Fossil Fuels

• The remains of ancient organisms that changed into coal, oil, or natural gas

• Provide most of the energy used today• 2 main problems

• Supply is limited• Obtaining and using them causes

environmental problems

Fuels for Different Uses• Used for 5 main purposes:

• Cooking• Transportation• Manufacturing• Heating & cooling buildings• Generating electricity to run machines &

appliances

• Suitability of a fuel for each application depends on the fuel’s energy content, cost, availability & safety, and the byproducts of the fuel’s use

Electricity – Power on Demand

• Energy in fuels is often converted into electrical energy in order to power machines because electricity is more convenient to use• Can be transported quickly across long or

short distances

• Disadvantages of electricity:• Difficult to store• Other energy sources have to be used to

generate it

How is Electricity Generated?• Electric generator: converts mechanical

energy (motion) into electrical energy• Uses a turbine (wheel that changes the force

of a moving gas or liquid into energy that can do work)

• Water is boiled to produce the steam that turns the turbine

• The water is heated by burning a fuel (coal, gas) or by fission of uranium in nuclear plants

• The turbine spins a generator to produce electricity

Energy Use in the U.S.• People in developed societies use much

more energy than people in developing countries do

• The U.S. uses more energy per person than any other country in the world except Canada & the United Arab Emirates• Uses more than 25% of its energy resources to

transport goods & people (trucks & personal vehicles)

• Residents of U.S. & Canada have some of the lowest gasoline taxes

Energy Use in the U.S.

World Energy Use

How Fossil-Fuel Deposits Form• Coal

• Forms from the remains of plants that lived in swamps hundreds of millions of years ago

• Much of the coal in the eastern U.S. formed about 320 million to 300 million years ago

• Formation of coal:• As ocean levels rose & fell, swamps were covered with

sediment• Layers of sediment compressed the plant remains• Heat & pressure within the Earth’s crust caused coal to

form

• Oil & Natural Gas• Result from the decay of tiny marine organisms

that accumulated on the bottom of the ocean millions of years ago

Coal

• Two major advantages of coal• Relatively inexpensive• Needs little refining after it has been

mined

How Electricity is Generated in the U.S.

• Coal: 50%• Nuclear: 20%• Natural Gas: 18%• Hydroelectricity 7%• Oil: 3%

Coal Mining & the Environment• Surface mining has a bigger effect on

the environment• Toxic chemicals can leach into nearby

streams• A lot of research focuses on 2 things:

• Developing better methods of locating• Developing less damaging methods

Air Pollution• Higher-grade coals produce more heat

and less pollution than lower-grade coal• Sulfur is a major source of pollution

when coal is burned• Clean-burning coal technology has

dramatically reduced air pollution in the U.S.

Petroleum• Oil that is pumped from the ground

(also called crude oil)• Petroleum product: anything that is

made from crude oil• Accounts for 45% of the world’s

commercial energy use• Most of the world’s oil reserves are in

the Middle East

Steps in the Oil-Drilling Process

• Exploration wells are drilled• If oil can be extracted at a profitable

rate, wells are drilled• Oil is transported to a refinery to be

converted into fuels & other petroleum products

Environmental Effects of Using Oil• When petroleum fuels are burned, they

release pollutants• Contribute to the formation of smog and cause

health problems• Sulfur: a pollutant that contributes to acid rain• The carbon dioxide released may contribute to

global warming• 2 things that have reduced air pollution from

cars in many areas:• Emission regulations• Technology (catalytic converters)

Natural Gas

• Provides 20% of the world’s nonrenewable energy

• Methane (CH4)• Has become more common to use

because it produces fewer pollutants than burning other fossil fuels

Fossil Fuels & the Future• Supply about 90% of the energy used in

developed countries• Cost will likely increase as the demand for

energy resources increases• Oil reserves: oil deposits that can be extracted

profitably at current prices using current technology

• The relative cost of obtaining fossil fuels influences the amount of fossil fuels that we extract from the Earth