Letters to the Editor
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Physics anyone?
Pablo:According to Dan Berger, senior project designer at SPG Solar, we can expect to generate about 6.5 kilowatt-hours (kWh) per square meter of solar panels per day.
Shotsie:Solar radiance density is about 1000 watts/m**2 - if all the energy falling upon a 1 meter square panel was converted to electricity, then maybe you could obtain 6.5 kilowatt-hours per day. But, a photovoltaic panel is about 10% efficient, so you'd get 0.65 kW-hour per day ( 1000 watts * 10% = 100 watts average output times 6.5 hours). Even solar thermal panels are limited by the Carnot cycle to 50 - 60% efficiency at best.
Walter:So all you need in 600 square miles of conventional solar panels. Sounds perfectly feasible to me, especially when you factor in other sources and emerging improvements.
No Walter, Shotsie is right. You need at least 6000 square miles of conventional (photo-voltaic) cells. I think this article needs a correction.
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In the desert
If we put solar panels in the desert, could we then grow things under them that would benefit from the shelter from the light and the heat? Then we would be getting double usage out of land that is otherwise useless.
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The "Giant Factory" Solution
Other commenters have written similar things: building grand installations for energy collection is not the way we're going to go. That's a solution born of thinking straight out of the Industrial Revolution, which is what got us into this mess.
As for quantity, we could easily get the energy we need. The first step however is to free ourselves of the outrageous contortions we've gone through to make fossil fuels cheap.
Future civilizations will wonder, why did they go to all that trouble to get oil?
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Centralization of power
Part of the thing with alternative energy debate that bugs me is how much emphasis there is on centralization -- centralized solar or wind is as pernicious as centralized oil, coal, or gas, in the sense of leaving people dependent on the power providers, rather than independent of them.
A diversified energy approach as to means of power would be good, just as a diversified view of energy decentralization would also be vital.
As others have pointed out, plenty of empty roofs in need of solar cells, plenty of places to put wind generators. And additionally, I would think a decentralized, diversified power grid would be less vulnerable to shutdowns or attacks.
What it wouldn't do, however, is benefit energy provider companies, so odds are we won't see that kind of diversified and decentralized power system in our future. It's likely why those kinds of advocates of alternative energy tend to favor nuclear because it requires centralization, or big-ticket centralized solar or wind projects.
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Mike Sulzer
You need at least 6000 square miles of conventional (photo-voltaic) cells. I think this article needs a correction.
Nope. You guys need to check your arithmetic. Sorry.
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Fact Check Please!
As others have noted in their posts, Mr. Paster is way off on the efficiency of solar PV panels. 1366 watt per square meter arrive from the sun at the top of the atmosphere before being scattered and attenuated by clouds, dust etc on its way to the surface of the earth. Solar panels are from 10-20% efficient so a solar panel in orbit above the atmosphere can produce 136.6 - 273.2 watts/square meter. The average 'sunny' location in the U.S. (say L.A.) receives on average 5.5 hours of sunlight per day. Simple multiplication of 273.2 watts/square meter * 5.5 hours yields 1502.6 watt hours/ square meter or 1.5026 kilowatt hours per day for a 1 meter square panel. AND THIS IS BETTER THAN THE BEST POSSIBLE CASE since we are assuming no loss of solar energy in the atmosphere (no smog in L.A. right?) and the most efficient solar cells out there. Typical cases will be much less.
For a good intro to solar pv facts see the following link:
http://www.solarbuzz.com/Consumer/FastFacts.htm
I'm all for renewable solar energy but grossly underestimating the challenge serves no ones interest.
I'm disappointed in Salon for publishing this without even a cursory fact check, it shows unbelievably low editorial standards on the part of the Salon management. This could have been checked out in 15 minutes on Google.
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I'm sure someone would protest the harm to scorpions
It's a lose lose scenario in America. No matter what you do you'll wind up in court hamstrung by someone. Sure, carpet the desert with solar cells. Then the anti defacing the desert beauty people pop up. And if you have to fence off the arrays then the pro illegal alien people pop up. And so on. I say we just chuck the whole idea in the trash. Let's go back to the middle ages.
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Future Solar Panels will not be silicon-based
It is true that it would take forever (and be horribly expensive) to make all the photovoltaic cells we need if they were silicon-based. But new solar cells are not. I don't understand the technology, but the new cells are thin-film, silicon-free, and involve various types of nanotechnology. The cells are already in production (by Shell) in Germany. They are thinner, and easier and cheaper to maintain, than silicon-based cells.
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Diversity
is the long-term answer.
Sure, it's *possible* to generate all our electricity from PV panels - or from any other single source. But it's not the smart/efficient/cost effective way to go. In fact, over-reliance on single energy sources is the problem. I'm old enough to remember the old saw about how nuclear would make electricity "too cheap to meter". Never happened, not even for the French who get most of their electricity from nuclear energy. (They pay more then Americans do for residential electricity, once all the fees, taxes, and other costs are calculated).
Where the sun shines a lot, PV panels on a roof are a good idea. In other places wind is a good idea. Hydro, geothermal, they all have applications. And of course conservation, and the use of electricity for those applications where it's the best technology for the purpose.
The big problem is that there's no simple, single solution. For example, is it more environmentally friendly and cost-effective for someone in the South to put PV panels on their roof, or a solar water heater? Or for someone in the Northeast to install a geothermal system?
The article also ignores the energy cost of manufacturing the panels (it's a big reason they cost so much) and their expected usable life (nothing lasts forever).
I must also call shenanigans on the 12,000 kwh per person per year, and the assumption that the demand will always grow. Controlling our population and waste are a big part of the picture too.