Solar Breakthrough Could Provide Power Without Solar Cells 223
An anonymous reader tips a University of Michigan news release about the creation of what's being called an "optical battery" that could lead to the use of solar power without traditional solar cells (abstract). Quoting:
"Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not conduct electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. Under these circumstances, the magnetic effects develop strength equivalent to a strong electric effect. 'This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation,' Rand said. 'In solar cells, the light goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load. Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source.'"
Fun with Magnets! (Score:2)
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So how long until this becomes practical on a personal scale?
You must be new here.
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So how long until this becomes practical on a personal scale?
Nobody knows, potentially never. It's just basic research, and it could be very interesting just for it's own sake. However they need to package it somehow, to give people an idea how basic research fits into overall scientific and technological progress. It does fit there, and of course we constantly get advances which were rest on basic research done 30 years ago.
However if you want to use something now - you can just ignore this news. On t
The future's so bright... (Score:5, Funny)
Beyond the theoretical limit (Score:5, Informative)
The press office at U. Michigan has gone a long way from what they actually did to what they are speculating might be theoretically be possible. What they actually did was to predict a theoretical effect which has not yet been demonstrated. The press office then suggests that if you concentrate sunlight by a factor of a hundred million-- about seven hundred times higher than the theoretical concentration limit-- that this as-yet-unidentified material might be able to convert the light into electricity.
This is a bit speculative. They've predicted an interesting theoretical effect. Let's keep it at that, which is a nice piece of work, and leave the speculation to science fiction writers (like me).
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You're right that the concentration factor is about 100 million times (from ~1000W/m^2 sunlight at the Earth's surface), which is crazy high, but I wasn't aware there was a theoretical concentration limit. Where did you get that from and what's the rationale for it?
Theoretical limit to solar concentration (Score:5, Informative)
I wasn't aware there was a theoretical concentration limit. Where did you get that from and what's the rationale for it?
The theoretical concentration limit is straightforward-- it comes from the fact that the sun has a non-zero solid angle. Basically, a concentrator works by increasing the fraction of the sky that's filled by the sun, and the best you can do is to make the light come from the whole sky. (Well, there's also a factor of n, the refractive index).
The book Solar Electricity by T. Markvart gives a calculation (page 237-- it's available on googlebooks)
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Alas, "pages 113 to 291 are not shown in this preview". How frustrating.
Wow, that's annoying.
Okay, it makes sense for lenses, but is it true for mirror/tower systems as well?
Yes, it's a general result for any optical system, of any kind.
Obviously you'd hit a practical limit long before you tiled the ground with mirrors all the way to the horizon that pointed back at a tower concentration point, but it would still seem like a very high concentration factor would be theoretically possible.
Hmmm... with a bit of google hunting I found this page, where it states the maximum concentration factor is 46211x [volker-quaschning.de],
Actually, that's only if you concentrate light onto one side. In principle, you can double that, concentrating light onto both the front and the back. Then (the Winston concentrator trick) you can increase the factor a little more with a high-index secondary.
and that the maximum theoretical temperature is 5500C. That makes sense for temperature,
Right, maximum temperature is the temperature of the surface of the sun.
and I'm guessing intuitively that the same rationale would exist for the light flux -- the equivalent of whatever it is at the Sun's surface is the maximum that could be attained.
Exactly.
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You would think.
But, no, you use that to beat the concentration limit: that would violate the second law of thermodynamics.
The proof is left to the student :)
Re:Beyond the theoretical limit (Score:5, Interesting)
There's a theorem in imaging that says you cannot focus a light source to create a beam any more intense then at the surface of what is emitting the light. A consequence of this is that you cannot heat something to hotter than the surface temperature of the sun by concentrating sunlight in any way, even if you had a lens the size of the solar system. The spot size that you get will just keep getting bigger.
Incidentally if you were able to do this it would violate the 2nd law of thermodynamics, because you would be moving energy from a cooler object to a warmer one without doing any work, thus decreasing the total entropy of the universe.
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There's a theorem in imaging that says you cannot focus a light source to create a beam any more intense then at the surface of what is emitting the light. A consequence of this is that you cannot heat something to hotter than the surface temperature of the sun by concentrating sunlight in any way, even if you had a lens the size of the solar system. The spot size that you get will just keep getting bigger.
