Can you solve this puzzle?

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Across
  1. 3. The scottish physicist that discovered the term of potential energy
  2. 5. Vietnam's largest energy source
  3. 8. What is the UN agency for renewable energy?
  4. 10. Most used non-renewable energy in the world
  5. 13. What country uses the most energy?
  6. 14. Most used energy in the world for electricity
  7. 15. The earliest source of energy used by man was...
Down
  1. 1. Natural gas is transported mainly by....
  2. 2. The energy that comes from a source that won't run out
  3. 4. The energy from the sum of potential and kinetic energy
  4. 6. The person who discovered the concept of energy
  5. 7. The purest source of energy in the world
  6. 9. The least popular source of energy in U.S
  7. 11. A loudspeaker converts electrical energy into ... energy
  8. 12. A form of renewable energy that is made from biomass