Liquid coal is on the horizon

There was once a time when almost every home had a coalbin in the cellar. Shiny black nuggets rolled into the bin from the coalman’s truck providing fuel for the furnace. The coalbin held a certain fascination for the young and most children managed to tumble into its dusty black depths — at least once.

In the 1950s the oil man gradually replaced the coalman and the cellar became a basement with a recreation room. Then in 1973 the oil crisis came along. Oil-importing countries faced a shortage of the fuel because of the Arab boycott during an Arab-Israeli dispute. What fuel could replace oil?

Scientists accelerated their studies of alternative methods of generating energy. They also considered new ways of using the old standby, coal. With vast supplies of coal still available and with the technology to control the pollution factor, the coalman may return. This time he will be able to deliver liquid coal — with no ashes to be shovelled. New form of coal

At the University of Toronto’s department of chemical engineering and applied chemistry, Prof Olev Trass is directing a team of researchers who are improving the methods of harvesting the residual coal left behind in the “ponds” when mined coal is washed. The process can salvage billions of tons of combustible material left after decades of washing coal. Close to 90% of the fuel left in the ponds can be converted to a new form of coal and, at the same time, potential sites of pollution gradually eliminated.

The chemical engineering group has refined a method originally developed by the National Research Council of Canada. “The U of T method,” says Trass, “can reduce capital and operating costs by 30% compared to the nrc method.” Liquefying coal

In the basic process of liquefying coal, the coal is ground and mixed with water to make a “slurry” (from the Middle English slory or sloor, variously meaning a mixture, mud, paste). Then oil, usually fuel oil, is added to the slurry, coating the particles of coal that cling to each other forming spherical agglomerates. By a process of screening, the valuable agglomerates of coal and oil are saved while the impurities are washed away in the water.

“You might say it’s a kind of panning for coal,” says Trass. The efficient and economical method of slurrying combines the grinding and agglomeration steps. The process can be used both for recovering coal from waste ponds and for better cleaning of newly-mined coal.

The project has been supported by the Natural Sciences and Engineering Research Council, the University Research Incentive Fund of the Ontario Ministry of Colleges and Universities and General Comminution Inc. Alternatives needed

Although Canada is not faced with an energy crisis, Trass says it is important that alternatives be developed to avoid being vulnerable to oil shortages created by political action or war. Since Canada still imports a large amount of oil, reclaiming discarded coal offers a valuable interim strategy for providing fuel for domestic use as well as for export. By using her coal discards and increasing coal mining, Canada could save much of the foreign exchange being expended when oil is imported.

“The push will come when the Arabian supplies run low. At present there are `proven supplies’ of oil to last for 15 to 20 years, whereas the supply of coal will probably continue for another 300 years. Even the coal ponds alone will yield several decades’ worth of material for making slurry fuel. And when we do run out of oil, 75% of the replacement fuel will be coal,” says Trass.

At present the coalman visits three homes in Nova Scotia where the furnaces burn brightly with slurry. The cost of converting to pumpable oil is relatively low. Trass says that if oil prices rise even a little more, coal slurry may be used for the electrical generating stations in the Maritime provinces and along the Atlantic seaboard. At today’s oil prices the incentive to convert is still not strong enough, “but this could change rapidly.” Now have the technology

We now have the technology to control the pollution and meet the standards in most areas. At U of T coal slurry is purified to emit 50% to 75% less inorganic sulphur than ordinary coal. (Emissions of sulphur and nitrogen oxides that combine with moisture in the air produce acid rain.)

Today Canada is in the forefront of research on creative ways to harvest coal — “partly because Canadians were still working on coal slurry as late as 1971, when the `farewell conference’ to this kind of work took place,” explains Trass. “But then, when the oil crisis came two years later, Canada being the last to stop such studies suddenly found itself in the lead.” Studying advantages

The United States, Germany, Italy and Sweden are studying the advantages of using coal slurry. The Swedish and Italian programs are especially extensive, despite the fact that those countries do not even produce coal. Sweden is now phasing out its nuclear programs and so is considering coal as a possible replacement for nuclear energy.

Trass believes that a number of alternative sources of energy, including sun, biomass, wind and nuclear power, will be used eventually. “I believe nuclear energy will one day be proven reasonably safe and will regain the pre-eminence it lost when the accident at Three Mile Island raised a public outcry and emotional response which was highly exaggerated by the media. The subsequent Chernobyl accident was, of course, dramatically more serious.”

So the coalman may be back, with a Canadian product, a flowing coal that needs no coalbin and offers security against any potential oil crisis. Robina Salter is a freelance journalist and author of a novel, Hannah, published by McClelland & Stewart, Toronto.