Clean Coal Technology

1
Clean Coal Technology

• Sam Harris

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Overview

• Burning and current use of Coal
• Clean coal technologies
• Is clean coal actually clean?
• The future of clean coal and politics
• Summary

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Types of Coal

• Lignite (brown coal) - 25 to 35 carbon, around
  70 when dry
• Subbituminous 35 to 45 carbon
• Bituminous 45 to 86 carbon
• Anthracite (black coal) 86 to 98 carbon

4
Coal and Electricity

• There are about 600 U.S. coal plants.
• Coal generates 54 of our electricity
• There are 249 projected coal power plants to be
  built between 1999 and 2009, another 483 by 2019,
  and another 710 by 2030

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Burning of Coal

• In 2002 fossil fuels released 23 billion tons of
  CO2 into the atmosphere
• of the 23 billion tons 41 was from coal
• Burn 1 ton of black coal and you get 4 tons of
  CO2
• Anthracite releases 67 more CO2 than methane and
  brown coal releases 130 more CO2 emissions than
  methane
• Coal also contains trace amounts of sulfur and
  Nitrogen that when burned can cause environmental
  issues

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The Effects of Sulfur Dioxide from Coal

• In the 1960s trees as well as aquatic life in
  lakes were dying
• Due to acid rain from sulfur dioxide emissions
  from burning of coal
• Created scrubbers to clean the coal
• The sulphates had reflected light back into space
  keeping the earth cooler
• Once the sulphates were gone the temperature of
  the earth rose

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Why is coal still used?

• Cheapest for power stations relative to the
  amount of heat it generates when burnt

http//www.economist.com/business/displaystory.cfm
?story_id10145492
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How does a coal power plant work?
http//www.cs.wright.edu/egr190/Alternative20ene
rgy/coalart.gif
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http//upload.wikimedia.org/wikipedia/commons/d/d6
/Coal_power_plant_Datteln_2_Crop1.png
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So what is clean coal?

• It is actually a vague term that does not
  describe any one process
• Can include the removal of nitrogen and sulfur
  that create acid rain
• Can include the storage of CO2
• The term clean coal is abused

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Clean Coal Technologies

• Coal washing
• Wet scrubbers
• Low NOx burners
• Electrostatic precipitators
• Gasification
• Carbon Capture and Storage (CCS)
• Fuel Cells
• Magnetohydrodynamics

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Coal Washing

• Grinding coal into pieces and passing it through
  gravity filtration
• One technique Putting coal into a barrel with a
  liquid with a specific density where the coal
  floats and the impurities sink

http//news.bbc.co.uk/1/hi/sci/tech/4468076.stm
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Wet Scrubbers

• When the emissions reach the flue of the furnace
  limestone and water are sprayed
• The SO2 reacts with the calcium carbonate
  (limestone) to form gypsum (calcium sulfate)
• The gypsum is collected and used for construction
• 99 effective

http//news.bbc.co.uk/1/hi/sci/tech/4468076.stm
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Nitrogen Oxides (NOx)

• Use of
• First stage combustion occurs in an oxygen
  deficient zone where NOx is usually formed
• Second Stage hydrocarbons are formed which react
  with the already formed NOx
• Third Stage - internal air staging completes the
  combustion but may result in additional NOx
  formation, which can be minimized by completing
  the combustion in an air lean environment

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Electrostatic Precipitators (Particle emissions)

• Creates an electrical field that removes unwanted
  charged particles
• 99 effective

http//news.bbc.co.uk/1/hi/sci/tech/4468076.stm
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Gasification

• Coal is reacted with oxygen and steam to form a
  syngas (mostly hydrogen and part CO)
• Syngas is cleaned and burned which then turns a
  turbine
• As gas cools it heats water, which turns another
  turbine

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http//news.bbc.co.uk/1/hi/sci/tech/4468076.stm
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Gasification (continued)

• Gasification is seen as part of zero-emission
  system
• Improved SO2 and NOx emissions (already low)
• Unproven on widespread scale
• Up to 45 efficient
• Currently only demonstration units exist on a
  trial basis
• Right now syngas being cleaned at low
  temperatures. In the future will be cleaned at
  higher temperatures, increasing efficiency
• Costly, but current coal power plants can be
  modified

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Carbon Capture and Storage (CCS)

• Capturing CO2 and storing it underground
  (geosequestration)

http//news.bbc.co.uk/1/hi/sci/tech/4468076.stm
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CSS (continued)

• There are many problems with CSS
• CO2 is hard to capture
• Once captured it needs to liquified which takes
  20 of the energy yielded from the coal
• Where the CO2 is stored needs to be monitored
• There are only so many places that are good for
  mass storage
• Transportation could be costly

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Fuel Cells

• Allow hydrogen from coal to react with oxygen to
  produce electricity electrochemically
• Still in early development
• Costly

http//www.australiancoal.com.au/cleantech.htmfue
lcell
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Magnetohydrodynamics

• Coal is burned to form an extremely hot gas or
  plasma
• Given electrical charge by adding a compound like
  potassium salt
• The charged gas or plasma is passed through a
  magnetic field and electricity is produced
• The heat from the combustion gases is used to
  turn a steam turbine too
• Still in development
• Costly

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So is clean coal really clean?

• Unfortunately there is no way to make coal clean
• Processes like gasification can make coal burning
  more efficient, but it still burns plenty of CO2
• CO2 can be stored underground using CSS, but that
  could lead to more problems in the future
• Best solution STOP USING COAL!!!!

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Clean Coal and Politics

• Barack Obama has said that he would develop five
  first-of-their-kind coal-fired plants with CCS
  technology
• Wants to spend 150 billion over 10 years for
  renewable energy sources such as wind, solar,
  biofuels, plug-in hybrids and clean-coal
  technology
• Wants to cut carbon-dioxide emissions from power
  plants, oil companies and other industries.
• But we're talking politics.

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Summary

• Coal is very inefficient and is a huge cause of
  global warming, but cheap
• Clean coal is a term that describes many
  different technologies
• Clean coal is by no means clean
• CSS will be put in use in the near future, which
  may or may not be a good thing

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Works Cited

• "Clean Coal Technologies - Examples." Australian
  Coal Association. Australian
• Clean coal technology How it works." BBC News.
  28 Nov. 2005. BBC News. 6
• "Coal power Still going strong." The Economist 15
  Nov. 2007.
• Davidson, Paul. "Major issues await Obama." USA
  Today 6 Nov. 2008.
• Flannery T. 2005. The Weather Makers How Man is
  Changing the Climate and
• "IEA Clean Coal Centre." IEA Clean Coal Centre.
  IEA Clean Coal Centre. 6 Nov.
• Schirber, Michael. "What Exactly Is Clean Coal?"
  Foxnews.com. 3 Nov. 2008. Fox