So I've been thinking.

[Massacure]

The U.S. made 3.719 trillion kilowatt-hours of electricity in 2004.
That is 3,719,000,000,000 kilowatt-hours. Daily insolation ranges from 3 kilowatts to 5 kilowatts per square meter per day in the U.S. Lets take the center - 4. 3,719,000,000,000 / 365 / 4 = 2,547,260,273 kilowatts. Solar cells are only 20% efficient or so. So multiply by 5, we get 12,736,301,369 kilowatts peak that we need.

That is also approxamately the square meters we need (1 kw per meter per hour). So multiply this by 10.7 square feet in a square meter and we get 136,278,424,648. When we take the square root of this 369,159 feet in each direction. That is about 70 miles. We could put it in the middle of the desert. Or we could take a 50 x 20 section, and put it on various homes. That is 170 million homes. But what about factories and warehouses and offices?

Solar cost about $4 dollars a watt. How much of it is profit though. With the profit it would cost about $10 trillion. Could the government do it cheaper though?

Plus if we use only solar, we need batteries. I don't have time to do that though.

Anyone wanna check my math?

[dweller]

1. hell no, i'm not a mathman.

but if we could get these greedy oily bastards out of the way? , we could live on a much more peaceful, greener planet.

'course, there could be some blood in the process i suppose.
dp

ohwell, on edit: this is what i was hoping for with Kucinich. A new energy policy for the future.

[SnoopDog]

2. Solar farms...

It only makes sense to the citizens - but not to our government.

We will have to build it - then they will come.

[NNadir]

3. Here are some variables you might want to include in such a calculation.

1) Cloudy/rainy days.

2) Peak vs constant load. (You alluded to this with the matter of batteries, but this would most profound cost of such a system, not the cells themselves, especially when you include the heat losses - inefficiencies - associated with the storage and re-release of energy.)

3) A big one: Transport costs. You cannot just "put it in the desert," because there are no deserts in Maine. Electricity is only transportable economically for around 1000 km.

4) The change in cost per watt should such a system be mass produced on the scale you suggest. Contrary to what you may read elsewhere, mass production might not uniformly reduce the cost since some materials, like Cadmium Selenide, might become more rare and expensive.

5) External costs: The costs of wastes in construction of such an infrastructure. The cost of damage to life and property in constructing the system.

6) The cost of providing water to construction workers working in the desert for millions of man hours to build the plant.

7) The cost of maintenance of the system: Damage from wind storms, dust storms, corrosion, life time, power lines, etc.

Ten trillion dollars by the way, is a huge amount of money. It is for instance, twenty times more money than George W. Bush dumps on future generations each year to provide graft for Halliburton and other criminal embezzling companies. It is one dollar spent every second for about 33,000 years, about four times as long ago as the dawn of agriculture.

In general, I think PV solar energy and wind energy have an important role to play in our energy future. I do not believe that single huge facilities are likely to be constructed for economic and infrastructure reasons, but I do believe that tax benefits, issues in peak loading, and the climbing costs of non-renewable fuels will further drive individuals to install such systems where appropriate. However one should be aware that such systems are not suitable everywhere.

To install such a system in my own home, the investment of tens of thousands of dollars aside, would be of dubious environmental advantage, since I would have to cut down huge trees on my property (and my neighbor's property were he willing), thereby: 1) Dumping the sequestered CO2 into the air, 2) reducing the detoxifying effect of trees, 3) and changing the heating and cooling properties of my home in the various seasons in a negative feedback kind of way. To expand on point three and to put it another way, the reduction of the external cost created by electrical generation would be offset by increasing the external costs of heating and cooling my home provided by passive heating and cooling.

Still, doing the kind of calculations you have is a real good start at helping yourself to understand issues in energy. Good work.

[Massacure]

4. Well,

1) That is average daily. It don't think it assumes perfect conditions.
2) I said the desert just to show how small (or large if you want) it needs to be. It can be put in sections on many roofs.

I agree with the rest of it though.

edit: Oh, and the electricity grid needs to be updated quite a bit. Could that 1000 miles be extended if it were updated I wonder?

[NNadir]

5. No. Updating the grid would not effect the economics of shipping power.

The limitation is physics and not the conditions of the lines.

Power is shipped at very high voltage and low current to reduce the losses due to resistance. Why this is so is explained in this link:

http://www.bsharp.org/physics/stuff/xmission.html

The power from high voltage long range transmission lines is stepped down using transformers at power substations, which is possible because 1) Thomas Edison didn't get his way and create a direct current power grid, 2) Telsa invented, and Westinghouse improved and commercialized the transformer.

In the United States, power is shipped from substations to localities at 220 volts and is stepped down one more time to 110 Volts, just before entering a home, using those small transformers that one sees hanging on power poles every third or fourth house.

