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Chemistry LibreTexts

7.3: Powering the United States

  • Page ID
    204215
  • Learning Objectives

    • Determine if an energy source is renewable or nonrenewable.
    • Realize what sources provide the most power for the United States.
    • Compare and contrast the different types of energy sources.
    • Understand the environmental impacts of energy sources.
    • Compare and calculate the amounts of energy produced from each source (using kilo, mega, and giga units)

    Source of Energy

    Production of electricity can involve either one of two primary energy sources. For example, a country employs nonrenewable sources like natural gas, petroleum, coal, or nuclear energy to supply power to homes and industry. In addition, an area might choose to incorporate renewable energy sources to meet their consumers' needs. Examples of these would include biomass, hydropower, geothermal, wind, and solar energies.

    Figure \(\PageIndex{5}\): Chart illustrating electrical power generation in the United States. Image taken from: https://upload.wikimedia.org/wikiped..._source_v2.png

    As of 2017, the current United States population is approximately 326 million people. Supplying electricity to a population of this size requires many different types of sources. At this time, the majority of electrical output is the result of fossil fuel combustion.

    Table \(\PageIndex{2}\): Energy Conversion: Typical Heat Values of Various Fuels (units are Megajoule/kilogram)
    Firewood (dry) 16 MJ/kg
    Brown coal (lignite) 10 MJ/kg
    Black coal (low quality) 13-23 MJ/kg
    Black coal (hard) 24-30 MJ/kg
    Natural Gas 38 MJ/m3
    Crude Oil 45-46 MJ/kg
    Uranium - in typical reactor 500,000 MJ/kg (of natural U)

    Coal

    In the United States, coal is the cheapest option as an electrical source. The coal industry estimates that there is approximately 260 billion tons of coal yet to be mined in this country. Assuming the daily rate of coal consumption remained constant, the United States should have enough coal reserves to last over 230 years. Annually, The United States produces over one billion tons of coal. This value equates to approximately 12% of the world's supply.

    Figure \(\PageIndex{6}\): Image taken from: https://upload.wikimedia.org/wikiped...the_US.svg.png

    Heavy equipment is utilized to extract coal from the surface of the earth. Surface mining can lead to residual chemicals from the coal entering the water supply and surrounding soils. Many states, namely West Virginia and Pennsylvania, still use coal miners to dig coal from underground reserves. Although regulated, this occupation can be particularly risky with exposure to particulate chemicals that can affect the lung and hearts of workers. In addition, gaseous chemicals inside the mine can combust easily if a spark is present. This could result in trapped workers and fatalities at the site.

    There are 600 coal-burning electric plants in the US delivering \(44.9\%\) of American electricity and producing 2 billion tons of \(\ce{CO_2}\) annually, accounting for \(40\%\) of U.S. \(\ce{CO_2}\) emissions and \(10\%\) of global emissions. Coal-burning facilities also produce \(64\%\) of the sulfur dioxide emissions, \(26\%\) of the nitrous oxide emissions, and \(33\%\) of mercury emissions. Sulfur dioxide and nitrous oxide combustion are precursors to acid rain and industrial and photochemical smog. Mercury, a heavy metal toxin, affects the neurological system and can cause behavior and intellectual disorders. Incomplete combustion of carbon can produce particulate matter. These carbon-based solids gather in the atmosphere and make visibility difficult.

    Trace amounts of radio nuclides can be detected in coal.  Uranium and thorium isotopes that are present will eventually decay to other species.  When burned, these substances become airborne and release their decay products.  All chemicals and matter resulting from the combustion process can cause heart, lung, and immunity disorders. In addition, high combustion areas can affect the average lifespan of individuals and species living in these areas.

    Figure \(\PageIndex{7}\): Two pictures of Beijing in 2005. The picture on the left shows the city after two days of rain. The picture on the right shows smog gathering in the atmosphere. The image is taken from https://upload.wikimedia.org/wikiped...ugust_2005.png

    Coal can be cleaned to remove some impurities (like sulfur-based species), but there is no such thing as "clean" coal. Industries that burn coal can install scrubbers in their smokestacks to grab many pollutants before their enter the atmosphere. In the United States, the Environmental Protection Agency (EPA) regulates all pollutants resulting from the combustion process except for carbon dioxide.

    Natural Gas

    Natural gas combustion does not produce as many types of byproducts. It is a much cleaner fuel to burn and there would be less environmental and health problems related to this fuel choice. Greenhouse gases are still produced when this fuel is burned. Unfortunately, natural gas exists deep within the ground and can be difficult to extract.

    Figure \(\PageIndex{8}\): Natural gas reserves in the United States. Image is taken from https://c1.staticflickr.com/9/8743/1...08652510_z.jpg

    Hydroelectric

    Hydroelectric sources provide almost 7% of the United State's electricity. To use this type of energy, a large body of water needs to be present within the area. A river is intentionally dammed to create a large water supply. With monitored releases, the dammed water is allowed to fall to a lower altitude. This motion will turn a turbine which will produce energy. Unlike fossil fuel combustion, hydroelectric sources do not release toxins into the atmosphere. As a result, this method of energy production does not contribute to global warming, acid rain, or smog production. Some disadvantages of hydroelectric power include disruption of an aquatic ecosystem. Construction of hydroelectric facilities requires large areas of land that could involve uprooting and affecting human and animal populations. human population. Lastly, altering land geology can cause severe flooding.

