− | The main sources of energy at the beginning of the 21st century are divided into two types: nonrenewable ([[Oil as an energy source|oil]], [[natural gas]], [[coal]], [[tar sands]], [[oil shales]]) and renewable ([[nuclear]], [[hydroelectric]], [[geothermal]], [[solar]]). | + | The main sources of energy at the beginning of the 21st century are divided into two types: nonrenewable ([[Oil as an energy source|oil]], [[natural gas]], [[coal]], [[tar sands]], [[oil shales]]) and renewable ([[nuclear power|nuclear]], [[hydroelectric]], [[geothermal]], [[solar]]). |
| Sources of energy used by mankind have changed widely. Similar changes should be expected in the future. [[:file:AAPGSt54Figure1.JPG|Figure 1]] depicts the changes of energy sources over a 150-year period. | | Sources of energy used by mankind have changed widely. Similar changes should be expected in the future. [[:file:AAPGSt54Figure1.JPG|Figure 1]] depicts the changes of energy sources over a 150-year period. |