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.
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?
Panels On The Roof (Score:3, Interesting)
- DaftShadow
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%.
Re:Cost is the issue (Score:2, Interesting)
Re:where the facts? (Score:2, Interesting)
Re:Cost is the issue (Score:2, Interesting)
Frankly I'm in favour of biting the bullet and making this a personal routlay, and am looking forward to doing so when I have a property to do it to. If someone can afford to buy a house, they can afford to put some bloody photovoltaics on the roof and if that adds an extra 6 months to their mortgage then so be it. For once it'd be nice to see economics take a back seat to environmental responsibility.
Re:Here's an Idea (Score:5, Interesting)
Its not exactly a new idea. [wikipedia.org]
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:where the facts? (Score:2, Interesting)
I was really hoping they would (but knew they wouldn't) link to a specific journal article about the devices being used. If anyone knows if this group has produced a scientific article (IEEE, AIP, etc...), I would appreciate a link. I did a quick IEEE search on multi-junction solar cells and didn't find anything about the device mentioned in TFA.
Bright Future (Score:2, Interesting)
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:transport losses? (Score:3, Interesting)
Re:transport losses? (Score:2, Interesting)
And how much gallium arsenide would you need? (Score:1, Interesting)
GaAs thickness on cell = 100 microns
Density of GaAs=5.32 tons per m3
%Ga in GaAs=48%
a quick back of the envelope calculation indicates that you might need
46445387.5 tons of gallium to generate all the world's power
USGA figures give world 1996 production as 70 tons, and suggest world reserves of 1 million tons at grades of 50ppm in bauxite, although Ga in zinc deposits may also be potentially useful. However, this looks some way short of the 46 million tons required.
Gallium is actually pretty common - average crustal rock has 19ppm Ga, much more than so called "common elements" like lead or copper. Unfortunately we never get large rich deposits of it concentrated in one place, so extraction cost, in terms of money and energy is too big.
Back to the drawing board (at least for global energy supplies..)
Of course, there might be a mistake in my sums...
A.Geologist
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:transport losses? (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.
Weather, TOC, etc.. (Score:2, Interesting)
Keep in mind a few things when people are talking about 'solar paneling a roof'..
- Here where I live, we have a ton of pine trees.. they dump a ton of pine needles on my roof. I'd say at peak, almost
Obviously the same would apply to Snow until it melts off (which takes how many hours during the day, of which you're getting far from peak efficiency from your panels with?
When it hits the rainy season, you have similar issues since your typical week is overcast?
- Reflecting the suns heat is desirable in the warm months, but not in the cold months. Currently I count on the sun during the day to help heat my house in the winter. If I panel my house with the same goal of attempting to collect/reflect all that sunlight during the summar to save/run my AC, I also have to run my heater more often because my house doesn't warm up?
- what the TOC on solar panels anyhow? I fully realize that the cost of replacement will go down as demand and technology increase.
I can get 10+ years from my current roof.. how often do solar panels need replacing? keep in mind they will be getting hit by (branchs | snow | heavy rain | leaves/pine needles | occasional base balls | people walking on them to clean them | cleaning chemicals | other forms of harsh weather such as hail and/or debris in hurricanes, etc..). Someone throw me some real-world numbers here?
I'm not trying to be a neigh-sayer, just trying to keep people aware of the every-day issues associated with such things.. i'm far from an expert on solar paneling, but these are some things that 'average joe' will want to know. And lets face it.. if you want it to get wide-spread adaptation, you gotta get the 'average-joe' vote.
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:transport losses? (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, by contrast create jobs with a high risk-premium, but they also create less jobs per kilowatt than any other electrical provider, as the plant size is bigger, and there are fewer of them generally.
AIK