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Performance of the New England Power Grid During Extreme Cold, December 25th to January 8th

The Independent System Operator for the New England power grid (ISO-NE) has produced a summary brief describing the challenges associated with Arctic Outbreak 2017-2018, a period of substantially below normal temperatures that lasted from Dec.25, 2017 until Jan. 8, 2018.

After describing the intensity of the cold wave with a number of graphs, charts, images and words, the brief made the following sobering statements about the fuel mix used to supply power demand.

  • Overall, there was significantly higher than normal use of oil
    – Coal use also increased over normal use
  • Gas and Oil fuel price inversion led to oil being in economic merit and base loaded
  • As gas became uneconomic, the entire season’s oil supply rapidly depleted

The brief includes the following graph showing the daily electricity contribution in MWhrs from various fuel sources.

A major contributing factor to the rapid depletion of fuel inventories was the sharp increase in oil-fueled power production starting on Jan 4. Nuclear electricity production dropped on Jan 4 by about 8,000 MWhrs and dropped again on Jan 5 by roughly the same amount.

Pilgrim Nuclear Power Plant was scrammed at about 1:15 pm on Jan 4 because one of its two large transmission lines fell down during Winter Storm Grayson. The plant, which had been running continuously at or near full power for 225 days, was not returned to service until Jan 10 and did not achieve full power output until Jan 12.

The majority of the power that had been supplied by Pilgrim was replaced by burning more oil. As the winter storm moved away from the region, generation from wind also fell.

The below pair of charts from the brief should also be food for thought for those who claim that what regions like New England really need is more solar power.

Note: PV resources in front of the meter are intended for supplying the grid.

Note: PV behind the meter are intended mainly for on-site generation.

Fuel supply challenges

Though there were no large scale power outages, keeping power flowing to customers required some heroic efforts on the part of fuel truck drivers, Coast Guard ice breakers, and power plant operators.

It even required the suspension of usual rush hour traffic procedures that prevent the Weymouth Fore River Bridge from opening. As the Coast Guard explained in its press release announcing the temporary allowance for critical vessel traffic, “…recent extreme weather and ice accumulation in the Weymouth Fore River has made it difficult for tank vessels and barges to deliver time-sensitive resources such as home heating oil and kerosene, and fuel for power plants and public transit.”

Even though road conditions were treacherous, fuel trucks were pressed into overtime service to prevent the catastrophic consequences of running out of fuel during an event where temperatures were often well below 0 ℉ and the wind was howling. Keeping fuel oil supplied to homes, businesses and power generators required the suspension of normal driver rest requirements.

The ISO-NE brief describes trucking as the main fuel supply logistical constraint and states that:

  • Carriers are at their physical limits
  • Drivers need time off to rest, even with State Waivers in effect
  • The break in the weather this week [beginning Jan 8] will provide much needed relief

Both the rush hour bridge openings and the suspension of truck driver rest rules had the potential to alert large segments of the population to the fact that their electricity supply system was closer to collapse than sunny summary statements of “reliable performance” might imply. Fortunately, no tragic consequences occurred – this time.

Not a perfect storm

Though the weather event was unusual, it was certainly not unprecedented. It’s no surprise to note that it sometimes gets cold and dark in New England during the winter. There are some who incorrectly label the entire event as a “bomb cyclone,” overlooking the fact that moniker only applies to the rather strong nor’easter that raced up the Eastern Seaboard on Jan 4.

Others with longer memories apply a more accurate label of “New England winter,” to reflect the fact that winter weather can vary from year to year, but it is something that requires routine preparations. It isn’t a surprising act of God when it is a little colder than average, just as it shouldn’t be surprising when a winter ends up to be a bit warmer than average.

Senate Energy and Commerce Committee Hearing

On Tuesday, Jan 23, 2018, Senator Lisa Murkowski, the Chair of the Senate Energy and Natural Resources Committee, convened a hearing to discuss the performance of the electric power grid during certain weather conditions. Most of the testimony and questioning focused on the two week period from Dec 25-Jan 8, but the nature of the topic allowed participants to expand the discussion to other memorable weather events including droughts, heat waves and tropical cyclones.

Though it’s possible for people to watch the archived video of the hearing and find reassuring commentary confirming whatever biases they have, I watched with growing concerns for New England’s ability to handle routine weather events without major economic disruption and potential loss of life. (I’ll admit that my training as a professional worrier – also known as an engineering officer in the Nuclear Navy – biases me toward concern when others are complacent.)

