Fossil fuels are formed  from the remains of plants and animals over millions of years.  Coal, petroleum, and natural gas are fossil fuels.

What can we do to conserve fossil fuels?  What would do if we used them up?

Alternative energy resources

Demand for oil has doubled every 20 years since 1900 due to increased population and increase of energy using devices.

Our reserves of fossil fuels are being used up.

The alternatives are:
Wind energy - it's clean, it's free, but wind doesn't blow constantly so there are few locations which could use wind.

Geothermal energy - heat from within the earth.  It can only be used in areas with past or present volcanic activity.

Water or hydroelectric energy - It is non-polluting, but expensive to build.   It also changes ecosystems.

Tidal energy - can only be used in a few places in the world

Nuclear energy - radiation is dangerous, waste products produced are dangerous

Solar energy - energy from the sun, it's free, non-polluting