Wind turbine operators to curb operations in severe weather

Environment Canada can't block wind farms from being built close enough to throw off its weather radar readings, but it's won the right to order turbines curtailed during severe weather in southwestern Ontario, documents obtained by The London Free Press show.

Under a 32-page agreement negotiated with NextEra Canada, Environment Canada can order the Florida-based wind energy giant to reduce wind farm operations in extreme weather that could jeopardize public safety. Following a call from Environment Canada to its operation centre in Juno Beach, Fla., NextEra has 20 minutes to "feather," or adjust, turbine blades back in Ontario so they won't contaminate radar readings, according to the agreement provided to The Free Press under the federal Access to Information Act.

The curtailment can last up to an hour, but can be extended by Environment Canada if dangerous weather conditions - southwestern Ontario is located in a tornado alley and heavy snow belt - persist.

Ground Zero for industrial turbines in Ontario, with the biggest and largest number of wind farms in the province, southwestern Ontario has been a hotbed of rural opposition to the highrise-sized installations, which took off after the Liberal government began signing sweetheart deals with energy companies - paying them far more for their electricity than consumers pay - under its Green Energy Act in 2009.

But while much of the opposition to the wind farms has come from activists concerned about health, land values and control over where the towers can be built, which the province took away from municipalities, the contamination of weather radar readings by spinning turbine blades - known as "clutter" - is an international concern.

Scientists in the United States and Europe have shown that a weather radar signal bounced off a spinning turbine blade can appear to be a rotating cloud or tornado. The wind farm operations can also distort precipitation estimates. While southwestern Ontario depends on Environment Canada's only radar station in the region, in Exeter, north of London, for severe weather alerts, the agency has no jurisdiction over where potentially distorting wind farms are built, Anne-Marie Palfreeman, manager of Environment Canada's national radar program said.

Wind turbines located within five kilometres would be a major concern, since the towers themselves can block the radar signals, she said. Wind farms built within 50 km show up on the radar and can distort what meteorologists see, she said.

A spokesperson for NextEra said the company has now reached agreements with Environment Canada covering its Bornish, Jericho and Bluewater wind farms, all north of London and within 50 km of the radar station.