Spencer Ahrens, Matthew Ritter, and Eva Markiewicz created a solar dish that boils water (or sets wood ablaze) at a cost cheaper than heat from gas, oil, or coal. (Melanie Stetson Freeman – Staff)
MIT team plays with fire to create cheap energy
New solar dish harnesses power from heat – at a size and cost that make soaking up the sun even more attractive.
By Mark Clayton| Staff Writer for The Christian Science Monitor/June 18, 2008 edition
Melanie Stetson Freeman – Staff
The MIT team shows off its solar dish by lighting a wooden board on fire.
Cambridge, Mass.
Out on a lawn at the Massachusetts Institute of Technology with joggers and traffic passing nearby, Spencer Ahrens is demonstrating what looks like either the future of solar power – or perhaps a death ray.
Thrusting a 12-foot board up into the air in front of a large mirror-covered satellite-type dish, Mr. Ahrens, an MIT graduate student, waves the board, looking for an elusive sweet spot where reflected sun rays converge.
With three student teammates looking on, he steadies the board once its tip begins to glow. Shining white in the reflected solar rays, the wood suddenly bursts into flames. Students laugh as smoke billows in the breeze.
This burning-board trick may seem like a YouTube stunt, but it’s actually a visceral demonstration of a device with a serious purpose: to make super-cheap solar heat.
From garage inventors to government scientists, many have tried to make a solar dish that focuses sun rays to generate power. What makes this student project different is not that they’ve done it – but that they’ve done it so cheaply, building this dish with off-the-shelf parts.
“A lot of good people have built working dishes, but generally they’re more expensive, more complex, and harder to build,” says Matthew Ritter, an Olin College of Engineering student who’s also part of the team. “We use widely available materials – that’s our breakthrough.”
The student team has already formed a company – Raw Solar – that they hope will one day have an assembly line cranking out cheap solar dishes that individually or in large arrays could supply affordable heat to a college campus, suburban home, or third-world village.
A few minutes later, the real demonstration begins. A pole protrudes from the front of the solar dish – similar to the rod that sticks out from satellite-TV dishes. Wrapped around the end of it is spiral tubing, which the team fills with water from a garden hose. With the dish swiveled to face the sun, the tubing glows white. Boiling water sputters from the far end of the hose, which lies in the shade beneath the dish.
The secret: frugal design
Materials and construction are fairly simple. Aluminum tubing is riveted to a steel cross bracing. Affixed to that frame are strips of mirror from a local supply house. High-heat barbecue paint coats the coil collector at the apex of the pole.
“Small solar thermal is a kind of power that has really been traveling under the radar,” says Micah Sze, an MIT business school graduate tapped to help market the technology. “People have been focusing on electricity from the sun, not the heat market. We think there’s an opportunity to supply heat to large institutions like universities and someday individual homes.”
“Concentrating solar power,” as this type of system is called, is seeing a boom. At least 4,500 megawatts of capacity is in the development pipeline, according to the Solar Electric Industries Association in Washington. That power is about 13 to 20 cents per kilowatt – cheap enough to compete with peak power prices of fossil fuel plants – but not yet off-peak regular prices.
The goal is to bring the price down. Many older and current systems are very complex, involving a host of motors to keep dozens or hundreds of carefully polished mirrors focused on the sun. So the team focused instead on making a dish that only requires a simple electronic system to keep it aimed at the sun – and pump water into the collector coil to be heated into steam. The MIT team says their unit will produce steam heat for less than the cost of heat from oil or natural gas.
The steam is “low temperature” – about 212 to 400 degrees F. – not high temperature steam generally used to power electric turbines in conventional power plants – which can surpass 700 degrees F. Still, this “process heat” can be used cost effectively in manufacturing, food pasteurization, and heating buildings.
Making good ideas better
Part of the genius here may also be all about knowing where to look for technology. The MIT students, for instance, did not take a go-it-alone approach. As part of his “Energy Ventures” class, MIT lecturer David Pelly was hunting for some of the best new energy ideas that needed development and marketing – and discovered Doug Wood’s solar dish.
An inventor who lives on Fox Island off the coast of Washington State, Mr. Wood’s backyard is filled with all manner of solar dishes he has built – but most are enormous, he says. After working with the MIT team, they settled on a dish that is just 12 feet across.