That's true, but it only applies to imaging optics. Non-imaging optics, hyperbolic concentrators being one of the commoner cases, are not subject to this limitation. If I'm remembering right -- it's been about 25 years -- there was pioneering work done at the University of Chicago in the late 80's using hyperbolic concentrators to achieve concentrations considerably above those of the surface of the sun. This doesn't violate the Second Law because you only get the amount of light that falls into the collect
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Making sun light hotter than the Sun is possible by using a concentrator with a high index of refraction, such as sapphire.
This is allowed by the 2nd law of thermodynamics because light is reflected, spread, and lost outside the concentrated zone, thus increasing the total entropy.
Kim0+
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So to your first post, the claim is not that you cannot collect all the light nor that you are in fact able to focus it to exactly the intensity of the source. In your system the translucent sphere serves to prevent us from focusing the light anywhere near the intensity of the original source, so there is nothing wrong with that. Further, we would now find ourselves unable to focus the light to a spot any more intense than the surface intensity of the translucent sphere. If one were to envelop the whole
more green vaporings (Score:2, Flamebait)
Wait, what? (Score:5, Funny)
Electromagnetism consists of equal parts electricity and magnetism?
You mean... That fool Maxwell was right?
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What happens to EM radiation if you remove the M? My physics is zero; I kinda get photon-electron pinball game, but if you bleed the magnetic power away, what happens to rest of it?
[ps. sorry if my tourettes addled puppy chimes in, he seems to have lost his way home and soiled himself]
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You can't have E without M. Magnetism just comes from relativistic effects on electricity. Take a look at http://en.wikipedia.org/wiki/Relativistic_electromagnetism [wikipedia.org] for an example.
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Isn't a static electric charge an example of E without M?
I know you can't have a magentic field without an electric field, but is that really a two-way relationship?
Re:Wait, what? (Score:4, Informative)
Isn't a static electric charge an example of E without M?
What is a static charge? I can choose a reference frame where the charge is in motion, and thus produces a magnetic field. If you look carefully at the fundamental equations of electromagnetism, you see things like "the force on the charge is proportional to the velocity of the charge," and "the induced magnetic field is proportional to the rate of change of magnetic flux."
Both of these statements immediately imply the question in whose reference frame are we to measure the velocity of the charge or the rate of change of magnetic flux? In one frame to another the velocity is different, as is the rate of change of flux. But no matter what reference frame you pick, the particle does the same thing. This means that the electrical force and magnetic force are actually the same force, but they appear to be different when you choose some particular reference frame in which to measure them. You could have chosen a frame in which both fields took on different values, yet the net effect on the particle is the same.
It is relativity which causes the apparent splitting of the one unified force (electromagnetism) into two different forces (electricity and magnetism). You cannot have one without the other, or rather, you can have as much or as little of one as you want, depending what frame you measure in.
They are the same and can't be separated.
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"the induced magnetic field is proportional to the rate of change of magnetic flux."
Quoting myself there... Obviously, what I meant to say is the induced electric field, not the induced magnetic field.
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I know you can't have a magentic field without an electric field, but is that really a two-way relationship?
Actually, you can't. A magnetic field induces an electric field across conductive elements proportional to its strength and the conductors' position relative to the magnetic field (and the right hand rule, of course). It's the basis for many measurement tools.
The reason you don't constantly get zapped by the earth's magnetic field is that a) it's pretty weak, and b) you're not that great a conductor (sorry if I dashed some dreams there)
If you were silly enough to hug a strong enough electromagnet, you cou
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Bah, should uncross my eyes before replying. Didn't see the "can't", thought you said "can". Sorry, my bad!
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The article implies that the 100Million times stronger magnetic field is where the power is tapped from; thus it would have to weaken the field. What happens to the light?
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The article implies that the 100Million times stronger magnetic field is where the power is tapped from; thus it would have to weaken the field. What happens to the light?
It ceases to exist. There is no law of "conservation of light." It's okay for light to disappear.
Interesting, but doesn't seem very practical (Score:3)
If you have 10 million watts per square centimetre of light focussed on something there are far more efficient ways to convert it into useful power.
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Yeah, the something will suddenly be a high temperature gas suitable for boiling water or even blowing itself through a turbine.
