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Solar Cell Achieves 40% Efficiency
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 shade the ground and absorb the heat (energy) that the surrounding ground and air would normally receive. I guess, taking extra heat (energy) from one place, and adding it to lots of others may not be bad...
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?
That means you NEED enough GAS powerplants to power the whole world too, as they're the only type of power plant you can literally turn the dial and turn up the output.
No, they're not. Hydro plants can do this as well. The UK uses several hydro plants like Dinorwig 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%.
Its not exactly a new idea.
http://michaelsmith.id.au
Why not just start making it mandatory for every high-rise and large-roof building structure to be covered with a certain percentage of solar cells that power part of the building during the day and feed the rest back into the grid? After all, the concrete and steel aren't doing anything with the sun.
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.
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. :-)
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, Nelson Gallery, and the Starlight Theatre.
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.
I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
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.