The U.S. energy mix is changing.
A decline in coal use exceeded the combined increases in natural gas, petroleum, and renewables use from 2014 to 2015 reflecting a long-term decline in usage of the fuel.
Natural gas consumption increased most out of all sources on record domestic production levels that have kept natural gas prices low. The existence of a cheap substitute like natural gas has precipitated the fall in coal usage in the electric power sector, the primary consumer of coal. In 2015, demand for coal in the power sector reached its lowest level since 1987
A vast majority of the gains in natural gas production come from shale gas and tight oil plays from deposits unlocked by hydraulic fracturing (fracking).
The EIA estimates that natural gas production from shale and tight oil will increase steadily at the expense of traditional sources for decades to come.
Both wind and solar generation expanded significantly, growing by 31% and 5%, respectively, in 2015.
Wind additions were focused primarily in the Great Plains region with Texas installing a majority of new capacity. Solar additions were concentrated in California and North Carolina though only California saw a relatively significant increase in distributed solar capacity.