GSC 1620 Chapter 14

Energy Resources – Fossil Fuels

Energy Resources – Fossil Fuels• As societies evolve from primitive to

agricultural to industrial/technological, and population increases, the per-capita consumption of energy increases (see figure)

• In the U.S., and industrial societies worldwide, most of the required energy is derived via combustion of fossil fuels (see slides)

U.S. Energy Consumption (1949-2000)

U.S. Energy Consumption Profile (2012)

• Oil ~36.5%• Natural Gas ~27.3%• Coal ~18.3%• Nuclear ~8.5%• Biomass ~4.5% • Hydroelectric ~2.8%• Wind ~1.4%• Solar ~0.25%• Geothermal ~0.12%

TraditionalFossil Fuels (~82%)

Renewable Fuels (9.0%)

Source: U.S. Department of Energy statistics

(oil)

Annual per capita consumption of the traditional fossilfuels in the United States

What’s the U.S. population?

Fossil Fuels

• Oil, coal and natural gas are known as the traditional (conventional) fossil fuels

• Fossil fuels – the trapped remains of plants and animals in sediments and rocks that have been converted to combustible substances

Coal

• Coal – a combustible rock containing more than 60% carbon

• Microscopic examination of coal reveals that coal is almost exclusively derived from the transformation of land plants (see slide)

Coal• The

photomicrographs on the right show the cell walls of plants (top) and compressed spore cases (bottom) typically visible when coal is viewed using a high magnification power microscope

Coal• The coalification (coal formation)

process involves a slow (hundreds of thousands to millions of years) transformation of land-based organic matter, buried in low-dissolved oxygen water basins (e.g., tidal flats, swamps, bogs), by a series of microbial, physical and chemical reactions that concentrate the element carbon (see slides)

Coal

• Peat is considered a precursor to coal; the commonly recognized coal types include lignite (> or = 70% C), bituminous (> or = 80% C) and anthracite (> or = 95% C)

• The U.S. hosts about 25-30% of the world’s coal reserves (verified quantities). This amount could fuel our economy, at the current rate, for close to 200 years! (see slides)

Coal

• If the U.S. is so well endowed with coal reserves, why don’t we derive an even higher percentage of our energy from coal combustion?

• The world’s coal resources should be adequate to meet demand for at least a few hundred years (see slide)

Projected World Coal Production

Coal Mining Impacts

• Coal is mined by surface (e.g., strip miming) and subsurface (e.g., shaft and tunnel) methods – each of these has associated hazards for miners and the environment (see slide, recall our discussion from chapter 13)

U.S. Coal Production

Coal Mining Impacts• Coal mining is still a dangerous

profession but note how the number of annual fatalities has decreased with the increase in surface mining and better safety practices*(see figure)

• * Unfortunately 2010 was not a safe year for coal mining – Remember the underground mine accident in WV?

U.S. Coal Mining Fatalities

Coal Mining Impacts• Coal use environmental impacts:• 1) Acid rain – sulfurous gases released

during coal combustion combine with oxygen and water vapor to produce sulfuric acid aerosols and acid rain

• 2) Acid mine drainage – ground or surface waters react with sulfur-containing compounds and generate sulfuric acid; the subsequent drainage can acidify waterways and soil to the degree they can’t support life (see slide)

Abandoned U.S. coal strip mine and acidified waters

Coal Mining Impacts• 3) Ash and other air pollution – coal ash is

a respiration hazard and can carry toxic metals into waterways and soils, combustion of some coals also releases toxic mercury vapors (especially in the U.S. Midwest)

• 4) Strip mining disturbs large areas and prior to land reclamation laws most were abandoned, degrading the terrain and surrounding ecosystems (see slide)

U.S. coal strip mine

Coal Mining Impacts

• Be aware: within the last 10-15 years, some coal mining companies have used environmental law “loopholes” to practice mountain top removal mining

Example of mountaintop removal mining

Coal Mining Impacts• 5) Mine collapses

– a problem wherever old shaft and tunnel mining occurred; wooden support beams rot or are consumed by underground coal fires leading to surface collapse Collapse pits

Coal Mining Impacts• 6) Underground coal fires

– unmined coal ignited by careless waste disposal or natural processes (e.g., lightning striking an exposed seam of coal); once these fires spread underground they’re almost impossible to extinguish

• Underground coal fires promote ground surface collapse and release toxic gases (e.g., Centralia, PA) (see slide)

Coal Mining Impacts• 7) Carbon dioxide

emissions and increased risk of “greenhouse warming” climate change; About 42% (2011) of U.S. electricity is generated by burning coal

• Another concern: due to the abundant supplies of coal, many utility companies wish to build large numbers of additional coal-fired electricity plants to meet our increasing electricity demand; ash disposal a problem

