THE ROCKEFELLER EFFECT

It takes energy to produce energy. To produce and deliver fuel one has to expend energy in mining, processing and transporting it. This has given rise to "energy accounting," where profits and losses are posted in BTU's or other energy units rather than in dollars.

But just as a dollar accountant can come out with very different profits (without ever swindling) depending on the accounting method, so an energy accountant can come out with a very different result for the same fuel by using different methods of accounting.

For example, in deep-mining coal, you extract only 57% of the mined volume, the rest is supporting structure or otherwise unrecoverable. Of the mined coal, 8% is lost in processing, and of the processed coal, 1% is blown off the trains by the wind, and another 1% of equivalent energy is burned by the railroad engine. If the coal is burned in a power plant, only 38% of its energy content is converted to electricity, and of that another 8% is lost as heat in transmission. When all losses are considered, the consumer's electric input terminals end up with a meager 18% of the energy originally contained in the coal underground.

For other fuels burned by power plants, the figure can be even more discouraging. For nuclear fuel (where 38% of the fissile uranium is lost in enrichment) the system efficiency is only 16%; for offshore oil it is 13%, and for onshore oil lO%. The maximum system efficiency (energy out over energy in) is attained by strip-mined coal, and even then it is only 25%.

These low figures have caused many people, such as Oregon's senator Hatfield, to wring their hands in despair. If the system efficiency is 25%, they figure, at takes 4 BTU's to produce 1 BTU. One might even conclude that it is more efficient to burn diesel oil for heat than to use it in an engine that pumps more oil.

There is obviously something wrong with this argument, for it says that it is better to eat the seeds than the harvest.

It is not hard to find the source of the fallacy. System efficiency treats all forms of energy alike, regardless of whether the energy was produced by man or by nature. When you leave 38% of the coal in a mine, or when you lose 38% of the fissile uranium atoms in the diffusion process, you lose energy that you did not put there in the first place. You lose energy only in the sense that you suffered a business loss of several hundred thousand dollars when Nelson Rockefeller failed to include you in his list of benefactors for political gifts. A true loss is not quite the same thing as an unrealized profit.

But system efficiency is not the only way to characterize an energy system. Let us define the energy gain as the ratio of output energy to manconverted input energy. This will tell us how much energy we make available per BTU actually invested.

What is man-converted energy? Example: In transporting coal, some energy is lost by burning fuel in the engine. It is lost as heat, and the conversion to heat was made through human efforts. On the other hand, some energy is also lost by the wind blowing coal dust off the trucks. This energy is lost in the form of potential chemical energy, and the conversion to chemical energy was performed, millions of years ago, by the sun; it is not manconverted. (This loss will, however, show up in the resulting energy gain, since that much less energy becomes available.)

We calculated the energy gains for power plants burning different kinds of fuel, the available energy being that at the terminals of the consumer, and the investment the man-converted energy in mining, processing, transport, conversion, and transmission. Using the Bureau of Mining's statistics, we came up with the figures in the table below. (For imports, only domestic energy investments were considered, e.g., for imported petroleum products, the only investment is energv for transportation in the US).

fuel energy gain

coal, strip-mined 16.2

coal, deep-mined 13.5

gas 4.9

uranium 235 3.6

oil, US refined 2.7

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imported gas 6.9

imported petroleum products 18.9

hydropower 42.9

Now the figures tell a different story. In strip mining coal, for example, one makes 16.2 times more energy available to power consumers than was invested in the entire production chain. To say that it takes 4 BTU's to produce 1 BTU is to count the "losses" of the sun in geological history.