Where are the 70% Efficient Solar Cells? 798
VernonNemitz asks: "Back in 1984 a patent was granted for silicon chip micro rectennas, which would convert visible photons into electricity in the same way that ordinary rectennas convert microwaves into electricity, at perhaps 70% or greater efficiency. Nobody could make such solar cells back in 1984, but we certainly can today, with sizes of antennas that would capture everything from infrared to the edges of UV -- and the patent has expired. So, where are they?" Currently the most popular type of solar technology is photovoltaics, however PV technology only has an efficiency of about 7-17%. With the potential gains claimed by the technology in the cited patent, has anyone even tried to build one of these units to see if it can live up to the given promise, or at least prove to be a technology than we should be exploring?
But is it real? (Score:3, Interesting)
Where are they? (Score:5, Interesting)
The patent just expired. It takes a while to develop and prove out a new technology.
I see lots more work on windmills for alternative power. Many have shelved solar panels because the current ones have poor performance.
Heres a company - up to 80% efficiency. (Score:5, Interesting)
Also there was a story about 2 weeks ago, mentioning solar energy breakthrough using full-spectrum layering. Does anyone know anymore about this. I was unable to find it in Google News.
Nanotech material, once they arrive, will of course make 90% efficient material practical.
Planet P Blog [planetp.cc] - Liberty with Technology.
Re:Where are they? (Score:5, Interesting)
Possibly overlapping Patents? (Score:4, Interesting)
Where are the 70% Efficient Solar Cells? ask GWB (Score:1, Interesting)
What would happen if all the major automakers decided tomorrow to start building electrics? GWB's texan constituants would have a cow. They would be trying to pass laws to outlaw them.
When it was clinton/gore presidency, everything was dumped into technology, the GM EV1 is a classic example of the innovations that occured under a goverment that supported research that would cut out our dependance on foriegn (read Iraq) oil. IIRC Clinton even made it a law that all US automakers would have to have an electric vehicle on the market by 2008, and that these cars would have to be built along strict goverment guidelines.
When Bush became president, he wasted no time in modifying the law. Current guidlines are on par with a golf cart with turn signals and mirrors. Fords paltry offering into this market is just that, a golf cart with mirrors and turn signals.
Sorry I turned this comment into a political rant, conspiracy theories aside, the fact that GWB would kill the alternative fueled car laws and go after Iraq oil is all the proof I need.
Why we have to have 80%+ (Score:5, Interesting)
You can read about here on my website [floatingplanet.net] for more info. Some in the oil industry are thinking that peak will be hit within the next two years. This might explain our rush to invade Iraq.
Either way, as oil reserve dwindle and demand goes up, it will create a highly destabilized politic - and if you think the repression we've all been feeling lately is bad, it will only get worse... UNLESS:
We wean ourselves (QUICKLY!) off of Oil. The Hydrogen economy is just waiting in the wings. All of the technology is essentially there. The cost factors will become not only competitive, but cheaper and cleaner than oil, once we start migrating our energy infrastructure over to Hydrogen.
Lets hope this happens before we end up in some kind of nigthmarish Oil Fedual/Fascist Global New World Order.
Planet P Blog [planetp.cc] - Liberty with Technology.
Re:Where are the 70% Efficient Solar Cells? ask GW (Score:5, Interesting)
Do you have a URL for Bush's guidelines on electric vehicles?
Re:Heres a company - up to 80% efficiency. (Score:2, Interesting)
From the website you linked:
"This high efficiency is made possible by the use of polarization, which causes absolutely no loss in the available light energy, yet organizes the light to aid its conversion to deliverable electric current."
http://www.howstuffworks.com/sunglass4.htm
"A polarized filter passes only the light that does not match its orientation. Only the part of the light wave that is not aligned with the slots in the filter can pass through. Everything else is absorbed."
It seems to me that if the filter absorbs light not in the correct orientation, then the available light energy would be decreased.
So who is right? howstuffworks.com or polar-solar.com?
