Embed Size (px)
Citation preview
The Coal, Hard Facts
By: Anna Duban Sources of Energy for the Future10/8/13
Background
• Coal began formation in Carboniferous Period, 290-360 million years ago
• Swamp plant life stored energy from photosynthesis. This plant energy was trapped for years under heat and pressure of dirt and water above, thereby forming coal.
Properties• Sedimentary rock, blackish-brown in color• Composed of carbon, hydrogen, nitrogen, oxygen,
and sulfur • Combustible• Non-renewable (cannot be replenished in a short
period of time).
Coalification & Ranking
• Coalification- The degree of change as coal matures from peat (decayed vegetation) to anthracite (fully mature coal). The degree of maturity affects the coal’s physical and chemical properties and in turn its energy potential.
• Coal is then ranked according to its quality, dependent upon:– original vegetation type– depth underground– temperature and pressure– length of time allowed to matureHigher ranked coal has greater concentration of Carbon & higher
energy content, while lower has greater moisture content.
4 Ranks (least to greatest): lignite, sub- bituminous, bituminous, and anthracite.
Why is coal so important?• Advantages:
1. Relatively inexpensive, stable
2. Most abundant fossil fuel in the U.S…
USA Energy Reserves – Billion barrels of oil equivalent (Source: Bloomberg New Energy Finance, 2013)
…and worldwide
There are recoverable reserves of coal in almost 80 countries.
Fossil fuels reserves-to-production ratios at the end of 2010:
Source: BP Statistical Review of World Energy 2011
Yet…
• Global coal reserves differ from actual coal resources. – Reserves include coal that is economically recoverable
at a given time, taking into account mining costs and available technology.
– Resources include all potential coal deposits.
Therefore:
“Coal resources are around 17 times larger than coal reserves and account for over two thirds of all non-renewable energy
sources including…oil and gas.” - World Coal Association
Globally Dependent on Coal for Electricity
-Most coal is used domestically, with only 15% of total global production imported/exported
• In countries and regions such as Europe, China, and India, where coal reserves are higher than those of any other energy source, coal is utilized domestically for the majority of energy needs.
• Coal contributes to 41% of world’s electricity
- In the U.S., which has the largest coal reserves in the world, over 92% of produced coal is used to generate 37% of total net electricity.
1 lb of coal = power for 10, 100 watt bulbs
for 1 hour
Incremental world primary energy demand by fuel, 2000-2010 (Mtoe)
Source: IEA World Energy Outlook 2011
Other uses of Coal
Industry• The elements methanol and ethylene, separated from coal,
contribute to the formation of plastics, tar, synthetic fibers, fertilizers, and medicine.
• Concrete and Paper
• Steel: 68% of the world’s steel is produced from coal.
• Small portion for heating commercial buildings, military facilities, homes
Disadvantages• Environmental
- Emissions: - SO2 acid rain, respiratory illness
- NOx smog, respiratory illness
- Particulates smog, haze, respiratory illness, lung disease
- CO2 Greenhouse gas
- HCl Mining, cleaning, transporting coal releases methane
(vented for safety reasons).
2,249 lbs/Mwh of CO
2
13 lb/Mwh of SO
2
6 lb/Mwh
of NOx
Negative Impacts on Water - Mercury & heavy metals neurological and
developmental damage; low air concentration but deadly upon contaminating water; fish humans
- Fly & Bottom Ash- storage in landfills and power plants leak into groundwater
- large quantities of water used to remove coal impurities through steaming and cooling
- rainwater causes runoff of arsenic and lead from coal piles
- 70 % of coal comes from surface mines, which are utilized to remove mountain tops and deposit soil and rock in valleys. This leads to the covering of streams.
Presently…•Average efficiency of coal-fired power plants is 34%
“Upgrading the world’s older (>30 years old) and smaller(<250 MW) coal power plants with newer, larger coalplants would reduce global greenhouse gas emissions
by 5.5%”- World Coal Association
What is being utilized to increase coal efficiency and reduce harmful emissions?
• Fluidized Bed Combustion• Supercritical & Ultra supercritical Boilers/ Integrated
Gasification Combined Cycle• CCS- Carbon Capture & Sequestration• Flue Gas Desulphurization “scrubbing”- removes SO2 before
it leaves smokestack• Electrostatic Precipitators- attract particles through an
electric field
- Fluidized Bed Combustion - reduces SOx and NOx emissions by 90% - Coal is burned in a reactor, and gas is fed through a bed to maintain the turbulence of the fuel; improves heat transfer and waste recovery; allows overall mechanism to operate at lower temperatures
Integrated Gasification Combined Cycle (IGCC)/ Ultra Supercritical Technology
-A gasifier converts coal to syngas, which drives a turbine and generates electricity
- Coal is combined with oxygen and steam to produce syngas, comprised of H2 and CO; gas is cleaned to remove impurities (sulfur); resulting gas drives turbine
Waste heat from first turbine is recovered to produce steam and drive a second turbine= combined cycle system
Result: Clean- burning hydrogen for modern cars!
Ultra supercritical is under development and could potentially increase efficiency to 50%
Efficiencies of Boilers vs. CO2 Emissions
Carbon Capture & Sequestration (CCS)
Capturing CO2 that would otherwise be emitted into the atmosphere and injecting it deep underground
• Pre-combustion CCS
• Post-Combustion CCS
• Oxyfuel
Oxyfuel and post-combustion capabilities can be added to current power plants.
Higher operation costs and lower efficiencies than traditional plants; 10-40% more energy is required to separate, capture, and sequester the CO2.
$1 billion price tag.32 million tons of CO2 stored worldwide
http://www.youtube.com/watch?v=ROEFaHKVmSs
Schematic Diagram of CO2- Enhanced Oil Recovery
Contribution of different power sector technologies to reductions in CO2 emissions
Source: IEA Energy Technology Perspectives 2010
Final Thoughts-Coal use will inevitably increase by 60% -90% of demand from developing countries
Although it is environmentally harmful, we all depend on coal today for 1/3 of our energy usage. Would you like to have your cell phone or laptop always 1/3 below fully-charged?
• Obviously, coal cannot be eradicated without drastically altering our present lifestyle, and it is a significant contributor to many materials used today (cement, steel, aluminum), not to mention other green energy such as hydropower & wind energy.
• Therefore, coal is here to stay, but it is up to the collaboration between our governments and informed citizens to work towards supporting clean coal technology.
Works Consulted
Cleancoalusa.org. American Coalition for Clean Coal Electricity, 2013. Web. 3 Oct. 2013.
“Coal.”Epa.gov. U.S. Environmental Protection Agency, 25 Sept. 2013. Web. 2 Oct. 2013.
“Coal.” Iea.org. International Energy Agency, 2013. Web. 2 Oct. 2013.
U.S. Energy Information Association. Eia.gov. U.S. Department of Energy, 2013. Web. 1
Oct. 2013.
Worldcoal.org. World Coal Association, 2013. Web. 4 Oct. 2013.
