North Carolina

Does NC solar power make air pollution worse? Duke Energy in the middle of debate.

Both advocates and critics of solar energy have pounced on a Duke Energy request to North Carolina regulators that would let the company run five natural gas plants more often to supplement solar power.

Here’s the crux of Duke’s request: Because the solar energy Duke buys is intermittent, with output rising and falling each day, often out of sync with times of peak energy demand, it has to be supplemented by other sources.

Natural gas-fired plants can quickly generate electricity when needed at critical times. The problem, Duke says, is that they release more air pollution when they ramp up and down throughout the day rather than operate steadily.

Duke is asking the state to let the plants run more often — up to 24 hours a day — to improve their efficiency. Running the plants more will increase Duke’s emissions of the greenhouse gas carbon dioxide and air pollutants including nitrogen oxides, a component of ground-level ozone.

Duke’s request is relevant news in the nation’s second-biggest solar state (North Carolina trails only California in installed capacity). Duke says it’s connected to enough N.C. solar to power nearly 500,000 homes.

It also put the utility giant in the middle of dueling interpretations of the Duke emissions data and a claim — that solar energy makes air pollution worse — which Duke says it never made.

‘Outlandish claim’

The Environmental Working Group, an advocacy organization that has labeled Duke “Public Energy Enemy No. 1” in part for not investing more in renewable energy, says “the nation’s largest investor-owned electric utility is pushing an outlandish claim that the growth of solar power will increase air pollution.”

The group asserted that Duke’s depiction of increased emissions, as an indirect result of solar power, is at odds with findings of the federal government’s National Renewable Energy Laboratory.

“I hope everyone who reads Duke’s claims will try to picture a herd of highly paid executives clustered around a conference table fretting themselves sick about the pollution being caused by solar panels and windmills,” president Ken Cook said in an Aug. 20 news release.

By the time the group had blasted the company, Duke had already released its own statement, suggesting that past media articles had mischaracterized its request of regulators.

Duke credited the growth of solar energy, along with the replacement of coal-fired power plants with cleaner-burning natural gas units, for steep overall declines in its carbon dioxide, sulfur dioxides and nitrogen oxide emissions.

The claim that solar energy causes more air pollution is “faulty logic,” Duke’s statement said. “It’s like saying an electric vehicle is bad since it will increase your electric bill, while neglecting to mention the cost savings of not buying gasoline.”

Duke wants to increase operating times for natural gas-fired power plants in Rockingham, Goldsboro, Asheville, Richmond County and Rowan County. Applications to modify the air permits for three of the sites have been submitted so far but the state Department of Environmental Quality has not yet ruled on them.

Conservatives warn of government subsidies

Conservative think tanks, meanwhile, say Duke’s emissions data confirm the need to be skeptical of government subsidies for solar and wind power.

North Carolina’s North State Journal, in an Aug. 14 article, reported that “the move to increase solar power might be leading to an increase in the very emissions alternative energy sources aim to reduce.”

The article quoted experts from the Institute for Energy Research, which touts free markets and “constrained” government, and the conservative Heartland Institute voicing concern over the emissions increases.

“This should shock everyone responsible for North Carolina’s air quality, and the nation’s energy policy,” Donald van der Vaart, a former N.C. environment secretary in Republican Gov. Pat McCrory’s past administration, says in the North State Journal article. Van der Vaart is now a senior fellow at the John Locke Foundation, a free-market, limited-government think tank in Raleigh.

In fact, research published by the National Renewable Energy Laboratory in 2012 showed that adding more solar and wind energy to the electric grid would force fossil-fueled power plants to adjust their output as Duke describes.

While emissions of carbon dioxide and nitrogen oxides may increase as a result, the lab said, “these impacts are modest compared to the overall benefits of replacing fossil-fuel generation with variable renewable generation.”

Bruce Henderson writes about transportation, emerging issues and interesting people for The Charlotte Observer. His reporting background is in covering energy, environment and state news.