“Our big discovery was that small worked better, cheaper, than any of our huge old models,” Wood says. “Getting the size right was the critical breakthrough.”
This summer, the team plans to relocate its fledgling company to the San Francisco area in order to find funding, as well as to tap the burgeoning solar-power expertise in the region.
Fortunately for traffic and pedestrians here at MIT, the Raw Solar dish is unlikely to be of any use as a laser-style device. When lowered toward street level the beam deflects.
“Yes, I know it probably looks like a ray that could fry Boston,” Ritter says. “But it actually loses power very quickly beyond the focal point, so there’s no actual danger. You can’t accidentally step into the focal point. Nobody walking along the sidewalk will get toasted.”
( More stories )
Comments
2. Andrew | 06.19.08
@satellite dishes with mirrors: Not if you want to receive television at the same time. Radio/tv dishes have to remain pointed in a fixed direction to keep gathering signal from the satellite, whereas a solar parabolic reflector would have to track the sun. Building a reflector from a satellite dish would not be as cost effective as building one from scratch, I’d think.
Not to mention the focal point would be the same or near the same as the receiver equipment and most RF gear is not rated to take 200+F
3. Westhighlander | 06.19.08
Why don’t we learn from history and how about some common sense
In the first — Why don’t we learn category — most of these “breakthroughs” are just recycled 70’s Carter-era stuff
In the Common Sense category — it is most embarrassing that MIT students can’t divide by 2
So if we want to properly evaluate the potential for solar — Let’s get realistic about energy density and hence cost per KWhr — there are places where solar energy can contribute — but there isn’t any free lunch
At the top of the atmosphere all you can get is 1360 W/m^2 – and then there is night (so let’s divide by 2 for the average – when you include atmosphere and clouds – you have better be prepared to divide the average by another factor of two – and there is a need for storage
To recap – assume that you can track the sun (otherwise be prepared to only get output for about 4 to 6 hours per day) – a realistic assumption is an average of about 250 W/m^2.
In perspective a good Euro-style 220V water heating pot (tea or coffee?) can heat with an input of 2 KW (with 100% conversion efficiency) – that means to boil a pot of water fro a cup of tea- — you need to collect solar energy over 8 m^2 (average) or 2m^2 at noon on a cloudless day – translates into a bit less than 4m diameter collector (average) or a bit under 2m diameter collector (peak cloudless noon)
The most valuable contribution that can come from solar energy in the next few decades (aside from the remote mountaintop, highway sign, swimming pool heat, etc) is to manufacture hydrogen directly from water using a catalyst such as TiO2 without electricity involvement – in principle that could be useful assuming the cost of the catalyst can be low enough and that the hydrogen can be easily stored at low cost
The rest is worse than a pipe dream it’s a dangerous delusion
The real alternative energy — GO Nukes!!!
Westy
4. Jimbo | 06.19.08
These teams are killing america by stripping hard working, apple pie eating petroleum companies of the meager profits they need to feed their American sizd families. I’ll bet these hippies are vegitarians doing nothing but support Red Chinese tofu production.
5. R. Cooper | 06.19.08
An even more inportant use for developing countries might be solar cooking. currently, massive deforestation results from gleaning of cooking firewood.
6. Luise Perenne | 06.19.08
I’d go for the solar cooking angle, a welcome change from the charcoal-fired backyard barbeque mentality. And all free! Get with the new renewable fuel technology.
7. Andrea Coffey | 06.20.08
Westhighlander (above on 19june08), wake up!
“Nukes”, over their entire life-cycle, use vastly more energy than they ever generate. They never have been, and never will be, a solution. Except for creation of nuclear weapons. And we’ve too many of those already.
8. Sylvan Finger | 06.20.08
Solar energy is not the answer to all of our energy problems but from what I hear it can help. It depends on where you live. I’ve heard that the dishes can capture more energy than the flat panels. I wonder why California’s PG&E didn’t use the dishes in the desert.
9. Daniel | 06.20.08
I read similar article also named o.us poetry, and it was completely different. Personally, I agree with you more, because this article makes a little bit more sense for me
11. Sam Crutsinger | 06.20.08
Westy, geeky grouches like you test my faith in humanity.
