13. Scientists are trying to find other alternative sources of energy.
14. One percent of the solar energy reaches to the earth is enough to provide the power for the total population.
15. Viet Nam can be an advanced technology in solar energy.
16. The energy can be stored a number of days.
17. Car will use solar energy instead of gas by the year 2030.
18. Energy from the wind has been used for centuries to move ships, grind grain, pump water and to do other forms of work.
19. On cloudy days you can use solar energy too.
20. Almost all our energy comes from oil, coal, and natural gas. We call them fossil fuels.
