ALTERNATIVE ENERGY AND CONSERVATIONEnvironmental Science

Chapter 18 Section 2

Alternative Energy• Energy sources that are still in development.

• In order to become a viable option for the future, the source must be proven to be cost effective.

• Government investment is often the only way to research some of these.

Tidal Power• A tidal power plant works much like a hydroelectric dam.

• Tide rises water flows behind the dam.• Sea level falls water is trapped behind the dam.• Water is released turns a turbine that generates electricity.

• Expensive to build and very few suitable locations to put them.

Ocean Thermal Energy Conservation• In the tropics, the temperature difference between the

surface of the ocean and deep ocean waters is as much as 24 degrees C.

• Example: off the shore of Hawaii• Uses temperature difference to generate electricity.• Ocean thermal energy conversion (OTEC).

• Use surface water to boil sea water.• Turbine runs an electric generator.

Hydrogen – A Future Fuel Source?• Hydrogen is the most abundant element in the universe.

• It can be burned as a fuel.

• It is found in every molecule of living things and in water.

• No pollution is released when burned.

Hydrogen – A Future Fuel Source?• The Challenge of Hydrogen Fuel

• Two main problems:• Current methods used to produce hydrogen are not very efficient. They

require a lot of energy, are expensive, and cause pollution.• A lot of hydrogen is needed to produce the same energy as a tank of

gasoline.

Hydrogen – A Future Fuel Source?• Fuel Cells

• Produces electricity chemically, by combining hydrogen fuel with oxygen from the air.

• Water is the only byproduct.• Can be fueled by anything that contains plenty of hydrogen,

including natural gas, alcohol, or even gasoline.

Energy Efficiency• The percentage of energy put into a system that does

useful work.

• More than 40% of all commercial energy used in the U.S. is wasted.• Most is lost from inefficient fuel-wasting vehicles, furnaces, and

appliances.• Some lost from leaky, poorly insulated buildings.

Energy Efficiency• Efficient Transportation

• The design of the internal combustion engine has hardly changed since 1900.

• May change radically in the next 50 years.• Gasoline prices in the U.S. have been so low that there is little

motivation to make cars more efficient.

Energy Efficiency• Hybrid Cars

• Examples of energy-efficient vehicles.• Use a small, efficient gasoline engine most of the time, but also use

an electric motor when needed.• Cost less to refuel.• Fewer harmful emissions.

Cogeneration• The production of two useful forms of energy from the

same fuel source.

• Example• The waste heat from an industrial furnace can power a steam

turbine that produces electricity.• Can then be used or sold to an electricity company.

Energy Conservation• Saving energy.

• Can occur in many ways:• Using energy-efficient devices.• Wasting less energy.

Energy Conservation• Cities and Towns Saving Energy

• Osage, Iowa• Saves more than $1 million each year.• Plugged leaks around windows and doors.• Replaced inefficient furnaces.• Insulated hot water heaters.

Energy Conservation• Conservation Around the Home

• Best way is to add insulation around the home to reduce energy loss.

• Most common areas are doors and windows.

Energy Conservation• Conservation in Daily Life

• Use less resources.• Washing clothes in cold water uses 25% of the energy needed to

wash clothes in warm water.