Chapter 9 Energy Sources Section 1 Fossil Fuels

How Often do you Use energy??

Can energy be created or destroyed?? No It can only be converted to different types of energy

Name one example of how energy is transformed.

Energy Usage in the U.S. 37% is used by industry and agriculture to manufacture products and produce food 27% is used for transportation 20% is residential related (heating, cooling, appliances in homes) 16% is business related

Sources of Energy in U.S. 85% comes from burning petroleum, natural gas, and coal The other 15% comes from nuclear, hydroelectric, and biomass etc.

Fossil Fuels These are formed from the decaying remains of ancient plants and animals Examples: Coal, petroleum (or oil), and natural gas

The energy in fossil fuels Which do you think has more chemical potential energy: Coal or Wood??

Petroleum Very Flammable! Mixture of mainly carbon and hydrogen

Fractional Distillation Occurs in oil refinery plants Crude oil is heated in the tower Some of the chemicals boil and vaporize to the top and are collected The others like asphalt and waxes remain liquid and are drained off

What are uses for petroleum?

Natural Gas Composed mostly of methane Use in a stove, furnace, hot-water heater, or a clothes drier

Coal Solid fossil fuel 90% of all coal in U.S. is burned by power plants to generate electricity

Chapter 9 Energy Sources Section 2 Nuclear Energy

Nuclear Energy Over the past decades, power plants that do not burn fossil fuels have been developed Nuclear plants convert nuclear energy  electrical energy

Called nuclear fission: Nucleus of atom splits

Nuclear Energy Nearly 20% of electricity in the U.S. comes from nuclear power plants In 2003, there were 104 nuclear reactors producing electricity in 65 nuclear plants in U.S.

Nuclear Reactor Uses the energy from controlled nuclear reactions to generate electricity Fig. 12 on p. 265

Parts of a Nuclear Reactor Fuel Undergoes nuclear fission

Parts of Nuclear Reactor 2. Control Rods Control nuclear reactions

Parts of Nuclear Reactor 3. Cooling System Keeps the reactor from getting to hot and being damaged.

Parts of Nuclear Reactor 4. Core Where fission takes place.

What is Nuclear Fuel?? Only uses certain elements Uranium isotope: U-235 Most commonly used Naturally occurring uranium must be enriched so that it will contain more of the U-235 isotope.

What is Nuclear Fuel?? The uranium dioxide is in pellet form (about the size of your pencil eraser) These pellets are placed end to end in a long tube Several hundred tubes are bundled together and placed in the reactor’s core

What is Nuclear Fuel?? One reactor contains about a hundred thousand kilograms of uranium For energy kilogram of uranium that undergoes fission, 1 g of matter is converted into energy Equal to burning over 3 million kg of coal!!

Nuclear Fission The uranium-235 nuclei decay which releases neutrons These neutrons are absorbed by other U-235 nuclei which causes them to split into two separate nuclei that release more neutrons The process then repeats

Controlling the Reaction The reaction must be controlled or it will release energy in explosive amounts

Controlling the Reaction This is where the control rods come in Made of boron or cadmium Absorb some of the neutrons

Nuclear Power Plants The heat produced during the fission process heats water and produces steam

Nuclear Power Plants Steam turns turbine Rotates electric generator

Nuclear Power Plants And then like magic, BAAM! Electricity!

What about the Risks?? Although it doesn’t release harmful air pollutants, nuclear power can be harmful

Risks The water must be cooled before being released back into the environment

Risks Elements used are very radioactive Could damage any living organism

Examples of Accidents Occurred in 1986 in Chernobyl, Ukraine A reactor core overheated and caught fire which led to an explosion that destroyed the building’s roof Radioactive material were carried via wind over a large area 28 people died from radiation sickness and over 260,000 other may have been exposed

Disposal of Nuclear Waste After three years the spent fuel (uranium) must be disposed of

Low Level Waste Can be sealed in containers and buried 30 m deep in special locations Examples: Clothing, air filters smoke detectors

High Level Waste Stored in deep pool of water to absorb the nuclear radiation. They are placed in ceramic glass and sealed off in metal-alloy containers. Buried in stable rock formations or salt deposits hundreds of meters below the ground.

Chapter 9 Energy Sources Section 3 Renewable Energy Sources

Energy Options More fuel is needed but fossil fuel is decreasing Nuclear Reactors produce too much radioactive waste

Renewable Resource Energy source that can be replaced after use Alternative energy source

Sun’s Energy Solar Energy Devices use photovoltaic cell- converts radiant energy  electrical energy A.K.A. Solar Cells

Energy from Water Uses moving water to turn a turbine and rotate an electric generator Dams built for this are hydroelectric dams

Energy from Water Hydroelectricity- electricity from energy of moving water Supplies 8% in U.S.

Disadvantage of Hydroelectric Dams Disturbs balance of natural ecosystem Blocks fish migration Location far from regions that need power

Wind Energy Use energy of wind to turn propeller Propeller spins electric generator Produces electricity

Advantages of Wind Energy Do not consume nonrenewable resources Do not pollute the atmosphere or water

Disadvantages of Wind Energy Not everywhere has enough wind Only 20% efficient Noisy and change landscape Disrupt migration patterns of birds

Geothermal Energy Thermal Energy from hot magma Used to generate electricity

Geothermal Power Plants Drill well and pump in water Magma heats and turns to steam Steam returns and spins turbine

Geothermal Power Plants 16% efficient Releases some sulfur compound containing gases Limited supply

Alternative Fuels Cars with electric motors Biomass fuel- organic matter wood, sugarcane fibers, rice hulls, and animal manure