Chapter 18 crossword puzzle

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Across
  1. 8. organic material that comes from plants and animals.
  2. 9. a cell producing an electric current directly from a chemical reaction.
  3. 10. the use of the sun's energy directly for either heating or cooling purposes.
  4. 11. energy generated in ways that do not deplete natural resources or harm the environment, especially by avoiding the use of fossil fuels and nuclear power.
Down
  1. 1. a form of renewable energy that uses the power of moving water to generate electricity.
  2. 2. prevention of the wasteful use of energy, especially in order to ensure its continuing availability
  3. 3. use of less energy to perform the same task or produce the same result.
  4. 4. a process or technology for producing energy by harnessing the temperature differences.
  5. 5. use of solar energy to heat a fluid -- either liquid or air -- and then transfer the solar heat directly to the interior space or to a storage system for later use.
  6. 6. type of renewable energy taken from the Earth's core.
  7. 7. energy from a source that is not depleted when used, such as wind or solar power.