Solar Cell Achieves 40% Efficiency 632
Fysiks Wurks found on the U.S. Department of Energy website news of a breakthrough in solar energy efficiency. From the article: "...with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance." A page linked from Wikipedia's article on solar energy calculates the land area that would need to be covered by solar collectors at 8% efficiency to meet the world's energy needs (using 2003 figures). At 40% efficiency, it looks like a square 265 miles on a side in the American southwest would do it.
transport losses? (Score:5, Insightful)
B.
Re: (Score:3, Insightful)
How about conversion to something like hydrogen?
There are lots of desert areas that I'm sure could be used for energy generation, at least it would be better than polluting our way to global death....
Re:transport losses? (Score:5, Insightful)
That statistic is simply an illustration in any case. Obviously there are some other places in the world where such installations could be put; perhaps some less sunny ones would require more space to reach equivalent capacity.
In any case, I think that a 100% solar earth is unlikely:
* Much of the time it is night, and storing that much juice in batteries is impractical. Things like hydroelectric storage and thermal solar plants could help with this problem, but its a whole different research issue.
* In the event of, say, a major volcanic eruption or meteor impact, world power production would plummet. That could be the least of our worries.
Solar and wind are like the icing on the clean power cake. They are great for the role they serve, but you can't have them for dinner without getting a stomach ache.
Re: (Score:3, Insightful)
While the major volcano/meteor event you mentioned could deplete the nuclear buffer, it would do that (and worse) now.
At the very least, considering the effects on the economy that nearly free energy would have, we could build enough nuclear power plants to completely handle our energy needs in case such an
Re:transport losses? (Score:5, Funny)
Re:transport losses? (Score:5, Insightful)
I agree that local micro power is another good peice of the puzzle. My number one goal in life is to eventually live in a home with a net energy surplus. Of course, my penchant for running Linux on old hardware might turn into a barrier to this.
While the major volcano/meteor event you mentioned could deplete the nuclear buffer, it would do that (and worse) now.
Well, given a 'minor' event like Mt. Saint Helens, light blocking would only be a minor concern to the overall energy supply as we have it now. Obviously ash and debris in equipment, supply chain interruption and so on would be another issue entirely.
Hell, we could sell of the surplus nuclear energy to subsidize projects like the complete mechanization of food production, -- obviously using our nearly free energy. Or just lower taxes (though I would prefer the former)
Well, that's a different question, one I hadn't considered too deeply. Still, until we develop a 'perfect' single energy source a la Mr. Fusion, there will have to be a wide variety of energy sources in order to have a stable energy system. Nuclear/fossil systems require finite and largely imported fuel. Wind, solar and geothermal require specific geography. Hydroelectric fsks up the ecosystem. Each has its place in the ideal system, however limited.
Re:transport losses? (Score:5, Informative)
And even at low power levels, your fuel will keep fissioning merrily along, so in essence you're throwing away a finite resource. Also, your buffer will be significantly more expensive than the solar energy you're using as primary.
If you have an abundant source of renewable energy, you're better off using some of that to drive a buffer. Hydro buffer plants such as Dinorwig (see elsewhere in this discussion) have been shown to work well.
Re: (Score:3, Insightful)
Re: (Score:3, Insightful)
No, dummy! (Score:3, Funny)
And to those who complai about the weather, once we build the space elevator, we can put solar collector in orbit and beam power down to earth!
With all that power, we can finaly build robots to clean our homes, cook our food, even "companion" models!
Cold fusion, solar energy, space elevators, and robo wives! I think I just messed my mylar pants!
Re: (Score:3, Interesting)
It's not a coincidence nuclear power stations are often run as a base load, running at 100% of capacity basically full time.
Re:transport losses? (Score:5, Interesting)
The minimum power a nuclear plant can produce electricity at is around 20%, but this is due to non-nuclear issues (turbine vibrations, steam quality, etc). As far as the reactor is concerned, you could theoretically run at 5% power indefinitely, however there are issues associated with running at less then 100% power for extended periods of time. What happens is that in order to run at low power, you have to use the control rods to control power level, but if you deplete the core with control rods in you create axial asymmetries.