==>Lazn
PVs can exceed 35% efficiency (Score:4, Interesting)
This article mentions Tecstar--apparently the leading supplier of high-output PV cells for space missions. They made the cells for the Mars lunar rover, among other projects.
The difficulty is that manufacturing the cells is very difficult and expensive, requiring multi-million dollar Metal Oxide Chemical Vapor Deposition (MOCVD) machines. Due to variations in the rather elaborate manufacturing process, the yields vary greatly, and also produce cells that have widely varying efficiencies. Some cells fall below a given spec, while others exceed the spec.
In order to achieve a given power output for a space system, they are able to mix the under and overperforming cells into an array that provides the necessary power.
So, although some cells may only provide 30% output, a few will exceed specs, and thus provide > 35% efficiency. The challenge is delevoping manufacturing processes that improve yield and thus reduce costs.
Why aren't we ever going to see these type of cells on earth? Cuz they cost millions of dollars to produce, and there is a multi-year order backlog for them for planned space missions. Unless hundreds of millions of $ gets directed towards making them a commodity, well, you know the story...
What about Biodiesel? (Score:2, Interesting)
Hydrogen has some very significant prospects, but at present, it's to far off, diesel, and biodiesel are far more likely short-term replacements for Gasoline. The only problem with both is the public's long-standing dislike of diesel engines (they make a lot of noise, they make a lot of smoke...), and the current price of biodiesel (about 75% more then diesel in the US). Public awareness can be repaired (modern diesel engines are quiet, efficient, and reletively vibration-free), but it takes time and money. And since regular oil prices are going up very quickly, the second problem will reslove it's self in the next few years automatically.
Re:Anyone know the energy in sunlight? (Score:4, Interesting)
if you take all the unused building space in america and covered them with solar cells (of today's technology and efficiency) you could generate (more than) all the power we use (even if we convert all cars to electric cars). the neat thing is that the "unused building space" doesn't mean "cover the desert with solar cells" is just means to put solar cells on every roof top, on the top of the medians along the highways. granted this is a difficult task, but what if every residential house that was built had to have it's roof coated in solar cells and put on the grid. after a while you'll be generating quite a lot of power.
another cool thing that is in development is turning the huge windows of office buildings into solar panels. in high-rise office buildings, it's not uncommon to have 10 foot tall windows that span the entire room. usually these windows are tinted and the office generally has blinds or curtains to keep all the sun out (to reduce cooling costs in the summer, and having that much sun in the office would make it to bright anyway). so rather than just using some type of tinting that reflects the light partially, i've seen some cool work with dithering (very) small solar cells in the windows, these will absorb light and turn it into electricity. so you'll get two benefits: tinted window and extra electricity for the building.
just simple solutions like that could help our upcoming power crisis when we run out of oil.
Re:Where are they? (Score:5, Interesting)
Re:Research (Score:2, Interesting)
It's not a bomb, and it doesn't hurt people directly, but windmills and things like higher gas mileage can lower the demand for, and price of, oil, thus destroying an oil-producing country's balance sheet. It's an effective way to eliminate a geopolitical competitor. It's cheaper than war and the "attacked" country can't exactly complain to the U.N. like they could in the face of an outright attack. There are a few drawbacks:
1) Some of those oil-producing countries might be allies (or at least temporary allies). For instance, if you were to lower the price of oil to hurt OPEC, you'd also hurt Russia.
2) Some of your competitors would gain as well. China comes to mind - they produce very little oil of their own and their economy is still very industrial. Low oil prices would be great for them.
3) Finally, do you really want to wreck the economy of certain states? Would the U.S. really be better off with a crippled Saudi economy, which would be a breeding ground for even more hatred? 20 years ago 10 million poverty stricken, U.S.-hating arabs would have sat relatively impotently in the Middle East, but these days a country can be attacked by a few angry people. Big topic!
So windmills might be more dangerous than a few nuclear weapons after all.
