ORION, MI—GM’s assembly plant here saves $1 million annually by using renewable energy sources and now ranks as the 8th largest user of “green power” in the United States.

WASHINGTON—In 2012, manufacturers consumed 24 percent of all the energy used in the United States. No sector of the economy has more to gain from using energy resources more efficiently, but progress on energy efficiency faces a bevy of obstacles, according to a new report from the Department of Energy.

MACUNGIE, PA—The Mack Trucks assembly plant here is among the sites helping Volvo Group North America achieve its goal of reduced energy consumption under the U.S. Department of Energy’s Better Buildings Better Plants Challenge five years earlier than expected.

WASHINGTON—Nine automotive assembly plants are among 70 US manufacturing facilities that have achieved Energy Star certification from the Environmental Protection Agency for their superior energy performance in 2014. Together, these 70 factories cut their energy bills by $725 million and reduced greenhouse gas emissions by more than 8 million metric tons.

PUNE, India—Volkswagen plans to reduce energy consumption at its assembly plant here by 436 megawatt hours per year by equipping the assembly line with high-volume, low-speed fans. The carmaker also aims to reduce water usage at the facility by 1,636 cubic meters annually.

In April, electronics assembler Mack Technologies completed work on a substantial installation of money-saving technology at its factory in Westford, MA. The company didn’t get a new paste printer, reflow oven or pick-and-place machine. In fact, the plant’s slick new technology had nothing to do with assembly.

WASHINGTON—Total energy consumption in the manufacturing sector decreased by 17 percent from 2002 to 2010, according to the U.S. Energy Information Administration. The decline in energy intensity reflects both improvements in energy efficiency and changes in the manufacturing output mix.