Energy Energy- the capacity to do work –Work- force through a distance Joule- amount of work done –4 Joules = 1 calorie –Calorie- energy to heat 1 g of water 1°C

Power Power- rate of energy flow Watt- measure of power –Kilowatt-hour (kwh) 1000 watts exerted for 1 hour.

World Energy Consumption

Per Capita Consumption 20 Richest Countries Consume –80% of natural gas –65% of oil –50% of coal U.S. and Canada consume 25% of available energy

How We Use Energy

Fossil Fuels Buried organic matter compressed over millions of years Lead to global warming Examples –Coal –Oil –Natural Gas

Making Fossil Fuels

Coal Pro –Vast Reserves Con –Very dirty –Destructive Extraction

Coal-fired Power Plant

Mining for Coal

A Strip Mine

Oil 600 Billion metric tons –½ is recoverable –Gone in 30 years In 2000, proven reserves = 650 billion barrels –Mostly in Middle East Problems –Contains high sulfur –3-6 million metric tons in ocean/year

Oil Reserves

Refining Oil

Hubbert’s Peak

Modern Prediction

Natural Gas Third largest commercial fuel Only ½ CO 2 as oil Difficult to store and transport Could last 60 years

Nuclear Power Derived from splitting atoms Relatively cheap energy Problems –Radiation kills –Nuclear waste

Nuclear Fission

Nuclear Reactor

“Renewable” Energy

Renewable as Part of the Whole

Solar Energy Using energy from the sun to do work Very little waste

Passive Solar

Solar Oven

Active Solar

Photovoltaic Cells

Fuel Cells Use electrochemical reactions to produce electricity Hydrogen is hard to store and transport About as efficient as the best fossil fuel engines

A Fuel Cell

Hydrogen Car

Biomass Wood and other plant matter Burns much cleaner than fossil fuels Renewable fuel source 40% of world’s population uses wood –Leads to deforestation

Hydropower Falling water has a lot of energy In 1925, 40% of world’s energy came from hydropower Totally destroys ecosystems

Hydroelectric Dam

Wind Energy Pros –Very Clean –Very Abundant Cons –Requires expensive storage

U.S. Wind Potential

Wind Generator

Renewables

Geothermal, Tidal and Wave Energy Geothermal –Only useful in a few places Tidal and Wave Energy –Lots of energy, but very hard to harness –Potentially huge environmental impacts

Geothermal Energy

Wave Energy