Letters to the Editor
-
wbswhav
Any "technical" article that starts off saying that solar panels convert beams of light into electrons is suspect. The electrons were there already, this is only metaphorical. The photons from light cause electrons in the panels to pile up and want to move through wires.
Well, to be quite correct, photons cause electrons in these materials to move to a higher quantum state and flow one way into a layer of adjacent semiconductor (as you say, 'pile up') which results in the induction of an electromotive force: if the force is directed to a circuit the electrons flow around back to the original location in the cell and you get a current.
Electrons don't actually move much but do flow, or, technically, drift. It's a mistake to suppose an electrical circuit is analogous to a water hose. It's more like a hydraulic system.
I won't be quoting Maxwell's equations at anybody today.
-
Walter_map
From the article:To generate 3.6 trillion kWh per year, we would need to install about 1.5 billion square meters of solar panels, or around 586 square miles.
So divide 3.6 trillion kWh per year by 1.5 billion square meters and get 2400 kWh per square meter per year. This is the number Paster sites from Dan Berger converted from per day to per year. But this number is the amount of energy one could expect to receive on a solar panel, not the amount of energy produced by PV cells. (1000 watts per square meter is about what you get with the sun directly overhead; you get a lot less on average, of course, so 6.5 kWh per day out of a maximum possible of 24 is reasonable.)
Paster left out the efficiency factor; if the efficiency is 10%, then you need ten times 600, or about 6000 square miles.
-
Yes, spread it out.
Slackie has got it. Decentralizing the panels would allow less transport reductions in power. If panels were affordable, then nearly every house could have panels and storage. The question is if THAT is feasible. All the tax money being spent on biofuels would be better spent on converting to solar.
I can see huge areas covered by panels, but that would be more unfeasible. And there are questions about the math here, as one poster wrote. 7.5 square feet of panels seems awfully small for one person. Heck, I could have 3 people on my garage...if this were true.
-
and of course, good old efficiency
about 56% of the energy in the US is wasted. a lot of it can be prevented. pays for itself, as they say.
http://graphics8.nytimes.com/images/2008/04/06/weekinreview/revkin-650x1075.jpg
-
@elydog
"All the tax money being spent on biofuels would be better spent on converting to solar."
Not unless people get a lot more electric cars (not hybrids, true electrics) and solar-power them.
In the USA, less than 3% of our electricity comes from burning petroleum, and the percentage keeps dropping as old systems are retired. Oil is just too expensive compared to other methods. (Wind will soon supply more kWH than oil, if that hasn't already happened.)
Biofuels (mostly ethanol) are basically a stop-gap to stretch the gasoline supply, used for auto transportation, not electricity.
The PV panels described would replace coal, natural gas and nuclear generation of electricity. They won't save much oil at all, if any.
The real breakthrough PV needs is to reduce the dollars-per-watt.
-
Multiple thoughts...
I keep finding articles & discussions asking if "technology X" can/should/will be the sole source of power for the country. Gah. This look for a silver bullet solution - one that has *NO* failings whatsoever and covers *ALL* situations, *ALL* the time - is such an amazing distraction (and one of the reasons the electric car "died", imho). We're not doing that now with our varied sources of energy, and each of the big ones has at least one major problem. We're going to dither ourselves to death.
Decentralization just seems so blindingly obvious. Ken Adelman, previously interviewed in Salon years ago & someone I worked with, is quoted as saying we should pressure the power companies away from supplying general power and instead supplying maintainance power - when the sun doesn't shine, the wind doesn't blow... the cows don't crap? Point being they make power when your home system doesn't and otherwise balance things out. How that works should be something they can swing.
The number of 12,000 kWh/year usage is high, even for Americans. The average household use is 830 kWh/year, before the recent trend - however (un?)successful - to try bringing that down. I have 1 (one) neighbor who is that high and he's embarrassed by it. Personally, I'm at ~500 kWh/month or a little less, and only due to being 95%+ electric but still using gas during the Dec-Mar period for heat. I'm that electric due to roughly 1/3 of my roof covered with solar panels, both PV & thermal. I can use all the hot water I want & about 600 kWh/month without paying our power company a dime, and even with my small EV I'm still not maxed out. Did I mention that electricity is cheaper than gas?
Yes yes yes, solar is "expensive". At about half the cost of a tricked out Toyota Sequoia - before rebates & tax deductions on the solar bring it to about 20% - and it will last much longer. The solar was cheaper than my kitchen remodel. The warantee is for 30 years, at which point the PV will be at 80% of it's output. I wouldn't be surprised to need to do some work on the thermal, maybe replacing the pump and glycol, but the PV should be fine. I challenge anyone to maintain their SUV for that long and have it work out; possible, but at a lot more cost.
And of course, in the case of solar it's about to get cheaper, probably on the order of wind or less.
The problems really are more political & social than anything else. Even Lovelock, Dr. "we'll be down to 30 mil people living at the poles due to climate change" is so NIMBY that, despite how generally intelligent I think he is, I so want to bitch slap him. Everyone buying into the above NIMBY crap, the "expense" boondoggle & other industry generated propaganda are keeping the status quo happily humming. I still keep finding repeats of the Reagan-inspired lie that "solar never pays off it's energy cost"...
(BZZT! http://www1.eere.energy.gov/solar/pv_basics.html)
There's a reason doom & gloom types like Kuntsler resonate.