U.S. carbon dioxide emissions fell to a new 25-year low during the first six months of 2016, helped in large part by power plants switching from coal to natural gas and renewable sources of electricity, according to a Wednesday report by the U.S. Energy Information Administration.

Mild weather also played a role. Many regions across the country experienced higher-than-normal temperatures last winter, which reduced demand for heating fuels, the agency said.

Energy-related carbon emissions in the first half of the year were 2.53 billion metric tons, the lowest since the same period in 1991. Full-year emissions for 2016 are on pace to be 5.18 billion metric tons, which would be the lowest on record since 1992, according to the latest federal projection.

The numbers mean the U.S. is on track to reduce energy-associated carbon emissions by at least 1.5% this year compared with a 3% drop last year.

"They're not huge decreases, but our carbon intensity is going down as a nation," said Allen McFarland, an analyst with the U.S. Energy Department. "Carbon intensity has been generally falling since 2005."

Natural gas and coal are burned to generate electricity, but gas produces roughly half the carbon emissions of coal. Advanced production techniques applied to wells from Texas to Pennsylvania have unleashed abundant gas reserves, pushing down the cost of the fuel.

During the first half of the year, total U.S. energy consumption fell 2% compared with the same period in 2015. The decrease was especially notable among residential power users, with consumption falling 9%.

One big driver is the nation's steady march toward greater energy efficiency. Revamped federal standards have reduced energy consumption for everything from lightbulbs and refrigerators to industrial motors. State-level carbon-reduction goals are also pushing companies to make products that consume less energy, especially when in standby mode.

California, for example, recently proposed the nation's first energy-efficiency standards for computers and monitors after finding they are responsible for 7% of commercial electricity use and 3% of home power use. The new requirements, expected to be adopted by year's end, would go into effect in 2019.

A shift toward renewable energy also helped reduce carbon dioxide, the greenhouse gas linked to climate change. Wind, solar and hydroelectric power sources generated 9% more electricity in the first half of the year than in the first half of 2015, the Energy Department said.

The U.S. Congress recently extended federal tax incentives that encourage the development of wind and solar power, so experts predict continued gains in renewable output for the next few years.

Utilities and big companies continue to buy more renewable power, partly because prices have been dropping. Duke Energy Corp., which provides power to homes and businesses in southeastern states and across the Midwest, raised its renewable-energy targets by 33%. The company now expects to control 8,000 megawatts of renewable energy capacity by 2020, up from a goal of 6,000 megawatts set in 2013.

Duke's changing generation mix "has lowered our overall carbon dioxide emissions by 28% since 2005," said Randy Wheeless, a spokesman for the company.

Write to Rebecca Smith at rebecca.smith@wsj.com

 

(END) Dow Jones Newswires

October 12, 2016 18:05 ET (22:05 GMT)

Copyright (c) 2016 Dow Jones & Company, Inc.
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