Duke Energy is proposing that its future electricity mix rely heavily on renewables and nuclear power to reach its 2050 goal to be carbon neutral, the utility said Tuesday.

Why it matters: As one of America’s largest utilities, Duke’s sketch of this potential future is a bellwether for how a range of companies and states hope to achieve their similarly aggressive goals in the next 30 years.

Where it stands: Duke, which provides electricity to more than 7 million customers in the Carolinas, the Midwest and Florida, said in a report that huge leaps in innovation must happen in order to achieve its carbon-neutral goal by 2050, a target roughly in line with the Paris climate agreement.

The utility also said natural gas, which is increasingly opposed by some environmentalists due to its heat-trapping contents, is essential to help balance out variable wind and solar, even as its role in the energy mix decreases out to 2050.

Duke's 2050 scenario also relies heavily on a vague bucket of low-carbon technologies that aren’t commercially viable yet, which could include small modular reactors or equipment that can capture carbon emissions from natural gas plants.

By the numbers ... Duke’s 2019 → 2050 generation mix:

Coal: 24% → zero.

24% → zero. Renewables (wind and solar mostly): 5% → 36%.

(wind and solar mostly): 5% → 36%. Natural gas: 31% → 6%.

31% → 6%. Nuclear: 31% → 28%. This relies on an assumption that federal regulators grant Duke additional operating licenses to allow their existing reactors to run 80 years, a move numerous utilities are making. Just a few reactors at other companies have been approved so far. (Duke hasn't yet officially requested its extensions.)

31% → 28%. This relies on an assumption that federal regulators grant Duke additional operating licenses to allow their existing reactors to run 80 years, a move numerous utilities are making. Just a few reactors at other companies have been approved so far. (Duke hasn't yet officially requested its extensions.) By 2040, the report includes the catch-all category of to-be-determined low-carbon technology for 16% of its mix. By 2050, it’s projected to be up to 30%.

Flashback: This mix is far more aggressive, especially with regard to its lack of reliance on natural gas, compared to a similar report Duke issued in 2018 under pressure from shareholders. That report was before the company’s 2019 climate goal.

In its 2018 scenario, the share of gas between 2017 and 2050 stayed about the same at one-third.

In Tuesday’s report, gas still increased in the (relative) short-term to make up 42% of Duke’s energy mix in the 2030s. By the 2040s it starts declining to 25%, and by 2050 it drops off a cliff to 6%.

After 2030, the scenario assumes all new natural gas plants will provide backup to variable wind and solar resources, not as a main source of power themselves.

What they're saying: The report suggests Duke will need to drastically increase the amount of electric capacity it has on its system to account for both coal closing and new demand.

"You’re talking almost about rebuilding the system," said Stephen Arbogast, director of the Energy Center at University of North Carolina's business school, who wasn't involved in the report but viewed it before publication. "The sheer magnitude of what they’re talking about doing is extremely challenging."

One level deeper: Left unmentioned was the potential cost for consumers in this scenario.

Duke didn’t perform official modeling on electricity prices out to 2050 "because it would be highly speculative and dependent on the regulatory constructions in each of our jurisdictions," a spokesman said.

"We did not want to speculate in a high-profile report that would cause confusion."

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