If the sun is shining and this is heating oil pumping through your house, you’re not paying to heat the building and your carbon footprint during the day shrinks considerably. If it’s heating your water tank too, that takes care of your top 2 power consuming appliances. At night you can use gas or whatever, but you’ve cut your heating bill probably in half. If you let this thing get the place nice and toasty while it is working then you don’t have to use much power to heat the place at night.
Around the 40th parallel the sun pumps about 3.9 kWh/m^2/day into the earth, so this has a theoretical peak output of about 15 kWh/day. That’s about half of my personal power usage. The roof of my building is nice and flat and could easily handle more than one of these, more like half a dozen actually. That would capture more heat than I would know what to do with. If they can spin up a 1kW alternator, even for 4 hours/day, with that heat… sign me up.
New technology doesn’t have to solve ALL of your problems to be a great idea. I’ll be keeping an eye on these guys. I can’t wait for the day when we all generate all of our own power and aren’t under the thumb of utility monopolies and gas stations.
13. Michael Crumpton | 06.20.08
Westy is just plain wrong. I have seen a homemade dish less than 1 sq meter bring a cup of water to boil in about a minute. Youtube is filled with good examples of that. I don’t know where his figures come from, but at ground level 1 sq meter has an average of 1kw of energy hitting it (during the day), and assuming a mirror efficiency of 95% that is 950 watts focused on an area smaller than a stove burner.
If his figures were true, then none of the solar power plants would work, and that is not the case, even in Germany, which is hardly known for it’s intense sun.
His tagline (Go Nukes) says it all. BTW the sun is a Nuke.
14. Max M | 06.20.08
“that means to boil a pot of water fro a cup of tea- — you need to collect solar energy over 8 m^2 (average) or 2m^2 at noon on a cloudless day” - Westhighlander
I boiled a cup of water (3 dl) in my heater, and it took almost exactly 1 minute.
So I used 0.016 KWH (1KW * 1/60)
With your own numbers:
250 W / M² => 0.25 KW => 24 * 0.25 = 6 KWH per day
6 KWH / 0.016 KWH = 375 Cups of tea / day
That is not too bad.
16. Max M | 06.20.08
Oh shoot. It is me again. It just struck me that 16 watts for 0.3 l cannot be right. 1 watt = +1 degree Celsius in 1 liter. to raise the temp from 8 to 100 degrees it should take 92 / 3 = 33 watts, so I checked my cooker again. It is 2 KW 
But it is still 187.5 cups of tea.
17. Paul | 06.20.08
Quite funny the thing about water heating using the sun going under the radar.
I mean throughout Chinese and Asian cities you will see dozens of solar water heaters on every roof. Private houses public buildings, companies everywhere. I’ve even seen them on boats. Must be 10s of millions of users.
I included a link to a page of companies making them, they’re a little more hi-tech than the tin can these kids are making, don’t dazzle airplanes or subject the neighbors to a death ray either. Not only that in the summer months they give you a nice hot shower in the morning.
19. Asian | 06.20.08
Living at the equator, we have plenty of sunlight but little money to buy the tech/equipment.
Anyway, when the page first loaded, did everyone’s eyes immediately focused on the girl’s boobs?
20. daniel daou | 06.20.08
TO Andrea Coffey | 06.20.08
“Nukes”, over their entire life-cycle, use vastly more energy than they ever generate.
EVERY method uses more energy than in generates. (You’d have a perpetual machine if you produced more energy than the one you use.)
21. tony | 06.20.08
Why is MIT taking credit for the invention of a guy from the state of Washington? Why do conservatives think that only 15% of our nations energy supply can ever come from wind or solar? Why do liberals even dare say that nuclear fission plants are negative net energy? These polarizing statements are counterproductuve. We have to come together here. We need all the solar we can get. We need all the wind power we can get too. We need at least 45 new standard nulcear plants that Europe and Canada have proven are safe. We need to switch our cars to plug-in electric and compressed natural gas. We need to end our dependence on oil from non-domestic sources. We need more domestic refineries. We need all the conservation technologies to use the energy we have more wisely. We need to be able to drill 45 miles offshore too. Cuba and China are already drilling off the coast of Florida. The fact that we can’t is nuts! In short, we need to compromise, and shotgun this energy problem with every answer we have that makes sense. We need to come together and all pull in the same direction, regardless of political orientation. This is a twenty year long problem that will take decades to solve. Let’s get started now people!
