THE ENERGY BUGS

And then, hi-ho!, there are bugs that mine metals, including uranium. They are not exactly the latest mining technique, for they mined copper for the ancient Romans, and for the Spaniards in the 17^th century (though their masters, of course, did not realize what was going on).

The little miner is thiobacillus ferrooxidans, which classical scholars will recognize as "the sulfur bug that oxides iron." It is, indeed, sulfur the bug is after; it attacks it in metal sulfides by way of a chemical reaction using oxygen from the air, and manufactures sulfuric acid in the process. The acid dissolves the metal and the solution flows out from the bottom of a heap of ore wetted with water.

It works for copper (in mines or waste dumps) and it works for uranium. In Canada, bugs are cleaning up what's left in the almost fully depleted Stanrock mines, and at Agnew Lake, Ont., they are at work in the world's first mine specially designed to produce uranium by underground microbial solution mining. In France, a close relative of the old ferrooxidans strain is extracting uranium, and Sweden is looking into developing its uranium deposits biologically.

In the US (where copper has been mined by microbial solution for some time) and in Japan, an even more challenging problem is being looked into. There are microscopic amounts of uranium in fresh water and in the sea: no more than 3 parts per billion, but then, there is a lot of water in the sea. In fact, the sea contains enough uranium for millenia of energy. Wanted: a bug that will concentrate these microscopic and diffuse traces, a bacillus uranoportans Gofmani (we are proposing to name it after another creature that makes a big deal out of every tiny trace of radioactivity.)

Meanwhile, British scientists at Warren Spring Labs at Stevenage have found a sulfur-eating, metal-mining bug that likes it hot: some 30 degrees C hotter than ferrooxidans can stand. The increased temperature accelerates the biochemical reaction and makes the process more productive. The British group can produce copper from ore continuously by microbial solution in a laboratory-sized plant. They believe a full-size plant producing thousands of tons of copper a year is now feasible.

And after copper, uranium.