1. Energy Sources 1

2. Law of energy conservation
The law of conservation of energy states that energy may neither be created nor destroyed. 
Energy in a system may take on various forms (e.g. kinetic, potential, thermal, light, etc.).  
The sum of all the energies in a system is constant.  Energy in a system is continuously changing from one form to another. 2

3. Earth's Energy Sources
The earth has two basic sources of energy.  Energy from the sun that reaches the surface of the earth is called external energy.  Energy that reaches the surface of the earth from the core is called geothermal or internal energy. 3

4. Earth's Energy Sources (con’t)
Geothermal or Internal Energy Sources (0.1%)
- is generated within or because of the earth
- heat from the core (gravitation compaction)
- radioactive decay
Solar Radiation or External Energy Sources (99.9%)
  - 40% of light that reaches earth is reflected back into space by the atmosphere and oceans.
- some is used by plants in photosynthesis
- some is absorbed by the atmosphere, lithosphere, and oceans and eventually released back into space. 4

5. Renewable Vs. Nonrenewable Energy Sources 5

6. Renewable Energy Resources6

7. Geothermal Energy - Is thermal energy that is stored in the Earth
Geothermal Energy - Is thermal energy that is stored in the Earth.  Geothermal energy comes from several sources; the formation of the Earth, radioactive decay, volcanic activity, etc. 7

8. Solar Energy - Is energy that is produced by the sun and is captured by humans.  There are several types of solar driven energy systems; solar hot water, solar thermal electricity, and solar cells (photovoltaic arrays)
Solar hot water            Solar thermal electricity              Solar cells (PV) 8

9. Biomass - Is organic matter that has stored energy through the process of photosynthesis. Biomass can take many forms such as: plants, animals that acquired energy through food chains/food webs, as well as the waste products of those animals.  The energy is released through combustion (or burning).  Combustion also releases the carbon dioxide that was stored in the original plant materials. 9

10. Water Energy -
Hydroelectric power uses the kinetic energy of the moving water to create electricity. 10

11. Wind Energy
Uses a device to convert kinetic energy from wind to mechanical energy. The mechanical energy is then converted to electricity. 11

12. Nonrenewable Energy Resources12

13. Oil (petroleum)
Oil is a kind of fossil fuel, a source of energy that comes from the remains of plants and animals that died millions of years ago.  These remains experienced great heat and pressure from the layers of sand and silt that were deposited on them over millions of years, as a result the plant and animal materials  were converted into crude oil. 13

14. Natural Gas
Is a combustible mixture of Hydrocarbon gases that is formed by methanogenic organisims in marshes, bogs, and landfills or by organic material that is deep in the earth, and has been exposed to great heat and pressure over millions of years. 14

15. Coal
Is a type of sedimentary rock that is combustible.  Coal is made of mostly carbon and some other elements.  Coal is the most abundant of all the fossil fuels.  It is formed from stored energy in plants. There are different types of coal. 15

16. Nuclear energy - Nuclear energy is energy in the nucleus of an atom
Nuclear energy - Nuclear energy is energy in the nucleus of an atom. There are two types of nuclear energy: fission and fusion. The fuel most widely used by nuclear plants for nuclear fission is uranium. Uranium is nonrenewable, though it is a common metal found in rocks all over the world. Nuclear plants use a certain kind of uranium, referred to as U-235. This kind of uranium is used as fuel because its atoms are easily split apart. 16

17. Sources
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