Big nuke power plants are designed to be base load generating plants, running at 100% all the time. They are sensitive to making power changes on the fly and if you shut down completely, you can't go back online for a couple days due to xenon. However, there is no reason why you couldn't design a smaller reactor designed for peak loads or emergency use. It would work just like a naval reactor: compact, high power, and using highly enriched uranium.
Re: (Score:3, Interesting)
Re:transport losses? (Score:4, Informative)
Grid power would fall in price - because a) there is reduced demand for it (everyone is using their own panels) and b) supply would increase (people can sell the excess electricity from their panels back).
Re: (Score:3, Interesting)
The new jobs created by the Solar energy (and Wind sector) thus far are on the whole very good jobs, and there would be more jobs in a renewable economy, look at the O&M component of these "Concentrator" systems. They have moving parts, they require education to install, and the jobs would be create in every state and county. Nuclear plants,
Re:transport losses? (Score:5, Insightful)
Energy as we collect it now, has some non-obvious costs. What does pollution from burning fossil fuels cost us in terms of healthcare? What will sea-level rise cost us? (hint: NYC, LA, DC, Miami, New Orleans, Mobile, and others are very close to sea level, and those are just the US examples.) Would we really have spent $300B and 2,906 American lives (so far) in Iraq if we didn't need to "stabilize" the region that supplies most of our oil?
Part of every dollar that you pay in taxes, at the store, at the hospital, in fact pretty much everywhere, is an energy cost.
Re: (Score:3)
And what better place to put them than on building roofs? Nice and high to help catch the sun and avoid damage/vandalism, and pretty much every building already has a connection to the Grid anyway. While you're at it, might as well route the power generated through the building's electrical system, feeding any surplus back into the Grid.
That way the big power compani
Re: (Score:3, Insightful)
NO, get rid of that power robbing, terroist target, lightning rod, ice gathering, bird killing, people killing, expensive ass eye sore.
I don't know how many billions of dollars our federal government spends on that grid every year, but anything to minimilize thing would be sweet, even if it takes more energy to produce a solar panel than it ever produced (fairly cert
Re: (Score:3, Insightful)
Think in-city clustered 12 story apt buildings. A simple building, 1 apt per floor, say a 1000 sq ft apt. So we have 12 'stacked houses' that have a single 'shared' 1000 sq ft roof. So 1000 sq ft of roof needs to support 12 'houses' of energy. Unlikely. THAT'S why the grid comes in. In clustered/dense city dwelling environments, roof top energy generation will be insufficient to cover the usage. We'll always need a 'grid' in that environment. How we fuel/supply the grid may be d
Re:transport losses? (Score:5, Informative)
I'll get about a quarter of the cost back in refunds from the power company right up front. The remaining cost (around $25k) will roll into my mortgage, which will increase it by around $100 per month (30 year mortage at 6%). My monthly electricity bills should be reduced by at least $150. It just makes sense.
The fact that I care about the environment just makes it an even better deal.
Re: (Score:3, Informative)
Re: (Score:3, Informative)
Right off the top you get $29,000 from other oregon and city taxpayers to buy your system. In any state without subsidies, that means over THIRTY YEARS longer payout period. Most solar cells degrade substantially by 20 years (10-20% less power output). Likewise, I'm betting like MOST states, that not just anybody can get those $29k in credits in Oregan. There is probably a fairly limited budget (a few million) and once that is gone each year, there are no more subsidies until the next calendar year.
I'm
Re: (Score:3)
You can't be certain that global warming won't produce a net gain of usable land.
You can't be certain that money *WASTED* on solar power today couldn't be spent much more effectively in a few years when it drops an order of magnitude in price.
You can't be certain that the average house price maintenan
Re:transport losses? (Score:4, Interesting)
As for the original poster's comment about a volcanic eruption distrupting energy supplies and using nuclear for backup, there are ways to deal with power loss: energy displacement. The cheaper electricity gets, the more the world will use electricity-intensive industrial processes -- for example, aluminum smelting (that is, to say, use of aluminum use would displace steel use). Such processes can scale output based on available power supply. If the price of energy leaps due to a shortage (say, from dust blocking out the sun), such industries will be economically forced to curtail their production until the dust clears, thus freeing up power for everyone else to use (aluminum prices would spike, and steel use would begin to take over). Long term light shortages would be more problematic, but short term wouldn't be. Not that I think the world ever would be completely solar powered, but I just felt I should point this out.