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Yes, like igniting a fuel pellet in a fusion reactor.
Magnetic Fields ... (Score:2)
So do we now have to ask "Solar cells - How the f*ck do they work??"
Don't hold your breath. (Score:5, Interesting)
I'm really surprised that the article didn't mention "5 years" as a time scale for when this will be viable, since that's the typical duration mentioned in these sort of articles --- far enough in the future that most will have forgotten about it by the time we get there, but near enough to still feel like it's worth anticipating (in other words, the perfect length of time for a project that needs funding to continue, but may never actually produce desired results).
Solar power (Score:2)
Sure it's all great now, but what happens when we run out of sunlight?
Re:Solar power (Score:4, Funny)
Wait till morning.
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Wait, isn't that backwards? I'm confused.
Rand? Did I see the word Rand? OMG it is John. (Score:2)
Kudos to the University of Michigan! (Score:2)
This looks like some really promising work. I still want to crush your football team on the gridiron, though. 3 Cheers for U of M Physics! 3 Cheers for Rich Rodriguez!
Pursuing patent protection (Score:2)
Solar thermal competition? (Score:2)
At 10% effeciency I'm not understanding the appeal.
The light has to be concentrated which means tracking electronics, hardware, mirrors, maintenance..etc.
You can get about 30% effeciency today by pointing concentrated solar energy at a stirling engine.
The effect itself is more intersting to me than the possible use in solar energy.
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It is the simplicity. Both manufacturing and maintenance. Current solar panels top out at 19% efficiency, but take a whole host of environmentally bad chemicals and processes to make. Then they degrade over time. This suggests common glass could power the world.
You approach 30% on a sterling engine, with a perfect source and sync. But you have moving components that will wear out and need maintenance.
Basically, imagine a piece of glass with integrated lens with wires on it - solid state, reliable, durable,
Pics (Score:2)
So... (Score:2)
...how long before we never hear about this one again?
Energon Cubes (Score:2)
None of this is worth crap until (Score:2)
Yes but... (Score:2)
You can do the same thing by smearing a thin layer of ripe banana on graphite-coated paper. Nearly .5 watts per square meter.
All you need is paper, a fat pencil and a bunch of ripe bananas.
Seem like they could oscillate the light (Score:2)
And create a moving magnetic field over coils wound around the medium. Instant power.
It'll never work! (Score:2)
Let's build more nukes!
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And it must be focused to an intensity of 10 million watts per square centimeter.
That ought to be enough to melt the glass, don't you think?
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Yes but no absorption (Score:3)
And it must be focused to an intensity of 10 million watts per square centimeter.
That ought to be enough to melt the glass, don't you think?
Well it won't get hot if there is no absorption of the photons. Of course I don't see how it produces energy without absorbing the photons.
Basically the science writer was scrawling gibberish. There's probably something really interesting here but getting it from this article requires advanced degrees in Kremlinolgy and Tea Leaf reading to determine what the scientist really wanted to say.
My guess about what they are trying to say is that the energy is not being stored by promoting electrons from a valenc
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It's a wiki, for god's sake, couldn't you have deleted the image ref?
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I didn't know it was a wiki for all the goatse i was getting around my family
Stop giving the troll lulz! It's like a catnip to them!
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I thought that cat macros were catnip to trolls...
Re:I've been reading about solar breakthroughs (Score:4, Insightful)
The trouble is that it's still cheap to get fossil fuels.
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Re:I've been reading about solar breakthroughs (Score:4, Informative)
That's because they don't pay their due externalities [skepticalscience.com].
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To paraphrase Ballmer: "Externalities! Externalities! Externalities!"
It's turtles all the way down, no one is paying all their due externalities.
cutting out the middlemen (Score:2)
Imagine a world where all the energy you'd ever need could be purchased by the kilowatt, for a reasonable cost - say, $0.50/watt. Suppose the most energy your house would ever draw is 10,000 watts (a hot day in Phoenix in July). For an initial outlay of "$5,000" (or so), the electrical needs of your home would be met forever.
Suppose this new understanding of the physics of light evolves to the point that it could power an automobile with just the surface area available on the roof.
Whatever will the millions
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even if all that was true, there is still one problem.
you can't store electricity. it is an on demand only product. so when the sun went down your electric car still wouldn't work.
