Chemical energy is produced through the process of photosynthesis. Plants grow by using the energy in light to build organic molecules out of CO2 from the air and H2O from the ground. Energy sources that originate from this process are called organofuels.

1. 0.3% of the energy that hits the earth is captured by plants.

2. Fossil fuels are the most common source of energy in our society. We use them to produce our electricity, drive our cars, and heat our homes.

3. Coal, petroleum, and natural gas are all fossil fuels. That means they come from the remains of living organisms that have been trapped underground for millions of years.

4. Fossil fuels can be burned. The heat released can be used directly, or it can be used to heat water. The steam from the hot water can be used to turn a turbine and produce electricity. This is how most of our electricity is produced.

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5. There is a limited amount of fossil fuel stored in the earth. We are currently using this reserve faster than it can be replaced. Because of this we call fossil fuels non-renewable. Energy sources that can be generated at the same rate that we use them are called renewable.

6. Plants and animals are in a dynamic relationship. The oxygen we breathe in the air is a by-product of the process of photosynthesis. So, we depend on plants both for our food (energy) and our air (oxygen). Plants depend on us too. Animals breathe in oxygen, and breathe out carbon dioxide (CO2). Plants get CO2 from the air and use that for photosynthesis. When we burn fossil fuels (by driving our cars or generating electricity), CO2 is released into the atmosphere. If we produce too much CO2 by burning too much fossil fuel, we may disrupt the balance between plants and animals.

7. It takes approximately one pound of coal to produce one-kilowatt hour (KWH) of electricity. This process releases about two pounds of CO2 (global warming) into the atmosphere, and uses 0.7 gallons of water. Sulfur dioxide (acid rain), nitrogen oxide (smog), and mercury contamination (polluting air and water) are all products of conventional electricity generation. The mining and transportation of fossil fuels also affects the environment. The cost of the pollution produced is not part of electric utility bills or part of the cost of gasoline, and so it is called a hidden cost. Hidden costs are paid for indirectly through taxes and a reduction of environmental quality.

8. There are other types of fuel available from the energy stored in plants through photosynthesis. These are called biomass fuels. Burning wood is the main source of energy in many developing nations.

9. Bioconversion is another way to obtain energy from plants. Some plants (sugar cane for example) can be used to make a type of alcohol called ethanol. Ethanol can be mixed with gasoline and used as a fuel in automobiles.

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