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Why Was There a Blackout in Alberta?

Just what went wrong yesterday in Alberta to cause rolling blackouts and electricity prices that were 50 times higher than normal?

The AESO manages the system with multiple generators unavailable [Larger Size]

Alberta, Canada was hit by rolling blackouts yesterday (9th July 2012) as the state sweltered through a heatwave that sent temperatures north of 30 degrees celcius.

The unexpected loss of power had some calling for an investigation into excessive use of market power.

How did the blackouts occur?

The AESO did not have enough available generation to securely meet the demand for electricity, so it switched off the power to some houses and businesses across the state until it could securely meet the demand.

Securely meet the demand

I’ll explain what I mean by securely meet the demand. The AESO is constantly asking the question: What is the worst thing that can happen next? There is always a list of things that could go wrong. And that list is as long as your arm:

  • A generator could suddenly shut down without notice;
  • A main powerline could fail and be unable to transport power;
  • A major circuit breaker (a big power switch) could stop functioning;
  • and more..

Securely operating the system means that, yes we are ok now, but we’ll still be ok even if one more thing goes wrong.

One of the tests that the AESO use to determine if they are secure is to ask: How much additional generating capacity do I have up my sleeve?

If the answer is “less than 500 MW” (about the size of one large gas power station) then they are not secure. They are in the danger zone, and if one more bad thing happens while they are in the danger zone, the entire power system could collapse. Restoring from a system collapse can take days.

So what happened yesterday?

Looking at the chart above, we can see that three additional generators went out of service at 1300 hrs. On the temperature chart darker red colours mean more generators simultaneously out of service.

It was then that the AESO declared Energy Emergency Alert 1 (shown on the demand chart. Darker colours mean a more severe alert level). This means, I still have about 500 MW, I hope nothing else bad happens, because we could go under 500 MW.

Soon after Alert 1 was sounded, one generator came back online, but then another two went offline. One step forward and two steps back.

This was enough to sound Energy Emergency Alert 2 and Alert 3 at almost the same time.

At Alert 2, customers that have previously agreed to help out by reducing their demand do so. And at Alert 3 there is no choice but to shut down entire suburbs at a time. Desparately clawing for a 500 MW buffer.

So AESO had no choice but to switch off load

But isn’t it strange that so many generators went offline at once? The price for electricity increased by 5000% (50 times higher). Those generator owners were earning a lot of money. C$ 57 million – for 6 hours work.

While the natural response is to call these generators out for being so greedy, take a look at the temperatures (for Edmonton). They are only a few degrees below the highest ever recorded temperatures. Most power equipment is only designed to withstand a certain temperature range. Operating outside of that range can damage the equipment.

A similar situation happened in Tasmania in 2009. The high voltage line connecting it and the mainland was not designed to cope with temperatures above 35 degrees. The shutdown of that cable, and other coincident shutdowns meant widespread rolling blackouts and 20,000 customers without power.

We’ll watch this case carefully, the AESO have already committed to a review but not to releasing the results (unlike the Australian Energy Market Operator that publicly releases investigations). Let’s hope that any lessons are learned and quickly implemented so that we do not see a repeat this summer.

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