Clean Coal TechnologySam Harris

http://i.treehugger.com/images/2007/5/24/coal%20chunks.jpg

Overview

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

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

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

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

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

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_id=10145492

How does a coal power plant work?

http://www.cs.wright.edu/~egr190/Alternative%20energy/coalart.gif

http://upload.wikimedia.org/wikipedia/commons/d/d6/Coal_power_plant_Datteln_2_Crop1.png

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

“Clean” Coal Technologies

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

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

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% effectivehttp://news.bbc.co.uk/1/hi/sci/tech/4468076.stm

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

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

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

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

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

Carbon Capture and Storage (CCS)

● Capturing CO2 and storing it underground (geosequestration)

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

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

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.htm#fuelcell

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

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!!!!

“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.

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

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