Posted by
Karl Lembke on Tuesday, June 03, 2008 1:33:43 PM
The price of gasoline has climbed over four dollars per gallon where I live, and seems ready to continue to climb. So have the prices of food, and anything that has to be trucked or flown from where it's made to where it's sold. And so have people's blood pressure.
We hear lots of calls for energy independence, and lately we're starting to focus on approaches besides drilling for more oil. Nuclear power is an option.
One option we really ought to consider is solar power. However, unlike most of the Greenies who dream of covering every rooftop with solar cells, I'd vote for the solar power satellite option. The solar constant is roughly 1.36 kilowatts per square meter. If we assume a power conversion efficiency of 10%, each square meter of solar panels will generate some 136 watts of electric power. Every square mile generates 340 megawatts of power. Since sunlight in geosynchronous orbit is available pretty close to 24/7, each square kilometer of panel generates some 8 million KWH of electricity per day, or just under 3 billion KWH per year.
According to
Wikipedia, the US consumes some 3.8 million GWH per year. (One GWH is a million KWH.) The 3 billion KWH per year generated by that square mile of solar panels is 3000 GWH per year. This is just over three quarters of a percent of the national consumption of electricity, but we can always add more panels.
Increase the size of the panel to ten miles on a side, and we increase the electricity generated a hundred-fold. A ten-mile square panel will generate three quarters of the electricity we use. Twenty miles on a side, and it produces three times the electricity we were using in 2005. 100 miles on a side, and we're up to 75 GWH per year -- about four times what the entire planet used in 2005. And a 100 mile square is tiny. Satellites in geosynchronous orbit are spaced three degrees of arc apart. That works out to a separation of a little under 1200 miles. There's lots of room for a really big satellite. (Although it might be best to have several smaller ones, to guard against accident or other failure modes.)
Now, how do we get all these solar cells up into orbit? It costs a fortune to boost stuff into orbit – some ten thousand dollars a pound. Jerry Pournelle has estimated we could build and orbit enough power satellites to make the US energy independent for less than the cost of one year of the Iraq War – call it a hundred billion dollars. But there's a way to lower the cost, and which would yield enormous other benefits as well.
This article at Tech Central Station proposes an "Erie Canal for the 21st Century".
...like the Erie Canal, a space elevator would be more than just a testament to good old-fashion American ingenuity and know-how. It would have broad, practical economic and political ramifications. For instance, just as the Erie Canal lowered the cost of shipping a ton of flour from $120 to less than $6, a space elevator could similarly open up space by radically reducing the price of hauling the equipment and supplies into orbit. Today, it costs anywhere between $10,000 and $20,000 to launch a single pound of material into space. With a space elevator, replacing and updating the communication and satellite infrastructure upon which modern society is now so dependent would be fast, inexpensive and easy.
It has been estimated that a space elevator can be built for $12 billion. It is a large amount of money to be sure, but so too was the Erie Canal.
Assuming a reasonable adjustment for cost overruns and bureaucracy, let's call it $120 billion. Once it's built and working, the cost of lifting people and equipment into orbit would plummet. I once calculated the cost of electricity needed to boost something into orbit, if we could use all the energy for lifting only payload. It was about 25¢ per pound. Since some fraction of the power used will have to go toward lifting the elevator itself, it won't be that low, but even $10 per pound is cheap compared to current rates. And such a drop in price would make installing a solar power satellite a lot cheaper.
And when we convert from using oil to using electricity, or electrically produced synthetic fuels, or other sources of energy, we may have to restrain our urge to gloat when OPEC no longer has any buyers for its oil. Of course, we'll be more than happy to sell them all the electricity they need.