As for hydrogen production, there's a much nearer-term option that I find really keen: Honda's "Home Energy Station" concept. Basically, almost every home in the US has natural gas lines running to it. Currently, natural gas is the cheapest way to produce hydrogen, so producing as much hydrogen as you need, straight from your natural gas line, seems a reasonable proposal. Of course, this raises the question, "Why not a natural gas-powered car? Why waste the energy converting it into hydrogen?" Well, apart from the very high energy efficiency of using hydrogen in fuel cells, with Honda's system, the energy released in converting natural gas to hydrogen isn't wasted. The waste heat from the process fires your water heater, so it's an almost lossless system unless you're consuming large amounts of hydrogen and using almost no hot water.
Re: (Score:3, Informative)
Carbon monoxide is highly flammable. It has the same NFPA rating as diesel (2). Burn it, recapture the energy. With a good countercurrent heat exchanger, you approach 100% efficiency. You can never reach 100%, and eventually it's not worth the effort to try for more, but you can get close.
It's less efficient than burning all of the natural gas to heat your water
Of course it's less efficient than burning the natural gas when you only consider the heat; you're getting hydrog
PROGRESS WE BE SCREWED! (Score:3, Insightful)
And what about all the buggy whip makers!
Who is thinking of THEM!
Grandpa was a Buggy Whip Salesmen (Score:5, Interesting)
Actually, my Grandfather was a buggy whip salesmen.
After returning from The Great War, WWI, he was disabled (indeed he'd been declared dead & in the morgue at one point - mustard gas.) The job he could get was selling buggy whips, and his territory was the US Midwest & Canada. He was away from home for long stretches of time, and as you can imagine had some pretty amazing tales to tell of traveling to remote ccommunities back when travel was HARD.
However he saw the car taking over and once he'd saved up enough money he did the smart thing: Opened a service station.
Later it went bust in the Great Depression. He then started again, in putting in power lines, then power plants, and eventually became VP of a a large construction firm and responsible for many of the major structures still standing in Kansas City including the Liberty Memorial [libertymem...museum.org], Nelson Gallery [nelson-atkins.org], and the Starlight Theatre [kcstarlight.com].
The point is, he really was in the buggy whip business and when the new technologies came in he adapted and took advantage of them. Then when the bust came he reinvented himself again and took his skills and when into an entirely new career. Not a new high-tech story, rather from a fella raised in a sod hut in the Oklahoma Territory where buffalo were a constant threat.
Re:Grandpa was a Buggy Whip Salesmen (Score:5, Insightful)
Circumstance dealt him a series of "losing" hands, but he didn't bitch and moan and expect someone else to "make it right". He worked, very hard I'm betting, and became wealthy.
Based on what's I've read in that other discussion, he must have been a very wicked and greedy man.
I salute him.
Re:PROGRESS WE BE SCREWED! (Score:5, Insightful)
Yea, if only they could manage that! We could have a spirited argument on Slashdot article about it!
Well, when they're making them more efficent (sometime in the future, obviously), they could also work on making them indestructible as well! Like my windows.
Yes! Obviously they'll go bad, because everything has a short lifespan....ya know, like my house's foundation. It's only got 6 months left!
Ok, ok, enough of that. Seriously though. Did you read the SUMMARY? Did it even occur that maybe you should look up the lifespan of a solar panel before MAKING UP statistics? (40+ years, according to a cursory Google Search for "solar panel lifespan"
Please stop, its just painful.
Re:transport losses? (Score:5, Insightful)
Also note that in your calculation you also have to add the savings in electricity. That is, you don't have to have equal price to conventional roofing, but you have to have the equal proce of conventional roofing plus the saved payment of electricity in some reasonable amount of time. So if the money saved on your electricity bill in, say, the next three years makes up for the extra cost of solar cell roofing, it's still more profitable to do it. (Well, actually you'll also have to account for the interest you would have gotten for the money during that time, because the money you pay for electricity next year will still give interest this year, while the money you spent on the solar panel will not.)
