A COAL PIPELINE WITHOUT WATER

And that brings us to the final point about the water argument: It becomes irrelevant when the pipeline is pneumatic rather than a slurry line.

Ever bent on staying ahead of the times, we reported on pneumatic lines in May 1978, based largely on the 1975 U. of Illinois report The Coal Future, and some research abroad. The main trouble, we wrote then, seems to be that these lines are untried.

No longer. A system called Tubexpress is now running at a demonstration facility in Houston, and though it can carry any type of cargo, it has been developed (since 1969) primarily to carry coal and lignite.

Unlike the pneumatic lines envisioned by the U. of Illinois report, with fine coal particles suspended in the air stream pumped through the line, Tubexpress works much like the tube carrying checks between customer and teller in a drive-in bank.

A capsule containing the coal (or other freight) is pushed through a tube by air pressing on its rear end, which is equipped with a seal (a flexible plastic disk) to prevent the air bypassing the capsule.

This dissimilarity, first of all, eliminates the danger of explosion present in the suspended-coal-dust pneumatic fine. The coal need not be crushed into fine size, let alone pulverized; its size is not essentially different from that carried on railroad cars. There is therefore nothing to explode.

The capsules run on four wheels, their planes inclined 45 degrees to the vertical, in low-grade steel piping with the simplest welded joints, for the system operates at low air pressure. The top of the capsules is open, since the air moves with the capsule, so that the coal cannot be blown off.

At the loading point, the capsules are loaded as a continuous stream moving butt to butt through the (automatic) loading station. Once loaded, they spread out, since the transit speed is 10 to 15 times the loading speed; but it is the loading speed that, together with the pipe diameter, determines the throughput of the system.

When the capsule moves down a steep hill, it is not pushed by the air, but moves the air through the pump. The pump then becomes a turbine, its (electric) motor becomes a generator, and the surplus energy to be disposed of in braking is not turned into heat (as it is in the brake linings of an automobile), but into electricity.

No doubt the energy stiflers in environmentalist garb will go to court to protest the afternoon naps lost by the moles, but to reasonable people it is obvious that a buried system of this type has no significant environmental impact. In fact, it can considerably reduce the hazards of shipping toxic materials: Not only can it safely transport radioactive materials (which are not terribly dangerous anyway), but it can ship chemical toxins without having to evacuate 230,000 people (as happened in Canada after a chlorine carrying train derailed not long ago) when there is a mishap.

[More: Tubexpress - Preliminary Literature, available to AtE readers from Ampower Corporation, 1 Marine Plaza, North Bergen, NJ 07047.]