Thanks to the availability of cheap, abundant, and cleaner-to-burn natural gas, U.S. use of coal to generate electricity has fallen to lows not seen since 1949, when the federal government first started keeping statistics. And with increased pressure to cut greenhouse gas emissions linked to climate change, energy experts say the coal industry is at the beginning of what may be a long slide to obsolescence.
But that doesn't mean that coal will become completely useless. MIT researchers are looking at other ways to utilize coal's molecular complexity and harness it to make a new generation of electronic devices - including some that could become part of the switch to renewable energy.
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In an article in the journal Nano Letters, the MIT scientists describe how various types of coal could be used to create thin films with adjustable electrical properties. Eventually, according to the scientists, coal could be used to fashion solar panels, batteries, or various types of electronic devices.
"When you look at coal as a material, and not just as something to burn, the chemistry is extremely rich," Jeffrey Grossman, an MIT professor in materials science and engineering, said in a press release.
For the first time, the paper characterizes in detail the chemical, electrical, and optical properties of thin films of four different kinds of coal: anthracite, lignite, and two bituminous types.
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Some naturally occurring coal varieties have a range of electrical conductivity that spans seven orders of magnitude, making them suitable for a wide range of electronic uses - and without the extensive purification and refining that silica, a standard raw material in electronics manufacturing, requires.
For that reason, coal might provide a cheaper alternative.
The researchers demonstrated coal's potential by using it to make a simple electrical heating device, which could be utilized for jobs such as defrosting car windows or airplane wings.