More on the Mount Dennis Generator

From: insidetoronto.com
Image from: insidetoronto.com

Steve Munro is a tireless blogger who is an authoritative voice on transit and politics in the GTA. He recently posted an article about the proposed Mount Dennis generator and some interesting points have emerged in his article and also in the comments section. As an aside, comments sections are IMHO as interesting and sometimes as informative as the articles to which they are attached.

Readers are no doubt aware that late last year, Metrolinx and its partner Crosslinx Transit Solutions proposed that an 18MW gas-powered generator be built to supply electricity in the extremely rare event of a Toronto Hydro outage. Later proposals designed to soften the blow claimed that heat could be recovered from the generator and used for heating purposes.

Steve maintains that the heat recovery idea could only be useful if the generator was operating regularly rather than the claimed (by Metrolinx) use as a standby. Also, according to Metrolinx, only one of the 6 generators would be used for heat recovery while the other 5 would be untouched.

He received information from Metrolinx stating that:

An alternative (to the gas powered generator) would have to provide the same basic functional requirements as the proposed natural gas powered facility.

The gas-powered facility was proposed in order to provide the ability to maintain service when the power goes out and improve transit resilience, lower the cost of power by eliminating any contribution to peak power demand from the new system, and ensuring it does not contribute to the need for more transmission or generation infrastructure.

Steve notes that there are several electric train systems coming on line and Metrolinx stated that there is already an ample electrical supply for these trains. He concludes that the main goal of the generator is to reduce electricity costs rather than provide an emergency backup.

In the comments, one reader suggests that in a true emergency, gas supply is only guaranteed for 3 hours. Another points out that the natural gas supply relies on line pumps which need electricity from the grid. Yet another states that running the whole line from one generator is impractical because of the voltage drop that would occur over the 19km length of the Crosstown Line.

Apparently the generating system at Pearson Airport sells power to the grid at peak times and this income pays for its operating and maintenance costs. The generator is fired up every week to ensure that it is reliable (i.e. at least 52 days a year) and supplies the airport with power on those days. Because the airport covers a relatively small area, transmission losses are minimal (unlike along a 19km transit line).

Incidentally, the last time power was knocked out to Terminals One and Three back in February, the emergency system failed to operate, leaving much of Pearson in the dark.

Read Steve Munro’s article here.