IPC—Chapter 10

Energy Sources

Fossil Fuels• How many different ways have you

used energy today?

• Law of Conservation of Energy states: Energy cannot be created or destroyed—only converted or transformed

• More energy is used in the US than in any other country in the world

• (Energy Usage charts—pg. 291)

Fossil Fuels –cont’d.• Fossil fuels— such as petroleum

(oil), natural gas and coal: they are formed from the decaying remains of ancient plants and animals

• Burning fossil fuels is a more concentrated form of fuel than other sources (ex: wood)

Petroleum• Petroleum—a highly flammable

liquid formed by decayed ancient organisms– A mixture of thousands of chemical

compounds– Fractional Distillation: A process that

separates hydrocarbons in petroleum to be used to produce different materials

– Petroleum is used to manufacture fuels, plastics, synthetic fabrics, lubricants, asphalt, etc.

Natural Gas• Natural Gas—gaseous compounds

produced by same processes that produce petroleum– Composed mostly of methane• Also contains other hydrocarbon gases• About ¼ of energy consumed in the US

comes from burning natural gas• Natural gas powers stoves, furnaces, hot-

water heaters, clothes dryers, etc.

Coal• Coal—a solid fossil fuel that is found

in mines underground– At one time powered most of the US– Now, 2/3 of energy in US comes from

petroleum and natural gas, and about ¼ comes from coal

– 90% of coal used in the US is burned by power plants to generate electricity

Origin of Coal• Coal mines were once the site of

ancient swamps where large, fernlike plants grew.– Coal formed from this plant material.• Worldwide, the amount of coal that is

potentially available is estimated to be 20 to 40 times greater than the supply of petroleum

Generating Electricity• Almost 70% of electrical energy

used in the US is produced by burning fossil fuels

• The overall efficiency of burning fossil fuels is listed in table 1 on pg. 296

• There are undesirable side effects of burning fossil fuels, such as: smoke, carbon dioxide concentration in the atmosphere, pollutants, sulfur dioxide, etc.

Nonrenewable Resources• Nonrenewable resources—all fossil

fuels—resources that cannot be replaced by natural processes as quickly as they are used

• Conservation:

one way to reduce the use of fossil fuels is to obtain energy from other sources

ex:????

Section 2—Nuclear Energy• Some power plants convert nuclear

energy to electrical energy (w/out using fossil fuels)

• Nuclear power plants produce about 8% of all the energy consumed in the US

• There are currently more than 100 nuclear power plants in the US

Nuclear Reactors• Nuclear reactor—uses the energy

from controlled nuclear reactions to generate electricity

• Reactor core—where fission takes place in a nuclear reactor– Ex: for every 1 kg of uranium that

undergoes fission in the core, 1 g of matter is converted into energy

– The energy released = energy released by burning more than 3 million kg of coal

Nuclear Power Plants• Nuclear fission reactors produce

electricity in much the same way conventional power plants do

• Overall efficiency of nuclear power plants is about 35 %, similar to that of fossil fuel power plants

Risks of Nuclear Power• Nuclear power plants do not

produce air pollutants released by fossil fuel burning OR carbon dioxide

• HOWEVER:

• Mining of uranium can cause environmental damage

• Water used as a coolant in the reactor core must cool before released into streams/rivers

Release of Radioactivity• Fuel rods containing radioactive

elements could cause damage to living organisms if released from the reactor core

• 1986—Chernobyl, Ukraine– Reactor core overheated, chemical

explosion blew a hole in the reactor– 28 people died/possible 260,000

exposed to radiation

Nuclear Waste• Nuclear waste—any radioactive by-

product that results when radioactive materials are used

• Low-level waste: usually contain a small amt of radioactive material– Usually do not contain radioactive

materials w/long half-lives.– Sometimes is released into air or water

More on Nuclear waste• High-level waste:

**Generated in nuclear power plants and by nuclear weapons programs

**Stored in a deep pool of water

**Spent fuel is buried 100’s of meters below ground in stable rock formations or salt deposits

Nuclear Fusion• Fusion—the most concentrated

energy source known

• Fusion reactions occur only at temperatures of millions of degrees Celsius.

• The use of fusion as an energy source remains in the future