|  | Public Health Safety | Environmental Health

What Are the Steps That Its Takes to Turn Coal Into Energy?

The United States has more coal than any other nation--some estimates place the amount at nearly 300 billion tons, enough for the next 240 years based on current usage. In the search for clean energy, coal has gotten a black eye. But new technologies are changing the way coal is processed into energy. Innovations in energy conversion aim for cleaner fuel as much as for lower costs.

  1. Coal to Synthetic Gas

    • Boston and other “modern” cities in the 1800s fueled romantic gaslight in streetlamps and homes by burning coal--emitting dirty clouds of pollution in the process. Today, the conversion of coal to synthetic gas is accomplished with increasingly sophisticated methods to minimize the release of carbon dioxide. Catalytic gasification mixes coal and a solid catalyst with steam in a narrow cylinder. The mix is pressurized, and the result is hydrogen and carbon monoxide (synthetic gas) with some carbon dioxide. Separation and safe disposal of the carbon dioxide are the current challenges in the production of cheap, clean synthetic gas from coal. This process can be taken one step further to make liquid fuel--synthetic petroleum.

    Coal to Liquids

    • Diesel and jet fuel are the end products of one coal conversion. A process called coal-to-liquids (CTLs) converts coal to a synthetic gas and then to a combustible liquid. CTLs are cleaner than regular fossil fuels--liquefied coal emits far fewer particles and hydrocarbons (55-60 percent less than fossil fuel), decreasing air pollution and smog. The 2009 cost of CTLs was $45 a barrel, a price that could remain stable and not fluctuate wildly as the world market for fossil fuels can. CTL diesel today costs about $1.24 a gallon before taxes. To make liquid fuel from coal, begin by putting the coal in a gasifier, a distiller that forces the coal to react to air, oxygen, or steam. This process forms a synthetic gas called "syngas," which then travels to another reactor chamber. The syngas combines with cobalt, iron, or another solid catalyst in the second chamber, turning the mix into hydrocarbons. When this mixture cools, it becomes liquid fuel.

    Coal to Electricity

    • Coal is most commonly used to produce electricity. The solid coal is ground into a powder and mixed with hot air. Then it is burned in a furnace to heat water, resulting in steam. The steam from this boiler causes the blades of a turbine to turn, powering a generator. Magnets inside a copper coil in the generator complete the transformation of coal into electrical energy. The “used” steam is captured in a condenser, which returns it to the cycle and continues the generation of electricity. The U.S. Department of Energy is currently working on an alternate method to use coal gasification to produce electricity in an emissions-free power plant.

Environmental Health - Related Articles