SOURCES OF ENERGY

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Across
  1. 2. Hydroelectric power factories generate about 19 percent of the world's electric power. Such factories convert the energy of falling ... into electric energy.
  2. 4. Plants are renewable resources because plants might get cut down, but they can ... back.
  3. 5. We use forms of ... to operate machinery, to heat and cool our homes and offices, to provide light and to transport people and goods.
  4. 7. ... power plants use steam from the depths of the earth to run turbines that drive electric generators.
  5. 8. Hydroelectric power factories cost less to operate than fossil-fuelled ones and do not ... the air.
  6. 10. The earth contains only a limited supply of ... fuels such as coal, petroleum and natural gas.
Down
  1. 1. Soil can be considered as a renewable ... because crops can be grown on the same land for years if the soil is cared for properly.
  2. 3. There are different kinds of natural resources. Some of them are ... and some are non-renewable.
  3. 6. One day, these limited sources of energy will run out and will not be replaced, so scientists and governments are working to ... other infinite sources of energy such as solar energy or wind power.
  4. 9. Fossil fuels come from plants and animals that ... millions of years ago.