Coal and natural gas-powered electrical generation trend lines.

(Chart courtesy U.S. E.I.A.)

Natural gas-powered electricity surpassed coal-generated electricity for the first time in the United States during the month of April, according to new figures from the U.S. Energy Information Agency.

But the report cautions that the numbers only represent one month, and that the month in question, April, is " traditionally the month when total electricity demand is lowest." Plus, "Monthly coal-fired generation is expected to continue exceeding natural gas-fired generation for the remainder of 2015." Still:

On an annual average basis, coal has lost generation share to natural gas and, to a lesser extent, renewables. The current downward trend in coal-fired generation began in 2007, when increased U.S. production of natural gas (particularly from shale) led to a sustained downward shift in natural gas spot prices and increased generation from natural gas-fired generators.