|Fig. 1: Coal Fired Power Plant. (Source: Wikimedia Commons)|
The majority of the United States electricity is produced the same way it has been for over 100 years, by steam. Steam is a thermal energy that must be converted into a mechanical energy to be able to produce electricity. Inside of a large power plant there are many working pieces that must work in unison to create an output of electricity. Water first will be turned into steam by a large boiler, where the thermal energy of an outside heat source (coal, oil, nuclear, wood) is causing the water to turn to steam, the steam is then piped throughout the facility where it will become extremely pressurized and meet the Steam Turbine where the thermal energy of the steam will then become mechanical in the spinning of the turbine. Once the pressurized steam causes the turbine to spin, the turbine will have a direct output to a generator where electricity will be produced and distributed from the power plant. 
|Fig. 2:Steam Turbine Generator. (Source: Wikimedia Commons)|
The first modern Steam Turbine was developed in 1884 by Sir Charles Parsons, it created 7.5 kW of electricity. This invention had just revolutionized water travel, and had given us endless possibilities for the future. The Steam Turbine was easy to scale-up so it would be easy to create more electricity from it. 
Turbines now have more than 500 million kW of capacity.  The fundamentals behind Steam Turbines have not changed in the past century. High pressurized steam must spin a turbine. A turbine is made of blades placed in a specific order, and position in order to spin as efficiently as possible. The shape, amount, and arrangement of the blades are what differ from turbine to turbine.
|Fig. 3: Turbine Blades. (Source: Wikimedia Commons)|
There are no direct environmental damages caused by Steam Turbines themselves, but in order to create the steam to turn the Steam Turbines an outside heat source must be provided. For example varying clean natural gas, to solid waste, including all types of coal, wood, wood waste, and agricultural byproducts (sugar cane bagasse, fruit pits and rice hulls), the burning or incinerating of these natural materials releases pollutants into our atmosphere specifically Greenhouse gases. 
There are other ways of creating steam which are more efficient. Steam Turbines are still the most prominent generation of electricity for the United States, so there is constant research being done to decimate the amount of pollution that occurs to spin a turbine. Steam Turbines will not disappear, they will just become more efficient and less pollutant.
© Daniel Starwalt. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 "The Steam Turbine," New York Times, 6 Oct 1902.
 "C. A. Parsons Dead," New York Times, 13 Feb 1931.
 M. L. Wald, "Power Plants Try Burning Wood With Coal to Cut Carbon Emissions, New York Times, 3 Nov 13.