Re:Heres a company - up to 80% efficiency. (Score:2, Interesting)
Re:Where are they? (Score:5, Interesting)
The downspout on an office building is going to produce proportionally less electricity. Let's assume you have a 4000 square meter roof 100 m high and you get 100 cm per year of rain. That's 4 million kg of water dropping 100 m. Since E = mgh, you get a potential annual power yield of 4 gigajoules. Over the whole year, this comes out to an average of 126 watts. Factor in unavoidable generation losses, and you'd be lucky to power a single light bulb with the rainwater from an entire office building.
Re:Why we have to have 80%+ (Score:3, Interesting)
We're suffering a major drought now and people who study the environment tell us that we'll need 2 years of record hard precipitation to get the ground moisture back to normal.
I'm not a big believer in global warming being all our fault, but I do know it's going to be a real ugly summer on the western prairies.
Re:Where are the 70% Efficient Solar Cells? ask GW (Score:3, Interesting)
Innovation my ass. The work the GM researchers did was excellent, and the GM EV1 v2 would have been even better. However, it doesn't change the fact that the EV1 program was all PR fluff, that was quickly flushed down the toilet once the cars started coming off lease (and this was before GWB was elected.) No EV1 was ever sold to my knowledge - because they were only leased, never sold. Now, how much innovation can you have when you take back the product that was supposed to be innovative? Toyota has done more for alternative fuels (RAV4 EV, which can be purchased, but only in California, and of course, the Prius) than GM's EV1 ever did.
IIRC Clinton even made it a law that all US automakers would have to have an electric vehicle on the market by 2008, and that these cars would have to be built along strict goverment guidelines.
That's news to me. Perhaps you were thinking about the California ZEV mandate instead?
I'm all for electric (I have a 1KW array I'm going to be putting up during spring break), but don't give credit where credit isn't due. After all, people started buying SUVs under the Clinton administration, and only now, are people turning against them (conservative christians and environmentalists alike now decry the excessive fuel consumption.) SUVs = terrorism is the new message. I never saw the Clinton-Gore people say that, probably because they were just as addicted to the oil/car industry as the Bush people are.
Re:Hydrogen? (Score:3, Interesting)
Not likely.
According to this site: http://www.nmsea.org/Curriculum/7_12/The_Solar_Re
You need 33,400 square km to produce enough energy, now their efficiency estimate is about 2x what we are acepting here. So, double that to 66,800 square kilometers. The US has 9,158,960 of total area. So, to produce all of our electricity at 17% efficiency requires 0.7% of the total land area. Which is of course a meaningless number without some other reference. So, the mojave desert is about 65000 sq km, the sonoran desert in Arizona, California, and Mexico is 310,000 sq kilometers.
So, figure between rooftops, and god forsaken places in the middle of nowhere there is definitely enough room to put enough solar to power the entire US. Storage is a problem, but that is what hydrogen is for.
Of course, without fossil fuels to rail against rabid environmentalists will be pissed about covering large stretches of land with PV.
Re: Who elected George Bush anyway? (Score:3, Interesting)
These guys [archive.org] did.
(And I STILL think it's funny that the guy who did the map colored the Bush counties red, rather than the Gore counties. B-) )
Re:Heres a company - up to 80% efficiency. (Score:3, Interesting)
To be honest, I don't quite understand what role polarization plays in this ... can anyone clear this up?
Production rates. (Score:1, Interesting)
i was involved with SMUD's greenergy programm.
1) PV cels are the answer, i read this pattent and its physically impossible now or in the future.
