Renewable Energy

Alternative Energy & Conservation

Chapter 18

Section Two

Alternative Energy

• Energy sources that are still in development

• For future use, it must be cost effective

• Environmental effects must be acceptable

• Research is often government funded

Tidal Power

• Using the rise and fall of the oceans to generate power

• Twice daily event caused by sun, moon and Earth’s gravitational attraction

• Works much like a hydroelectric dam

• High cost to build and maintain

• Few suitable locations in the world

Tidal Power

Ocean Thermal Energy Conversion

• Based on difference between surface and deep-ocean water temperatures

• Generation process uses up to 1/3rd of the energy produced

• Environmental effects are unknown

• One experimental power station in Hawaii

• Fresh water is a byproduct

Hydrogen – a Future Fuel Source

• H can be burned as a fuel with no pollutants released into the air.

• It combines with oxygen to produce water vapor• Takes large amounts of energy to produce the

hydrogen in the amounts needed• Fuel Cells may be the engine of the future,

electricity comes from combining hydrogen with oxygen

Energy Efficiency

• Percentage of energy put into a system that does useful work

• EE = energy out/energy in x 100

• Most devices are very inefficient

 

Device Efficiency %

Incandescent light bulb

5

Fluorescent light bulb

22

Internal combustion engine

10

Human body 20 – 25

Steam turbine 45

Fuel cell 60 

Cogeneration and Conservation

• Cogeneration – production of two useful forms of energy from the same fuel source

• Energy Conservation – saving energy– Bicycling

– Carpooling

– Public transportation

– Plug air leaks in houses

– Energy efficient furnaces and windows

– Increased insulation