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 CO2 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