Our Energy Budget
Earth's Energy BudgetThe total energy from the sun that reaches the upper atmosphere is approximately 54.4 x 1020 kJ per year. Nearly all of this is either reflected for radiated back into space. The picture below from the National Oceanic and Atmospheric Administration shows the solar energy budget.
Solar energy warms the land, ocean, and the atmosphere. A very small amount of the solar energy reaching the Earth is converted into electricity through photovoltaic cells. These are devices that use silicon or other materials to convert sunlight directly into electricity.
Indirectly, the sun is the source of:
There are some non-solar energy sources as well.
US Energy UseThe US Energy Information Administration provides an annual energy review. Below is there latest data on energy in this country. It shows the source of energy and use of that energy. The units are quadrillion BTU with a total of 94.6 quadrillion BTU for 2009.
Petroleum provides 94% of energy for transportation but only about 1% for electricity. In the US as a whole, electric power comes from coal, nuclear energy, natural gas, and renewable energy. Hydroelectric power makes up most of the renewable energy electricity. In Illinois, nearly half of our electricity is from nuclear power and most of the rest is from coal-burning power plants.
In the graph below you can see how energy sources in the US have changed over time. The fossil fuels (coal, natural gas, and petroleum) remain our largest source of energy.