Tom Shepstone
Natural Gas NOW
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It is undeniable; adding more solar power to the grid means decreases the environmental performance of baseload energy systems and grow air pollution.
A North State Journal article about power generation in North Carolina reveals the problem introduced by too much solar power being added to the grid. Solar power is intermittent and erratic. Add too much solar power to the grid and the power plants depended upon to supply electricity are constantly shutting down and starting up again, which both economically and environmentally inefficient. It increases air pollution.
The intermittency of solar power casts a dark cloud over its environmental performance and the electrical grid.
Here are the facts from the story (emphasis added):
A seven-month investigation and numerous public information requests have revealed the move to increase solar power might be leading to an increase in the very emissions alternative energy sources aim to reduce.
Duke spokeswoman Kim Crawford confirmed that increased solar power on the state’s electric grid is increasing emissions of nitrogen oxide (NOx), a dangerous air pollutant. She said that reductions in carbon dioxide (CO2) emissions could also reverse if current solar growth continues without policy changes…
Crawford provided measurements showing that even on sunny days — when solar power is at its maximum output — more NOx pollution is released into the air than would occur if no solar electricity were used and natural gas were used instead.
That’s because traditional power plants — including cleaner burning natural gas plants — must scale back electric generation to accommodate solar energy surging onto the system when the sun rises, and power back up when the sun sets and solar energy dissipates. That starting and stopping reduces efficiency and incapacitates emission control devices, increasing pollutant levels.
On other days solar energy is erratic and can result in more frequent cycling of reserve sources, further decreasing power plant efficiency. This increased cycling can result in increased emissions and undue wear and tear on the expensive equipment…
“After committing $2 billion in tax credits, and more than $1 billion in electricity overpayments for solar power, we now learn from Duke that nitrogen oxides have actually increased, and that CO2 may be headed in the wrong direction,” said Donald van der Vaart, former secretary of the N.C. Department of Environmental Quality and State Energy Policy Advisor in the McCrory administration…
“This issue deserves a re-look, and it needs to be done fast,” Dan Kish, distinguished senior fellow at the Institute for Energy Research, said after reviewing Duke’s data.
“It’s great for the Wall Street financiers, and those in it to make a fast buck while the sun shines, but it’s leaving us with an increasingly unstable grid and externalities such as more pollution,” Kish said. “The regulators have to remember that their job is to make sure that quick buck artists don’t pick the pockets of consumers and leave them with a weaker, less resilient grid.”
…Under its current permits in the heavily regulated market, Duke must completely shut down the backup combustion turbines when solar peaks under a full sun, then restart them when the sun recedes.
Duke wants DEQ to issue new permits allowing combustion turbines to throttle up and down from a “low load” idling operation instead of switching completely off and on as solar waxes and wanes. In its permit applications Duke said that would lower pollutant emissions and reduce stress on equipment…
Without any solar power in the mix, “a typical combined cycle combustion turbine emits NOx at approximately 9-11 lb/hr, assuming 24 hours of ‘normal’ operation,” Crawford said. That is equivalent to 264 pounds of NOx emissions daily. When those same plants are operated to supplement solar power facilities, daily emissions more than double to 624 pounds a day, based on a table in Duke’s application.
If DEQ agrees to Duke’s alternative operating scenario, a combustion turbine would emit 381 pounds of NOx daily — still 44% more pollution than operating without any solar power on the grid…
The data on carbon dioxide emissions from Duke is less certain the NOx figures. “We expect a slight increase in CO2 emissions at the plant level from turndown versus shutting down and restarting,” Crawford said.
In general, she said, increasing solar generation tends to decrease CO2 emissions if nuclear generation and other factors remain constant.
“As the amount of solar generation increases, however, this effect will diminish and could reverse at some point due to decreasing room for more efficient generation,” said Crawford. More lower efficiency generators, designed for short cycles, could ultimately be used to provide contingency power for intermittent solar, according to Crawford.
She cited studies that concluded utilities must cut solar power off from the electric grid more frequently as solar production expands. That’s because more electricity is produced than can be used or exported to other states.
North Carolina law does not allow utilities to shut off solar power when it’s not needed, with a few minor exceptions. Crawford said if Duke does not win approval of its permit modifications to allow combustion turbines to idle instead of turning off, the utility is left with only two viable options to deal with growing solar generation.
It could export excess energy to other regions, but transmission capabilities are limited.
Alternatively, Duke could dial down nuclear generation, but doing so would increase CO2 emissions. Crawford said that “it’s possible that nuclear generation could be impacted by solar; however, we cannot say that definitively at this point.”
Kish said if utilities take nuclear plants offline to accommodate solar energy it would reverse previous reductions of CO2 emissions, and wreck the economics of the grid.
“Renewable energy sounds good, but it performs terribly. If you want electricity available when you need it, you don’t want intermittent, unreliable, renewable energy,” Kish said. “It’s like a cancer on an efficient grid, with its ups-and-downs forcing other sources to pick up the slack in the most inefficient ways, which, in some cases, are more polluting.”
That last paragraph summarizes a powerful reality. Intermittent power is a hindrance not a help. Natural gas only is far more effective environmentally than solar on top of gas. but that’s not even the worst of it, because natural gas is essential to renewables development. This Duke Energy data is the Achilles Heel with respect to renewables; they’re not only uneconomic but create additional costs and additional air pollution, both of which are completely avoidable if we put away hedge-fund rent seeking and green political correctness.
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