[See the end for the update which discusses the bus fleet.]

Green Power comes up from time to time in the transit wars, especially when anti-LRT and anti-trolley bus factions trot out observations about “dirty” peak power.  Strangely, we never hear this sort of remark about subways, but some of those projects have enough hot air in them that Calgary’s “Ride The Wind” slogan has a whole new meaning.

Calgary is proud that its LRT network is entirely powered by wind energy, and I thought it would be worthwhile to compare the TTC’s power requirements with the capacity of the wind farm that Calgary uses.

TransAlta Wind supplies the power, and their current installed farm of 252 turbines generates 731,000 MWh (MegaWatt hours) per year.  They are planning to expand with higher-output turbines.

For comparison, the generator at the CNE, a comparatively small installation, produces 1,815 MWh per year.  Its generator is one quarter the capacity of the newest TransAlta installations.

The TTC’s annual power requirement is cited as 436,000 MWh in a December 2007 report on their environmental plan (at page 9).

Supplying the TTC would require a wind farm on the order of 50 of the new generators planned by TransAlta, presuming that we could obtain comparable all-year wind in Ontario matching Alberta’s climate.

This would not, strictly speaking, power the TTC but would feed into the grid to offset demand elsewhere.  The TTC’s demand has strong peaks, and wind just doesn’t work that way.  Some peak power will inevitably come from peak generation capacity, whatever technology that may be.

As the TTC moves to increase its use of electricity for propulsion, there will be a lot of debates about the power source.  In all of this it’s worthwhile to know the scale of what we are discussing.

Update:  In another thread, the enternal question of trolley buses and possible alternatives is churning again.  Supposing that the automotive industry actually manages to create an electric bus (remember that this is the same industry that is in danger of going bankrupt for lack of meaningful R&D).  What would an electric bus fleet’s power requirement be in Toronto?

As a starting point, I will use the trolley bus because it is a well-known, well-documented form of electric bus using modern propulsion equipment.  It is highly unlikely that any new vehicle will improve substantially on its power consumption.  The power consumption for trolley buses reported by APTA (American Public Transit Association) is .18 mile/kWh.  This is equivalent to 5.56 kWh/mile or 3.45 kWh/km.

In 2007, the TTC bus fleet operated 107,609,000 km, and if this had entirely been at the average consumption of the trolley bus fleets included in APTA’s numbers, this would require 371,251 MWh of power.  Note that this is not far below the existing electrical power requirements of the TTC.  If we add the numbers together, we get more than all of the wind power now generated by TransAlta Wind.

Alas, if we insist on using battery or fuel cell buses, we will suffer very considerable conversion losses within those systems, and the total power requirements will be even higher.