Coal Mining Impacts

(CNN) -- Tennessee state officials slapped the Tennessee Valley Authority with $11.5 million in fines Monday for a massive coal sludge spill in December 2008.The state Department of Environment and Conservation imposed the penalties after determining that the billion-gallon spill violated state clean-water and solid waste disposal laws.In a statement announcing the fines, Environment Commissioner Jim Fyke called them an "appropriate" response "to an unprecedented event."TVA spokesman David Boruff said that the fine was expected and that the utility would not challenge it.The December 22, 2008, spill began when a dike collapsed at a retention pond at the TVA power plant in Kingston, about 35 miles west of Knoxville. The mixture of water and ash was enough to fill nearly 800 Olympic-sized swimming pools, spreading across more than 300 acres of land and fouling the adjacent Emory River. There were no deaths, but three homes were destroyed and about a dozen others damaged.The spill contained some toxic chemicals, such as arsenic, selenium, lead and radioactive materials like chromium and barium. But the TVA and the federal Environmental Protection Agency have reported that air and drinking water in the area were safe and that the levels of toxic substances in the spill did not exceed federal standards.6/14/09

Petroleum

• Petroleum – any naturally occurring solid, liquid or gaseous hydrocarbon compound or hydrocarbon compound mixture

• Hydrocarbons – organic chemical compounds containing various proportions of hydrogen and carbon; e.g., methane (natural gas) – CH4

• Examples of liquid and solid petroleum?

Petroleum• Oil and natural gas are thought to form

by the same slow (probably hundreds of thousands of years or more) transformation of buried organic matter that create coal (see slide)

• However, evidence suggests the primary organic matter source for oil and natural gas is microscopic sea plants (phytoplankton) and sea animals (zooplankton)

Conventional Oil and Natural Gas

• For conventional economically recoverable deposits of oil and natural gas to be formed, the generated oil and/or gas must migrate into a porous and permeable reservoir rock and be constrained from further migration by impermeable rocks of a geologic trap (see figures) Example of a petroleum trap

Source rock

Different types of oil/gas traps

Conventional Oil and Natural Gas

• The U.S. is not well endowed with conventional oil or conventional natural gas reserves (see slide)

ConventionalPetroleum

Oil and Natural Gas

• The U.S. consumes approximately 7.3 billion barrels of oil and 20 trillion cubic feet of natural gas annually!

• Given our limited domestic reserves (see table), what does this suggest about the source (foreign or domestic) of a large proportion of the oil and natural gas we consume each year?

• Should this situation concern us?

Conventional Oil and Natural Gas

Conventional Oil and Natural Gas

• Worldwide, the known oil reserves are projected to be exhausted by about 2065 (see slide)

Conventional Petroleum• However, as exploration

and drilling technology advances, more oil could be recovered from previously undrilled regions, as suggested by Chevron’s 2006 discovery in deep waters of the Gulf of Mexico

Promising ocean petroleum exploration technique

ConventionalPetroleum

• The massive oil spill into the Gulf of Mexico in spring 2010 when BP’s Deepwater Horizon rig collapsed casts doubts on our ability to safely produce petroleum from deep waters

Conventional Petroleum

• However, as we’ll see there are nontraditional (unconventional) sources of oil and natural gas that have yet to be significantly developed

Future Petroleum Recovery Prospects from Conventional Reservoirs• Primary oil recovery – well yields oil with

minimal pumping or gushes• Secondary oil recovery – water pumped

into reservoir to force the oil toward the well; primary plus secondary recovery extract only about 33% of oil in the trap!

• Enhanced recovery – pressurized carbon dioxide gas, hot water or steam injected into reservoir to force oil toward well; subsurface explosions used to enhance reservoir permeability

Future Petroleum Recovery Prospectsfrom Conventional Reservoirs• Enhanced recovery may extract another

40% of oil in the trap (75% total)• Obviously enhanced recovery techniques

are more expensive and may lead to additional ground subsidence or groundwater pollution (e.g., hydraulic fracturing)

• Another highly political issue: should drilling for natural gas and oil be allowed in the Arctic National Wildlife Refuge (ANWR)?

Future Petroleum Recovery Prospectsfrom Conventional reservoirs

• Surface studies suggest about 8-15 billion recoverable barrels underlie ANWR and the National Petroleum Reserve – Alaska (NPRA), depending on the commodity price (see slide)

• An Act of Congress, signed by the president, is necessary for exploratory drilling and production to begin

• What’s the status of ANWR?

A Possible Radical Transformation is Underway

• Hydraulic fracturing and horizontal drilling have the potential to radically reshape energy production and consumption in the United States within the next decade!

• Significant petroleum (gas and oil) production, from both conventional and unconventional sources, is likely from these techniques!

2/12/13

Nontraditional (Unconventional) Fossil Fuels: Methane from Impermeable Rocks/Sediments

• The most economic unconventional fossil fuel in the U.S. – “shale gas”

• Produced from highly impermeable shale deposits by the controversial technique: hydraulic fracturing or “fracking”

• Estimates suggest 50 – 75 years of this resource in the U.S.

