Oil and Energy

so I love the idea, but it still is not practical. If I did my math right, just the cost of the elevator, at your estimate of $120 billion (you're right, any gov't project will overun by at least 10x) and assuming free solar panels, to provide electricity for the US for one year, comes to roughly $31.50 / KWH.

Yeah, that will be spread over many years, but you're looking at nearly a 30 year Return On Investment at today's rates (~9cents/KWH).

This also excludes administration and maintenance costs, as well as security costs, since this will instantly turn into the largest terrorist target in the world.

Well, let's go over the numbers.
The figure of 3.8 million gigawatt hours per year works out to 3.8 X 10^12 KWH/year.

The money spent is $120 billion, or 1.2 X 10^11 dollars. If we charge all of this price to the energy program (which we wouldn't), that's

1.2 X 10^11 ÷ 3.8 X 10^12 = 0.0315

Charging all this cost to the first year of energy production adds 3.15¢ to each KWH.

I'm not sure you did your math right.

Also, solar panels aren't the only thing that would be shipped into orbit. Anyone who launches a satellite these days is willing to pay $10,000 for to boost each pound of the satellite into orbit. They expect to make enough from the satellite to pay that money back. When the cost drops to $10/pound, you can bet a lot more people will want to put stuff into space, and they'll pay good money for the left. Energy will be far from the only revenue source for the elevator.

Protecting it is another matter, but when a very conservative revenue stream* generates close to $450 million per year, that can buy a lot of security.

* Average speed from earth surface to orbit is 1000 MPH. At 22,500 miles up, that's 22.5 hours one way. A Boeing 747-81 has a takeoff weight of some 970 thousand pounds. (485 tons) Its empty weight is 205 tons, for some 42% payload capacity. Let's assume a space elevator car weighs an even 500 tons, and has a 200 ton payload. The cost of the energy needed to boost a pound of mass to geosync orbit is very low. I think I calculated it once at 23¢. But let's call it a buck. Of that buck, 40% is payload, so we're up to $2.50 per pound of payload. Charge another $7.50 for administration, environmental controls, etc, and we're up to $10/pound.

One round trip in 45 hours works out to just under 195 round trips per year. Call it 150, on account of maintenance, loading, unloading, etc.

150 * 400,000 * $7.5 = $450 million.

Ok, I looked it up. I've never been good with giga and billion decades. So...

Gigawatt is 10^9 watts, so 3.8 million gigawatts is 3.8*10^6*10^9 = 3.8*10^15 watts = 3.8*10^12 kW

Billion = 10^12. $120billion = 120*10^12 = 1.2 * 10^14

1.2*10^14 / 3.8*10^12 = $31.50/kw

And a 1000MPH elevator?? Both ways?

Like I said, I love the idea, I just don't think it would work.
This all also neglects drag on the structure from a moving base (earth), wind shear, etc...

In the US, a billion is 1,000,000,000 = 10^9. In the UK, this number is (has been) called a "milliard", and a "billion" is 10^12.

There's your factor of 1000 difference.

(I'm not aware of "giga" having the same ambiguity, though.)

Remember, the elevator would be outside the atmosphere during most of the trip. Using any decent mag-lev technology, the main limit on how fast the thing can go will be coriolis forces. At a high enough speed, there will be a lateral force applied to the elevator, and an equal force will have to be applied to keep the elevator car attached to the cable.

Thanks for setting me straight!