Re: (Score:3, Informative)
1 Manufacturing solar cells is currently an extremely energy intensive process, it also creates a startling amount of toxic waste. Solar Cells need to be replaced on a regular basis as well.
2. Solar Cells are extremely expensive. I don't know about these 40% jobs, but something tells me they won't be a lot cheaper than our current top of the line cells. We're talking about a project in the trillions of dollars to do what you describe.
Re: (Score:3, Funny)
Doesn't it say in the bible somewhere that it's a sin to stay up after the sun goes down? Regardless, maybe we could get back to a more wholesome existence and put a stop to all that late night fun I hear people having outside while I'm stuck here coding until I go crosseyed.
Re:transport losses? (Score:5, Interesting)
Aslong as you're doing less than covering grid-use though, you're better of with a storage-mechanism that wastes less, such as pumping water to a magazine higher up.
You can store substantial amounts of power. If your magazine is 400 meter higher than the powerplant, then each additional cubic-meter of water up there contains 1Kwh. Thus, for example, the Veltdalslake (western Norway) with a size of about 12km^2 and 25 meters of regulation, at 1100m can store on the order of 900 million Kwh -- which counts as a substantial battery in my book. :-)
Re: (Score:3, Informative)
Re:transport losses? (Score:5, Insightful)
At a large enough distance, all things are the same. Which removes distinctions which in real life are useful.
For example, the phrase "renewable energy-source" actually has meaning. True, one can claim that *no* energy-source is renewable -- because entropy will always increase, and for example solar-power is nuclear, and infact the sun is going to run out of fuel at some point.
Or you could argue the oposite; that pretty much all energy-sources are renewable; oil coal and gas come from organic matter afterall, so given a long enough time, there's no reason why they shouldn't renew.
But this is just playing word-games. You've told nobody anything new with this. We're talking here and now and on human timescales.
Oil won't renew -- in the next 10, 100 or 1000 years. So for practical purposes it's non-renewable.
The sun won't run out of hydrogen the next 10, 100 or 1000 years, and furthermore it doesn't run out any faster if we install solar-cells. So for all practical purposes, the sun is a constant source of energy.
Wait, I can handle this. (Score:3, Funny)
Homer: Woo-hoo!
Bart: Dad, all that bacon cost twenty-seven dollars.
Homer: Yeah, but your mom paid for that!
Bart: But doesn't she get her money from you?
Homer: And I get my money from grease! What's the problem?
Re:transport losses? (Score:5, Funny)
However it's quite obvious that the sun must be shut down as quickly as possible: First, as you aready said, it's using nuclear energy, and of course nuclear energy is known to be bad. But for the sun, it's not even abstract: The sun is known to continuously send radioactive radiation. Fortunately the earths magnetic field and atmosphere are saving us from most of it, but what if the magnetic field fails? Also note that we are already quite certain that the sun will end up destroying all life on earth when (not: if) it finally fails. So we really shouldn't tolerate such a dangerous nuclear reactor so close to earth.
Re: (Score:3, Funny)
Re: (Score:3, Funny)
Re:transport losses? (Score:5, Informative)
If you are just going to put bare panels somewhere it makes more sense to stick them on the top of existing poles instead of in some big facility since they act as discrete units anyway. Once they get rolled out there really isn't much that has to be done with them - the photovoltaics that existed when Einstein was young probably still work.
Personally I think we are already seeing the start of one of the major potential uses for photovoltaics - appliances that don't have to be plugged into the grid. If the prices come right down things like solar mobile phone chargers may well become mainstream.
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Also (not contrary to anything you were saying), I did not read the article, but the summary said 265 miles on a side, which turns out to be 70,225 square miles. Texas is 268,581 square miles [texasalmanac.com]. A solar array that large would take up a little over 26% of Texas. When put in that perspective, that's a huge mass of land. Using "265 on a side" just doesn't do the size justice.
