| A | B |
|---|
| Wind power | Fastest growing energy source in the world |
| biomass fuels | consist of plant material burned for fuel |
| the sun | where all energy ultimately comes from |
| passive solar heating | use of sunlight to heat buildings directly |
| active solar heating | gathering solar energy by collectors to heat a home with water |
| photovoltaic cells | found on some calculators |
| oxygen | comined with hydrogen to form water in fuel cells |
| energy effeciency | percent of energy that does useful work |
| energy conservation | process of saving energy by using less of it |
| fossil fuel | nonrenewable resource formed by organisms long ago |
| coal | formed in the Earth's crust by dead plants millions of years ago |
| surface coal mining | removing top layer of earth's crust for coal |
| nuclear fission | splitting of a nucleus |
| nuclear fusion | combination of atoms to form one nucleus |
