Energy flow in the US
Note that 68.2% of the energy generated is lost as heat or in transmission. A similar figure (66.4%) applies to electricity generation alone, which remains dominated by thermal production (natural gas, coal, and nuclear), in which only around one-third of the energy contained in the source is converted to electrical energy.
It should be noted that production from intermittent sources, i.e., wind and solar, represents only a fraction of the turbine or panel’s capacity. A wind turbine, for example, generates electricity at an annual average rate of 25%–35% of its capacity. And it generates at or above its average rate only 40% of the time.