Even without physics considerations, if one wanted to raise efficiency merely by raising the voltage, when one considers the possibility of replacing these systems, the cost in infrastructure is mind boggling.

The environmental cost would also be mind-boggling. One of the motivations for inventing PCB's (polychlorinated biphenyls) was to provide dielectric material for transformers. PCBs are excellent for these purposes because they are extremely stable (hence their environmental persistence), their high thermal conductivity (allowing for efficient cooling) and their high dielectric constant (the conduct very little electricity and thus don't short circuit.) Although PCB's are no longer manufactured and replacement materials have been developed, there are still huge numbers of "grandfathered" transformers out there containing them, transformers that operate perfectly well and may almost be considered "immortal" in the sense that - having no moving parts - they are expected to have very, very long life times.

If these transformers were replaced, one would have to destroy the PCBs they contain. The fact that there is very little infrastructure to accomplish this is just one part of the problem. The other is technological: There is only one known means of destroying PCB's (other than intensive radiation) and that is supercritical water oxidation. This process is very energy intensive, and thus it is easy to imagine circumstances in which any energy gained by increased voltage would be offset by the energetic losses in destroying materials old transformers and building new ones.

One could imagine, of course, placing additional step down transformers in the line and simply increasing the voltage in the power lines, but all transformers, even the best ones, are inefficient and lose energy to heat. Thus again, the increased transmission efficiency might not be balanced by overall system efficiency, especially on a cost benefit analysis.

Finally, the biggest restriction on increasing the voltage and line efficiency is that all materials have a breakdown voltage, which is the voltage at which even insulators ionize and become conductors. This is what lightening is, air exceeding it's breakdown voltage. Typically, for air the breakdown voltage, which is a function of humidity, is in the hundreds of thousands volts range. Transmission lines that exceeded this voltage would simply short circuit when exposed to air. All of the insulators associated with transmission lines have breakdown voltages as well and this is why there are additional limitations on power transmission efficiency via using higher and higher voltages.

Researchers have considered that there is only one way to overcome the physical limitations on power transmission over distances, which is to make superconducting transmission lines, wherein the resistance is zero. However, all known superconducting materials must be cooled to very low temperatures: For most metals, these temperatures, are colder than liquid hydrogen or and in some cases, liquid helium. These cooling liquids themselves require huge energy inputs to produce and maintain. Some superconductors exist that are superconducting above the temperature of liquid nitrogen which would make them somewhat more economically acceptable, at least in respect to the energy cost of producing the temperatures. These high transition temperature superconducting materials however are not metals, they are ceramics, and often contain oxidized forms of somewhat exotic - and difficult to separate - elements like the lanthanide metals (and/or the related element yttrium). Being ceramics they are not really usable in industrial circumstances: They are brittle, cannot be drawn into wires, are very expensive, and can only carry very low current densities before transitioning back to insulators.

[RafterMan]

6. Your units are wrong, but it comes out more or less right

You use 3-5 kilowatts per square meter per day, when what you mean is 3-5 kilowatt-hours. Thus the panel generates ~1kwh/day/m^2 -- I don't know how 1 kw/meter/hour got in there. And in reality, that number is a little high for current panels.

Since you need ~10 billion kwh/day, you need about 10 billion square meters or $10 trillion at $1000/panel. At 6% interest over the 25-year lifespan of the panels, that's about $800 billion/year, or ~22 cents/kwh. Not horrible. If you built 1/25 of it per year and rotated new panels in as others got old, it'd eventually be about $400 billion/year, but in the early years you wouldn't be getting much electricity for your money.

It's a thought, but I'd rather see them spend a few tens of billions to get the efficiency up and the cost down -- triple the efficency at one-third the cost would make solar a compelling consumer choice, rather than a big government project. There are interesting projects right now that promise to do either one of these -- if we get both together, problem solved.

[NNadir]

7. For 800 billion dollars a year, you could get 200 nuclear plants

which would be cleaner, safer, more reliable, and higher yielding (less than 5c per kilowatt hour). They would produce electricity immediately.

This reality varies considerably with public perception but is nonetheless reality all the same.

The fact is though, there is no such money for either type of infrastruce investment in cleaner forms of electrical generation. The United States is completely bankrupt.

We have not yet begun to pay for electing a complete moral, economic, and environmentally vaccuous piece of pathetic shit as our President, mostly because the people to whom we owe money are afraid of what will happen when this house of cards collapses. But the ostrich strategy will not prevent the house from collapsing in any case.

[RafterMan]

8. Sure, I'm all for nuclear

And of course when you add in installation, maintenence, wiring, etc. you're looking at a cost about 10x that of normal generation technologies. That's where I come up with my formula of 3x the efficiency at 1/3 the price.

But I always view these "100% replacement" scenarios as just a marker in a game -- in reality, there are no 100% solutions.