Energy

Part 2 – Fossil Fuels

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

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

Coal is dead plants not dead dinosaurs

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

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

Steps of Clean Coal Technology1. Oxygen is introduced to burn coal

completely2. Coal is pulverized to burn more completely3. Ash is removed using electrostatic

precipitators4. Steam is condensed and returned to the

boiler

5. CO2 is removed using live and then sequestered

Steps of Clean Coal Technology

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

CoalPros 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

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

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

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.

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

Clean Burning Methane

Not Clean burning Coal,

wood, crude oil, gas

Clean Burning vs. Dirty Fuels

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

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

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

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

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

HydrofrackingPros 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

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

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

Oil 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

Natural GasPros 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

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

Synfuel Pros and ConsPros 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

Case StudiesArctic 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