Re: (Score:3, Funny)
Re: (Score:2, Insightful)
Re:transport losses? (Score:5, Informative)
Bzzt! Wrong answer. Hydrogen requires a completely different infrastructure that has never been massively developed. Transporting hydrogen trapped in a hydrocarbon is feasible and could use the same infrastructure, but hydrogen itself is a much more complicated issue. You either need to cryogenic cooling or you need to build infrastructure that has low hydrogen diffusion and low hydrogen embrittlement (and probably very high pressure to move a significant energy density of hydrogen around if you go the gaseous path). People who want hydrogen for various industries tend to steam reform it from hydrocarbons instead of using this oil infrastructure you think can transport hydrogen.
Re: (Score:2)
NO WAR FOR SILICON!
Re: (Score:3, Insightful)
How much is the total electric bill for the world?
Why is there a need to transport? (Score:5, Interesting)
It seems to me that if we had started doing this years ago it may have a) reversed some of our energy problems and b) potentially made solar panels more affordable so I could cover my home's roof with them.
Re:transport losses? (Score:5, Insightful)
It's a lot more practical to scatter a large numer of smaller solar-plants around than it is to do the same with nuclear, oil or coal-powered plants.
If you do this, for example, by installing them on the roofs of homes you get 2 extra benefits:
Re: (Score:3, Funny)
A large solar collector would also.. (Score:4, Interesting)
What about the cost in sending that energy down the wire? Would it be best to build one big-ass solar array? Or would it be better to distribute smaller collectors over a large area, even if the sunlight is not optimal?
Re: (Score:2)
PV cells have a lower albedo than the Earth as a whole, at least solid land, anyway. So over land they will result in more heat being transferred to the amosphere than the soil under them would have. Sea water has a pretty low albedo so I don't know if this applies ove
Re: (Score:2)
How about... (Score:2)
Re: (Score:2)
265 miles on a side... (Score:2)
where the facts? (Score:5, Informative)
The multi-junction part comes from the idea that you can, using a solar cell, only extract as much energy from a photon as the size of something called the band gap of the material that the cell is made from. At the same time, a solar cell can only absorb photons with energies higher than the band gap. If the bandgap is small, as it is in silicon, then you can absorb most of the suns rays, but you can only get about 1 electronVolt of energy out of each one no matter how much energy the photon has. Since the bulk of photons emitted by the sun have more than 1 electronVolt of energy Si solar cells waste alot of the energy in sunlight as heat. If you make the solar cell out of a semiconductor with a larger bandgap then you absorb fewer photons (more of the solar spectrum lies below the critical energy for absorption) but you extract more energy from each photon. So, for a solar cell made from one material there is a sweet spot in terms of the bandgap that maximizes the energy extracted. Multi-junction cells try to overcome this by combining multiple devices with different bandgaps so that you can maximize both the total number of photons converted to electricity and the energy extracted from each photon.
Re:where the facts? (Score:4, Insightful)
Re:where the facts? (Score:5, Informative)
It's not necessary to do it that way. The way these multi-junction cells work is you have several layers of different semiconductor materials (with varying band gaps as the parent said). The material with the largest band gap is on top and the band gap of the material decreases as you go down the layers of the device. If a photon is not absorbed in the first layer (meaning the photon doesn't have very high energy, since, as the parent also said, the photon must have greater than the band gap energy to be absorbed), then it continues on to the next layer to be absorbed, then the next layer. This way, you are extracting the maximum amount of energy out of each photon.
That isn't a perfect explanation and any experts out there, please correct anything that's wrong.
Downsides (Score:2, Insightful)
Firstly, these solar cells are no doubt incredibly expensive - any high efficiency ones are. Secondly, they're probably made using rare and/or exotic materiels, making manufacturing in bulk tricky, and thirdly there's likely to be a lot of pollution created in the manufacturing process for by-products et cetera (it's a problem with less efficient cells too, but the more efficient ones
Re: (Score:3, Insightful)
Presumably, you'd want the capacitance spread out across the grid- not
And That... (Score:4, Interesting)
And that is what fuel cells are really for. Forget having hydrogen delivered to your home so that you can use a fuel cell as a generator. No, you use photovolic at the home to generate a tank of Hydrogen so that you can convert it back to electricity when you need it. The real promise of fuel cells is for use as a very clean battery.