2) why are PV cells sooooo expenxive.
a) demand ( there are not enought people buying PV cels to drive down the costs)
b) production ( there arent enough production companies making them, ie no price wars)
c) profitability ( threre isnt allot of money to be made in the PV industry)
2) heres the solution.
if you own a home
a) contact your local power companie, ask if they have a green energy alternative. they will subsidise part of the cost involved with installing solar panels.
b) take some equity out of your home and install solar panels, eventually they will pay back the loan and intrest. if fuel goes up it will make your hose verry attractive.
c) by law if you pruduce more energy than you consume the power companie has to buy the excess energy from you. ie you will be getting a check from your power companie.
d) if you are buying a home, see about having the instalation of solar panels added into the cost of your home. on the average it is about 20K to have an adequate solar system installed. subsidized its about 12K.
if a large amont of people did this the price of solar panels would drop through the floor.
the problem is its like intel making a new chip and only having about 100K people they can sell it to, a celeron would cost about half a million dolars.
Re:Heres a company - up to 80% efficiency. (Score:1, Interesting)
Light may be organized in all and any direction.
Before reception, it is good to make the light
oscillate in the plane of the dipole.
Iguess,
Alternatively, they might have two perpendicular dipoles, if they wanted. But I guess they don't.
Petrus
Re:It would certainly be nice. (Score:3, Interesting)
Oil is solar power! (Score:4, Interesting)
I think it is a good idea, anyway. The only energy that is not solar is geothermal and nuclear.
The problem with oil shale and other deposits... (Score:3, Interesting)
Even if the earlier projections of running out of oil come true, there are enormous amounts of "oil" that can be extracted from oil shale (at $80/bbl) and liquid fuels can be produced from coal (methanol is especially easy) and plants (ethanol, biodiesel). All of these become practical with $3/gallon gas
The problem is that it doesn't matter how much per gallon you get. If it takes more energy than is in a gallon of oil to extract a gallon of oil from the shale, for example, you are not producing energy. The same problem exists for coal: At some point, it takes more energy to dig it out of the ground than you get from burning it. When this happens, you can continue to produce at a net energy loss, but you need to get energy from somewhere to do it. Where are you going to get that energy without oil?
That's the real, serious problem we're going to be facing in the short term. It's not going to be lifethreatening in my productive lifetime. Sucks to be growing up now though. The sad fact is people won't change, but hey, I get to fiddle while it goes down! (sarcasm)
Re:U-235 vs. U-238 (Score:3, Interesting)
These sources may keep hydrocarbons around for a long time.
Another trend is the end of the population explosion. Many contries in the world are now at negative population growth rates, and that trend is increasing rapidly.
Currently, it's cheaper to get gas - it costs Kuwait only $2/barrel for oil (the difference between that and the world price is all profit). Oil, as has been pointed out, is just too darn good, from an economic standpoint.
The biggest problem with alternative energy (including nuclear, which we *should* use a lot more of) is storage - especially for automotive uses. I simply do not foresee an adequate battery technology coming down the line. Fuel cells may eventually reach the cost, density and safety needs, and we could produce fuel using nuclear generated electricity.
All of this assumes enormous investments and drastic changes in very expensive infrastructure, so it is not going to happen any time soon.
Personally, I am for continuing the large levels of research into these techologies, but not for rationing (by price or any other way) oil for automotive use. The global warming arguments, even if valid, leave decades in which to start changing, and it would be foolish to destroy our economies (with the unpredictable political consequences - such as the rise of anti-environmental or even fascist governments).
Re:Theoretical problems with optical rectennas (Score:3, Interesting)
IIRC, the rate of attenuation of an electromagnetic wave in a conductor is
sqrt(2/wus),
where
w = 2*pi*f = frequency of the wave, in radians
u = permeability of the conductor, maybe 4*pi*10^(-7) Henry/m for copper
s = conductivity of the conductor, maybe 6*10^7 mhos/m,
meaning that 1/e or about 37% of the wave decays in this distance into the conductor.
If my numbers are right, f = 5.2*10^14 Hz for yellow light, and the skin depth in copper for yellow light is then 2.8*10^(-9) m, or 2.8 nm.
Since the wavelength is 570 nm but the skin depth is only 2.8 nm, it seems that a copper antenna would instead act more like a mirror, reflecting the radiated energy rather than absorbing it.
