General considerations 2
U.S. energy consumption by sectors.& 2
Fossil fuels 4
Non-conventional oil 5
Non-conventional natural gas 5
Nuclear power 5
Renewable energy 7
Energy storage and transportation fuel 9
All the energy we consume is generated by using the four fundamental interactions of nature: gravity, electromagnetism, the weak nuclear force and the strong nuclear force to create work. Fission energy and fusion energy are generated by electromagnetism and the strong nuclear force. Most forms of terrestrial energy can be traced back to fusion reaction inside the sun, with the exception of tidal power, geothermal energy and nuclear power. Geothermal energy is believed to be generated primarily by radioactive decay inside the Earth. Radioactive decay energy is generated by both the weak nuclear force and electromagnetic force. Tidal energy comes from the gravity energy and kinetic energy of the Earth/Moon system.
Most human energy sources today use energy from sunlight, either directly like solar cells or in stored forms like fossil fuels. Once the stored forms are used up (assuming no contribution from the three previous energy sources and no energy from space exploration) then the long-term energy usage of humanity is limited to that from the sunlight falling on Earth. The total energy consumption of humanity today is equivalent to about 0.1-0.01% of that. But humanity cannot exploit most of this energy since it also provides the energy for almost all other lifeforms and drives the weather cycle
U.S. energy consumption by sectors.
World energy production by source: Oil 40%, natural gas 22.5%, coal 23.3%, hydroelectric 7.0%, nuclear 6.5%, biomass and other 0.7%. In the U.S., transportation accounted for 28% of all energy use and 70% of petroleum use in 2001; 97% of transportation fuel was petroleum