Re:Downsides (Score:5, Interesting)
No, they're not. Hydro plants can do this as well. The UK uses several hydro plants like Dinorwig [fhc.co.uk] to cover peak loads. Dinorwig can go from 0 to 1320 MW in 12 seconds, and has a peak output of about 1800 MW. It is built as an accumulator system, pumping water up the mountain at night (using excess capacity from nuclear and fossil fuel plants) so it doesn't depend on a huge water supply (river). Efficiency (W generated vs. W needed to pump the water up the mountain) is about 70%.
Thermal is slow to start - but you can be prepared (Score:5, Insightful)
It takes quite a few hours to build up steam from a cold start and it wears everything out quickly by thermal fatigue if you have a lot of restarts. What does happen is something called spinning reserve where coal is being burned and the turbines are spinning but the generators are not connected. The generators can be attached by a very large clutch and more pulverised coal can be fed in to bring things up quickly - I'm too out of touch to know how quickly now and worked in new plants of an old design. With hydro you just turn on the tap and things happen quickly - thermal needs time (which includes oil and nuclear too for people who forget that nuclear is stream power).
Anyway - the troll way above was doing the "one true energy" thing which you only get from idiots or salesfolk. Just becuase photovoltaics are not a drop in replacement for every base load power source on earth does not make them useless. In remote areas they have proven themselves for decades.
Panels On The Roof (Score:3, Interesting)
- DaftShadow
Re:Panels On The Roof (Score:5, Informative)
Re: (Score:3, Funny)
Hmm. Wonder how realistic this is.
Still does not solve much (Score:4, Insightful)
Do not get me wrong. These solar cells are most likely a good thing. Of course, it depends on how the true cost relative to other methods. But this country needs to quit subsidizing oil and coal as well as have a multi-prong research in energy storage to really make the alternatives happen.
Re: (Score:3, Insightful)
Obligatory suburban subdivision response... (Score:2)
NIMBY!
God, geeks are so incredibly stupid (Score:5, Insightful)
2. There is no reason at all to fill a desert with solar cells, and then transport the energy across to the other side of the planet. Solar cells are installed locally, like on your roof, or in your back yard, on every roof across the planet. Most of the electricity consumed would be as Direct Current right from your rooftop, with an inverter converting for those appliances you still insist on retaining that us AC.
3. For dense city sitatuions with high rises who's energy needs can not be met by rooftops, etc., electricity can be sent via conventional AC lines across the conventional power grid from say no more than 50 miles away. Not the other side of the world.
4. Those who produce an excess of electricity beyond their need, sell it into the grid.
Re: (Score:3)
life span (Score:2)
Re: (Score:3, Informative)
http://en.wikipedia.org/wiki/Photovoltaic?section= Energy_return_on_investment#Energy_return_on_inves tment [wikipedia.org]
I tried to calculate energy payback-time for different cells, and got results ranging from 8 months to 2 and a half years.
Even extreme PV-Cells bashers don't succeed in proving that payback-time exceeds 5 years, which still lefts you 3 times as much "free" energy.
Figures a bit out (Score:4, Informative)
13.9 trillion kW/h / 8776 (hours/year) = 1.58TW
This figure is comparable to the statement in the wikipedia that 2001 average world consumption was 1.7TW in 2001 [wikipedia.org]. So our sources agree within a reasonable margin.
According to the wikipedia, the energy density from solar energy reaching the surface as a global average is 170 W/m2 [wikipedia.org]. At 40.7% efficient, that's 69.2W/m2.
Using the lower figure of 1.58TW calculated above, you'd need 22.8 x 10^9 square meters, or approximately 8800 square miles of solar cells to meet 2001 world demand. (Or "just" 1900 square miles to meet the peak US demand of ~3 trillion kWh in the late 90s). Of course, these areas halve if sited in an area of the US where the solar energy density is 375 W/m2 (4000 square miles for world demand, 860 square miles for US demand).
