Ch. 18.1 Renewable Energy Today

A. Renewable Energy Energy from sources that are constantly being formed. Life on Earth has always been powered by renewable energy – the sun!

A. Renewable Energy Other forms of renewable energy: wind, biomass, moving water, Earth’s heat.

B. Solar Energy Passive solar heating – uses the sun’s energy to heat something directly (i.e. sunlight coming through windows).

B. Solar Energy How? Homes positioned according to the yearly movement of the sun benefit most from passive solar energy.

B. Solar Energy Active solar energy – Sun’s energy is gathered by collectors and used to heat water or to heat a building.

B. Solar Energy Photovoltaic Cells – solar cells, often placed on roofs, that convert the sun’s energy into electricity. Also used in calculators and to power the space station.

C. Wind Energy Wind farms – large arrays of wind turbines, such as in California. Turbines spin, and this mechanical energy is converted into electrical energy.

C. Wind Energy The windiest spots on Earth could generate more than 10x the energy used worldwide.

C. Wind Energy Some farmers place 1 or 2 windmills on their land and then sell the electricity it produces to the power company!

D. Biomass Power from organic (living) things, such as plant material and manure. Methane – gas produced from decomposing organic wastes. Can be burned to generate heat.

D. Biomass Alcohol – liquid fuels derived from biomass. Ex. Ethanol – produced from corn and currently used as an alternative to gasoline in the Midwest.

E. Hydroelectricity Hydroelectric Dams – accounts for 20% of the world’s energy, making power affordable and renewable.

E. Hydroelectricity Benefits: Inexpensive to operate No air pollution

E. Hydroelectricity Disadvantages: Creates a reservoir, flooding the land, and possibly displacing people from their homes Can disturb ecosystems downstream

E. Hydroelectricity Micro-hydropower: Used in developing countries Floating turbines used in small streams

F. Geothermal Energy Power from the Earth’s heat – used to heat water and form steam, which turns a turbine, thereby producing electricity.