It's a transverse wave (Score:3, Interesting)
The problem here is likely timescales: light has a VERY high frequency (10^17 Hertz roughly, if I did my math right). At that frequency one doesn't push the electrons back and forth like a kinetic particle in the usual diode treatments so much as one excites interband transtions, which is how a regular solar cell works.
Re:OK, which forests do we cut to make solar farms (Score:3, Interesting)
1) One geographic source means that one heavy cloud day would eliminate all production.
2) Once the electricity is produced, you have to send it over transmission lines to the load (customers). Too much energy over one set of lines will melt it.
3) Build more transmission lines, and your local communities will complain about all the electric lines in the area, driving down the local value.
4) Natural disaster. One hurricane, tornado, hail or earthquake, and you've broken all of the glass in the whole plant.
So, the key to PV is decentralization. This means many many installations spread over hundreds (to thousands) of miles) at about 1 station per square mile. Each one would need its own DC to AC converter (to put energy on the grid), not to mention voltage regulators, plus telemetry so you can get the reading from the devices, all of which drives up the costs.
Re:The key to adoption is distributed power (Score:3, Interesting)
The United States & Canadian power grids (of which there are 3 AC systems running in parallel) is currently controlled by a number of Regional Transmission Companies, also working in parallel, and I happen to work for one of them. Fortunately, California & everything west of the rockies are AC-isolated from our Eastern Interconnection, so we east coast fellows (who happen to be running things correctly, not to mention profitably) won't have to suffer if they crash out.
But to your comments, you might want to take a look at recent distributed generation projects, like what's being built in APS territory. Secondly, anyone in the deregulated markets can form an electric co-operative, and buy/sell power to the bulk market. The rules are already in place. (aren't you curious why so many states are fighting deregulation?) The only problem is telemetry... the more distributed you get, the harder (and more costly) it is to collect the individual meters. PP&L is experimenting with automated meter reading using the telephone network, so there is progress in distributed data collection...
The next phase is demand-side response, which is the ability for the customers to adjust their load, and get paid locational pricing for decreasing their consumption. The key here is, you can't play in the spot market only when it's profitable, you have to play 100% of the year. Show me the public utility commission who's willing to risk raw pricing for its citizens...
As for the article, almost every example given was the Midwest-ISO & California-ISO version of how things are done, and frankly, they are in 2nd & last for a reason. And you're correct, the infrastructure does not exist for us to monitor everyone's generation in real-time. But then again, that's what state estimators are for.
p.s. EPRI doesn't exactly have the best reputation, which makes me wonder what agenda Wired had in chatting with them
Re:Heres a company - up to 80% efficiency. (Score:2, Interesting)
Ethanol is not good (Score:3, Interesting)
The motivations for the promotion of ethanol seems to be to provide a subsidy to corn farmers under the guise of an alternative fuel source so as to not encurr the wrath of international trade organizations like the WTO.
Re:It's a transverse wave (Score:3, Interesting)
Photovoltaic cells work on a very different principle. Because there's a significant amount of energy in each photon, enough to dislodge an electron from silicon's valence band into the conduction band (about 1eV), current can be generated.
If the photon lacks enough energy (has too long a wavelength), nothing happens except that the silicon heats up. If the photon is too energetic, it will still dislodge the electron but it won't impart all of its energy; the rest will again be wasted. These two effects account for much of the poor efficiency of PV cells on sunlight, which has substantial energy across the visible spectrum and into the near infrared.
Re:U-235 vs. U-238 (Score:1, Interesting)
Why don't you look up how a CANDU reactor actually works before running with it. CANDU reactors are not suitable for breeders. The plutonium produced is in very small amounts, that it would take tonnes of the waste to actually have enough to make a one-kiloton bomb. Not to mention the cost, and difficulty to do so. It's one of the main selling points of the reactor. You can sell them to whoever the hell you want, all they need is uranium ore and the ability to process it, and you never need worry about them using it for weapons manufacture. They can however burn plutonium, and this has been proposed as a way to get rid of all the plutonium cores from decommisionned missiles in the US and Russia with a fair bit of positive feedback.
