Across
- 6. percentage of energy that is actually used to perform work
- 7. another name for oil
- 8. electricity produced by flowing water
- 9. energy from the sun
- 11. mixture of methane and other gases
- 12. intense heat from Earth's interior that warms the magma
- 13. central core of an atom that contains the protons and neutrons
- 15. a change from one form of energy to another
- 19. can be replenished in a relatively short time
- 20. the energy-rich substances formed from the remains of organisms
- 22. blocks the flow of water
- 23. chemical compounds that contain carbon and hydrogen atoms
- 25. layer of material that traps air to help block the transfer of heat between the air inside and outside a building
- 27. made of living things
- 29. substance that provides energy as the result of a chemical change
Down
- 1. part of the nuclear reactor where nuclear fission occurs
- 2. a factory where crude oil is heated and separated into fuels and other products
- 3. two hydrogen nuclei are forced together
- 4. transport natural gas from its source to the places it is used
- 5. compounds that are made from oil
- 6. reducing energy use
- 10. splitting of an atom's nucleus into two smaller nuclei
- 14. rows of mirrors focus the sun's rays to heat a tank of water, making steam for electricity
- 16. when fuel rods generate so much energy that they start to melt
- 17. can be replenished but only in a long period of time
- 18. made of metal cadmium; placed in between fuel rods to absorb excess neutrons
- 21. when oil is first pumped from the ground
- 24. fuels contain stored chemical energy, which is released by this
- 26. adding alcohol to gasoline
- 28. rods of U-235