    The largest hydroelectric facility in the United State is located in Washington State along the Columbia River. Grand Coulee Dam produces over 6800 Megawatts of electrical energy for this region of the country. At this time, there are over 1600 hydroelectric plants in the United States.

    Figure \(\PageIndex{9}\): Arial view of Grand Coulee Dam. The image is taken from https://upload.wikimedia.org/wikiped...Dam_aerial.jpg

    Solar and Wind Power

    In recent years, the use of wind and solar sources has increased in this country. Both of these types of energy require large plots of land for their structures. In addition, both the sun and wind need to be present to generate energy. Wind and solar energy can be stored for days for days in which the climate does not produce adequate amounts of either. With wind energy, there is some concern about how the structures appear and affect wildlife. These devices can also be very noisy. At this time, Texas leads the country in the production of wind energy.

    Research has focused on making components of solar panels less toxic and more affordable for the average consumer. Many utility companies offer incentives for residents to install solar panels. In addition, some utility companies will buy back excess solar wattage from its own consumers. The state of California leads the country in the production of solar energy. The Ivanapah Solar Farm in the Mohave Desert generates over 390 megawatts of energy per year.

    Figure \(\PageIndex{10}\): Ivanapah is the largest solar farm in the United States in California.The imagee is taken from https://upload.wikimedia.org/wikiped...ity_Online.jpg

    Recently, Furman University installed its own solar farm. Click on this link to read more about how this university is using renewable energy to cut down on carbon emissions.

    Nuclear Reactors

    There are over thirty countries that use nuclear power to generate electricity. Commercial nuclear reactors can be found in North and South America, Europe, Africa, and Asia. The United States has the most reactors of any other countries. There are around ninety-nine reactors in the United States that provide around twenty percent of the electrical energy in the United States. Other countries, like France, employ around sixty nuclear reactors to produce 80% of their electrical power.

    Table \(\PageIndex{1}\): Nuclear Share of Electricity Generation in 2016. Data from International Atomic Energy Agency
    Country Number of Operated Reactors Total Net Electrical Capacity [MW]Nuclear Electricity Supplied [GW.h]Nuclear Share
    FRANCE 58 63130 386452.88 72.3
    SLOVAKIA 4 1814 13733.35 54.1
    UKRAINE 15 13107 76077.79 52.3
    BELGIUM 7 5913 41430.45 51.7
    HUNGARY 4 1889 15183.01 51.3
    SWEDEN 10 9740 60647.40 40.0
    SLOVENIA 1 688 5431.27 35.2
    BULGARIA 2 1926 15083.45 35.0
    SWITZERLAND 5 3333 20303.12 34.4
    FINLAND 4 2764 22280.10 33.7
    ARMENIA 1 375 2194.85 31.4
    KOREA, REPUBLIC OF 25 23077 154306.65 30.3
    CZECH REPUBLIC 6 3930 22729.87 29.4
    SPAIN 7 7121 56102.44 21.4
    UNITED KINGDOM 15 8918 65148.98 20.4
    UNITED STATES OF AMERICA 100 100351 804872.94 19.7
    ROMANIA 2 1300 10388.20 17.1
    RUSSIA 36 26496 184054.09 17.1
    CANADA 19 13554 95650.19 15.6
    GERMANY 8 10799 80069.61 13.1
    SOUTH AFRICA 2 1860 15209.47 6.6
    MEXICO 2 1552 10272.29 6.2
    ARGENTINA 3 1632 7677.36 5.6
    PAKISTAN 4 1005 5438.90 4.4
    CHINA 36 31384 197829.04 3.6
    INDIA 22 6240 35006.83 3.4
    NETHERLANDS 1 482 3749.81 3.4
    BRAZIL 2 1884 14970.46 2.9
    JAPAN 43 40290 17537.14 2.2
    IRAN 1 915 5923.97 2.1

    Today's nuclear power plants use fission reactions to generate energy for electrical production. One kilogram of U-235 can supply over 2.4 x 107 kilowatt-hours (kWh) of energy. In contrast, one kilogram of coal can only produce 8 kilowatt-hours of energy. Also, nuclear does not contribute to the problems of acid rain, smog, or greenhouse gas production.

    Nuclear and coal power plants can appear similar to most people. Both of these types of facilities have large cooling towers that release excess steam energy into the atmosphere. Nuclear power plants will have small, round, and dome-like structures to house the nuclear reactors. In contrast, coal-fired plants will have slender chimney stacks that tower above or at the rounder cooling towers.

    Vogtle_NPP.jpg
    Figure \(\PageIndex{11}\): (left) View of Vogtle Nuclear Power Plant (Units 1 and 2) in Augusta, Georgia produces approximately 2.3 gigawatts of power a year. (right) The Bruce Mansfield Coal Fire Plant in Shipping Port, Pennsylvania produces 2.4 gigawatts of energy a year. Images are taken from https://en.wikipedia.org/wiki/Vogtle...Vogtle_NPP.jpg and https://3.bp.blogspot.com/-WycgHj-jt...eMansfield.jpg

    Sources