Electricity from Coal

Coal is one of the most affordable and largest domestically produced sources of energy in the United States. It is used to generate a substantial amount of our electricity  about 37%. The challenge? Finding ways to burn it more sustainably. Historically, a wide variety of environmental impacts are associated with generating electricity from coal.

Since 1923, Duke Energy has designed and built our own coal-burning plants. And for more than three decades, we have operated one of the nation’s most efficient fossil generating systems. This means lower operating costs and lower electric rates for our customers.

We are committed to producing and delivering electricity in an environmentally responsible, cost-efficient and reliable manner  and take our responsibility to the environment very seriously. We work diligently to ensure our coal-fired plants comply with all state and federal environmental permits and we regularly monitor our facility operations with robust samplings of water and aquatic life. We also carefully manage coal combustion residuals and potential impacts to air, water and land.

In addition to modernizing our current plants, we are committed to building new ones that are cleaner and more efficient. We also effectively manage air emissions through a diverse mix of fuels to generate electricity. Using the latest emission-reduction technologies at our facilities, our emission levels of nitrogen oxide, sulfur dioxide and carbon dioxide are below the latest industry averages.

In a coal-fired steam station – much like a nuclear station – water is turned into steam, which in turn drives turbine generators to produce electricity. Here’s how the process works.

electricity from coal

1. Heat is created 

Before the coal is burned, it is pulverized to the fineness of talcum powder. It is then mixed with hot air and blown into the firebox of the boiler. Burning in suspension, the coal/air mixture provides the most complete combustion and maximum heat possible.

2. Water turns to steam

Highly purified water, pumped through pipes inside the boiler, is turned into steam by the heat. The steam reaches temperatures of up to 1,000 degrees Fahrenheit and pressures up to 3,500 pounds per square inch, and is piped to the turbine.

3. Steam turns the turbine

The enormous pressure of the steam pushing against a series of giant blades turns the turbine shaft. The turbine shaft is connected to the shaft of the generator, where magnets spin within wire coils to produce electricity.

4. Steam turns back into water

After doing its work in the turbine, the steam is drawn into a large chamber in the basement of the power plant. In this important step, millions of gallons of cool water from a nearby source (such as a river or lake) are pumped through a network of tubes running through the condenser. The cool water in the tubes converts the steam back into water that can be used over and over again in the plant.

The cooling water is returned to its source without any contamination, and the steam water is returned to the boiler to repeat the cycle.
Image

Frequently Asked Questions

  • Coal is our nation's most abundant energy resource. According to the U.S. Energy Administration, the United States is home to the largest recoverable reserves of coal in the world. They estimate that we have enough coal to last several hundred years, based on current consumption levels.

    Because of its relatively low cost and abundance, coal is used to create about half of the electricity generated in the United States. This availability and price stability play an important role in helping Duke Energy support economic growth in the regions it serves with a reliable and affordable supply of electricity.

    But all coal is not created equal. The chemical makeup of coal varies across the country and transportation costs to deliver coal to our power plants are significant drivers of which type of coal is burned at what facility. These factors and others help determine what emissions are produced during combustion and, therefore, what kind of control technologies are needed at each facility.

    Duke Energy has an aggressive fleet modernization program underway that has upgraded the larger coal units with sophisticated air quality controls while we begin retiring older, less efficient coal units.

  • The same rich chemical composition making coal a valuable energy resource also creates byproducts. These include nitrogen oxides and sulfur dioxide. Duke Energy recognizes that continuing to reduce power plant emissions is vital to improving air quality in the United States, and we have made significant improvements in reducing air emissions in the last decade.

    You can learn more about Duke Energy’s commitment to air quality and the environment in our latest Sustainability Report.

    Each coal-fired plant has stringent water quality permits to ensure local waterways are protected. Duke Energy also carefully manages coal combustion residuals, such as fly ash and gypsum, and looks for opportunities to recycle these into other products to reduce the volume landfilled on site.

  • Duke Energy has been using coal to produce electricity in the Carolinas since 1911. Those first coal-fired plants (in Greensboro, N.C., and Greenville, S.C.) only supplemented the company’s use of hydroelectricity. In the 1920s, the growing demand for electricity began to outstrip the availability of hydroelectric generation.

    Duke Energy began a shift to using coal as its primary energy source when Buck Steam Station, in Spencer, N.C., began producing electricity in 1926. With a station capacity of 369 megawatts of electricity, Buck could produce six times more electricity than the company’s largest hydroelectric generating station at the time, Wylie Hydroelectric Station, with a generating capacity of 60 megawatts.


@ Sign up for email