Neither correspond to the whopping (265x265) 70000 square miles the article summary claims. Sorry kdawson, looks like you're a magnitude out!
Gallium Nitride (Score:5, Informative)
Here's some links:
Indium-Gallium-Nitride can be made to absorb the entire spectrum of solar rays:
http://www.lbl.gov/Science-Articles/Archive/MSD-f
Tunnel Junctions - this is how you stick together many different layers of material, each layer with their own optimal absorption range (in terms of wavelength, aka. color):
http://www.hitachi-cable.co.jp/ICSFiles/afieldfil
(sorry, this is the best I could do, there was no simple paper explaining a tunnel junction. "tunnel" is for electron tunneling...)
In essence, you have different layers that absorb only one range of wavelengths (colors of light), and whatever isn't absorbed goes straight through, and the next layer absorbs another range, etc. etc.
As an aside, did you ever wonder how blue LEDs & lasers finally managed to get working? Nitrides paved the way for emission (and absorption) in a range of visible wavelengths, including blue. This is also why they're great for this application.
No streaks? (Score:3, Funny)
Buy windex stock now, that's all I'm saying.
Solar is already cheaper in some areas (Score:5, Informative)
Re:Cost is the issue (Score:5, Informative)
Re:Cost is the issue (Score:5, Informative)
Re: (Score:3, Insightful)
Plus I can't buy a residential wind turbine for $1/w. For a turbine (installed) in the 1-5kW range it costs about $3/w, with a big chunk of the cost being the tower & installation. $3/w is the same as the solar listed.
I haven't
Re: (Score:2, Informative)
Aren't the two related?
Also, FTFA:
Re:Cost is the issue (Score:5, Informative)
I bought an 80 watt peak solar panel in the summer, basically as a fun project and to investigate the practicality of generating some of my own electricity. Here is how it works out, using a monocrystalline panel (the most efficient panel commercially available at present):
Peak power is produced only within about an hour or so each side of mid day on a bright, cloudless, hazeless sunny day.
Three hours before or after mid day, the unit produces about 50% of peak.
Five hours before or after mid day, the unit produces around 10-15% of peak
At mid day, summer time haze with 10 miles visibility will cut output to around 80% of peak
At mid day, with thin cirrus clouds (still bright sunshine), output is around 50%
At mid day, on a bright cloudy day where shadows are still cast, output is around 15%
At mid day, on an overcast day, output is generally 5% or less.
In the winter, I've never seen the unit capable of producing more than about 25% of peak on the brightest winters day.
All in all, the average output even in the summer will only be 5% of peak (because of night time, and cloudy days). Winter time is even worse. So if you want to make sure you have an average of 200 watts - which really isn't a lot, but if you can store it or put it back on the grid it'll make your house more or less neutral in terms of the electricity you use, if you have the normal domestic cycle of being out and not using much electricity during the day. To get that average of 200 watts, you'll need 4000 watts peak of solar panels.
80 watt panels cost (in quantity) around £250 a piece. That'll cost you £12,500 *just* for the panels, without a grid tied inverter and storage system or installation (probably another 4 to 6 grand) - to get a measly average of 200 watts - i.e. just enough to power one Pentium 4 computer continuously. It's simply not worth doing at all unless you can put it back on the grid (not many electricity companies let you do that - yet), or store it in batteries - since if you have a normal domestic cycle, while your solar panels are producing near peak you will be away from the house and letting three or four thousand watts go wanting. You'll probably need three grand's worth of batteries if you can't sell back to the grid - and even deep cycle leisure batteries are going to need replacing at least once every 10 years. This is for a system which will only work reasonably well in the summer. In the winter, when the days are short and you need the most power, it'll hardly contribute anything - perhaps you'll get 50 watts average from £12,500 worth of solar panels.
