David O'Brien, president and chief executive officer of Toronto Hydro Corp., said the wires in distribution networks can behave in strange ways when major changes are introduced to the system.
"I'm going to be the first guy in line to buy an electric car, and by God it's about time," he said. "But people forget that our electricity system is designed around what we do today. It's not a forward-thinking grid.
For example, during the hottest days of the summer, power lines can overheat and short out unless they get a chance in the evening to cool down, which tends to be the case overnight when there's a smaller load on the system.
"If we start plugging in a bunch of cars overnight then you don't let the system cool down enough," O'Brien said. He added that the overnight load will get even greater as the province moves to time-of-use power pricing and more people have an incentive to run power-hungry appliances at night.
It's not a showstopper, he said, but an example of what needs to be considered as we move toward electric transportation. Companies such as General Motors, Toyota, Nissan and Ford have all announced plans to come out with plug-in cars within the next few years.
"We've got a couple of years now to get the industries together and start talking about how we're going to make it work."
Included in this discussion should be ways to allow more small-scale renewable energy, such as solar and wind, onto a grid that was designed to push electricity to consumers not take it from them, O'Brien said. "We have to rethink our whole transmission and distribution systems," he said.
Even before these trends take hold, Toronto Hydro has been seeing an increase in the frequency and duration of outages in pockets of its network, mostly in Scarborough, Etobicoke and North York.
O'Brien said 35 per cent of the utility's network is "beyond its life expectancy."
A $1.3 billion, 10-year rebuilding plan approved by the Ontario Energy Board will bring that figure down to only 25 per cent. Getting it to 10 per cent will take several billions of dollars, he added.
Alongside this renewal, Toronto Hydro is also preparing its customers for the introduction of time-of-use pricing in 2009, when electricity use during peak times will cost a premium and off-peak use will be rewarded with a discount.
The idea is to encourage people to shift electricity use from peak to off-peak times so overall demand is more evenly distributed throughout the day and the grid operates more efficiently. The utility has so far installed 550,000 "smart meters" and is reading information from about 400,000 of them.
A year from now all 670,000 meters will be installed and operational. Some customers are already being directed to a website that lets them get a sense of what their hydro bill will look like once time-of-use rates are formally introduced.
"I think 2009 will be a very interesting year," O'Brien said. "We'll do a pilot project starting with 10,000 customers and over a period of time transition them (to time-of-use pricing). It will be an evolutionary process, but I see next year as the big start."