Saturday, January 27, 2018

The Northeast Grid and the Oil

ISO-NE Report on Cold Weather Grid Performance

It was dramatically cold here in the Northeast from late December through January 8.  Temperatures of ten below were common. The grid used amazing (30% or more) amounts of oil, as the power plants could not get gas. (I wrote a couple of blog posts about this, which I reference at the end of this post.)

On January 16, ISO-NE issued a report on the grid behavior during this period. Cold Weather Operations, December 24, 2017 through  January 8, 2018.  This document is worth reading.   Frankly, in my blog posts, I simply did not know how bad things were becoming on the grid. Let me quote viewgraph 11 of the ISO report:
"As gas became uneconomic, the entire season’s oil supply rapidly depleted"

Pictures speak louder than words

This is a story best told in graphics.

As I noted earlier, the generation mix on the grid shifted heavily to oil. On December 24, 2017, oil supplied 2% of grid electricity. On January 6, 2018, oil provided 36% of the electricity. ISO slide 14 shows this very effectively.

Slide 14
from ISO report
Double click to expand
Other illustrations are from the same report

Update:  Ed Pheil pointed something out to me: if I don't explain that demand on the grid was rising between 12/24 and 1/1/, the decline in nuclear's share of the grid electricity (from 39% to 27% etc.) is inexplicable.  Did the nuclear plants go off-line?  No. But there are only so many nuclear plants, and they can make only so much power.

The chart below shows a steady line of "daily generation" for the nuclear plants.  It is the green line near the top of the chart. There's one exception: Pilgrim went off line when a transmission line failed.   You can see the dip.

Thank you to Ed.  This was a necessary clarification.

Slide 13

Local natural gas prices soared, while Marcellus shale prices remained fairly steady.  Electricity prices followed the natural gas prices. However, generators that could switch to oil did the switch. Oil was was less expensive. Natural gas prices rose about 30 fold (from around $3 to around $90, as shown below)

Slide 30

Due to power plants using lower-priced oil, however, prices on the grid rose from around $50 to around to $450/MWh, only a ten-fold rise.

Slide 55
Oil Depletion

The region was burning oil far faster than it was replenishing it.  On December 1, we had 68% (of the maximum oil) available to power plants.   On January 8, we had 19%.

Slide 21
For a more dramatic picture, ISO shows a single power plant's oil supply, which went from an eight-day supply to a one-day supply over the same period.
Slide 22
There are many important slides.  For example, slide 17 shows how the generators that were enrolled in the ISO-NE Winter Reliability Program really picked up the slack, and slide 18 compares the amount of oil burned in the two weeks of cold with the amount of oil burned the previous two years.  (More was burned in the two weeks of cold.)  

And then there was all the scrambling to keep things going. Slides 35 and 36 show that there were emergency conference calls about the grid---pretty much every day.  

What have we learned?

Much as I dislike burning oil for power, I dislike widespread outages even more.  I give ISO-NE tremendous credit for the Winter Reliability Program, and for keeping the lights on.

According to the last slide in the ISO program, replenishment of oil is the key issue for reliable operation during cold weather in New England.  ISO-NE is correct,  according to their charter.

slide 62

However, the ISO-NE charter is limited.  For me, the important thing is to keep Northeastern nuclear plants operating. Nuclear plants are thoroughly reliable.  (Yes, Pilgrim went offline due to a transmission line failure.) Nuclear plants keep making electricity, no matter what the weather might be, as long as there is a transmission line to send out their power. 

In cold weather, we need reliability. In cold weather, we need nuclear. 


Earlier blog posts:

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