Over some time there have been conflicting stories about the purpose of a backup power generation unit at the Mount Dennis maintenance facility on the Crosstown project. I have heard some rather wild statements from folks at Metrolinx that suggests they might be making things up based overheard water cooler chatter (not that offices tend to have water coolers these days, but it’s the idea that counts).

After the media scrum at last week’s board meeting produced more confusion, I sent in a set of questions for clarification. The boffins at Metrolinx are supposedly working on it. Yes, you. I know you read this site, so in case the memo hasn’t reached your desk, you might want to answer the following:

Regarding the backup generator at Mount Dennis: I have heard stories both that its purpose is for on site emergency power and for traction power to the main line. Another variant is that less than full power would be provided in an emergency at least to clear trains from tunnels. It does not make sense to have one huge generator capable of providing traction power to the entire route. At a minimum, a parallel distribution system would be needed to connect to the standard substation-based feeds along the line. Also, emergency power requirements are different for traction (750 VDC) and station power (110/220 VAC). Do you really expect me to believe you plan a totally independent power distribution network from Hydro? Another cockeyed variant is to use the generator to offset peak power demands. Please provide a detailed technical description of what this generator is expected to power and under what circumstances so that there is a single explanation of this project from Metrolinx.

I await a reply from Metrolinx that is coherent and credible.

Updated September 20, 2016 at 10:40 pm:

Metrolinx has provided the following information about their power generation proposal for Mount Dennis:

Metrolinx is working with Toronto Hydro to explore an alternative to the proposed natural gas powered back up facility near Mount Dennis Station. An alternative would have to provide the same basic functional requirements as the proposed natural gas powered facility. It would also be subject to any necessary approvals from the Province of Ontario and the City of Toronto. More info is coming in the near future I understand. 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. The proposal included: a traditional Toronto Hydro electrical grid connection at two locations; and,

building an 18 Megawatt backup power facility – six generators – (with capacity to heat the MSF office spaces) in the northwest corner of the MSF site, known as the backup power facility. CTS [the consortium building the Crosstown line] developed this proposal based on our RFP requirements whereby proponents were asked to design a system to achieve the power needs of the project, which included redundancy. The Energy Matters regime of the Project Agreement drove proponents to make the system as energy efficient as possible and to the extent possible limit peaks during the key hours of peak that challenge the grid. CTS is asked to forecast the following power supply needs for the system and commit to them for the 30-year Maintenance Period, a) Discrete Power Use: the total amount of power needed;

b) Transmission Peak Use: the peak amount of power needed at any point in time (i.e. during rush hour); and

c) Global Adjustment Peak Use: the peak amount of power needed during the time when Toronto Hydro’s network is a peak capacity. Each of the above peaks were assigned a $/MW or $/MW-h to determine the overall power costs of the project (that was unique to that proponent’s proposal). This cost was part of the proponents’ bid for the purposes of the financial evaluation. This regime exists to make bidders responsible for energy efficiency of their LRT system because Metrolinx will pay the energy bills for the 30 year Maintenance Period. The proposal from CTS to responded with a fully capable 18MW power facility with the ability to completely eliminate contribution to peak period on the grid. As a result of the proposal, CTS was able to reduce their evaluation costs for the Global Adjustment Peak Use and their Transmission Peak Use. The final power supply scenario provided for both a traditional connection to the Toronto Hydro network as well as the self-generating power facility. CTS’ obligations were to provide the power supply and HMQE’s obligations were to determine which power supply to use, i.e., either the backup power facility or the connection to the Toronto Hydro network. There are rules associated with changing of the power supply. CTS also committed to making one of the power generation units a co-generating unit (produces power and captures heat by-product). [Email from Anne Marie Aikins, Senior Manager, Media Relations, Communications & Public Affairs, Metrolinx]

This description begs a few questions:

If Toronto Hydro’s capacity is strained, how are we powering new facilities such as the TYSSE and proposed SSE? Does the TTC have to design for an alternative, power self-generation and transmission capability?

How does this claim square with statements made during the GO Transit electrification study that at the provincial level, spare power for RER was not an issue at all?

What additional capacity will be required to power the extensions to Pearson Airport and UTSC, and can this reasonably be sited at one location, Mount Dennis?

Updated September 22, 2016 at 8:20 am:



The acronym used above “HMQE” refers to “Her Majesty the Queen’s Entity”, a short form for the combined Metrolinx and Infrastructure Ontario Entity.

The primary purpose of the generator is supposedly for “Bulk Power Disruptions”, that is to say an outage from the provincial supplier, Hydro One. There have only been three such outages since (and including) the major blackout of August 2003. However, other explanations for the generation capacity emerge from time to time.

Crosslinx Transit Solutions (Crosslinks), the winning proponent, proposed an 18MW (six 3 MW engines) natural gas fired power plant to achieve 40% reduction in life-cycle electricity costs, as well as, provide backup power to protect against Hydro One electricity transmission failure (e.g. June 2013 flood at Hydro One Manby Station left 300,000 people without power for days in west Toronto and east Mississauga). Back-up power is required to ensure that LRT trains can be removed from tunnels, and provide emergency ventilation in the event of a power failure. [From the city’s report Update on Metrolinx Proposed Power Plant for Eglinton LRT, p. 3]

In other words the primary function is to reduce electricity costs rather than simply having backup power. There is no business case to show how generating their own electricity would be cheaper for this line than direct purchase from a utility.

Toronto Hydro requires additional distribution capacity for the Crosstown line and will have implemented this by the time it opens. However, this will not, according to Metrolinx, be in place soon enough to allow early testing. That statement does not explain just how much power testing would require as opposed to full operation of the line, nor whether Toronto Hydro is already capable of providing power for the testing phase.

The City’s report also speaks of heat recovery for use on site and by nearby developments. This would only make sense if the generators were operating fairly regularly, not as occasional backup units.

GO Transit’s RER power feeds will come directly from Hydro One and they will not be constrained by local transmission capacity.

Metrolinx has yet to comment on power for the Crosstown extensions, but they have confirmed that the Finch LRT will not include a comparable power facility in its design.

This entire scheme is looking more and more like a noble idea gone wrong. The specifications for this facility are in a section of the Crosslink project contract (“Output Specifications”, Schedule 15) that is completely redacted from the public version. It is intriguing that the contract contemplates the possibility that the cogeneration facility might be dropped from the project (section 20.18).