- Duke Energy alerted its consumers of an extreme cold event from 4–10 a.m. Feb. 2.
- During that time, coal, natural gas, and especially nuclear kept homes powered and warm, while solar didn’t produce any power at all until the latter part of the alert period
- Policymakers should heed this lesson and reform state law so that it doesn’t outlaw coal and natural gas electricity generation, which it currently would do by 2050
On Feb. 1, citing expected “[e]xtremely cold temperatures,” Duke Energy sent an alert to its customers requesting that they “voluntarily reduce their energy use from 4–10 a.m. on Monday, Feb. 2, to help lessen the energy demand on the grid and reduce the potential of temporary power outages.” Duke had already obtained an emergency waiver from the U.S. Department of Energy to utilize their power plants up to their maximum generation output levels “notwithstanding air emissions or other permit limitations.”
The timing for voluntary conservation is instructive. The early morning hours typically feature the highest energy demand. It’s the coldest part of the day, so home heating is working the hardest, and people are starting to wake up and add other home energy uses — including lights, water heaters, stoves, dishwashers, and even washers and dryers — to the grid.
Fortunately, there were no power outages that morning. Still, like Sherlock Holmes’ dog that “did nothing in the night-time,” that lack of incident offers important clues for electricity policy going forward.
Lessons from a bitterly cold morning
Duke’s alert pinpointed North Carolina electricity customers’ time of most critical need: 4–10 a.m. What met that need?
For media and politicians like Gov. Josh Stein and former Gov. Roy Cooper, the expectation was clear. Renewable resources like solar and wind are the answer. “Duke needs to generate more electricity, but how?” asked The News & Observer through one of its environmentalist-sponsored pieces. “The Southern Environmental Law Center and groups such as NC WARN say the state and Gov. Josh Stein must press Duke to move more toward renewable energy sources including wind power and solar with battery storage.”
This expectation is baked into state energy policy. Under the state’s Carbon Plan as currently set up, electricity generation is supposed to be “carbon neutral” by 2050. It would mean the end of any generation from baseload coal and natural gas sources of electricity by 2050, with reliance entirely on solar, wind, batteries, and hydropower, and then use nuclear energy for baseload generation with the hope that the technology will be there for some natural gas plants to be converted to run off hydrogen.
Policymakers are making a very expensive bet — while sticking electricity customers with all the costs and risks. Duke Energy’s most recent plan filed with the North Carolina Utilities Commission (NCUC) as required by the Carbon Plan law showed the following planned capacity additions between now and 2040:
- Solar: 14.2 Gigawatts (GW)
- Natural gas: 11.0 GW (note: added by 2040, but all to be retired by 2050)
- Nuclear: 3.5 GW
- Coal: –8.1 GW (retirements)
Unfortunately, even though Duke expects nuclear to be about four times as productive as solar, Duke’s plan is to add more than four times as much solar capacity (3.5 GW of new nuclear vs. 14.2 GW of new solar).
New Solar, Natural Gas, and Nuclear Capacity: How Much Is Planned by 2040 vs. How Productive Each Source Is Expected to Be
Source: Duke Energy Carolinas Resource Plan 2025 and author’s calculations
In other words, Duke plans to build the least amount of the most productive resource — and the most amount of the least productive resource.
Hour-by-hour actual power generation in an emergency
In terms of current capacity, here is how much Duke has of each of the power sources of policy interest to media, Stein, and Cooper. These are, of course, their nameplate capacities, their “maximum rated output”:
- Solar: 5.1 GW
- Natural gas: 15.1 GW (including 6.0 GW of baseload and dispatchable combined-cycle plants and 9.1 GW of “peaker” combustion turbine plants)
- Nuclear: 9.4 GW
- Coal: 8.9 GW
How did these resources perform relative to their maximums? How did their generation compare with their capacity? In other words, what powered the state during this emergency?
After all, “maximum” implies a minimum. As explained here, nameplate capacity “is not the same as power generation, and it differs significantly according to the type of power plant.” For example:
When Strata Solar applied to the NCUC in 2012 to build a 5 MW solar facility on former Gov. Roy Cooper’s Nash County land, the company noted in its application that “Solar is an intermittent energy source, and therefore the maximum dependable capacity is 0 MW.” Its nameplate capacity was 5 MW, but as with all solar facilities, its generation at any moment in time depends entirely upon the time of year, the time of day, and the weather (which is what the application means by “intermittent”). It might occasionally reach 5 MW, but it could very well be at 0 MW.
The following table and chart give the hour-by-hour outputs by those sources during the emergency alert period.
Duke Energy hour-by-hour generation during emergency alert, in GWh, select sources
Duke Energy capacity vs. generation during emergency alert, by select sources and hour
As evident from the table and chart, when North Carolinians needed power the most during dangerous, life-threatening cold, they received it from thermal generating sources — natural gas, coal, and especially nuclear, which not only met but far exceeded its rated capacity. Solar power was nonexistent during the early morning hours, and even later that morning it still provided power well below capacity.
The long-range forecast calls for reliable resources
Media present nameplate capacity as if it were reliable power, so they would say that 5.1 GW of solar capacity is “enough to power” a million homes. In practice, all that solar capacity in the early morning hours powered no one’s home.
Fortunately, North Carolinians had access to enough natural gas and coal generation to keep their homes powered and warm. State law hasn’t yet shut those sources down. But under state law as it currently stands, those sources will not be available after 2049. What will we do then?
Policymakers should take this lesson of the lack of outages — despite hours of solar nonproductivity — as a warning. Reform state law before reliable, productive options are legally rendered unavailable for future emergencies, when their absence will be felt the most.
