Chapter 12 Nonrenewable Energy Resources

 April 22, 1970  Several events in the 60’s prompted the creation.  Well explosion off the coast of Santa Barbara CA in January, million gallons of crudes oil dumped.  Our reliance on oil and other fossil fuels has only increased.  Spills can happen during any part of the process: leaks, explosions, extraction, transport.  March, 1989: Exxon Valdez super tanker crash into Prince William Sound, Alaska. 53 million gallons.  April, 2010: BP Deepwater Horizon oil well in the Gulf of Mexico. Killed 11 workers, injured 17, 206 million gallons of oil dumped.  2005: BP oil refinery in Texas. 15 workers killed.  April, 2010: Coal mine explosion in West Virginia. 29 miners killed.

 Most of our energy comes from nonrenewable sources (sources that cannot be replenished).  Two main categories: Fossil fuels and Nuclear fuels.  What affects the rate at which energy is used?  Availability  Affordability  More recently, environmental impacts.  In 2005, U.S. used 355 GJ per person per year (5x greater than the world average)  Overall, 20% of the world uses 70% of the energy

 Nonrenewable energy resources- fossil fuels (coal, oil, natural gas) and nuclear fuels. Nonrenewable Energy

 Commercial energy sources- those that are bought and sold, such as coal, oil and natural gas.  Subsistence energy sources- those gathered by individuals for their own use such as wood, charcoal and animal waste. Energy Use

 Up to 1875: wood predominant energy source.  1875: Coal came into wider use.  Early 1900’s: oil and natural gas join coal as primary sources of energy.  1950: Nuclear enters the mix and hydroelectricity becomes more prominent..  1970’s: decline in oil and resurgence of coal.  Today (U.S. and worldwide): in order of increasing importance…oil, coal, natural gas.  Major outputs of energy use are work and waste (heat, CO 2, and other pollutants).

 Produces 70% of the energy it needs. 30% from other countries.  Energy use varies both seasonally and regionally.  Air conditioning/heating needs.  The type of energy used is a function of many factors: ease of transport, amount of energy per mass of fuel, etc.

 Certain types of energy are better suited for particular jobs:  Transportation: gasoline or diesel is preferred because it is a liquid source which is relatively compact meaning it has a high energy-to-mass ratio, they also provide or cut off the energy with great speed. Down side, they are bigger pollutants, require a great deal of refining, etc.  One of the best ways to determine the best source for the job is to consider the energy efficiency.  Second law of thermodynamics: as a source of energy is transformed its ability to do work diminishes.

Process of Energy Use

EROEI (Energy return on energy investment) Energy obtained from the fuel Energy invested to obtain the fuel **The bigger the EROEI, the better.

 Public transportation is much more efficient than traveling by car (because most people travel alone). Car efficiency goes up as more people are added.  In the United States vehicle choice plays an important role. Most do not choose by fuel efficiency alone but also by comfort, convenience and style.  Recent legislation says that by 2016, the overall fleet average MPG must be at 35.

Overall Fuel Efficiency of U.S. Automobiles

 Sources of energy:  Primary: coal, oil, and gas (burning at the source).  Secondary: Electricity (obtained from the conversion of a primary source).  Electricity is clean at the point of use but there are many pollution tradeoffs before that point.  Greatest efficiency comes with the fuel that entails the fewest conversions from the original source.

Electricity Generation

 The burning fuel from coal transfers energy to water, which becomes steam.  The kinetic energy contained within the steam is transferred to the blades of a turbine, a large device that resembles a fan.  As the energy in the steam turns the turbine, the shaft in the center of the turbine turns the generator.  This mechanical motion generates energy. Electricity Generation

 Most coal burning power plants are about 35% efficient. Energy Efficiency

 Cogeneration- using a fuel to generate electricity and to produce heat.  Example- If steam is used for industrial purposes or to heat buildings it is diverted to turn a turbine first.  This improves the efficiency to as high as 90%. Cogeneration

 Coal- a solid fuel formed primarily from the remains of trees, ferns, and other plant materials that were preserved million years ago.  Four types of coal ranked from lesser to greater age, exposure to pressure, and energy content.  These four types are: lignite, sub-bituminous, bituminous, and anthracite.  The largest coal reserves are in the United States, Russia, China, and India. Coal

AdvantagesDisadvantages Energy-denseContains impurities PlentifulRelease impurities into air when burned Easy to exploit by surface miningTrace metals like mercury, lead, and arsenic are found in coal Technological demands are smallCombustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere. Economic costs are lowAsh is left behind Easy to handle and transportCarbon is released into the atmosphere which contributes to climate change Needs little refining Advantages and Disadvantages of Coal

