FAR OUT AND COOL

Producing fresh drinking water from brine and polluted water takes immense amounts of energy. Fortunately, this energy is provided by the sun, which distils the water and raises it to great heights, whence it comes down as clean rain water. Less fortunately, that is not enough, and many densely populated regions, such as the Los Angeles area, must import drinking water from elsewhere; but supplies are getting ever tighter.

Large scale desalination of sea water requires enormous amounts of energy, which by present proposals will be supplied by nuclear plants. But two researchers of the RAND Corporation have come up with an alternative proposal, which is both far out and cool: Get the fresh water where 2/3 of the earth's supply is stored: in the ice of the Antarctic. Collect icebergs and tow them home.

Arctic icebergs tend to be jagged and liable to tip over, creating dangerous eddies; but in the Antarctic they are flat and stable. An escort ship would provide nuclear electric power (1000 MW) to drive propellers mounted on the sides of the icebergs, which would be tied together in a 50 mile convoy traveling at about 1 knot, reaching the US after an 8 months' journey, and delivering enough fresh water to fill one third of the reservoir behind Hoover Dam.

What melts icebergs in moderate latitudes is not the sun (to any significant extent), but the warm water, and the authors of the report propose to provide the necessary thermal insulation by trapping the molten water (a poor thermal conductor) between the iceberg and a plastic sheet wrapped around it, thus preventing thermal convection by moving water.

The environmental, social and economic factors are also discussed in the report, which recommends this method on all counts.

The icebergs produced each year in the Antarctic (mainly by glaciers moving into the sea) contain as much water as the annual rainfall of the continental US, so why let them be turned into useless brine? The penguins are not likely to embargo them.