Monday, December 12, 2005

Ocean power, baby!

One of my favorite topics of casual research and conversation with friends is energy. As in, what on earth are we going to do when we run out of fossil fuels? Most scientists estimate that we have 30-40 years of fossil fuels remaining, although the estimate varies wildly based on the uncertainty in the factors going into the prediction. The growth of the economies in China and India is already increasing consumption dramatically. If the third world starts using energy like the USA uses energy, then we are in big trouble. There are some things that will alleviate the problem:

1) Natural gas

Supposedly, we still have vast reserves of natural gas, compared to crude oil. We could build an infrastructure for distributing natural gas and convert our vehicles. However, natural gas is not as efficient (BTU/kg) as gasoline, so we won't make the switch until we have to. Once again, however, this is an unrenewable resource that we will consume until it is gone.

2) Tar sands

Supposedly, the Utah, Colorado, Wyoming area has more petroleum reserves than the entire Middle East. The problem is that it is locked up in tar sands and requires more money to extract. However, once fuel prices get high enough, the extraction will prove economical.

3) Spontaneous generation?

I read a while back that there is a scientist who claims that petroleum is not really a fossil fuel but it is spontaneously generated from deep within the earth's crust, and therefore renewable. As part of his evidence, he points to the fact that most major oil reservoirs have produced far beyond their original estimates. Sounds like nonsense to me, but I thought I would throw it in.

4) Cheap solar cells

Supposedly, scientists in the USA and Europe have invented plastic solar cells that are much more cost-effective than traditional (silicon?) solar cells. The new cells should be cost-competitive with fossil fuels for power generation on a per KW-Hr basis. They claim that they they should be in mass production within 3-4 years. One can envision vast arrays of solar cells in the desert, feeding power into transmission lines. However, talk is cheap. Time will tell if this will really come to pass.

5) More nuclear power

No nuclear power plants have been built in the US for several decades. With increasing fuel costs, that will probably change. Given the small amount of fuel used in the power generation process, there is essentially an unlimited supply of nuclear fuel. The problem lies in the difficulty of building new plants. Nobody wants one on their backyard due to fears of another Chernobyl accident and they require a large supply of water. Another problem, of course, is the storage of the spent fuel rods. New technology is supposed to make it possible to re-process many of the old rods, extracting more energy and making the waste less radioactive at the same time. Once again, time will tell.

6) Dead cats

A German inventor figured out a way to power cars with dead cats. He has since denied using dead cats (you can use any kind of bio-waste to fuel the vehicle), but one can always hope this catches on. :)

This brings me to the main topic of this post: ocean power. One of the more fascinating and potentially most promising ideas I have seen is to harness the power of the ocean to solve our energy needs. This technique was developed by an 80 year-old inventor named John PiƱa Craven. There is an excellent description of this technique in an article in Wired magazine. The main idea is that there is a huge reservoir of super-chilled water at the bottom of the ocean (just above freezing). This water can be pumped to the surface using large plastic pipes. The temperature difference between this chilled water and warmer surface water can be used to drive an ammonia-based heat exchanger connected to a turbine/electrical generator. The best thing about the process is that it is clean and renewable. Some small-scale tests have shown great promise and the technique is currently undergoing larger tests by the U.S. Navy. The inventors envision massive floating power platforms in the ocean where the energy is used to convert water to hydrogen. The hydrogen would then be transferred to large tankers and distributed around the world for use in fuel cells. This will be an exciting development to watch in the next few years. For the sake of our kids and grandkids, let's pray that it works out.


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