Mary Elaine Schabell, age 13, of Mundelein, I11., for her question:
HOW IS GAS MADE OUT OF COAL?
At the present time, coal is used to generate about half of the electric power in the United States. This is done by burning coal under boilers containing water. Steam then comes from the boiling water and it spins turbines which turn generators to produce electricity. One ounce of coal can make as much electricity as 100 tons of water falling one foot.
Early in the 1970s, the growing shortage of clean¬burning natural gas brought about the realization that research should be conducted to see if gas could be made from coal. Private industry and a large amount of assistance from the federal government was called upon.
Scientists felt it was necessary to develop a high heat value gas that could be sent through pipelines and replace natural gas for home heating. They also hoped to find a low heat value gas that could be used to fuel electric power plants. The latter gas would be cheaper but could not be transported by pipeline.
Coal was converted to high heat gas by burning in a closed vessel and blowing oxygen and steam through it to produce methane, the principal ingredient of natural gas.
By 1973, two power plants were in operation and were producing high heat gas. Additional plants have been planned, with some of them set for construction during the 1980s. Pilot projects to produce low heat gas are still planned for the immediate future.
In some of our steelmaking and other manufacturing plants, older methods of coal gasification are being used, but these methods contribute to air pollution and produce only low heat gas.
The Fischer Tropsch process is a method of developing chemicals from coal by oxidation. The procedure calls first for turning pulverized coal into a gas by exposing the coal to oxygen and superheated steam. The gas, a mixture of carbon monoxide and hydrogen, in turn is passed over various solid catalysts to change it into useful products. Cobalt catalysts have been used to change the gas into diesel fuel. Iron catalysts can change it into gasoline.
Today the electric utility industry uses about 300 million tons of bituminous coal each year. The aluminum industry, which uses great quantities of electricity, is building plants in coal regions in order to be closer to the low cost sources of electric energy. The wave of the future, however, calls for additional expansion of research that will enable us to do better in the years to come.