Mr. Gordon van Weile, the president and CEO of ISO-NE, provided both stark warnings for the future and a reminder that he has been sounding the warnings since at least 2013 without any substantive action being taken. Each time a non-gas fired generator retires, the situation gets more fragile. That is especially true when the retiring resource is a nuclear plant that has been reliably running at full power 80-95% of the time.

When there is a sustained cold weather event, natural gas availability hits a virtual wall where prices rise at astronomical rates indicating that there is no gas left to be purchased, no matter how much the buyer is willing and able to pay. When prices in a region rise to be 20 or more times higher on one side of a pipe compared to the other, it means there is no more room in the pipe.

Mr. van Weile described the precarious nature of New England’s fuel supply during the cold spell.

While we weathered a stretch of extremely cold weather and a blizzard, we remain concerned about resupply of these resources during the remainder of the winter season and are in close coordination with state and federal officials about the challenges of ensuring adequate oil supplies to the region. Finally, given the fuel constraints, the rapid depletion of the oil inventory, and the reality that resupply was several days away during the peak of the cold weather period, our biggest operating concern was that we would experience a large, multi-day system contingency during this period or that oil-fired generators would run out of fuel before they could be resupplied.

Pilgrim’s Jan 4-Jan 9 Shutdown

It’s difficult, even during a period of incredibly steady performance by 98 out of 99 nuclear plants, to engage in discussions about the importance of nuclear energy for the resilience of the U.S. power grid when the 99th plant shuts down unexpectedly and remains shutdown for what is now going on six days.

paraphrasing a nuclear industry cliche, during a weather event an outage anywhere is an outage everywhere. That is especially true when it is unplanned and lasts an unexpectedly long time.

On the afternoon of January 4, the Pilgrim Nuclear Plant operators manually shut down their power station as a result of what I would term an overabundance of caution and fear of criticism from life-long opponents. The plant was returned to service almost six days later. Though the transmission line was back in service in approximately two days, the shutdown was extended because the plant operators decided to repair a small steam leak.

Aside: Steam plants leak. It is the nature of the technology. That is especially true as plants age. In many cases, the leaks are a minor annoyance and repairs can be deferred with no fixed deadline. It’s dependent on situation; during one of my patrols we managed a rather irritating steam leak for more than a month so we could complete our scheduled mission. End Aside.

Investigation into details of Pilgrim’s shutdown

The specific instigator of the decision to shut down was the loss of one of two 345 kV transmission lines that allow Pilgrim to deliver its power to the grid.

There is no external or regulatory requirement for a nuclear plant of Pilgrim’s design to immediately shut down in such a circumstance. The required action is to work diligently on restoring the line and to limit the duration of operations with just one outgoing transmission line to a period of 72 hours. If the nature of the failure is such that it is unlikely to be resolved in the allowed time, most operators will choose to shutdown once that fact is known.

Pilgrim, however, has a local procedure that requires a prompt manual shutdown if it loses either one of its outgoing transmission lines during a storm event. According to Patrick O’Brien, that procedure was developed based on past operating experience. When one transmission line goes down, the plant is in a condition where the loss of the second line would result in an automatic trip and a more significant cycle on the plant’s systems.

In response to a question about the possibility of delaying such a shutdown in a case where the grid operator had declared that the power was needed and shutdowns should be avoided, Mr. O’Brien stated that there is no process to allow situational judgement by plant operators. He acknowledged that there is a process by which a local procedure could be changed, but that requires a full impact review that cannot be waived.

During most of the period that Pilgrim was shutdown and completing the deferrable repair, the wholesale price of electricity in New England and New York averaged approximately $200 per MWh. As demonstrated during a separate period of demand caused by similarly cold weather with the plant operating, it is reasonable to state that lack of supply from Pilgrim added something close to $100/MWe to wholesale power prices.

If this analysis is correct, the loss of Pilgrim at a time of high demand cost New England customers approximately $1.5 million per hour. (Roughly 15,000 MW of demand x $100/MWh) On the other side of the ledger, a number of entities associated with fuel deliveries and power generators collected an extra $1.5 million per hour for six profitable days.

