Tuesday, March 21, 2006

Energy! Where does it come from?

Well believe it or not all energy on earth is derived from atomic reaction. And the biggest reactor on earth is not on earth. It is 8 minutes by light speed away at that big bright spot in the daytime sky. Oil is solar energy, hydro electricity is solar energy, wind power is solar energy, firewood is solar energy, ethanol is solar energy, coal is solar energy, waves and ocean currents are solar energy. Even geothermal energy is solar (maybe not our sun but some sun somewhere and when) energy.

Lets roughly rank these in ascending order of 'efficiency': geothermal, oil, coal, ethanol, firewood, waves and currents, wind, hydro, solar cells. Now I certainly don't claim to have these all in exactly the right order, but you can see the drift. By the way 'efficiency ' would be the ration of energy put in to energy retrievable (or is it the other way around). The basic rule is that the more steps you are away from the atomic reaction that fuels it all the worse off you are. There are other considerations, of course. The cost of retrieving the energy stored and of handling the by products of that retrieval are certainly two big ones.

Geothermal for example is several steps away from the original energy, but it is not very expensive to harvest in some areas of the world and creates little or no pollutants (though there could be side effects of wide spread use such as volcanic triggers and even 'core cooling') but it is readily available only some areas.

Oil? Well let's see. Use sunlight to grow a plant, feed the plant to an animal, bury the animal under centuries of weather (powered by sunlight) erosion, hunt it down and get it out of the ground and refine it and then burn it for the energy left.

Coal? Well let's see. Use sunlight to grow a plant. Bury the plant under centuries of weather (powered by sunlight) erosion, hunt it down and get it out of the ground and crunch it up and then burn it for the energy left.

Ethanol? Well let's see. Use sunlight to grow a plant. Chop the plant up and feed it to yeast. Distill the yeast pee to get alcohol. Burn the alcohol for the energy left in it.

As you can see there isn't much difference in the 'efficiency' of those three. Ethanol's big advantage is the ability to reduce "centuries of weather (powered by sunlight) erosion" to a few days or weeks of yeast feeding. Its quicker than coal or oil but it isn't much closer to the source.

And they all three require a huge expenditure of energy to harvest the energy. Oil has actually reached the point where it is energy negative. It now cost more energy to get than it produces.

So why is oil still used? Well there is a huge infrastructure all ready in place, it is quite portable, and it is economically storable in even small to medium quantities.

What about coal? Mainly it has pollution problems, is not easily transported, and cannot be readily stored in small to medium quantities. For these reasons only a limited infrastructure has ever been developed.

What about ethanol? It is portable and readily storable in even small to medium quantities, but there is almost no infrastructure, and, frankly, due to its inefficiency and cost not much reason to develop any.

All energy sources have some drawbacks but there is just no reason to think that switching one grossly inefficient system for another is the best way to go.

0 Comments:

Post a Comment

<< Home