Energy

Motion, position and energy Work and energy

related Energy = ability to do

work Work = process of

changing energy level

Energy formsMechanical energy Kinetic plus potential

energy

Chemical energy Energy involved in

chemical reactions

Radiant energy Electromagnetic energy Visible light = small part

Electrical energy Charges, currents,

etc.

Nuclear energy Energy involving the

nucleus and nuclear reactions

Energy conversion Any form of energy

can be converted into another form

Energy flows from one form to another in natural processes

Energy conservation

Energy is never created or destroyed Energy can be converted from one form to another

but the total energy remains constant

USA Energy sources today

Primarily wood to coal to petroleum with increasing industrialization

89% can be traced to photosynthesis

Uses 1/3 for heating 2/3 in engines and

generators

Global sources

USA electrical generation sources 2005 data

Petroleum Oil from oil-bearing rock Organic sediments transformed over time

by bacteria, pressure and temperature Natural gas formation similar, except at

generally higher temperatures Petroleum and natural gas often found

together Supplies are limited

Los Angeles, 1920s and 1937

Coal

Accumulated plant materials, processed over time by pressure and temperature

Progression: peat to lignite to sub-bituminous to bituminous—in other words, it comes in different qualities from low to high energy

Impurities Minerals lead to ash Sulfur leads to sulfur dioxide gas (pollutant)

Petroleum, natural gas and coal = fossil fuels

Wyoming Surface Mining Almost all

the coal we burn for electricity comes from here—and a lot of the US as well!

West Virginia Strip Mining

Very bad for the environ-ment. Now, the land is being reclaimed.

Underground coal mining better for surface environment

That was then…

Underground coal mining is common around the world

This is now…still, one of the most dangerous jobs on Earth.

Moving water Renewable with rainfall Hydroelectric plants generate ~3% of US’s total

energy consumption Growth potential limited by decreasing availability

of new sites

Hoover Dam

The falling water turns magnets covered in copper wire…and presto-electrons move back and forth in the wire. We call it, electricity.

The electricity-generating turbines

That’s three million horsepower there--enough for over a million people.

And its water serves 18 million people.

Not bad for 1935.

Turbine Power!

Really, this is how all electricity is generated—just boil water and make steam, have the steam drive fan blades and as they turn, they spin a magnet surrounded by copper wire.

The spinning magnet attracts and repels electrons around the copper atoms and the electrons move in the wire along with the electromagnetic force that holds them in the atoms.

How it all works

Nuclear Based on nuclear fission reactions of uranium and

plutonium Water heated in reactor and then used to produce

steam to turn generating turbines Safety of nuclear power generation is

controversial

Typical nuclear plant

Typical nuclear engineer

Three Mile Island

Yes, they built it in the middle of a river

Susquehanna River

That’s the Chesapeake Bay

Nuclear reactor

15 million people live around the Bayor, about 4 Coloradoes

Modern Solar Technologies Solar Cells

Polycrystalline compounds that generate electricity when exposed to light Power Tower

Steam produced by focused sunlight generates electricity Passive Applications

Natural energy flow without mechanical devices Active Applications

Solar collector; sunlight heats air or liquid material Wind Energy

Sunlight differentially heats earth’s surface creating winds Wind then generates electricity

Biomass Utilizes material formed by photosynthesis

Agriculture and Industrial Heating Utilizes sunlight rather than traditional energy sources

Ocean Thermal Energy Conversion (OTEC) Generates electricity form the temperature difference between water depths

Geothermal Energy Energy from beneath the earth’s surface

Dry steam Hot water Hot dry rocks Geopressured resources

Difficulty in obtaining and economically utilizing

Hydrogen Used directly in fuel cell or burned to

release heat Produces no pollutants

Only emission is water

Problem is that hydrogen does not exist on or under earth’s surface in usable amounts Must be obtained from chemical reaction