The largest coal-burning power plant in the U.S. is the Robert W. Scherer Power Plant, which is operated and maintained by Georgia Power, the largest subsidiary of Southern Company. The plant is located in Juliette Georgia, just north of Macon, approximately 70 miles south of Atlanta and extends 12,000 acres in Monroe Country near Forsyth. The power plant is named after the former chairman and chief executive officer of Georgia Power, Robert W. Scherer.

The plant is capable of delivering 3,600 MW of power output, enough energy to power 1.5 million homes, five times the amount of homes in the surrounding eight counties according to Georgia Power.

Power Generation

The overall power generation of the Scherer Power plant is divided into four self-contained units capable of producing 880 MW of electricity. The operation of this power plant is based on the same principles as other fossil-fueled power plants.

Pulverized coal is burned in a boiler generating heat that is transferred to a series of high-pressure water pipes. The heat is then used to increase the temperature of the water inside these pipes far beyond the boiling point to produce steam at an impressive rate of 5.8 million pounds per hour. The high-pressure steam is then passed through a series of turbine stages that are connected by a common shaft. As the steam flows through the blades of each turbine stage, total pressure and total temperature drops as energy from the fluid is used to produce work on the blades, this work generates a change in the angular momentum of the turbine and by the principle of conservation of angular momentum, the rate of change of this is equal to the torque produced. The torque produced is then transferred to a generator through the same shaft at a certain angular velocity, this gives the power output generated. The turbine shaft consequently spins an electrical generator converting this
torque to electrical power. The electricity generated at each unit is conducted to a power transformer in a adjacent substation which increases the voltage. This high voltageelectricity is fed into transmission lines for it subsequent distribution to the surrounding counties and throughout the state.

The low pressure, low temperature and thus, low exergetic steam at the turbine exhaust is condensed to liquid through the condenser to be used again in the steam-generation process. The steam is converted to water instead of compressing it again in steam form because rising the pressure of a liquid requires less work than for a gas. The condensed steam is then pumped back into the boiler to close the cycle.

The cooling water used to decrease the temperature of the steam coming from the turbine exhaust is drawn from Lake Juliette and pumped through the condenser. The cooling water passes through the condenser and leaves with higher enthalpy. It then goes to four cooling towers, each measuring 530 feet tall and 400 feet in diameter at the base.

Water flows through the cooling towers at a rate of 268,000 gallons per minute. Through this process, 8000 gallons of water is lost due to evaporation. This lost water lost water is made up from Lake Juliette. The rate at which water is extracted from Lake Juliette is higher than the rate at which water is naturally fed into the lake by the Run Creek stream. To compensate this, an additional pumping station pumps water from the nearby Ocmulgee River to Lake Juliette. This process is done only when the Ocmulgee river stream is high enough to keep downstream users unaffected.

Fuel Consumption and Supply

Each of the four boilers in Plant Scherer is capable of burning 322 tons of coal per hour reaching temperatures of 1537 degrees Celsius. In conjunction, the boilers burn the enor- mous amount of 1,288 of tons per hour, which becomes 11 million tons per year. The continuous coal supply to the boilers is achieved by means of 100-car trains coming from the Powder River Basin, located 1,800 miles away in Wyoming. Thirty six two-mile long trains transport the necessary fuel during the ten-day trip between the Powder River Basin and the Scherer Plant. At full operation, five of these trains unload daily using an air-dump system which delivers the coal to the Plant Scherer storage area by opening a set of doors at the bottom of each car without the need of stopping the train. According to Georgia Power, the plant system is capable of unloading a 100-car train in half-hour.

Emissions

The Scherer Plant is catalogued as the single largest point-source of CO2 in the U.S. pro-ducing 17.5 million tons of carbon dioxide per year. This value has been reducing over the years following more strict environmental regulations.
Figure 1 shows the variation of the CO2e emissions over the span of six (6) years. Data was obtained from the Environmental Protection Agency (EPA) ”2016 Greenhouse Gas Emissions from Large Facilities” Report. As it is evident from the chart, the yearly CO2e emitted by the power plant decreased by 26% in 2016 relative to 2010. Although this reduction can be considered a huge milestone, Plant Scherer still holds the first place in CO2

emissions in the U.S. From the emitted pollutants, CO2 represents the major contributor of greenhouse gases emitted by Scherer plant in comparison to other pollutants like NOx, SO2, and CH4 by two orders of magnitude (i.e. 200 times NOx generated and 350 times the generated CH4), this can be observed in Figure 2 which displays the yearly emissions in metric tons of different pollutants in a logarithmic scale. Table 1 outlines the tons of pollutants emitted by Scherer Plant in a yearly basis.

Summary

 

References

[1] ”Electricity in the United States.” Electricity in the United States – Energy Explained,
Your Guide To Understanding Energy. Energy Information Administration
[2] Robert W Scherer Power Plant. Georgia: Georgia Power. Retrieved 11 April 2013.
[3] Tarantola, Andrew. ”America’s Largest Coal Power Plant Burns 11 Million Tons of
Bituminous a Year.” Gizmodo, 18 Oct. 2011.
[4] ”Explore Greenhouse Gas (GHG) Emissions from Large Facilities.” EPA Facility Level
GHG Emissions Data, go.usa.gov/xQCeq.