22. Mark Schlagenhauf | 06.20.08
Now combine the ability to heat a source with a sterling engine and you can run a whole household and more! A small device the size of a satellite dish and an engine the size of an air condition unit…!
23. cortina | 06.20.08
New buildings in Spain by law incorporate solar thermal energy for sanitary hot water. Essentially you run your water through pipes on the roof. You still need conventional water heating but you save part of your electricity bill…
24. BrdLvr | 06.20.08
Wouldn’t a proliferation of this technology and the harsh glare affect bird populations?
25. Kimble | 06.20.08
Haha this is the stupidest thing I’ve read in a while! They should know that there’s a reason why solar power isn’t commonly used to heat homes and institutions. They probably where those shorts because it’s so hot that you don’t need heating!
If that ugly thing had worked in cold and dark places it would be a real breakthrough, this is just sad!
26. GPM | 06.21.08
Great work - keepin’ it real by using off-the-shelf components. I also like the idea of cutting out the grid for delivery of energy.
Sign me up! While it may not be the absolute minimal cost solution, it should be cheap enough for the extra cost not to really matter. Plus it has an element of geek-chic and bragging rights over a cocktail.
And for the whining critics - lead, follow or best of all: get out of the way.
27. tomc368 | 06.21.08
The days of cheap energy are gone forever. The issues of energy conservaton and alternative fuel sources are no longer issues for future generations; they are ours now. The country needs those meatheads in Washington to develop a national energy policy. It can no longer be politics as usual, where the Democrats tax and subsidize, and the Republicans advocate ‘laissez-faire’ free market do-nothingism. We need a policy to establish direction, initiatives, and focus. They should determine that we use nuclear, coal, and alternatives (solar, geothermal, wind, etc.) for our statoonary energy needs (homes, buildings) and oil and natgas for our mobile transortation needs Cars, boats, planes, etc.) as well as manufacturing supplies (plastics, chemicals, fertilizers, etc.). The vast majority of the electrical capacity we have added in the past 20 years has been natgas fueled. The cost of natgas has gone up 300% in the past two years; in addition the cost of coal has gone up as well as the cost of transporting coal on diesel powered trains. What do you think this will do to our electricity costs shortly? If we used natgas to power our cars, buses, and trucks and solar and wind for supplimental electrical generation, we would be in a much better place today.
We cannot wait for the free market eceonomy to institute changes to our energy policies. Because energy is the backbone of our economy, the conversion process is too painful. We cannot be so stupid as to think a windfall profits tax on oil companies and gas subsidies to consumers will solve anything. Had we taken steps after the oil enargo of 1973, we wouldn’t be where we are now. We need a forward looking national policy established by Washington. We cannot wait for financial ‘grid parity’ before making a strong effort at implementing solar, wind, geothermal, and other alternative sources. On our present course, we will eventually get price parity as oil continues to climb upward; but what is the sense in waitng? We will seriously damage our economy by doing nothing now. The American citizen is expecting Washington to lead on this issue and they don’t get it.
If we want to wean ourselves from foreign oil, as everyone says we need to do; the ONLY way to do that is to use what we have HERE in America, in place of it. We should expand drilling on the outer shelf and in ANWR. We should institute subsidies and encourage the implementation of alternatives by not only the utilities, but individual home owners and small businesses. We should encourage the use of natgas for vehicle use and discourage it’s use for electrical generation. We should build more nuclear plants and use more coal using ‘clean’ technology. We should encourage energy conservation, lower the speed limit, raise the auto efficiency rates, subsidize alternative energy research, etc.; ….and encourage more projects like the MIT project.
Those who argue that instituting new exploration and drilling initiatives now won’t affect today’s prices and won’t increase availibility for 10 years, so they aren’t reasonable solutions to our problems, should ask that of those who will be dealing with these problems 10 years from now. Let’s make some changes now and help those down the road from us; unlike those who had these chances in the 1970’s DIDN’T help us. We need Washington to take a stand and make some tough, but important decisions.
