Energy & Green Tech

Termite-gut microbes extract clean energy from coal

Termites generally don't elicit a whole lot of love. But surprisingly, this wood-eating insect may hold the key to transforming coal—a big polluting chunk of the global energy supply—into cleaner energy for the world, ...

Energy & Green Tech

Does energy storage make the electric grid cleaner?

Carbon-free energy: Is the answer blowing in the wind? Perhaps, but the wind doesn't always blow, nor does the sun always shine. The energy generated by wind and solar power is intermittent, meaning that the generated electricity ...

Energy & Green Tech

Efficiency of silicon solar cells climbs past 26 percent

(Tech Xplore)—A team of researchers working at Kaneka Corporation has broken the record for silicon-based solar cell efficiency by producing a cell that was tested to be 26.3-percent efficient—an increase of 0.7 percent ...

Coal

Coal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. It is composed primarily of carbon along with variable quantities of other elements, chiefly sulfur, hydrogen, oxygen and nitrogen.

Coal was formed from layer upon layer of annual plant remains accumulating slowly that were protected from biodegradation by usually acidic covering waters that gave a natural antiseptic effect combating microorganisms and then later mud deposits protecting against oxidization in the widespread shallow seas — mainly during the Carboniferous period — thus trapping atmospheric carbon in the ground in immense peat bogs that eventually were covered over and deeply buried by sediments under which they metamorphosed into coal. In this manner, over time, the chemical and physical properties of the plant remains (believed to mainly have been fern-like species antedating more modern plant and tree species) were changed by geological action to create a solid material.

Coal, a fossil fuel, is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide emissions. Gross carbon dioxide emissions from coal usage are slightly more than those from petroleum and about double the amount from natural gas. Coal is extracted from the ground by mining, either underground or in open pits.

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