When operating, Pilgrim’s daily electricity production is the energy equivalent of approximately 9,300 barrels of oil. Delivering that much oil to the generators that needed to run to replace Pilgrim required the logistic supply capacity equivalent of almost 50 large tanker trucks each day.

Pilgrim is scheduled to permanently close in early June 2019. Entergy, the plant’s owner, has determined it is not profitable enough to overcome the costs, risks and managerial annoyances associated with operating the plant.

A loud and persistent subset of its neighbors has been vocally opposed to the plant’s existence since before it was built.

Some of those neighbors vehemently and publicly protested Entergy’s failure to shutdown the plant before the winter storm hit, claiming that the operators were putting profit over safety. When the plant did shutdown, those opponents did not petition for it to be restarted as soon as possible to keep the power grid secure, air pollution levels down, and electricity prices in check.

Instead, they staged a protest suggesting that the plant should be forced to remain shutdown and enter decommissioning a year ahead of the already premature date.

Here are excerpts from an email from Dianne Turco, the executive director of Cape Downwinders, explaining her organization’s position regarding Pilgrim specifically and nuclear energy in general.

As an organization, Cape Downwinders is focused on public health and safety regarding the operation of Pilgrim. We support clean, green, renewable, and safe energy. Nuclear certainly does not fit in that category.

It should be no surprise if Pilgrim goes down during a storm. That is one of the reasons why they are rated so low. In fact, in the past few storms, Entergy voluntarily shut Pilgrim preemptively. But not this time. They took the risk that threatens our entire region. Also, Pilgrim is not reliable baseload energy. When needed the most, Pilgrim has shutdown during blizzards and during the warmest days of the year due to temperature rise in Cape Cod Bay that interferes with the cooling water.

Cape Downwinders position on energy is certainly no nuclear. Release of radioactive isotopes into the environment are part of the operation of a reactor. The National Academy of Science has determined there is no safe dose of ionizing radiation. Studies have shown cancer increases around nuclear reactors and after nuclear accidents. Dr. Richard Clapp, who was head of the MA Cancer Registry, found the closer one lived or worked in relation to Pilgrim, the incidence of cancer was 400% higher. We need clean, green, safe, and renewable energy for a healthy planet. Neither nuclear nor fossil fuels meet that criteria.

I wasn’t too surprised when she did not respond to my follow-up email.

Ms Turco

Thank you for your response.

This morning, when I checked the dashboards published by ISO-NE giving real time information on electricity and fuel sources, only 7% of the grid supply came from non hydro renewables. Nuclear and gas were each supplying 33%, oil and coal combined for 27%.

93% of that 7% came from burning wood, refuse or landfill gas. 7% came from wind, 0% from solar.

You have the luxury of advocating. Fortunately, there are other people working hard to supply reliable electricity from capable sources – nuclear, natural gas, oil and coal.

The NAS says that evidence shows that radiation doses above 100 mSv can increase the risk of cancer. They also say that the risk increase is proportional to dose.

They say there is not enough evidence to conclusively show a threshold, so they make a conservative assumption and extend the proportional line down to zero risk at zero dose.

That means that risk is never zero, but approaches zero as doses approach the range of public exposure from nuclear power plants.

It is much, much lower than the health risk of exposure to below freezing temperatures.

Pilgrim is one of the worst licensed nuclear plants in the US, but it isn’t unsafe any more than the worst player in the NFL is an unhealthy couch potato.

Rod Adams

With persistent opponents like Ms. Turco, it’s understandable that a company might make the decision to exit. Operating power plants is hard enough when people occasionally express their appreciation for reliable service. It can be downright depressing to field sharp criticism for being unreliable after running for 226 days straight and maintaining a capacity factor in the neighborhood of 85% over a sustained period of years.

Why did Entergy take its time in returning Pilgrim to service?

Despite several attempts, I have been unable to determine the specific reasons why Entergy decided that they should take the opportunity presented by the downed power line to perform a repair that kept them from collecting revenues associated with generating power during a time of high demand and high prices.

It’s not a simple task to determine just how much money Entergy left on the table by not operating. It isn’t correct to simply take the wholesale price history and multiply it by Pilgrim’s 685 MWe capacity because the prices would have been lower if Pilgrim had been operating.

However, it’s clear that the steam leak repair cost several million per day in forgone revenues. Perhaps there were people in the decision chain that were reluctant to maximize their profits in the plant’s final years of operation because they did not want anyone to suggest that the shutdown decision was based on economics that had been overcome by events.