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Acid Mine Drainage The impact of mine drainage on a lake after receiving effluent from an abandoned tailings impoundment for over 50 years

 Petroleum- a mixture of hydrocarbons, water, and sulfur that occurs in underground deposits.  Oil and gasoline make this ideal for mobile combustion, such as vehicles.  Formed from the remains of ocean-dwelling phytoplankton that died million years ago.  Countries with the most petroleum are Saudi Arabia, Russia, the United States, Iran, China, Canada, and Mexico. Petroleum

Oil in U.S. 2.3% of world reserves uses nearly 30% of world reserves; 65% for transportation; increasing dependence on imports.

AdvantagesDisadvantages Convenient to transport and useReleases carbon dioxide into atmosphere Relatively energy-densePossibility of leaks when extracted and transported Cleaner-burning than coal Releases sulfur, mercury, lead, and arsenic into the atmosphere when burned Advantages and Disadvantages of Petroleum

 Natural gas- exists as a component of petroleum in the ground as well as in gaseous deposits separate from petroleum.  Contains 80 to 95 percent methane and 5 to 20 percent ethane, propane, and butane. Natural Gas

AdvantagesDisadvantages Contains fewer impurities and therefore emits almost no sulfur dioxide or particulates When unburned, methane escapes into the atmosphere Emits only 60% as much carbon dioxide as coal Exploration of natural gas has the potential of contaminating groundwater Advantages and Disadvantages Natural Gas

 Oil sands- slow-flowing, viscous deposits of bitumen mixed with sand, water, and clay.  Bitumen (tar or pitch)- a degraded type of petroleum that forms when a petroleum migrates close to the surface, where bacteria metabolize some of the light hydrocarbons and others evaporate. Other Fossil Fuels

 Hubbert curve- a graph that shows the point at which world oil production would reach a maximum and the point at which we would run out of oil. The Hubbert Curve

 If current global use continues, we will run out of conventional oil in less than 40 years.  Coal supplies will last for at least 200 years, and probably much longer. The Future of Fossil Fuel Use Burning all the world’s deposits of coal, oil and natural gas would raise the temperature enough to melt the entire ice sheet covering Antarctica, driving the level of the sea up by more than 160 feet. Study Predicts Antarctica Ice Melt if All Fossil Fuels Are Burned

 Fission- a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts. Nuclear Energy

Nuclear Reactors

 Fuel rods- the cylindrical tubes that house the nuclear fuel used in a nuclear power plant.  Nuclear power plants work by using heat from nuclear fission to heat water. This water produces the steam to turn the turbine, which turns a generator.  Control rods- cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction. Nuclear Reactors

AdvantagesDisadvantages No air pollution is producedPossibility of accidents Countries can limit their need for imported oil Disposal of the radioactive waste Advantages and Disadvantages of Nuclear Energy

 Radioactive waste- once the nuclear fuel can not produce enough heat to be used in a power plant but it continues to emit radioactivity.  This waste must be stored in special, highly secure locations because of the danger to living organisms.  Cannot be incinerated, disposed of using chemicals, shot into space, dumped on the ocean floor.  Remains a threat for 10 half-lives (the accepted number by scientists). Radioactive Waste

 High-level radioactive waste- the form used in fuel rods.  Low-level radioactive waste- the protective clothing, tools, rags, and other items used in routine plant maintenance.  Uranium mine tailings- residue left after uranium is mined and enriched. Radioactive Waste

 Current disposal of spent fuel rods is on location.  In 1978 the U.S. department of Energy began examining the Yucca Mountain site in Nevada as a permanent storage area.  In 2006 the DOE released a report confirming the soundness of the site.  A few years later after a presidential changeover, the project was cancelled. (Obama administration)

By 2008, Yucca Mountain was one of the most studied pieces of geology in the world. Between geologic studies and materials science, the United States had invested US$9 billion on the project. The DOE estimates that it has over 100 million U.S. gallons of highly radioactive waste and 2,500 metric tons (2,800 short tons) of spent fuel from the production of nuclear weapons and from research activities in temporary storage. Wikipedia

 Nuclear fusion- the reaction that powers the Sun and other stars. This occurs when lighter nuclei are forced together to produce heavier nuclei and heat is released.  Fusion is a promising, unlimited source of energy in the future, but so far scientists have had difficulty containing the heat that is produced. Fusion