Energy: Fossil FuelsPart II: Natural Gas and Coal

Natural GasNatural gas is produced by decomposition of deeply buried organic matter from plants & animals.

• natural gas is a mixture of 50–90% methane (CH4),

with smaller amounts of ethane (C2H6), propane

(C3H8), & butane (C4H10), and the toxic gas hydrogen

sulfide (H2S);

• when a natural gas field is tapped, propane & butane gases are removed as _____________________________

• natural gas is typically transported in pipelines from oil fields to users;

• since many oil wells are isolated, much of the natural gas is either _______ or pumped back into the ground because it is not economically feasible to transport it.

Natural GasCarbon dioxide emissions per unit energy produced is much lower for natural gas, as compared with other fossil fuels.

Conventional natural gas:

• trapped above oil deposits and is usually fairly easy to extract.

Unconventional natural gas:

• ______: gas locked in impermeable rock (usually sandstone)*

• ______: gas locked in shale beds (where gas originally formed)*

• ___________________methane

• Methane ___________ (frozen on ocean floor)

*Requires Fracking

Types of Natural Gas

Natural Gas Reserves

Natural Gas Reserves and

Demand

Natural Gas Consumption

Natural Gas Extraction: Fracking_________________: aka Fracking• rock (often shale) is fractured by

a pressurized liquid made of water, sand, and chemicals.

• When the hydraulic pressure is removed from the well, small grains of proppants (either sand or aluminum oxide) hold the fractures open.

Natural Gas Extraction: FrackingEnvironmental Concerns:• The frack fluid mostly contains water (89%), with another 9.3%

of the fluid being sand. The remaining chemicals constitute 1.7%, of the mixture.

• New fractures formed may allow migration of gas, chemicals, or other materials into drinking water supplies (either below the surface or in lakes/streams)

• Radioactive tracer elements and ___________ chemicals used in fracking fluids have also been found in ______________.

Natural Gas Extraction: FrackingEnvironmental Concerns: Several studies have found fracking fluids in the drinking water of nearby towns and residents.

Natural Gas Extraction: FrackingEnvironmental Concerns:• Fracking might cause

earthquakes in the area• EPA has not regulated the

process, and Obama supports the process

• https://www.youtube.com/watch?v=LAxsTJd7VCA• https://www.youtube.com/watch?v=4LBjSXWQRV8

Transporting Natural Gas• Pipelines extend

for hundreds of miles, which can be hazardous

• Pipelines may also leak

• Natural Gas is also transported in ships and trucks

Puget Sound Energy

• Natural Gas Supply:

Western US = 43%

BC = 35%

Alberta = 22%• Natural Gas Demand

Residential = 49%

Commercial = 26%

Industrial & Transportation = 25%

Natural Gas Lines: Aging Infrastructure• Many natural gas lines

to individual homes or businesses are old and starting to fail.

• Failure of a gas line can cause catastrophic explosions

• A smell is added to the gas, so that people will recognize when there’s gas present.

Natural Gas Explosion: February 7th, 2010

TRADE-OFFS

Conventional Natural GasAdvantages DisadvantagesAmple supplies Nonrenewable

resourceHigh net energy yield

Releases CO2 when burnedLow cost

Gas turbine Government subsidiesLess air pollution than other fossil fuels Environmental costs not

included in market price

Lower CO2 emissions than other fossil fuels Methane (a greenhouse

gas) can leak from pipelinesEasily transported by

pipelineDifficult to transfer from one country to anotherLow land use

Good fuel for fuel cells, gas turbines, and motor vehicles

Can be shipped across ocean only as highly explosive LNG

Methane Hydrates• Methane hydrates are

methane molecules (CH4) encased in an ______lattice

• Stable only at ______ pressures and _____temperatures

• Boils off at STP, and is extremely _______________

• Formed as a by-product from microbes living in ocean floor sediments

Methane Hydrates• Volume of methane hydrate

is massive, but technology does not currently exist to safely or ______________ extract it

• Fig. S10-7, p. S63

Methane Hydrate Deposits

Methane Hydrates• Catastrophic releases of methane

hydrate have been proposed to have caused major _________ shifts (due to massive CO2 release), and possibly mass extinctions in the past

• In order to mine it, safe methods need to be developed

• Various countries (including US) are investigating this potential resource

The Future?

• Fig. S10-5, p. S61

Coal

Natural gas

CoalCoal is a fossil fuel, produced from the buried remains of ___________ plants that died during the Carboniferous period (geologic era ending 286 million years ago).

Stages in the formation of coal over millions of years. Note the three types of coal.

Fig.15–13

CoalCoal is mostly carbon, with smaller amounts of water, _________ & trace amounts of radioactive materials and elements such as mercury. It is typically extracted by strip mining or underground coal mining.

Coal Sources & UsesAbout 66% of the world's proven coal reserves and 85% of the estimated undiscovered deposits are in the United States, the former Soviet Union, and China.

• Coal provides about ______ of the world's commercial electricity (22% in U.S.);

• used to generate 64% of world's electricity (57% in U.S.);

• used to make _______ of world's steel;

• China gets _____ of energy from coal, largest user;

• U.S. second largest user

Coal Sources

© Brooks/Cole Publishing Company / ITP

Locations of the major coal fields in the United States & Canada.

Fig.15–14

Coal: Environmental Concerns• Mountaintop Removal: The

process of removing the tops of mountains, mostly in the _______________s, to remove the coal seams beneath them.