28. Doug Wood | 06.22.08
Inventor responds. Not a blogger, but have a few minutes of free time.
One square meter of solar dish aperture is worth one barrel of oil per year (burned at 85% efficiency) in Colorado climate. Each m^2 should cost about $100… simple one year payback against oil and two years against natural gas, all without solar subsidies — very important for global warming mitigation.
China and India have told me they have raw materials and massive causal labor. They want rapid scale up with no new tooling nor capital bottlenecks.
Nothing new about solar dishes. The news is construction simplicity (without special tooling) and low dish materials cost.
Smaller dish size is cheaper due to the ground, rather than steel, supporting mirrors.
The frame was made from all identical parts. Only a paraboloid has that potential.
The mirrors are flexed into near perfect parabolic curves with force rather than with conforming substrates.
Two flexed dishes have survived record breaking hurricanes with zero damage.
Our first dish is 30 years old and the exposed mirrors (glass/silver/copper/paint) are in good shape with only minor degradation. The MIT mirrors are off-the-shelf low-iron glass/silver/palladium/paint and are even more durable ~ $1.65/square foot (Guardian Industries).
Amory Lovins recommended I put this into the public domain. NASA engineers advised a patent to pay for engineering improvements. A sole US patent was a compromise.
The question in search of an answer is: How cheap can solar get?
Background: http://www.harbornet.com/sunflower/pvdish.html
Warmth,
Doug.
29. Westhighlander | 06.22.08
Andrea somebody better tell the French
Andrea wrote — “Nukes”, over their entire life-cycle, use vastly more energy than they ever generate. They never have been, and never will be, a solution. Except for creation of nuclear weapons. And we’ve too many of those already.”
But rather than dreaming or wishing — if you actually look at the world through untinted lenses — Last count France was generating 80% of their electricty from nucelear power
Au contraire Doug — a recent study on “subsidies per kWhr” for electric generation showed the largest for Solar, 2nd larget for Wind and at the bottom of the list gas, coal and yes nuclear
Westy
30. Westhighlander | 06.22.08
Sam, wrote — “Westy, geeky grouches like you test my faith in humanity”.
Sam — Fortunately for you — Geeky Grouches such as myself (ie. scientists and engineers) have made it possible for you to have an Internet to pontificate upon, a vehicle to commute with (whether human powered, electrical, hybrid or the old “filler-up with”), something other than a cave to live in and something other than cow dung to heat it your domicile, and something other than a block of ice that you’ve been husbanding since February to keep your food from spoiling.
But — more to the point — Sam — I hate to break some bad news to you but your comments with respect to solar heating are not quite right:
1) “If the sun is shining and this is heating oil pumping through your house, you’re not paying to heat the building and your carbon footprint during the day shrinks considerably”, — well something has to pump the oil through your house unless you are dealing purely with convection — not very efficient
2) “If it’s heating your water tank too, that takes care of your top 2 power consuming appliances”. — well I have both a refrigerator and freezer and they are major consumers of energy year round and in the summer I do some limited amount of air conditioning and all year I circulate air — the sun doesn’t really help with any of those
3) “At night you can use gas or whatever, but you’ve cut your heating bill probably in half”. — well actually a lot less than in half — first you’ve got roughly twice as many wintertime dark hours as bright ones — 2nd the night is generally colder than the day — 3rd. even a no-solar designed house will have passive solar heat gain during a sunny day.
4) “If you let this thing get the place nice and toasty while it is working then you don’t have to use much power to heat the place at night”. — see above #3 — plus you fail to explain where all the nice toasty heat is stored when the sun is not shining.
