For roughly two hours late Friday morning, Duke Energy Progress took four solar projects, putting out 92 MW at the time, off the grid, citing exceptionally low demand and operational risk mitigation.
The four projects are all owned by Duke, have a nameplate capacity of 150 MW at peak generation and were off-line from 9:45 a.m. to 11:30 a.m.
Spring curtailments are nothing new in areas of exceptionally high renewable penetration, but this is a different scenario entirely. Earlier in the week, Duke warned solar producers and state regulators that, due to exceptionally low commercial and industrial energy consumption related to Covid-19 and mild weather, they may be further curtailments down the line, with the possibility that Duke will stop purchasing power that it’s contracted to buy under power purchase agreements (PPA) with independent producers.
A Duke representative said that the warning is especially valid for Duke Energy Progress.
pv magazine spoke with Duke Energy Communications Manager Randy Wheeless who says that the company is unsure when and if the curtailments will continue and to what degree, but that the possibility exists.
As for non-solar generational resources, Duke is required to keep on-line minimum levels of dispatchable power via traditional plants, as well as reserves to meet any demand caused by intermittent generation, like solar. For any non-solar facility to be curtailed, the situation would have to be dire.
“If it got severe enough you could get to that,” said Wheeless. “Obviously we have to keep some spinning reserves available all the time for North American Electric Reliability Corporation compliance. You could get to that point, but solar is the largest intermittent resource that we have around here, so it tends to be a solar story more than anything else… We have somewhere around 200 MW that we own and operate ourselves, so it makes sense that we’re able to affect our own operations first before we go to other operators.”
Under Duke’s curtailment process, set forth by the state regulators, in any incidence where curtailment is necessary, Duke-owned systems are the first to be put off-line, as was true last week. Following Duke facilities, the next to come down would be facilities procured under the Competitive Procurement of Renewable Energy Program and Green Source Advantage Program. If that isn’t enough, Duke moves to the 5% megawatt-hour a year “dispatch down” provision included in all PPAs under the Renewable Energy and Energy Efficiency Portfolio Standard Program. The final step, if necessary, would be to impose emergency curtailments on a rotating basis, non-discriminatory basis for all the utility’s facilities with Public Utility Regulatory Policies Act of 1978 (PURPA) contracts.
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This is Why we need storage.
““If it got severe enough you could get to that,” said Wheeless. “Obviously we have to keep some spinning reserves available all the time for North American Electric Reliability Corporation compliance. You could get to that point, but solar is the largest intermittent resource that we have around here, so it tends to be a solar story more than anything else… We have somewhere around 200 MW that we own and operate ourselves, so it makes sense that we’re able to affect our own operations first before we go to other operators.””
This is starting to sound like a rap song. Duke invokes NERC to require spinning reserves available, to meet grid dispatchable grid demands. Duke curtails their “own” (non-fueled generation) before they get on the phone, to detail their power is not needed by Covid-19 operations at home. If Duke was using the 12 hour energy storage model, curtailment would not be necessary as well as fueled “spinning reserve”. Duke “owns” 200MW and “chooses” to throw away non commodity, non-fueled generation to meet a “regulatory” call out for spinning reserve. I believe this would be a definition to a concatenated hat dance.
Sounds like a song and dance to keep their high cost operations afloat. Probably also something to do with their fuel contracts and they get paid to burn the fuel.
I’m really interested in this, but it would help to know which part of Duke you are writing about. Carolinas? What fraction of that part of Duke’s total solar is this? Does it actually curtail, or just go to a lower market price?
The insight into the dispatch/curtailment process was interesting and something I haven’t heard before.
Hello Ned, the curtailments will affect Duke Energy Progress and Carolinas, though Duke has indicated moreso Progress. The projects curtailed thus far represent 150 MW of the roughly 200 MW owned directly by Duke, though they were generating 92 MW at the time of curtailment. Yes, this is an actual energy curtailment.
Sounds as if the bottom line is that Duke is losing money due to the temperate weather we’re experiencing in the Carolinas. Additionally, they at some point in the past, contracted to purchase solar energy from outside parties who generate solar energy, correct? And their intention is to break those contracts? How is this possible? If there is a foreseeable lack of enough power to support Duke’s customers, why would you do that? And the solution is to cut back usage for Duke’s customers? I must be missing something here.
Once again, it’s all in the contracts. Many utilities are in the “business” of buying coal or probably now natural gas futures contracts. One utility that used to service my electrical needs, made a BIG mistake during the hurricane Katrina. Their long term natural gas futures that were bought in 5 year blocks, came due just after Katrina hit the gulf. The effect, the natural gas futures the utility bought were price spiked. After about 6 months natural gas prices stabilized and natural gas prices fell to new lows. The utility was stuck with overpriced natural gas and ended up increasing the “fuel charge” on every ratepayers electric bill until the gas contract was completed. Duke’s company owned solar PV is easy to “curtail”, they own the asset. What Duke gets in return for “curtailing” their own non-fueled less costly generation is they get to “use” their more costly fueled generation to at least try to keep the asset solvent until it pays for itself in operations, maybe 20 years down the road. IF enough people install their own solar PV with smart ESS on their homes, Duke will find itself in the unenviable position of fueled “stranded assets” and a ratepayer base that only needs Duke to supply their “surge load” capacity for their homes. This is just part of the Utility death spiral.
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