Duke Energy is the latest major utility to commit to a carbon-free future, with a plan to cut its emissions in half by 2030 and eliminate them completely by midcentury. 

This week's commitment, which includes plans to at least double Duke’s solar, wind and other renewables portfolio by 2025, is the largest carbon reduction commitment yet from a U.S. utility, due to the company’s size. 

Duke's regulated utilities serve electricity to nearly 8 million people in six states and operate a 51-gigawatt generation fleet, one-third of it coal and nearly three-quarters fossil-fueled.

It’s the first time Duke has pledged to zero out carbon-emitting resources from its fleet, albeit with a target deadline decades in the future. The move tracks with carbon-free energy mandates in states including Hawaii, California, New YorkNew Mexico and Washington — although no states served by North Carolina-based Duke have yet made such a move. 

Even so, other utilities have been moving toward long-range carbon reduction goals in anticipation of regulatory action. Xcel Energy, which operates the largest utilities in Colorado and Minnesota, has outlined a plan to reach zero-carbon electricity by 2050, ahead of moves toward similar mandates in both states. 

More immediately, Duke’s new plan improves on its 2017 goal to cut its 2030 carbon emissions by 40 percent, driven by “sustained low natural gas prices and declining costs for renewables and storage,” Tuesday’s press release noted. 

“A diverse mix of renewables, nuclear, natural gas, hydro and energy efficiency are all part of this vision,” Lynn Good, chairman, president and CEO, said in a statement. “In the longer term, innovation and new technologies will be critical to a net-zero carbon future.”

This means that, while Duke will rely heavily on increasing its share of solar power, energy storage, energy efficiency and electric vehicle infrastructure in future years, “new natural gas infrastructure will be required to fuel this transition and balance renewables,” the company's statement notes. 

The gas question

This reliance on natural gas aligns Duke with most U.S. utilities, including those in states with aggressive carbon reduction mandates. But it puts the utility’s plans at odds with analysts, regulators and activists who say that adding new fossil-fueled energy infrastructure runs counter to the pressing need to eliminate carbon emissions to combat the worst effects of global warming. 

The Beyond Carbon campaign, a $500 million effort by Bloomberg Philanthropies and the Sierra Club to halt all new natural-gas construction, warns that natural-gas plants could become increasingly uncompetitive against renewable energy and grid-scale batteries in future years. Wood Mackenzie Power & Renewables has been tracking renewables-plus-storage as an alternative to natural-gas-fired power plants, and its figures show these newer technologies are becoming increasingly competitive in key U.S. markets. 

Last week, the Rocky Mountain Institute released a report citing the threat that new natural-gas plants face from clean energy portfolios, such as the record-low-price solar-storage contracts being awarded in states like ColoradoCaliforniaNevada and Hawaii in the past few years.

RMI’s report also noted the rising tide of natural-gas plant construction or repowering plans being shelved — including Duke’s decision in April to shelve plans for a $100 million gas peaker plant in the face of community opposition. 

Duke serves about 7.4 million customer accounts in North and South Carolina, Indiana, Ohio, Kentucky and Florida, and owns 51 gigawatts of generation capacity — 42 percent natural gas, 33 percent coal, 18 percent nuclear, and 7 percent hydro and solar power. Duke's regulated utilities are on track for 500 megawatts in owned renewable capacity by the end of 2019, with a plan to reach 1 gigawatt in owned capacity by 2025. 

Duke Energy Renewables, the company's competitive energy arm, owns another 3 gigawatts of generation, made up of about three-quarters wind, one-quarter solar, and 1 percent energy storage, with plans to add another 3 gigawatts by 2023. 

Since 2005, Duke has cut its carbon emissions by 31 percent, largely through the retirement of 49 coal-fired units, totaling 6,190 megawatts of generation capacity. It has also invested heavily in modernizing its grid infrastructure with smart meters, sensors, grid controls and a number of groundbreaking microgrid and distributed energy resources management pilot projects.