Westy
31. Westhighlander | 06.22.08
Michael, and all the rest of the contributors who are math phobic or innumerate – I will leave all math beyond arithmetic and simple geometry out of the following calculation of solar heating
In the interest of getting rid of the “knee-jerk” negatives – I’m going to help all of you to understand the realities of solar heating
Note – all of the following numbers are available on Wikipedia (with sometimes a rounding process to simplify the numbers – always in the favor of the solar heater)
So let’s roll up our sleeves and brew some tea
I’m assuming the following:
TC = 20C — Initial temperature of the water is room temperature
TH = 100C — Final temperature of the water is sea level atmospheric boiling point — note I’m ignoring any heat wasted in actually boiling any of the water
S = 1000 Watts /m^2 — Solar Isolation Constant in Watts per square meter (about the area of a 1.2 m diameter reflector) at sea level at the latitude of Boston at noon on the day of the summer solstice with no clouds
M = 1kg – 1 kilo gram of water — ie. 1 liter of water – about enough for 4 cups of tea
C = 4.1814 kJ/kg — we’ll use 4 – Specific Heat of water – i.e. how much heat in kilo Joules to raise 1 kg of water 1C (at a temperature of 25C) – i.e. 1 Liter of water – equivalent to 1kilo Calorie (used in counting Calories for diets)
J = 3.6 kJ / kWhr – 3600 seconds in one hour, 1 Watt for 1 second is one Joule
Now our simple calculations:
DT = TH-TC = 100- 20 = 80 deg C - To bring the 1 liter of water from 20 to 100 deg C
H= DT x M x C = 80 x 1 x 4 = 320kJ = 1 kW for
T = 320 seconds = 5 min = time to bring the water to boil with 1 KW input
So here’s the tradeoff – at noon on the summer solstice a 1.2 m diameter reflector (assuming 100 % efficiency for the reflector and the absorber) will do the job in 5 minutes
Plug in a pot with 1 kW heating element (10 A at 100 V) and it also heats in 5 minutes
At a price at the plug of $0.15 US per kWhr (Suburban Boston electric rates) the pot of hot water costs about $0.013 US – Note the so-called buss-bar cost of generation of 1 kWhr is about $0.03 for a nuke and about $0.30 for solar photovoltaic with coal and natural gas close to the nuke and wind close to solar photovoltaic and solar thermal a bit cheaper than solar photovoltaic
Do it twice a day for a year and with the electric pot you’ve spent less than $10 US
So I guess if you get a 1.2 m solar reflector as a gift and you point it at the sun by hand when you want a pot of hot water and you only want hot water in the late spring through early Autumn and you only want it between 10 AM and 2 PM – well then I guess the solar heater is a good deal
As for me – I’ll take the plug-in-pot or in the winter or else in the summer I’ll just throw a pot on the Barbie along with the shrimp
Westy
PS: as bonus — my five point energy plan:
1) drill for all the oil that we’ve got wherever it’s located in North America and build the necessary refining capacity
2) dig for coal wherever its located
3) fission all the uranium that we can and build all the new plants that we can
4) conserve – don’t waste a drop of oil, a cubic meter of gas, a kilogram of coal or even an atom of Uranium — but don’t expect to grow your economy based on conservation alone
5) do all the research that you can to develop the next generation of generation, motor, energy transmission, energy storage, thermal insulation, heat-recovery ventilation, ground-water heat pumps, etc.
32. jim stuart | 06.23.08
Has anybody factored in the effect of dirt on the reflectors? Where I live, and I suspect in most places, the reflectors would be quickly covered with dirt and stop focusing properly, so that they would have to be cleaned perhaps every 2 or 3 days to maintain efficiency. What’s the cost of that compared with cost of the energy produced?
Secondly, does anyone make low priced, mass-produced tracking systems or components? If not, wouldn’t that be a good idea?
33. Lewis | 06.27.08
I don’t see where the innovation is. More like a high school science project. If that’s the best the MIT can do we are truly doomed.
34. Josephus | 06.27.08
We can also use the system that Tesla used for his electric Pierce Arrow Car in 1931. He took power right out of the aether, like a Flying Saucer does.
He did not dare to divulge how it worked, as he realized that the system could be used to power any kind of vehicle and supply power to any dwelling on earth. The investors of electricity and oil , Morgan and Rockefeller would have had him killed then and there. He did no take a patent out. I did.
I offered the invention to Canada as a Birthday Present in 1967 and found out that I was not a Patriot, I was an Idiot. What I had invented, could never ever be done in practice, it was just a theoretical problem from Faraday. The invention was ridiculed and rejected even by MIT and by the Canadian National Research Council up to four months after the patents were granted. My US patent lawyer phoned and predicted the Nobel Prize.
We can fly to the Moon in an hour or to Mars in a few hours more, wihout barf–bags, heat-tiles or osteoporosis but then the people, like Propulsion Engineers and other Nasa would lose their jobs.
