John Spears, Business Reporter | Toronto Star | www.thestar.com 26 September 2012
With about 2,000 megawatts of wind and solar power now flowing onto Ontario’s electricity grid, the province sometimes has to dump surplus electricity at a loss.
With 10,700 megawatts of renewables scheduled to come into service by 2018, can Ontario’s system handle the strain?
The Ontario Society of Professional Engineers has raised a skeptical eye at the province’s green energy plans.
But at a meeting organized by the society Wednesday, the province’s chief power planner said it’s under control.
“We’ll be ready for it,” Amir Shalaby of the Ontario Power Authority said after addressing the meeting at the Toronto Board of Trade.
Currently, wind and solar power flow onto the power grid whether needed or not. Wind power in particular is often most plentiful when it’s least needed, forcing power system operators to give it away for nothing, or even pay big customers to use it.
Renewable also fluctuates with winds and clouds, forcing the system to keep other generators – usually gas-fired plants – on standby to handle the wobbles.
None of this came as a surprise to system planners, Shalaby said; it was obvious that adjustments would be needed when the province embarked on its ambitious Green Energy Act, passed in 2009.
“It’s not going to go away; it’s going to be a challenge that’s part of the landscape for years to come,” he said.
Here are some of the approaches:
• By the end of next year, the Independent Electricity System Operator hopes to be able to switch turbines on and off the grid, vice president Bruce Campbell told the meeting.
The big unanswered question: How will the wind producers be paid when they’re switched off? Most hold contracts assuring them of full payment for all they produce, and they’ll need to be compensated if their output is curbed.
• Normally, it’s very difficult to throttle back the output of a nuclear reactor when there’s too much power on the system. It takes several days, and leaves the system vulnerable if demand suddenly jumps.
Bruce Power has figured out a way to reduce production by venting the steam produced by the reactors, instead of reducing power from the reactors themselves.
Of course, they’re still paid for the output they forgo. Consumers ultimately foot the bill through the “global adjustment” charge on their hydro bills.
• Numerous companies are working on ways to store energy when it’s plentiful and use it when it’s scarce. One way is to pump water uphill when power is cheap, then let it run through a generator when it’s expensive. Some firms want to do the same thing with air – pumping air into underground caverns or underwater balloons, and using the compressed air to run generators later.
Enbridge is working on hydrogen technology that would use surplus power to break up water molecules into hydrogen and oxygen. The hydrogen would be pumped into Enbridge gas mains – in effect using its pipeline system as a big battery for storing power.
• Reducing demand can be as effective as increasing supply. To help adjust to the minute-by-minute changes in power demand, Enbala Power Networks collects companies who can afford to delay drawing power from the system for short periods.
Municipal water pumping stations, industrial-scale refrigerators or big-building heating and cooling systems can often afford to wait for short periods before switching on. Enbala collects those firms, and installs equipment that allows system operators to make short-term adjustments by shutting off these big customers for brief periods.
That can help compensate for short-term peaks and valleys in wind or solar power output.
URL to article: https://www.wind-watch.org/news/2012/09/27/preparing-for-a-flood-of-renewable-power/