Clean Coal?

Created June 19, 2024 by Dr. Emily Harris


Clean Coal?

https://www.pbslearningmedia.org/resource/ayv09.sci.life.eco.cleancoal/clean-coal/

This video (link above) and accompanying essay examine ways to reduce the environmental impact of burning coal. Two technologies are discussed: turning solid coal into a clean-burning fuel gas (syngas), and capture and storage of CO2.

Video length: 5:03 min.

The Content may include certain ancillary educational materials, such as lesson plans, background essays, student activity sheets, and other printouts. ("Ancillary Materials"). You may modify, alter, and revise certain designated Ancillary Materials to meet specific instructional needs, provided that the following statement is prominently displayed on all such revised Ancillary Materials, in addition to any other proprietary notices, and with the understanding that WGBH and/or PBS, or any other indicated copyright holder shall continue to own the Ancillary Materials: "Revised with the permission of WGBH Educational Foundation ('WGBH') and/or Public Broadcasting Service ('PBS') (or other copyright holder indicated on the page). WGBH and/or PBS (or other indicated copyright holder) is not responsible for the content or accuracy of the revision.")

Discussion Questions

  • How much coal do U.S. consumers use in one year? What percentage of electricity consumed in the U.S. comes from coal?
  • What is the benefit of mixing coal with oxygen to create "clean" coal?
  • What are the main differences between clean coal technology and traditional coal-fired power generation?
  • What is meant by the term "carbon capture"? 
  • What are some of the obstacles and dangers associated with carbon capture and storage? Can you identify some possible solutions?

Teaching Tips

About the Science

  • The video gives an overview of coal electricity generation, clean coal technology, and sequestering carbon dioxide.
  • Clean coal is an umbrella term used to describe technologies that may reduce CO2 emissions (e.g. sequestration, coal gasification, scrubbers).
  • Provides statistics for overall annual U.S. coal consumption as well as average household usage, and then explains the need for developing a cleaner way to convert coal into electricity. [Note that coal consumption has been reduced nationwide since this video was produced.]
  • While promising, most applications of clean coal technology are still not ready for implementation.
  • Comments from expert scientist: It is a great idea to talk about the pros and cons of the coal industry and possible changes to technology both in terms of combustion technology and carbon capture. The Frontline documentary is a good place to start but I do not think the "background essay" is adequate.

About the Pedagogy

  • The video is accompanied by a background essay and discussion questions. 
  • It could be used as a whole class assignment to introduce coal to the students as a nonrenewable resource. I would recommend using the background essay as a warm-up or bell-ringer prior to viewing the video.
  •  If your school uses a one-to-one technology initiative it could be pushed out to your students through google classroom and students can watch the video and submit the discussion questions electronically.
  • This activity would also make a great station activity if you are covering multiple types of resources as a lesson or review before an assessment.
  • Please edit the discussion questions to more closely align with your lesson if needed. 

Technical Details/Ease of Use

  • The video has closed-captioned text that can be turned on/off.

Extension Activity

Students who finish early can be encouraged to visit the following website for further information on resources. 

The U.S. Department of Energy's Carbon Sequestration program website can be accessed here: 

http://fossil.energy.gov/programs/sequestration/index.html

Background Reading (essay)

Coal is the energy source used to produce most of the electricity in this country. When power-generating plants burn coal, their smokestacks release particulates and gases into the atmosphere. These emissions include carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and mercury, by-products of combustion that contribute to acid rain, smog, air and water pollution, asthma and other respiratory diseases, and the greenhouse effect. Clean coal technology is a new generation of energy-generating processes that seek to reduce coal's negative environmental impact. It comprises multiple strategies to clean coal prior to combustion and reduce hazardous emissions. Some of these strategies include coal preparation, pollutant removal, carbon capture and storage, and gasification.

The coal industry has found several ways to prepare coal before it is burned. For example, coal washing removes unwanted minerals by mixing crushed coal with a liquid and allowing impurities to separate and settle. When coal enters the combustion chamber, the focus turns to remove pollutants so they do not leave the plant. One removal device, called a "scrubber," is installed inside a smokestack, where it captures exhaust gases, including sulfur dioxide. Carbon capture and storage is a carbon dioxide management strategy that has not yet been put into practice. In theory, it involves capturing CO2 produced when coal burns and then storing it where it cannot later escape into the environment or pollute drinking water, such as in deep underground saltwater formations. While various capture and storage solutions have been proposed and tested on a very limited basis, they all have their drawbacks, not the least of which is the cost of implementation.

Coal gasification represents a promising new way to convert coal into energy. Gasification exposes coal to steam and controlled amounts of air or oxygen at a high temperature and under great pressure. Rather than burning the coal, these conditions break it up into its basic chemical components. These components then initiate chemical reactions that typically produce a mixture of carbon monoxide (CO), hydrogen, and other compounds. When carbon dioxide and mineral components are separated from the CO and hydrogen, what remains is "syngas" fuel, a clean-burning fuel that can generate electricity and produce steam to power a steam turbine.

Apart from CO2, which would have to be safely captured and stored for this process to be truly clean and safe, most of the mineral remains from the coal end up either as an inert "slag" that is safe to dispose of or in a solid or liquid form that has commercial value and can be sold. As attractive as this seems in concept, gasification technology has yet to be widely implemented in power-generating facilities. The cost of installing gasification equipment in existing plants across the country—or building new plants from scratch—and the sheer scale of CO2 that would need to be safely stored remain two of the biggest obstacles.

The U.S. has the world's largest known coal reserves—enough coal to last approximately 225 years at today's level of use. With coal likely to remain one of the nation's lowest-cost electric power sources for the foreseeable future, some argue that exploring technological solutions that will reduce its environmental impact seems appropriate. But others argue that because all fossil fuels are finite resources that will one day be used up, it makes even more sense to concentrate on developing renewable energy sources such as wind, solar, and geothermal power, and reducing our energy consumption.

References

Remixed from the original source

https://goopenva.org/courses/clean-coal/view

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