• Effects:• _____for coal miners and

requires fewer men• Destroys the tops of mountains• Overburden is pushed into

valleys• Sediment-laden water is no

longer usable for drinking or fish• Creates _________ downstream

Coal: Environmental Concerns

• https://www.youtube.com/watch?v=p5RcbPZXUZo

• https://www.youtube.com/watch?v=RPixjCneseE

Mountaintop Removal Mining

Air Pollution from Coal: Acid Rain and SootCoal contains sulfur and nitrogen impurities. Sulfur dioxide (SO2) and nitrogen oxides (NOx) are emitted from coal burning. These molecules react in the atmosphere to form sulfuric and nitric _________.

____ of all SO2 and ____of all NOx comes from electricity generated by fossil fuels (especially coal).

East coast uses a greater percentage of coal and has more acid rain.

Mercury Emissions from CoalCoal is naturally contaminated with mercury, which is released when it is burned.

Coal-burning power plants and industrial boilers are the greatest contributor to mercury pollution.

Waste heat

Coal bunker Turbine Cooling tower transfers waste heat to atmosphere

GeneratorCooling loop

Stack

Pulverizing mill

Condenser Filter

Boiler

Toxic ash disposal

Air Pollution from Coal: SootCarbon ________ both contributes to global

warming and is a harmful air pollutant (fine particulate matter.)

Methods of Reducing Air Pollution:

Precipitators

______________

Higher _________ coal

Videos on Coal:http://www.cbsnews.com/video/watch/?id=4969902n

http://www.cbsnews.com/video/watch/?id=6369590n

http://www.cbsnews.com/video/watch/?id=4969906n

http://www.cbsnews.com/video/watch/?id=5356259n

Scrubbers can reduce Sulfur Dioxide Emissions

Conversion of solid coal to

-Synthetic natural gas (SNG) by coal gasification

- Methanol or synthetic gasoline by coal liquefactionSynthetic fuelsAdvantages Disadvantages

Large potential supply

Low to moderate net energy yield

Higher cost than coal

Vehicle fuelRequires mining 50% more coal

Environmental costs not included in market price

Moderate cost High environmental impact

Large government subsidies

High water useLower air pollution than coal when burned

Higher CO2 emissions than coal

Clean Coal

Clean coal technologies aim to sharply reduce air emissions and other pollutants from coal plants

• Early clean coal efforts in the late 1980’s and early 1990’s focused on reducing acid rain through reduction of sulfur _____________

• New concerns include impacts of trace amounts of ________ and the effects of CO2 on global climate

“Coal is an abundant resource in the world…It is imperative that we figure out a way to use coal as cleanly as possible.”

-- Dr. Steven Chu, Secretary of Energy at his Senate Confirmation Hearing, January 13th, 2009

Clean Coal Power Initiative (CCPI):• Provides government co-financing for new coal

technologies that can help utilities cut sulfur, nitrogen, and mercury pollutants from power plants, as well as improve efficiency

• 2003: Eight projects selected. Two are currently in the operational phase; one has been completed; and the other 5 have been discontinued

• 2004: Four projects selected. One is in the operational phase; two are under development; one has been withdrawn.

• A third solicitation for projects is underway and is focused on developing projects that utilize carbon sequestration technologies and/or beneficial reuse of CO2

Clean Coal

Carbon Sequestration Involves injection of CO2 into geologic formations such as oil and gas reservoirs, unmineable coal seams, and deep saline reservoirs• Injection into ________________deposits can enhance

recovery of oil and natural gas• May be able to store CO2 produced from coal plants for long

periods of time• Norwegian company,

Statoil, is injecting 1 million tons of recovered CO2 into the Utsira Sand Saline Formation. This is the equivalent to the output of a 150-megawatt coal-fired plant

Oil rigTanker delivers CO2 from plant to rig

Coal power plant

Tree plantation

CO2 is pumped down from rig for disposal in deep ocean or under seafloor sediments

Abandoned oil field

Switchgrass Crop field

CO2 is pumped

underground

Spent oil or natural gas reservoir

Spent coal bed cavern

Deep, saltwater-filled cavern

= CO2 pumping

= CO2 deposit

Sequestering Carbon

Can Coal Be Clean?• Coal puts more CO2 into the atmosphere than any other fossil fuel

• More than 60% of coal mined in US comes from _______ mines

• Coal Sequestration is a new technology that is a long way from being implemented on a large scale in the US and is not currently economically viable without large government subsidies

Problems with carbon capture and storage

– Power plants using CCS• Would be more

___________ to build– Unproven technology– Stored CO2 would have to

remain sealed forever: no __________

– Large inputs of __________ to work

• Increasing CO2 emissions, negating some of “carbon offset”

– Promotes the continued use of coal (world’s dirtiest fuel)

Coal Pros & Cons

© Brooks/Cole Publishing Company / ITP

Pros:• most abundant fossil fuel;• U.S. has major reserves, will last 300 years at current

consumption rates;• high net energy yield;

Cons:• dirtiest fossil fuel, in terms of air pollution & carbon dioxide

released;• major environmental degradation

that result from extraction, processing, transport, & use;

• burning coal is major threat to human health –– estimated to kill or cause chronic respiratory disease for large numbers of people.

• Coal Mining is a hazardous profession: more than 104,000 miners have died in America since 1900

TRADE-OFFS

CoalAdvantages Disadvantages

Severe land disturbance, air pollution, and water pollution

Ample supplies (225–900 years)

High net energy yield

Environmental costs not included in market price

Low cost

Large government subsidies

Well-developed technology High CO2 emissions when

produced and burned

Air pollution can be reduced with improved technology

Severe threat to human health when burned

Radioactive particle and toxic mercury emissions

Fig. 15-14, p. 384

Coal-fired electricity

286%

Synthetic oil and gas produced from

coal

150%

Coal 100%

Oil sand

92%

Oil 86%

Natural gas 58%

Nuclear power fuel cycle

17%

Geothermal 10%

CO2 Emissions per unit of Electrical Energy

Things You Can Do…Cut down waste where you can