1. ALCOS: 11

5. Pros: 1. One of the best things about solar energy is that it doesn’t produce pollution. 2. Solar energy is renewable, because it comes from the sun. Cons: 1. Some climates don’t have enough sunny days to benefit from solar energy. 2. Although solar energy is free, solar cells and solar collectors are more expensive to make than other energy systems. 3. The cost of installing a complete solar-power system in a house can be one third of the total cost of the house.

7. Humans have used the energy of falling water for thousands of years. One example is a Water wheel. Water wheels were used to provide power to run factories and grind grain for things like bread. Humans have used the energy of falling water for thousands of years. One example is a Water wheel. Water wheels were used to provide power to run factories and grind grain for things like bread. Electrical energy produced by falling water is called Hydroelectric energy. Electrical energy produced by falling water is called Hydroelectric energy.

8. Pros: 1. Inexpensive 2. Causes little pollution 3. Is renewable Cons: 1. Not available everywhere. 2. Can only be produced when large volumes can be harnessed. 3. Building large dams can often destroy other resources such as forests & wildlife habitats. Examples are destroys migratory birds path and fish such as salmon can’t swim up stream to spawn. 4. Dams can also decrease water quality and create erosion.

10. There are two methods through which we can obtain energy from plants. 1. Biomass 2. Gasohol (Ethanol Gasoline)

11.  Biomass (organic matter) can be ◦ Uses:  Heat  Fuel  Generate electricity All this is called bioenergy. Wood, the largest source of bioenergy, has been used to provide heat for thousands of years, but there are many other types of biomass - such as plants, residue from agriculture or forestry, and the organic component of municipal and industrial wastes - that can now be used as an energy source.

12.  Biomass can be converted directly into liquid fuels for our transportation needs.  The two most common biofuels are ethanol and biodiesel.

15.  The energy produced by the heat within the Earth is called Geothermal energy.  In some areas, groundwater is heated by magma, or melted rock.  Holes can be drilled through rock and we can harness the power from the steam released.

16.  Geothermal power plants can harness the energy within the Earth by pumping the water/steam from within the Earth through generators that produce electricity.  The world’s largest geothermal power plant is in California and is named The Geysers.  This power plant produces electrical energy for 1.7 million homes.  Geothermal energy can also be produced on a smaller scale for individual homes.