Demand Shifting

There is actually no lack of electrical energy supply on average in Toronto. The problem the Province proposes to address with the construction of the Portlands Energy Centre is an imbalance in the time that energy is produced and the time that it is required. Gas-fired plants produce expensive electricity that is only economical at times of peak demand. There are many approaches that achieve the same result with fewer negative consequences.

Flow Batteries

The most significant thing we can do immediately to ease demand on the power grid, possibly on the Portlands, where existing transmission lines can be used, is to invest in a number of large storage options to capture electricity at times of low usage and provide power at times of peak demand. In particular, we should aim to capture plentiful and inexpensive nighttime energy during the summer, and discharge it during hot afternoons, when transmission lines are overloaded and electricity in general is scarce and costly.

One exciting potential for storage is a flow battery. At as little as $150,000 per MWh of energy storage, construction is economical, and operating costs are negligible, so energy at peak times could be delivered more cheaply than by the proposed Portlands Energy Centre. This means of delivering energy to the city has no emissions, no moving parts, minimum sound emissions and is powered by non-toxic saline solutions. Environmental and health impacts are very low and operation is not subject to the price fluctuations of a dwindling resource. Best of all, investment in such a battery is excellent preparation for greater investment in wind and solar energy, because it enables the city to shift electricity use from the time of production, enabling it, for example, to capture nighttime winds to cool houses during the day. The net savings at peak could be hundreds of megawatts. We might begin with peak contributions of 50 MW.

Enwave Enhancements

Another large project that could save hundreds of peak megawatts is a series of enhancements to Enwave. Deep-lake cooling capacity of the system could be expanded four-fold if we took advantage of nightly low periods to chill blocks of ice using the cooling capacity of lake water to enhance the efficiency of the compressors, then used the ice during the day for heat transfer, for a savings of 150 MW at times of peak use during the summer. This technology is well developed and used in Chicago, where the city centre is cooled by an ice storage system. Further savings at Enwave could be achieved through the construction of a highly efficient trigenerator. The combined contributions of the generation and absorption cooling would reduce demand at peak load by a further 150 MW for a total contribution at Enwave alone of 300 MW at peak.

Emergency Generators

All large downtown buildings have emergency generators. These generators need to be periodically tested. This testing is currently done without regard to grid demands. Toronto Hydro is implementing a program to operate these generators when demand peaks. Toronto buildings have 1,000 MW of generation potential, 20% of the peak load. A reasonable target for the next two years would contribute 150 MW to the peak.


Toronto Hydro's Peaksaver program, which reduces the amount of electricity central air conditioners draw during peak times, should be aggressively promoted with both advertising and financial incentives. Most customers perceive no difference in their comfort levels, and because electricity delivered at peak is more costly for Toronto Hydro, the program can be profitable even if substantial financial incentives are offered to join. Toronto Hydro estimated that by June 2006, 2,700 customers would subscribe to the program for a reduction of 7 MW with only a token incentive of a one-time $25 payment and an appeal to their sense of civic duty. This target has already been exceeded and a revised target of 100 MW reduction by 2007 has been set.

Total Shift from Peak Demand

We could shift at least 600 MW of demand away from peak times using these techniques. More aggressive use of storage and other options could increase this number. The ideas presented here are only examples of the kind of savings which could be achieved with creative manipulation of electricity demand patterns in the city. One advantage of addressing peak demand by shifting is that most of this can be accomplished by the City without provincial support. Even without any conservation, efficiency or other generation, the 550 MW plant is unnecessary.

This document is part of a three-part Realistic Energy Plan for Toronto:
Conservation, Demand Shifting, and Cleaner Power.