The post Performance of the New England power grid during extreme cold Dec 25-Jan 8 appeared first on Atomic Insights.

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Willem Post's picture
Willem Post on January 30, 2018

Thank you writing this article. It illuminates a getting worse condition of the NE grid due to scheduled closings of coal and nuclear plants, with gas and oil to follow, if the 100% RE folks get what they want. Those RE folks likely have near zero experience designing energy systems.

I just wrote an article that assumes the closure of these plants by 2050 or sooner and assumes greatly increased wind and solar, and small increases in NE hydro, refuse, bio, and assumes a 4-day wind and solar lull followed by another 4-day wind and solar lull in winter.

The required storage would need a capacity to deliver 1 TWh AC, assuming the batteries were fully charged at the start of the lull and all battery capacity would be available for service. If the latter is not the case, the battery capacity would need to be significantly greater.

No matter what the cost/kWh of delivered AC, the capital cost would several hundred BILLION dollars.

Willem Post's picture
Willem Post on January 30, 2018


Addition to my prior comment.

RE folks often talk about wind and solar being so competitive with fossil and nuclear. What they do not mention is the ancillary cost of storage.

There is no way one can close down nuclear, oil, gas and coal plants and not replace them with storage, which for the NE grid would cost about $1 TRILLION to cover seasonal variations.

My two articles covers just two consecutive 4-day lulls of wind and solar, which occur in NE, as in Germany.

Also overlooked is a battery system typically is not charged to more than 95% and not discharged to less than 25%, to ensure longer battery life, i.e., a maximum of 70% of the stored charge is available and could be discharged, if required.

Batteries are rated to discharge at a power level, MW, for a period of hours, MWh. The correct way of stating a battery rating 1 MW / 4 MWh of delivered AC.

After electricity is generated and placed in storage, about 10% is lost due to conversion from AC to DC and charging the battery, and if that energy is discharged, another 10% is lost due to conversion from DC to AC and discharging the battery, for a round-trip loss of about 20%; round-trip loss percentages vary with the type of battery.

The battery capacity and cost is much less with increased electricity from Hydro-Quebec (Alt. 2), and increased electricity generation that is not dependent on sun and wind.

Additional build-outs of generating plants (wind, solar, bio, hydro, etc.) are required to offset losses when storage systems are a part of the electric grid. Storage systems can provide services that generate revenues.

– If a battery were charged at 95%, the stored charge would need to be about 1.04/{(0.95 – 0.25) / 0.93, discharge/conversion loss} = 1.6 TWh DC; ideal conditions.

– If a battery were charged at 70%, due to: 1) not being fully charged just before the start of the first lull and 2) some percentage of the bat

– In the real world, the battery capacity and capital cost would need to be about 2.49/1.6 = 56% greater than for the ideal conditions.

– Just to cover 2 consecutive 4-day wind and solar lulls in New England during winter (after closing all gas, nuclear, coal and oil plants by 2050, or sooner, “to save the world”, per 100% RE pipe dream), the battery cost would be about $634 billion to 1.56 x 634 = $989 billion, at $500/kWh of delivered AC.

– Battery capacities to cover seasonal variations would be much greater.

NOTE: If a lithium-ion battery is rated at 1 MW/4 MWh AC, it can deliver a 1 MW level of AC power for 4 hours. The stored energy is 4/0.93/0.70 = 6.14 MWh DC, because the unit would be maximally charged up to 95% and minimally discharged down to 25% to preserve life, i.e., 6.14/0.93 = 6.60 MWh AC enters the battery. The delivered 4 MWh AC depletes the battery by 4/0.93 = 4.30 MWh DC. The remaining charge, 6.14 – 4.30 = 1.84 MWh DC, stays in the battery. Usually, batteries have a maximum discharge of 50% or less.

Willem Post's picture
Willem Post on January 30, 2018


Correction. A below paragraph should read:

– If a battery were charged at 70%, due to: 1) not being fully charged just before the start of the first lull and 2) some percentage of the batteries being off line for scheduled and unscheduled maintenance, the stored charge would need to be about 1.04 TWh/{(0.70 – 0.25, minimum allowed) / 0.93, discharge/conversion loss} = 2.49 TWh DC.