And the CANDU was designed in the 50's, not for the Manhattan project.
Educate yourself before you go on about something you don't know about:
http://www.ncf.ca/%7ecz725/#toc
Re:Why we have to have 80%+ (Score:2, Interesting)
Re:Hydrogen? (Score:3, Interesting)
Do you have any idea what it would take cover 66,000 km^2 with PV cells? The costs in dollars and natural resources would be astronomical. I don't even want to think about it.
And yeah, I think most people would be a little upset if we wiped out the entire mojave desert. Eh, we didn't care about that ecosystem, right? Sorry Mr Gila Monster!
In addition, we already know cities like Tokyo have distinctly different weather patterns due to all the manmade structures. I wonder how covering a few thousand kilometers with metal and glass would affect the weather for the US Southwest?
Thanks for giving me a good laugh, though.
Re:Hydrogen? (Score:2, Interesting)
No more than some other common human undertakings. How much natural resources were used to build housing and businesses across this country? How much forest was destroyed? How much earth is moved to mine coal? How many resources were required to build the road systems?
How many dollars and natural resources do all of our other energy resources cost, not to mention pollution?
And yeah, I think most people would be a little upset if we wiped out the entire mojave desert. Eh, we didn't care about that ecosystem, right? Sorry Mr Gila Monster!
Well, of course you couldn't use the whole mojave desert, it was just to give context. You would use roof tops across the country, combined with large scale production in places that have lots of sunlight. Spread out from Southern California to Texas most likely.
There is also the fact that there are other ways to harness solar energy than PV, that would supplment PV. This includes wind and hydro-electric. And, personally I don't have that much problem with fission power, yes, there are waste products that we actually have to deal with instead of just dumping them into the air, but I would rather deal with a few 100 tons of radioactive waste whose effect is generally well understood, than millions of tons of green house gases whose effects are unknown.
It would change the role of utilities. Utilities would provide extra power to those who cannot be self sufficient (businesses primarily), and they would purchase excess power to resell to businesses and store as hydrogen in order to provide energy to sell at night, on cloudy days, and auto fuel.
In addition, we already know cities like Tokyo have distinctly different weather patterns due to all the manmade structures. I wonder how covering a few thousand kilometers with metal and glass would affect the weather for the US Southwest?
And, how much does burning fossil fuels change the climate of the entire planet. The only other real alternative is fusion, and no one has figured out how to make that work, and it is perpetually 50 years off. Solar build out could start today. and, yes it would be decades before there was enough to replace fossil fuels, which is why you start today.
Re:Why we have to have 80%+ (Score:3, Interesting)
But oil is not "produced" that fast. It takes long times and enormous amounts of hydrocarbon matter under pressure (tens of millions of years of forestation followed by tens of millions of years of burial, e.g.). Those fields are likely just refilling as oil trickles out of porous rock due to the reduced pressure at the drilling sites.
It's like turning off your "dead" flashlight, then turning it back on and seeing a glow. Then doing it again. And again. You may be able to do it for what seems like forever in some cases. But the amount you get on each subsequent squirt is less, and becomes uneconomical on a global scale.
The reason oil is cheap now is that there is huge competition to produce it to take money from the demand pool. The time horizon is long enough that nobody is content to wait until someone else runs out. No sense being rich after you're dead. They want the cash in their pockets now. And they don't care what the state of the world is when the oil runs out, either, except those who are angling to be the supplier of the alternative when their slice of the oil pie starts drying up.
BTW, IIRC, OPEC has about half of all the oil that's left on Earth. The Saudis are about half that, and Iraq has maybe 6%. The US is in Iraq's league, and Venezuela is a bit bigger.
Oil is good for a few decades at current and future rates. Coal, on the other hand, could be around for another 600 years. And nuclear almost indefinitely.
Anytime anyone asks where the solar power is, I laugh and rev my engine.