By Don Butler, Ottawa Citizen
One of the inherent limitations of wind power is its unreliability. It produces electricity only when the wind blows. And how much it produces depends on how much oomph nature provides at any given time.
Ontario has wind power with an installed capacity of 1,636 megawatts, an amount expected to rise to 2,200 megawatts by early next year.
But in fact, it produces far less than that. Friday morning between 8 and 9 a.m., for example, wind was generating just 31 megawatts of electricity. Between 11 a.m. and noon on Wednesday, when winds were blowing more lustily, it was cranking out 669 megawatts.
In a recent study, Aegent Energy Advisors evaluated wind data for 2009 and 2010 from the Ontario Independent Electricity System Operator (IESO), which measures the output of wind turbines connected to the high voltage distribution grid.
It found that the average “capacity factor” over that time was 27.8 per cent, meaning that for every 1,000 megawatts of installed wind capacity, the average annual output would be 278 megawatts. But that doesn’t account for wind’s variability. That same 1,000 megawatts would produce no electricity at all at if there’s no wind, or as much as 949 megawatts in a stiff gale.
By comparison, nuclear power has an average capacity factor of about 90 per cent. Last year, nuclear reactors produced the equivalent of a continuous, around-the-clock output of 9,452 megawatts.
To replace that nuclear output with wind power, Ontario would require 34,000 megawatts of installed wind capacity, Aegent calculated. The turbines needed for that, it said, would consume 14,200 square kilometres of land — equivalent to a band 14 kilometres wide and 1,000 kilometres long.
Ontario would also need 10,000 megawatts of natural gas generation as a backup for periods when wind power was producing little or nothing, Aegent said.