Energy

Motion, position and energy Work and energy related Energy = ability to do work Work = process of changing energy level

Energy forms Mechanical 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

Susquehann a River That’s the Chesapeake Bay Nuclear reactor 15 million people live around the Bay or, 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