Don’t forget hemp oil.
What does a Gerbil (or whatever) on a treadmill count as?
I agree to a certain extent. I would argue, however, that because an energy source is not being used to any large extent now, it does not preclude its large scale use in the future. The use of biomass as a fuel is not widespread, though it is already being exploited in significant quantities in countries such as Brazil (in the case of alcohol). As and when the world’s oil stocks are used up, more biomass production is widely predicted. Economics and not physics prevent earlier adoption.
Finagle states,
“Well, there’re always the traditional ones – slaves and animals”
I think he is correct. Most of the work done on my sites is done by pure human power. When we use power tools, I imagine they increse our efficiency, but without skilled men they’d be useless.
I think Crafter Man already answered that question pretty throuroghly.
Ones that won’t be viable for 30 years, that are just theoretical or small scale. I was asking about forms of power we currently have access to that are proven to work on a large scale.
Ask those physics geeks sometime to explain to you the difference between force, energy, and power. You appear to be using the terms interchangeably.
Hint: You have apparently attempted to list the four fundamental forces, presuming you omit the word potential in item #4. (There is a difference between gravitational force, gravitational potential, and gravitational potential energy.)
I don’t suppose you can provide a cite for this? You’ve made this assertion in other threads, and so far as I can tell have backed it up solely by your gut intuition. How about something a little more authoritative?
The fact that the free market has not embraced PV systems for use in large-scale power distribution systems is a convincing indication that such systems do not pay for themselves. The folks who run the coal & oil companies are not stupid; if they truly believed PV systems were worthwhile, they would build them.
No. It is a convincing indication that the short-term return on investment on PV is small relative to the short-term ROI on other energy sources. And, of course, you completely neglect that the costs of various energy sources involve not only the energy costs of retrieving those sources, but a myriad of other costs as well - real estate, labour, etc.
The mere fact that one breaks even monetarily on PV systems after some years is an indication that they do produce net watts, since the energy costs of producing/transporting/etc the panels are passed on to the buyer.
I do not profess to know that PV are net energy producers. However, you have not provided one shred of evidence that they aren’t.
One thing that is not considered here is the usefulness of the energy to start and later. For example, one can feed a draft animal on stuff that grows wild, and can’t be effectively used for anything. But of course, the raw energy of the plantstuffs used to feed a draft animal exceed the work you get out of it.
Aren’t we always harvesting energy that was vessled for us? This is just another example of how it is cheaper to harvest that energy (by letting the animal wander around and eat scrub plants). If we had to build our own sun, I don’t think solar power (in any of the forms we use to harvest it, such as biomass) would be a net gain for us since so much energy is radiated away from us. The question isn’t how much total energy is stored and how much is lost in the conversion, but how much we invest in retrieving or converting it.
I do not have a cite; it is simply this electrical engineer’s gut feeling that a system based on PV technology requires more energy to manufacture, run, and maintain that what you can get out of it.
Tell you what, Gorsnak, if you truly believe PV arrays “pay for themselves” and are the wave of the future, you should take some capital and invest in it. Here are some links to get you started:
http://www.sunedison.com/invest.html
http://www.nanosolar.com/investors.htm
http://www.powertech-solar.com/investment.html
http://www.oksolar.com/info/money.html
Get back with me in 10 years and let me know how you’re doing.
While you’re at it, you might find the following interesting. It’s an article about a homeowner who installed a PV system:
http://www.hollowtop.com/cls_html/solar_power.htm
At least the guy is honest:
It’s also a “battery-less” system, which means they still need to be connected to the grid for it to work. What a colossal waste of money. :rolleyes:
So, still no evidence. Very nice. Perhaps you would like to point out where I have stated that I “truly believe” that PV is a net power producer? I don’t know. But I’d like to. Hence, I’d like some evidence, one way or the other. You have produced none, hence I don’t feel like I’m any closer to the answer.
Your investment “argument” is stupid. Even if there’s a major breakthrough and PV is the wave of the future, there’s no reason to believe that investment in current PV companies would pan out. Only with a crystal ball to determine which of these companies would turn out to be the Microsoft of PV would it be smart. The others may well go the way of Amiga.
And going without batteries and remaining hooked into the grid is not “a colossal waste of money.” It’s the smart way to go. Use the grid as a storage device. Batteries are expensive, and involve a loss of efficiency. Why not rather contribute your excess energy into the grid when you’ve got it, and draw energy when you need it and it’s dark? This has nothing to do with whether PV produces more energy than it costs to produce. It does have something to do with whether we can use solely solar power, but that’s not particularly relevant to my question. So long as we have a base of non-solar power production that can be varied, it makes better sense to vary that production than it does to dump PV-produced electricity into and out of batteries.
There is a distinction between something “paying for itself” and something being a worthwhile investment. A PV array might pay for itself in 10 years, 100 years, whatever. In my business, something would only be considered a worthwhile investment if it paid for itself within 5 years. I think we can take it as self evident that PV arrays do not usually satisfy this criteria. If this were not the case, it would be reasonable to expect that we would see much more of them. I think it would be a fairer challenge to ask Gorsnak to provide a cite that demonstrated a PV array has ever paid itself back, as per his contention. I think it is also fair to ask you to provide a cite, as opposed to a gut feeling, that
as per your contention.
I would not accept either postulation as being correct without seeing evidence. This is GQ after all. 
I have provided a cite in a past thread - in this post
The study cited there claims to take into account all the factors Crafter Man says are never taken into account - transportation, production of manufacturing facilities, etc, and says that PV cells in 2000 paid for themselves energywise (not costwise) in about 10 years out of a 30 year lifespan.
The study doesn’t show any of their numbers, however, so I take it with a grain of salt. Still, it’s the closest thing to evidence I’ve seen on the matter.
Like I said, I have no cite, and it’s my gut feeling (as an EE) that no PV-based power system has ever produced one net watt. It’s also my opinion that if technology progressed to the point where PV-based systems did produce net power, the power companies would be scrambling to build them.
Microwave. But you have to be careful – sometimes the satellite goes out of alignment and burns a path through your city, destroying property and setting fires. Oops.
A large-scale PV-based system also consumes quite a bit of permanent real estate. Did they also take into account the opportunity cost of the land? Probably not. And did they include the inefficiency of DC to AC inversion?
Real estate isn’t an energy cost, unless you’re planning on using it to grow biomass for energy production instead. Most rooftops aren’t being used for biomass production, to my knowledge. I don’t know if they included the inefficiency of inversion. What is it, about 10%? So add a year to their estimate. Doesn’t change the conclusion much. Anyways, the inefficiency of inversion is irrelevant to the question of whether PV is a net energy source. The only reason inversion is necessary is because we happen to use AC for most of our electrical needs - except that half the stuff I’m powering converts it back to DC before it’s finally used. Saying that PV only produces the amount of energy left after converting it to AC and back to DC again is like saying that the US dollar is worth $USD0.95, because that’s what I’d have left after converting it to $CAD and back to $USD.