If solar panels were 1/10th of the price they are now - yes, it'd be worth it. I'm waiting for the breakthrough in price, not efficiency (if the efficiency brings the breakthrough in price all the better). Even a moderate sized south facing roof - I've calculated just my shed roof replaced with solar panels could produce 1kW peak - is large enough for a decent peak output using current monocrystalline panels. Price is everything. If I could get the panels at 10% of what they cost now, you bet my shed roof (my only south facing roof) would be covered by the spring. But at the current price point? It's simply not affordable for the meagre amount of electricity you get. It's a shame because the panels aren't visually intrusive and they are silent and almost maintenance free, unlike wind turbines. I really really want solar panels to be worthwhile - but at the moment - at current prices, they simply aren't.
Re:Cost is the issue (Score:5, Insightful)
Lots of animals and wildlife flora/fauna live in the deserts. Many of which are endangered. Many of which provide valuable eco-service to the land around them. It might not be prudent to just blot out the sun with solar collectors and think everything's going to be okay.
I'd rather see these on rooftops, supplementing power sources in a more local fashion where their impact will be minimal.
Re: (Score:2)
Lots of animals and wildlife flora/fauna live in the deserts. Many of which are endangered. Many of which provide valuable eco-service to the land around them. It might not be prudent to just blot out the sun with solar collectors and think everything's going to be okay.
Tens of thousands (or more) of human beings were killed very recently over another energy source, oil. What makes you think a few snakes and scorpions are going to stop them if this is viable? And if you want an eco-service, by shading a
Re:Cost is the issue (Score:4, Insightful)
In addition, as to farmland in the desert, well here is a couple of thoughts:
Good point "National Security" (Score:3, Informative)
Re:Cost is the issue (Score:5, Insightful)
Looks like someone needs a refresher course in ecology. Deserts are very rich and diverse zones. Remember, a desert isn't just sand dunes. Just because it isn't green and not many people live there (the US West/Southwest) doesn't mean it's a barren wasteland. Also, the reason why the desert isn't farmland is because there is no water. The thing preventing Nevada from being a rich agricultural region is a rather large mountain range, not too much sun. Unless you can find a way of getting more water to the desert (like the Northwest) then it isn't going to produce squat.
Besides, other areas of the country still receive sunshine. I bet when you take into account the costs of maintaining the transmission infrastructure as well as the risks associated with a centralized power source most of the solar stations would be stationed near population centers instead of concentrated in one area.
Re: (Score:2)
Re: (Score:2, Interesting)
Re:Cost is the issue (Score:4, Insightful)
I'm sorry, but this should never have been scored insightful. Its obvious at best, troll at worst.
First of all, improved efficiency reduces the investment cost, thus reducing the cost per watt (at least in a proper market economy, which the energy market unfortunately isnt).
Second, COx emissions are not the only environmental threat. In time, studies will more than likely show that covering vast areas of land with shadow-inducing plates (such as solar plants) has a negative impact on local and perhaps regional eco systems. More efficient solar panels mean less land area covered by solar plants, which is a Good Thing ®.
It never seizes to amaze me how people fail to look at the big picture;
* new cars emits less Cox and NOx, but the production of new cars is a significant ecological strain
* biofuel is great in small scale, but greatly reduces the ecological diversity and might pave way for invasive species
* solar plants might provide all the power the world needs one way, but at the cost of placing vast land areas in shadow
Etc.
The harsh reality is that there is no quick fix, there is no gratis lunch.
Re:Cost is the issue (Score:5, Informative)
I don't know about how long ago you are talking, but the Energy return on investment [wikipedia.org] varies between a factor 4 and a factor 17 for current solar cells, rather than a number below 1 as you are suggesting.
Re: (Score:3, Insightful)
Re: (Score:2)
How about the empty quarter of Saudi Arabia?
For me, this represents an opportunity to generate the power where I will need it. Transmission systems will be less important in the future.
Re: (Score:2)
Re: (Score:2)
If the cost is high because of complexity then large scale manufacturing should be able to bring the cost down. Think how cheap LSI chips are. Of course you need the demand to be high so that volumes can be increased so that prices can come down and stimulate demand for which you need...
Re: (Score:2)
Must be solar powered.
Re: (Score:2)
But if we can get a great
Re:Here's an Idea (Score:5, Interesting)
Its not exactly a new idea. [wikipedia.org]