Word: underground
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Dates: during 1970-1979
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...present 600 million tons per year to 1 billion tons. The growth would occur, as the bill now stands, in regions where the land can be reclaimed after surface mining: mainly the Midwest and Appalachia. Reclaiming the arid stretches of the West would be more difficult. In the meantime, underground mining, which is the only way to extract most of the nation's 1.3 trillion tons of coal, should be expanded by using advanced technology: machines that continuously bore or shave seams and greatly increase production...
...energy that heats the homes of the Paris suburb of Melun (pop. 42,000) comes from a highly unusual source: a natural underground reservoir of hot brackish water located more than a mile underneath the town. French engineers boast that the system for tapping geothermal energy is the first of its kind. What makes it unique, they say, is the fact that the water is piped back into the ground for reheating, which means that Melun's subterranean furnace could keep working almost indefinitely...
...been tapped to make electrical power since 1904. In the mountains north of San Francisco, a rich geothermal area called the Geysers produces about 40% of the city's electricity. In most of these applications, the geothermal energy is released as scalding steam. Unfortunately, reserves of accessible underground water hot enough to produce steam (above 212° F.) have been found only in scattered areas of the globe, which has until now hindered wider application of geothermal energy...
Melun's underground reservoir contains hot (about 160° F.) but not boiling water. To get at it, French Engineer Pierre Maugis, 65, drilled a 5,850-ft. hole, which allows the water to escape to the surface. There, it is passed through a radiator-like device called a heat exchanger, which heats water from the city's regular water supply. The temperature of the city water is raised from about 50° F. to 149° F., hot enough to use in bathtubs or sinks filled with dirty dishes. The water is also sent through floor pipes...
...Melun project, Industry and Research Minister Michel d'Ornano is now asking Parliament to allocate $1.5 million for more geothermal well-drilling. Says he: "The increase in the cost of oil and the birth of new techniques oblige us to consider the energy potential of our underground wealth...