By StormEffect on 6/21/2008 4:16:34 PM , Rating: 2
Rotten Bastards, I was making an array in my backyard that was working out to a decent efficiency and they, with their *MIT* billboard (dailytech), steamroll (literally) all my dreams!

Will the steam turbine be self-recycling? Water is expensive here in the SOUTHWEST. Better be self recycling. How exactly does it need to be focused on the sun itself. How much energy does this collect on a cloudy day? HMM? Yeah, please come back to me with those answers please.

That, or let me in on the development/investment. :-)

I love solar energy.

how is this revolutionary?
By armred on 6/21/2008 4:56:30 PM , Rating: 2
Somebody built a better mirror? Hasn't this idea been around for centuries?

Good work on improving efficiency. Let us see it get deployed in large volumes in the near future, I guess that would be a challenge even for the smart folks at MIT, and something interesting for Dailytech to report.

Evil Genius
By Suomynona on 6/21/2008 6:07:28 PM , Rating: 2
Why, combined with my plastotronic ray I could melt the armies of the world and conqueror the globe. mua ha ha

Water you talking about?
By codeThug on 6/21/2008 7:36:37 PM , Rating: 2
For example, a dish the size of the RawSolar team's design costs only a third of water a larger dish would cost.
By FriedmannSolution5 on 6/22/2008 8:43:15 AM , Rating: 2
this is more of a PV project, but has hopes for cheap distributed solar technology:

By Woofer60 on 6/22/2008 4:02:39 PM , Rating: 2
While I applaud the enthusiasm of these kids, I can't help but chuckle a bit. Parabolic "cookers" have been around for ages. Heck, I built one from an old parabolic satellite dish by covering it with aluminum foil then polishing it. It isn't perfect by any means, but it does have a surprisingly tight focal point that easily melts metal. In use, the cooker (steel outside, ceramic liner inside) is a bit closer-in on the focal area and can flat toast some groceries. The main problem has been "too much heat". BTW, I'm talking a way old school dish that's about 3 meters across and has a fine metal mesh surface. Foil went on pretty flat, all things considered.

Texas Solar Power Company
By deadweasel on 7/8/2008 1:44:50 PM , Rating: 2
Texas Solar Power Co.

We are bona fide solar installers in the business for 13 years. We have not seen any technology offer what this does. Hopefully someone proves the applications for this technology.

If they don't, crystalline silicon is still the best energy bang for the buck of the renewable emission-free options.

By n0b0dykn0ws on 6/21/2008 9:29:05 PM , Rating: 1
Am I the only one thinking it?

The Ooh-ray!


death star
By knowom on 6/22/2008 5:42:17 AM , Rating: 1
For some reason it makes me think of the death star from star wars which is a bit scary.

My Idea
By Ammohunt on 6/23/2008 2:10:14 PM , Rating: 1
Damn they stole my idea. oh well.

For the Nay Sayers...
By ahdlm on 6/23/2008 2:53:51 PM , Rating: 1
I bought a little 9" diameter 5x magnifying mirror to fool around with.
I was careless where I set it down and it actually burnt a hole in my shirt before I knew what was going on. luckily that part wasn't in contact with my skin at the time.

this works, and it works *big*.

Its not the answer to every energy need, but it can certainly do an awful lot of work for very little cost.

"We can't expect users to use common sense. That would eliminate the need for all sorts of legislation, committees, oversight and lawyers." -- Christopher Jennings

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