Atmospheric carbon dioxide and nuclear energy.

Robinson et al. (1) make an extremely strong case for rejecting the view that the rising atmospheric C[O.sub.2] concentration is a grave danger and that the carbon emission from fossil fuel combustion should be drastically reduced regardless of cost. The authors go astray, however, in the section "Environment and Energy."

The authors point out that spent nuclear fuel can be recycled into new nuclear fuel. This is being done in several countries. But reprocessing spent fuel does not mean that there is no high-level nuclear waste. The production of high-level waste--mainly strontium-90 and caesium-137--is inseparable from nuclear fission. This waste must be stored safely for at least 600 years. Transuranic elements with long half-lives are also produced, but it may be possible to render them innocuous; until this can be done, they will have to be stored. This is not an objection to nuclear energy, but waste depositories are unavoidable.

The authors propose that U.S. nuclear generating capacity be increased from 90 GWe to 650 GWe. It is most unlikely that nuclear reactors can be deployed in the U.S. at a rate faster than 20 GWe per year; the program would therefore take more than 30 years to complete, and cannot start earlier than 2015, as design and construction takes 7 years. It is probable that U.S. electricity demand in 2050 will be higher than it is today, for example if gasoline-driven automobiles are replaced by electric vehicles. It is therefore far from certain that there would be 230 GWe of nuclear capacity available for production for export.

The authors state that "with plentiful, inexpensive energy, seawater desalination can provide essentially unlimited supplies of fresh water." But even nuclear energy is much too expensive. Desalinated seawater costs approximately $1.50 per cubic meter, and maize requires 450 cubic meters of water per ton harvested grain (wheat and rice require much more). The use of desalinated water for irrigated maize cultivation would thus raise the price of maize by approximately $700 per ton. There will not be "unlimited" supplies of fresh water until the cost of nuclear energy has fallen to a small fraction of its present cost. Whether this will ever happen is problematic.

The authors allege that "energy-intensive hydroponic greenhouses are 2,000 times more productive per unit area than are modern American farming methods." This probably holds the world record for exaggeration. Supplementing sunlight by electrical illumination in greenhouses would be far more costly than desalinated seawater.

The belief that technological breakthroughs can compensate for human irrationality and stupidity is wishful thinking. Remember General Patton's remark: "War makes all other forms of human endeavor shrink to insignificance."

Bernard Gilland

Espergaerde, Denmark

In reply: Commenting on the writer's points:

1. While there is some waste left over after reprocessing, the physical amount is reduced to such a great extent that it is an irrelevant problem.

2. Insofar as it being impossible to build the nuclear power plants we propose in less than 30 years, this is armchair technology limitation. Design and construction would take this long only if paper shufflers were allowed to use most of the time. Only 4 years were required to invent, build, and use the technology that won World War II--an enormous technological undertaking that far surpasses 50 nuclear power installations.

There are excellent designs for nuclear power plants now--that are being used to build nuclear power plants outside the United States.

Moreover, our proposal is for identical plants in 50 locations, so only one basic design is needed. Construction could proceed simultaneously at all 50 locations. All 50 of the plants could be coming on line 5 years from now, if the free market-freed from taxation, regulation, and litigation-decided to build them.

3. The writer assumes that desalinated water would be used to grow grain in an ordinary way. Grain can be grown with use of much less water or in localities with lots of natural water. Water is used for many things other than growing grain-human use, for example, in urban areas. California just approved a new desalination plant--with a power source far less economical than nuclear power.

4. As far as hydroponics is concerned, we give our reference, (2) which Simon based upon an actual working installation.

Arthur B. Robinson, Ph.D.

Cave Junction, Ore.

(1) Robinson AB, Robinson NE, Soon W. Environmental effects of increased atmospheric carbon dioxide. J Am Phys Surg 2007;12:79-90.

(2) Simon JL. The Ultimate Resource 2. Princeton, N.J.: Princeton University Press, 1996.