• In “shale gas” and “shale oil” the petroleum is extracted from the source rock, not a conventional reservoir rock

Shale Gas

• In the U.S., the Bakken Shale (North Dakota), the Haynesville Shale (east Texas and Louisiana) and the Marcellus Shale (portions of PA, NY, OH, WV) are current producers

• This technique has been proposed for Michigan’s Antrim and Utica Shale gas deposits

Source: National Geographic, Dec. 2012

Nontraditional (Unconventional) Fossil Fuels: Methane from Impermeable

Rocks/Sediments Controversy: 1) potential contamination of groundwater from “leaked” methane or injection fluid chemicals; 2) possible earthquakes caused by the injection of “flowback” (production well waste fluids) into the subsurface for disposal (see figures)

Source:National Geographic,12/2012

Unconventional Fossil Fuels: Methane from Impermeable Rocks/Sediments (Shale Gas)

Wall Street Journal 7/26/2011 National Geographic: Dec., 2012

Unconventional Fossil Fuels: Methane from Impermeable Rocks/Sediments

• These findings may slow the development of this resource

• Don’t confuse “shale oil” with “oil shale”!

Future Concern?

A Radical Transformation is Underway

• If the frequency of horizontal drilling and hydraulic fracturing continues to increase, the trend shown in the adjacent figure should continue

Unconventional Fossil Fuels: Oil Shale• Oil Shale - a nontraditional fossil

fuel; a sedimentary rock (not always shale) that contains no liquid oil but disseminated, fine-grained particles of a wax-like hydrocarbon called kerogen that may be converted by chemical and physical treatment into an oil-like liquid

Unconventional Fossil Fuels: Oil Shale

• The U.S. hosts most of the world’s reserves of oil shale; the richest deposits lie beneath portions of Wyoming, Colorado and Utah (see figure)

Unconventional Fossil Fuels: Oil Shale• The energy (perhaps as much as 800

billion barrels of oil equivalent) contained in U.S. oil shale probably significantly exceeds all our other traditional fossil fuel sources combined

• Because of the disseminated, fine-sized kerogen particles these deposits would need to be bulk mined

Unconventional Fossil Fuels: Oil Shale• Environmental legislation now limits

the amount of airborne dust that can be generated during mining and requires reclamation of the mine site lands; the kerogen conversion process also requires large volumes of water

• The areas with the richest kerogen deposits lack the necessary water to meet the mining regulations and conversion process needs

Unconventional Fossil Fuels: Methane Hydrates • Pay attention for mention in the media of

“methane gas hydrates”– another nontraditional fossil fuel of which the U.S. has great resources, perhaps more even more than our oil shale resources

• These have been discovered offshore (e.g., Carolinas coast) in waters about 500 - 2000 feet deep and consist of a water and methane gas ice mixture (see figures)

• Concerns about how to raise them have hindered their production. Any idea why?

Source: Popular Mechanics,April, 2006

Unconventional Fossil Fuels: Methane Hydrates

Unconventional Fossil Fuels: Methane Hydrates

• The Japanese may have developed a technique to commercially tap these deposits!

Unconventional Fossil Fuels: Tar (Oil) Sands

• So there are plenty of nontraditional fossil fuels which may someday be exploited

• In fact, the Canadians are now exploiting another nontraditional fossil fuel, tar sands, and converting it to liquid petroleum

• Vast deposits exist in the Canadian province of Alberta

• How is this development affecting the political and environmental debate in the United States?

Unconventional Fossil Fuels: Tar (Oil) Sands

Canadian Petroleum Resources

This is about 240billion barrels morethan the world’scurrent reservesof traditional (conventional) oil!U.S. tar sandresources areminimal.

Fossil Fuels

• Are you surprised by the adjacent diagram?

Future Petroleum Recovery Prospects

• What does your text author really imply when she states that conservation may extend our petroleum resources?

Petroleum Use Risks

• Oil spills – about 600,000 tons of oil seep naturally into the oceans each year!

• Oil supertanker transports can carry 2 million barrels (about 80 million gallons)

• See table of some historic oil spills – much larger spills than that from the Exxon Valdez have occurred since 1989

Notable World Oil Spills

1989 Exxon Valdez Oil Spill

• Port of Valdez

Oil contaminated beach

Oil Spills

• How did the 1989 Exxon Valdez oil spill change the way oil is transported in U.S. waters?

Traditional Oil Spill Cleanup Approaches• Physical removal from land by hot-water

washing or pickup• Soaking agents – peat moss, feathers, wood

chips, corn cobs used to absorb oil• Sinking agents – sand, chalk, clay used to

absorb oil and sink it to the water’s bottom• Burning – oil ignited • Dispersing detergents – detergents used to

fragment the oil into small droplets that are then dispersed through the water column (“The solution to pollution is dilution”.)

Traditional Oil Spill Cleanup Approaches• Skimmer ships – inflatable

barriers (booms) deployed around spill and ships skim (vacuum) the oil from the surface; works best with small volume spills that haven’t spread very far

• Bioremediation – the use of natural or genetically modified organisms to degrade the oil into less harmful substances (e.g., water and carbon dioxide gas)

• None of these techniques is currently highly effective! Prevention is the best

“cure”.