Alberta gets cold in the winter

Alberta gets cold in the winter. Maybe you already knew that.

Last weekend it got cold enough that the Alberta Emergency Management Agency issued an alert: the electric grid was overtaxed, and was in danger of implementing rotating power outages unless Albertans cut back on their electricity usage immediately. The good news is that enough people responded right away to avert the crisis. The Globe and Mail reports on the story here, and YouTube has reported on it in a number of videos (for example, here).

How cold is "cold"? Calgary (in the south of the province) recorded temperatures as high as -17°F on Saturday, January 13; that same day, Fort Chipewyan (in the north) recorded temperatures as low as -49°F. (Neither of these numbers takes account of wind chill.) At those temperatures, a power outage could have been devastating, perhaps even lethal. It is tremendously fortunate that there was no need for one.

But it's hard to think that this weather—not to mention the consequent demand on the electric grid—was unexpected. As I suggested above, everybody knows that Alberta gets cold in the winter! So how did things get to the point where there was a serious risk of rotating outages? How could the system be functioning this badly?

A real answer requires real data, which is more than I have. The most I can do is to sketch how an analysis should be structured, and maybe incidentally to advance a hypothesis or two. If any of my readers live in Alberta, or are otherwise close enough to the event to have good data on what happened, please comment to set me straight! I would love to know the answer; and if my hypotheses turn out to be no more than hot air (excuse the pun), that's a small price to pay to get the facts.

The first step in an analysis is to understand the components that make up the system. According to the website of the AESO (Alberta Electric System Operator), 60% of Alberta's electricity comes from burning natural gas; 20% from wind turbines; 7% from coal; 6% from solar power; 5% from hydro power; and 2% from other sources. Last weekend, though, several of those sources were interrupted.

• According to The Globe and Mail, two of the natural gas plants were offline: one for maintenance, and the other (ironically) because of weather.
• According to EnergyNow.ca, the wind farms were shut down—even though there was wind—because in temperatures that low there is a high risk that the steel turbines will shatter.
• And several sources have pointed out that the biggest demand hit after dusk, when solar cells weren't collecting any sunshine.
• One report says that the coal-fired plants worked just fine; but at only 7% of the total supply (at least theoretically) they could only contribute so much. 

The second step is to understand the failures in those components that failed. Of these, I find the wind farms most interesting. I assume that there was some kind of FMEA done when the wind turbines were designed, and that it was this analysis which discovered the risk that steel parts shatter when they get too cold. Probably the shutdown protocol was defined as a protective measure, to reduce the risk of damaging or destroying the wind turbines.

In isolation from other factors, the logic here is impeccable. But in the context of the entire system, this "protective measure" means that when the weather gets very cold—in other words, precisely when we should expect the demand for electricity to spike—20% of Alberta's electric supply goes offline. Is that right? Is that how we want the grid to work?

This leads us to the third step of any analysis, and the one most likely to turn up unexpected conclusions: look at the system design as a whole to understand how failures might arise even when each component is behaving perfectly as designed. (See, for example, the discussions here and here.) Looking at the system also means understanding how it responds when individual components fail, as of course they are sure to do from time to time. And if you discover any critical points—places where the system is particularly fragile, or where it is highly likely to fail—those are the points you especially have to strengthen or stabilize. (Among other things, the system's capacity should be enough greater than demand that it can keep functioning even when some components fail.)

There is one more factor which will have to be part of any analysis, though it is not so much a separate step as a consideration that may affect the analysis in multiple places. Any decision made by or about a public utility is inherently a political decision, even if the utility is nominally private. This means that there will inevitably be factors involved in the decision quite different from those of pure design and operational functionality, and these factors cannot be ignored. As we have seen before: when the Quality process conflicts with the political process, the political process usually wins.   

The encouraging side to this last reflection is that it is to nobody's political advantage for the lights to go out in the middle of winter. So there is no reason to suppose that politics will get in the way of a proper root-cause analysis of last weekend's near-failure.