In the end the real break through for electricity won't be fancy solar cells, or something with magnets, a 10KVA mega capacitor that can let out a little current or a lot and be recharged by the out put of your solar / wind/ tidal/ nuclear/ bicycle, etc. 3-5 of them could run a house for a couple of days, and that would relive
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The fact that these systems are not in place does not mean they don't exist or can't be implemented.
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It's already happened, when electric refrigeration replaced the tremendous worldwide industry that harvested, stored, transported, and delivered ice. It was not necessary to break the laws of physics. We got more fresh food, and people found other jobs.
The problem with infinite cheap direct energy is entropy. Energy inevitably becomes heat pollution. But good solar isn't infinite energy, and the heat is already getting here.
There isn't anything more sure than the laws of thermodynamics. As long as you live,
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Yes, there was a story about faith, but a stupid story. People who believe in science believe in the scientific method. This does not mean that your two choices are faith or to understand all of physics from first principles.
Do you understand how meaningless a statement like "The physical universe is not a closed system" is? Obviously not. Don't bother answering, you can't compose meaningful statements about the world.
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...a reasonable cost - say, $0.50/watt.
I'd gladly pay $0.50/watt, if I'm guaranteed to have my watts delivered as long as I live. ...for $1500.
I'll take 3000.
That'd be 3kW*30yrs*365days/yr*24hr/day (assuming I live another 30 years) = 788,400 kW*h
$0.0019 / kW*h.
That's a real bargain!
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L-curve is applicable here (Score:3)
Okay, so the millions don't have much to worry about. It was the billionaires that I was really concerned about.
Through what other means (the artificial scarcity of energy has worked really well for a long time) can the planet's billionaires maintain the L-curve distribution of income [lcurve.org] in the economy? This is the only question which must be answered before revolutionary energy technology can be allowed into the market.
As I've said before, remember that JP Morgan only financed Nikola Tesla's research until he
open up your 'vision' a little (Score:3)
* Look at the housing market. How do we determine the value of a house? Look at who wants it, how much they are willing to pay. Those are the only two variables that matter.
Very few people pay cash for a house. The variable that matters more than any other is how much a "home buyer" can afford to borrow (from JP Morgan).
If electricity were free, then people would have more money to spend on ... *finite resources.* Consequently, the price of those resources would increase
If electricity were free, all resources would be essentially limitless. We could afford to desalinate water and pump it into the desert to make an artificial oasis, etc. Surplus has been a 'problem' for quite a while now (due mechanization & automation reducing the amount of labor required for many of the products humans need)...
Re:I've been reading about solar breakthroughs (Score:5, Interesting)
It's awesome that they are (apparently) directly generating electricity. Much better than the quaint method of boiling water to turn turbines.
Re:I've been reading about solar breakthroughs (Score:5, Funny)
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... It would be cool to go off of steam.
I see what you did there.
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Re:I've been reading about solar breakthroughs (Score:5, Funny)
WOOOOOOOSH
Yes, you're right, sometimes the steam lines leak.
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I keep trying to go off of steam, but those $10 deals keep suckering me back in.
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Yeah, it's amusing that nuclear power reactors can use the same method as a 1800's steam engine.
Amusing more that HydroElectric Dams can use the same method as a 200 B.C.E. Water Wheel [wikipedia.org].
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Comparitively to what? What better method do you have to turn heat into electricity?
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Some progress but we're still behind in many ways: http://www.wired.com/wiredscience/2010/02/quantum-photosynthesis/ [wired.com]
A leaf may not be as efficient as some solar panels when directly compared, but a leaf actually builds itself. So the leaf might be more analogous to quantum tech "solar panels" plus factories building the panels, converting the raw materials, etc.
Some plants can even grow from a single leaf.
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not sure it's totally awesome... (Score:3)
There are many ways to apparently inefficiently directly generate electricity that have nothing to do with boiling water...
You can run turbines in several ways w/o boiling water (e.g., wind, water).
You can generate electricity w/o turbines through chemistry (e.g., lemon battery) or quantum mechanically (e.g., photoelectric effect in solar).