Unfortunately my wife found the stack of letters with rejections, ridicule, insults and the paid-up loan papers to finance the Patent Applications.
She was furious and did not want me to work on it anymore. Love won.
She passed away and now I am working on it again.
I could use the Nobel Prize for funding but it is easier to get that prize by coming up with an idea about a black Hole (Which will not benefit anyone except a small group of scientists) than something that would benefit everybody except the oil barons.
Google: > One Terminal Capacitor Joseph < and wonder.
35. John Merriman | 06.27.08
I agree with Lewis: this seems a pretty sorry performance for MIT students.
36. Steve Nordquist | 06.28.08
Dirt…usually not so bad. Glass or plastic A/R-surfaced passivation to a metal reflector doesn’t degrade so fast that a thrice-a-week twilight cleaning with a wet rag is a big deal (just twice a month if you feel old, though.) The wind load is rather low. Visible light energy is less than the IR energy, so image-perfect polish is no dealbreaker.
Time saved not ever exchanging local weather reportage: Priceless.
Cooling provision of unaligned mirrors: Not bad. Integration with condenser coils and IR upconversion could help cool the earth albedo.
Effect of metal forms on rooftops on RF communications: Eh…not so good.
Effect on roof maintenance: Decent.
Westhighlander: It’s silly but I think you’d make people happier if you cited a source in the case of the solar $0.30/kWhr figure.
38. Cdoubleyou | 06.28.08
Westhighlander, you have clearly won this debate.
I wish someone like you was running for Prez. We have nothing but BS running for office.
39. Ahfoo | 07.27.08
Doug Woods. What up man!
Wow, great to hear from you. We’ve never corresponded, but I was massively inspired by your pictures back in the nineties when you posted to the solar thermal mailing list. So cool to see those pics again.
I’ve been working on my own designs ever since and I’ve always thought it would be great to try and find you and here you go and post to an article I’m reading on the Net.
So, what was the specs on what you concluded was the best way to go? Do you have a link that offers a little more detail? Or would that be in the patent? I like the big ones personally. I recall reading from SEGS that they seemed to think the bigger the better.
In a trough configuration do you think a fifteen foot aperture is excessive? I realize the devil’s in the details, but sometime it’s possible to speak in general terms as well. I’m interested in what you think. Also, isn’t a trough always going to win-out over a dual axis tracker in terms of simplicity?
Thanks again for posting those pics. Been a while.
40. Tom Evans | 07.27.08
When the USA has some leadership (e.g. YBG vs OWG) them maybe:
All traffic lights shall become “Smart” over next 10 years
All vehicles with more then 50mpg shall get a good tax break (now)
All vehicles with more then 100mpg shall pay no taxes (now) (e.g. The Air Car)
All vehicles with less then 30mpg shall pay carbon tax (now)
All new commercial buildings shall become net energy positive by 2030
Mercury lights shall be discouraged for home use
LED light research shall be encouraged
Significant tax breaks and investment credits for alternate energy and tech… with the requirement that the jobs to deliver the work stay in the usa. (don’t like it, don’t take MY tax money)
utilities must buy mandated increasing percentage of power from alts.
Food(corn)-fuel shall be baned. Waste fiber-fuel shall be encouraged
Water (the other big issue) shall not be free for industry, commercial, or home use (over some threshold).
Water shall not be used to hide pollution by dilution
—this is ONLY HARD because our “elected” “representatives” must spend all their time getting money and money is NOT SPEECH. Money is Property, and its used to BUY property…like congress. Those that have (lots of) money use it to keep themselves on top.
41. PC | 07.28.08
westh: Thermal energy can be converted to electricity in various ways. Stirling engines are a tried & true technology. Solid-state thermoelectrics show great promise. Think outside the thermal box.
westh then wrote:
“1) drill for all the oil that we’ve got wherever it’s located in North America and build the necessary refining capacity”
Why exhaust our oil supply when we can import it relatively cheaply from other places? We should reserve our own oil supplies for the time when it hits $500/barrel, then make a killing selling it to the rest of the world. This is contingent upon us becoming energy independent.
“2) dig for coal wherever its located” Same.
“3) fission all the uranium that we can and build all the new plants that we can” Same.
