The use of hydrogen fusion to supply energy is a dream that might be realized in the next century. This represents a relatively clean and almost limitless supply of energy. For example, there is enough hydrogen in the ocean to create 1034 J of energy via fusion.
Q: Compute how many years the energy needs of the world could be supplied with one millionth of the oceans’ hydrogen fusion energy, assuming the future world will use 9 times the energy we do now (the world's yearly energy usage now is around 4 × 1020 J).