Fossil Fuels: Coal - Types, Extraction, and Clean Coal Technology

1. Energy Part 2 – Fossil Fuels

2. Coal • Types: • Lignite – soft, lowest heat content • Bituminous – soft, high sulfur content, 50% of US reserves • Anthracite – hard, high heat content, low sulfur, 2% of US reserves

3. Coal • Supplies 25% of world energy • China and the US consuming the most • 87% of coal in the US is used to produce electricity • Clean Air Act: requires a 90% reduction of sulfur-containing gases from coal combustion

4. Coal is dead plants not dead dinosaurs

5. Extraction and Purification of Coal • Extraction methods: • Surface mining • Underground mining • Purification • Removes foreign materials • Screens for size • Crushes and washes coal to remove contaminants • May convert coal to liquid through clean coal technologies

6. Clean Coal • Process to reduce the negative impacts on the environment from burning coal • Washing coal to remove minerals and impurities • Capturing sulfur and carbon dioxide from flue gases • Others: • using natural gas • Microbial fuel cells charged with biomass or sewage

7. Steps of Clean Coal Technology • Oxygen is introduced to burn coal completely • Coal is pulverized to burn more completely • Ash is removed using electrostatic precipitators • Steam is condensed and returned to the boiler • CO2 is removed using live and then sequestered

8. Steps of Clean Coal Technology

9. Coal Reserves and Global Demand • Coal is the world’s largest sources of fuel used to produce electricity • US has largest reserve • China is largest producer • Reserves expected to last about 300 years

10. Pros Abundant, known reserves (300 years worth) Unidentified reserves (1,000 years worth) US reserves will last 300 years Relatively high net-energy yield US government subsidies keep prices low Stable, non-explosive; not harmful if spilled Cons Extraction methods disrupt environment and lead to pollution Underground mining is dangerous and unhealthy Up to 20% ends up as fly ash, boiler slag, sludge Releases mercury, sulfur, and radioactive particles into the air 35% of CO2 pollution 30% of NOx pollution Expensive to process and transport Pollution causes global warming Pollution controls are expensive Coal

11. Energy Crisis • Shortages of fuel in the world market • Mainly petroleum • OPEC (Organization of Petroleum Exporting Countries) • Control world Petroleum supply • OPEC decrease production to increase cost of oil or increase production to decrease the cost of oil • As prices for oil increase tar sands and oil shale become profitable sources of oil

12. Sorry, your car is not running on dead dinosaurs • Petrochemicals (derived from oil) are used for manufacture of paint, drugs, plastics, etc. • Natural Gas often found with oil deposits • Also with coral beds, shale, gas hydrates, and tight sands

13. Oil Extraction and Purification • Extraction: • Drill down to the oil, usually trapped in porous sandstone • Oil under pressure flows out naturally • Low pressure wells must be pumped • Purification: • Crude oil is sent to a refinery and “cracked” • Cracking = separating the components by boiling point • Produces: gasoline, heating oil, diesel oil, asphalt, etc.

14. Natural Gas Extraction and Purification • Extraction: • Usually present below non porous areas and above the oil • Extraction similar to oil extraction • Flows from well under own pressure and pumped into gas pipelines • 560 billion m3 produced in the US each year

15. Clean Burning vs. Dirty Fuels • Clean Burning • Methane • Not Clean burning • Coal, wood, crude oil, gas

16. Methane Hydrates • Methane locked in ice • Located in permafrost regions • At water depths greater than 1,640 feet (500m) • Natural gas uses expected to increase • Natural gas is clean burning • Natural gas plants are relatively cheap to build • US Natural gas consumption is expected to increase 40% • Due to use in transportation • Alternative liquid fuel

17. Oil Shale • Contains kerogen • Heating oil shale in the absence of air turns kerogen into oil • 3 trillion barrels of recoverable oil from oil shale in the world • 750 billion located in the United States • Largest reserves: Estonia, Australia, Germany, Israel, Jordan • In US Wyoming, Utah, Colorado

18. Oil Shale Mining • In suti – heat oil shale in the ground to extract oil and gas via pumping • Potential to affect aquifers • Surface Mining • Destroys environment • Moderate net energy yield due to high inputs required to extract oil and repair environment

19. Tar Sands • Contain Bitumen – semisolid form of oil • High in sulfur (~5%) = dirty oil • Represent about 2/3 of world oil reserves • Most in Canada and Venezuela • Keystone Pipeline • Moderate net-energy yield due to high inputs • Strip-mining • In suti recovery

20. Hydrofracking • Removes natural gas that was previously urecoverable • Process: • Chemicals are mixed with large quantities of water and sand • Mixture is injected into wells at extremely high pressure to create fractures in rock • Oil and natural gas to flow out of the well • Estimates 80% of natural gas wells will be with hydraulic fracking

21. Pros Process of bringing well to completion is short Well can be in production 20 – 40 years Makes it possible to access new reserves of oil and natural gas Stimulates the economy Allows independence from foreign sources of oil Cons Dangerous chemicals used in the process can enter the water supply Toxic, radioactive, caustic liquids pose storage problems Currently no regulations for fracking Results in contaminated water, air pollution, destroyed streams, and negative environmental impacts Hydrofracking

22. Oil World Reserves and Demand • 45% - 70% of world’s reserves already depleted • About 50 year supply left • Competition between emerging economies • 2/3 of oil in US is used in transportation • 1/4 of oil used in industry

23. Natural Gas World Reserves and Demand • US has an estimated 75 year supply • 34% in Middle East • 40% in Russia and Kazakhstan • 3% in US

24. Pros Inexpensive (prices increasing) Easily transported through pipes, etc. High net-energy Ample supply – short term Large US government subsidies in place Versatile – used in manufacturing many products Cons Limited reserves are declining Produces pollution Causes land disturbances through drilling Oil spills on land and ocean contaminate the environment Disrupts wildlife habitat Supplies are volitile Oil

25. Pros Pipelines and distribution networks are in place Easy to transport Relatively inexpensive Estimated 125 year reserve Less pollution than other fossil fuels Extraction leads to less environmental damage Cons H2S and SO2 released in process LNG is expensive and dangerous Lower net-energy Leakage of CH4 has more impact on global warming than CO2 Disruption to collection areas Extraction leads to waste water Land subsidence Natural Gas

26. Synfuels • Any fuels produced from coal, natural gas, or biomass through chemical conversion • Creates substances the same as crude oil or processed fuel • Eg: SNG – synthetic natural gas created through coal liquification

27. Pros Easily transported through pipelines Produces less air pollution Large supply of raw materials are available Can produce gas, diesel, or kerosene without reforming or cracking Cons Low net energy Plants to build are expensive Would increase depletion of coal due to inefficiencies Product is more expensive than petroleum Synfuel Pros and Cons

28. Arctic National Wildlife Refuge (ANWR): ANWR in NW Alaska (19 million acres) Drilling debate since 1977 Controversy: economics of oil recovery compared to environmental damage Keystone Pipeline System Transport synthetic crude and diluted bitumen from Canadian oil sands to refineries in Illinois, distribution hubs in Oklahoma, Texas ports Continuing debate over costs and benefits to US economy and environment Case Studies