You never know, this whole thing may turn out to be more like the Casmir effect or similar effect. Interesting, but not quite practical for anything yet. The danger is t
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Go to dow's website, you can order solar roof shingles today. Not what the article is about but a product that is surely less than 30 years old.
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Damn, I thought they had started shipping already. Sorry about that.
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Might be for Dow, but looking for a couple of minutes on Google shows several companies that sell them.
i.e.: a blog [umich.edu] from 2005/2006 and he had solar shingles back then.
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Yeah, there's a solar-shingle install on a model home just down the street from us. I couldn't tell you the brand-- but they're very clearly available.
Satellites not shipping products ... (Score:5, Interesting)
However I would not keep an eye to the shipping products to judge feasibility, I would keep an eye on satellites. Break throughs like the one in this story might first appear in the environment of much higher solar intensity found in space.
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I would keep an eye on satellites. Break throughs like the one in this story might first appear in the environment of much higher solar intensity found in space.
Good plan.
The solar intensity isn't that much greater in space (20-30% more than noon day son at the equator?) but it's certainly a more difficult environment to deal with -- size and weight are at a premium, and the stuff has to keep working for a long time in a hostile environment, so they're going to want to send up the very best.
However, many breakthroughs are about price -- making solar panels (or whatever we use to create power from sunlight) cheaper. I wouldn't expect to see those up in space, as th
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20-30% more than noon day son at the equator?
FWIW:
"Solar energy reaching Earth's orbit is 144% of the maximum found on the surface of Earth, and includes wavelengths that don't even reach the surface due to the atmosphere."
http://en.wikipedia.org/wiki/Space-based_solar_power [wikipedia.org]
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Nothing comes from it? During the last year, in most western countries below 50 degrees latitude, producing your own electricity using PV has become cheaper than electricity from the net if you count the taxes for the net electricity. And that's without government funding. Why did you think Google invests so much in that solar project of theirs? For their image? No, they're probably simply in it for the money.
The production capacity for PV panels already is 1/18th of the capacity we'd need for the entire wo
Re:I've been reading about solar breakthroughs (Score:4, Insightful)
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We've been over the energy- and cost-payback thresholds for solar power for quite some time. Even PV, which isn't quite as cost-effective as the solar thermal setups, has energy payback time in the 1-3 year range (depending on tech) and financial payback time well within warranty (with wide variation due to local insolation and electric rates).
Which is why we went ahead and stuck some on our roof. We're two years in, and four years from financial payback, and the system has a 25-year warranty. We're in a
Re:I've been reading about solar breakthroughs (Score:5, Insightful)
30 years ago, photovoltaic panels cost almost $40 per watt.
Today, the cheap ones are about $2 per watt.
Mods, how is ignorance insightful?
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He's hoping so hard for "breakthroughs" he's entirely missed four decades of gradual progress.
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The average energy payback time for silicon is 1-3 years. For thin film, it's a couple months.
Try again.
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The average energy payback time for silicon is 1-3 years. For thin film, it's a couple months.
Try again.
not by the time it reaches joe sixpack hobbyist.. i would have done a conversion years ago if i could.. sadly my house is situated in about the worst way for it.
If i ever build my retirement house it will be self sufficient. a mix of solar and water power
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Bingo. Virtually everything we have and use on a daily basis has started in this manner where someone finds some phenomena which can be honed, researched, and turned into a viable product used daily.
Solar is important. Since nuclear power is essentially set back at least a decade, anything that gets us free from coal and oil is a must have, not just for global warming, but to prevent countries having to go to war for their dino juice stakes.
What will be the key breakthrough that will change everything wil
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You do realize that you're reading a forum where there are people posting comments from the middle of nowhere across the planet using a cell phone a fraction the size of a TI-85 which can get data connection rates out in the middle of the woods that blow away the modem speeds most people connected with in the 1990s, right?
Of course, it all depends on what your definition of a revolution is. Today's batteries store 4-5 times as much energy as those of two decades ago. Today's solar cells are a tenth the co
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You forgot about SpaceX developing the cheapest heavy lift vehicle to date, Falcon Heavy (which is most likely going to get humans to Mars). ;)
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I did not visit, but this is a GOATSE link.
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Could this be placed in marijuana grow houses to harness some of the wasted energy to power a small meth lab?
Meth labs power themselves... with fire...