“4) conserve – don’t waste a drop of oil, a cubic meter of gas, a kilogram of coal or even an atom of Uranium — but don’t expect to grow your economy based on conservation alone”
Americans as a whole will never conserve unless it hits the pocketbook. Your steps 1-3, if successfully execute, merely drops the price of fuel/energy, and would result in people wasting more again.
“5) do all the research that you can to develop the next generation of generation…” YES!
42. jim | 07.28.08
Hi,
One real advantage to the MIT approach is no-permits-are-required!
Take a look at this article on solar:
http://www.extremetech.com/article2/0,2845,2326042,00.asp
where a big part of his effort was city-permits. He even had to install a cutoff-switch outside his fence by ordinance.
Soo, as these solutions come about, never forget the total cost, permits and all.
I have another idea that will arise:
That is to add DC on top of AC in the home wiring.
So many electric solutions begin with DC-AC conversion.
Thats a waste. Just bias the AC up with DC in the house wiring.
Add the DC from solar when the sun shines.
Then people will start making appliances that run on DC.
Stuff like refrigerators, pool pumps.
My third idea is to design a heat pump that uses DC power instead of AC.
Once again, I am saying “forget the conversion”.
Just have a few panels in the yard (not on the roof, where a permit reqrd)
that power a DC heat pump that supliments the heat/cooling of a house.
That would be mild investment and cut your big ticket item (air/heat) in half.
Contact me for more information.
jim pruett
gpscruise@gmail.com
43. J Byrdlip | 07.28.08
Sam Crutsinger — if you pump the oil thru a large brick structure (like a Russian fireplace {http://www.grannysstore.com/Do-It-Yourself/masonry_stoves.htm}) you could heat the house for night time also, so your cost is for pumping the oil. I’ll take a dozon.
44. David | 07.28.08
I think I did something similar to this when I was five using a magnifying glass. 
45. Kortlan | 07.28.08
Solar energy is not the silver bullet to solve all our energy needs … however, efforts to concentrate sunlight, especially via ridiculously cheap, mass-producible devices, are worthy endeavors. Try collapsing the parabolic curve onto a flat surface and reducing the weight to a thin, reflective coating. Comprise the whole of a few mass-produced components. I’d be happy to share my thoughts with the team.
kortlan1@yahoo.com
46. brian | 07.31.08
good job guys, looks promising.
WESTY your acting conservative on your calculations all the while maintaining an ignorant point of view with your philosophy!
Put a tracking motor on the thing, its not just for 2-4 hours a day, and store the heat energy. Were not talking about making coffee to just do a bunch of math calculations like you do! Were talking about heating homes here, and harnessing the suns ALREADY AVAILABLE energy, instead of creating other sources such as you are suggesting which is wasteful to begin with.
Place a few of those dishes(a re-engineered streamlined version) on a hot water/vegetable oil system with a 1000 gallon under home insulated storage tank/s, and use that for radiator/water heating throughout the day and night! thats not just 2-4 hours of heat here were talking about. Store it! Attach another to heat cells or harness that heat in other ways to run a generator/alternator that charges battery sumps to convert to high voltage.
Its a no brainer. In cold climates with even 70% cloud cover, all we need to do is add more dishes on the roof, THEY ARE CHEAP, and AFFORDABLE!
We all need solutions to make this stuff affordable, and thanks to these students at MIT, the word is finally getting out to the masses instead of staying inside some science book, or on some chinamans roof by poor inefficient usage.
You mention yourself we need all of these kinds of energy, yet you put down their effort, your being hippocritical, and dragging down impressionable morons like
CDOUBLEYOU with you.
You guys talk about no energy being perfect, and needing a perputual energy machine, all the while the sun is already perpetual atleast on the scale of our lifetimes, and is already producing relative-perpetual energy, all we have to do is harness it!
Get out with your drilling solutions, the world has cancer, we dot need any more pollution fallout from your ideas. Its all about CLEAN energy, what part of this do you NOT understand?
Go Doug Woods, and try to streamline this dish and make home kits that are unobtrusive to neighbors eyes so customers arent ego-blasted when they want to mount a few of these on their roof.
1. Will | 06.18.08
Could satelite dishes have mirrors added to create heat energy for central heating in houses?