Why wind power is more complicated than people imagine 

July 8 – a Thursday – was the height of Ontario’s heat wave, the day it reached 35 degrees in Ottawa, the day when air conditioners strained our electrical system to the limit.

Ontario was drinking power at a rate of more than 25,000 megawatts – that’s 25 billion watts – in the late afternoon. Not a record, but far more than most summer days.

Our nuclear reactors were pumping out more than 9,200 megawatts. Hydroelectric power (mainly Niagara Falls) supplied another 3,400. We burned gas and coal to generate another 10,200.

But wind power, one of the ways of the future, supplied just 107 megawatts of electricity. That’s less than half of one per cent of the province’s demand and enough to power a mere 32,100 homes.

Wind turbines dot much of Ontario’s landscape today – hundreds of tall, white structures with three giant blades. Most of them stand 80 or 100 metres high at the centre hub where those blades revolve.

We’ll be buying more soon. Ontario has contracted with the Korean giant Samsung to build wind turbine factories in Ontario and install hundreds more of the machines, some on breezy hilltops, more along the shores of the Great Lakes, and some standing in the lakes themselves.

On paper, the turbines we already have are able to supply nearly 1,100 megawatts. That’s called their capacity.

In practice their annual average is about 30 per cent of that, because wind doesn’t blow all the time.

And the reality is that in summer, the time when Ontario needs more electricity than at any other time of year, they produce far less even than 30 per cent of their capacity. (In winter, another high-demand time, they produce more – often around 70 per cent.)

The 107 megawatts they produced on the afternoon of July 8 equalled just more than 10 per cent of capacity. For much of July they produced 100 to 200 MW, but sometimes they produced even less – 85 MW on the afternoon of July 9, 72 MW on July 12, and all the way down to a negligible five MW on July 20.

On many of these days, Ontario got more electricity from wood fires and from burning waste methane gas at garbage dumps than from the expensive wind turbines.

So, is wind power worthless? Not at all. But it’s much more complicated than people imagine in the clean-sounding deal where Ontario decided to shut down all its coal-burning generating stations and build smog-free windmills.

Ontario has boosted wind by guaranteeing new wind farms a premium price of 13.5 cents a kilowatt hour, removing the need for wind to compete against cheaper coal and established nuclear plants. The guaranteed price is called a feed-in tariff. Ontario is also building new transmission lines to allow for new and expanded wind farms.

We will get more wind power. What we won’t get is an all-green grid where most of our lights, computers and factories are powered by the wind. At most, wind seems likely to supply up to 10 per cent of our power, and even that will vary with the weather.

As Ontario swings toward new sources of electricity for our lights and computers and factories, a lot of juggling becomes necessary.

“As the electricity system grows and diversifies, with more and more different types of generation coming into the mix, there’s more variability on the supply side,” says Robert Hornung, president of the Canadian Wind Energy Association. It represents wind energy producers.

“The system operators – their big job is to ensure that supply equals demand,” he said. “When somebody flips the switch, the power is going to be there. And they deal with a lot of variability. You’ve got demand that varies enormously from four in the morning to five in the afternoon,” as well as seasonal changes.

Despite recent growth, Ontario still gets a small proportion of its power from wind, and when the wind changes radically, it doesn’t upset the overall picture much. Someone adds a little power from gas or coal, and the supply stays the same.

But when there’s a capacity of 5,000 megawatts instead of today’s 1,100, this will change. Either a sudden increase or decrease in wind can surprise us:

– The wind drops. Gas-fired turbines must be standing by to pick up the slack.

– The wind rises. This doesn’t sound bad, but in some conditions it might be, if we suddenly have too much power.

This happened in the spring of 2009, though the wind wasn’t to blame. There had been very heavy snow that winter; runoff was filling rivers. The nuclear plants were running at a fairly constant level and suddenly we had a glut of hydroelectric power. Meanwhile demand was down; in April there was little demand for either heating or air conditioning.

With too much power on hand, Ontario has to get rid of it or risk overloading and damage to equipment. For a full month the price of our power was negative – that is, we were paying utilities in Ohio and Michigan to take it off our hands.

Private energy analyst Tom Adams thinks that could happen again when we lean more heavily on wind power. Wind turbines can shut down in high wind, but Ontario would still have to pay them for the power they aren’t generating, like a diner who orders a restaurant meal and doesn’t eat it. It’s called “curtailed output.”

“As wind becomes a big player in the power market, the dynamics of wind power, the come-and-go nature of wind output, becomes critical,” he said.

“You may get a spike of 7,000 megawatts of wind power that comes on at one o’clock in the morning.” Suddenly the Ontario Power Authority has to get rid of surplus power, or there will be damage. “This is a major, major concern.”

Variability is also an issue closely watched by the Independent Electricity System Operator, the Ontario body that provides a market where generators and consumers buy and sell electricity.

“I often think back to a weekend last fall, actually it was Halloween weekend, when we (had) a record of over 1,000 megawatts from wind between 3 and 4 p.m.” said IESO spokesman Terry Young. “And between three and four o’clock the next day it was seven megawatts. So it’s kind of gone from record high to near-record low in 24 hours.”

The other odd side of wind power is that when it falls off, we’re going to use gas-fired turbines to replace it. We traditionally used coal-burning plants but the Ontario Liberal government is phasing these out by 2014. Coal causes more smog and emits more carbon dioxide per unit of energy than gas. Some coal “units” are closed already. One plant in Mississauga is demolished.

But Adams and others argue this is the worst plan for a wind-loving province.

When they’re standing by, coal plants can run at about 20 per cent of full power. Gas turbine plants, however, must run at a higher level – about 60 per cent.

Adams’ analysis is that this will waste energy as Ontario builds new gas-fired plants for backup. As well, gas is more expensive than coal.

Expanding wind doesn’t fit with phasing out coal, says Norm Rubin of Energy Probe, a Toronto-based environmental policy organization. If these were pieces in a puzzle, “you couldn’t bang them together with a hammer.”

At the Canadian Wind Energy Association, Robert Hornung doesn’t see much risk.

A group of North American utilities has analysed the question. It finds that “you can get up to about 10 per cent of electricity coming from wind without having any really significant impact on system operations,” said Hornung. After that, the ups and downs of wind power are harder to handle. But he notes that Alberta has removed limits on wind installation originally set for just this reason.

“Because wind is so new in North America, there’s still an evolutionary process and learning process going on.”