"Changes in the fuel mix and improvements in electricity generating technology have also led the power sector to produce electricity while consuming fewer fossil fuels," its report read.
EIA anticipates a 29 percent share for coal in total electricity generation in both 2018 and 2019, down from the 30 percent last year. The share for natural gas, meanwhile, grows from 32 percent last year to 34 percent through 2019.
For renewables, save hydroelectricity, the share was slightly less than 10 percent last year and grows to nearly 11 percent next year.
Coal consumption in the power sector last year was at its lowest level since 1982. More coal was consumed than natural gas in the power sector, but gas-fired plants generated slightly more power than coal-fired ones because they're slightly more energy efficient.
The changing energy mix, meanwhile, is impacting levels of greenhouse gas emissions like carbon dioxide.
"Because coal combustion is much more carbon intensive than natural gas combustion, CO2 emissions from coal were more than double those from natural gas in 2017, even though natural gas provided more electricity generation," EIA's report read.
The change means total CO2 emissions from the nation's power sector were at their lowest level since 1987.
The U.S. government estimates the world total of technically recoverable shale gas reserves is enough to meet 60 year's worth of total global consumption. About half of that total is in five countries, with the United States in the leadership position.
A recent report from the U.N. Conference on Trade and Development said natural gas could contribute to a "smooth transition" to a low-carbon economy because it emits 40 percent less carbon dioxide per unit of energy produced than coal.
The main greenhouse component of natural gas, however, is methane, which is far more potent than CO2.
Beyond emissions, UNCTAD's report said hydraulic fracturing processes use large volumes of water and carry with them risks of groundwater or surface water contamination.
UNCTAD Secretary-General Mukhisa Kituyi said shale gas is attractive now, but countries looking to capitalize on the resources should understand the pros and cons.