Power failures, blackouts and other issues with the delivery of electricity for charging are a concern and have to be planned for. Let’s take a look at what might be done to help with different kinds of power issues.
For context, the Ottawa Hospital has generators that can take 1/3 of the load of each site and they would bring in rental generators if an outage went longer than a few hours.
The Confederation Line has 9 power connections to the grid and can continue operation if one of the connections fails. A city wide outage would stop all operations.
In the large part it all depends on how much money is spent on providing a solution vs the probability of an event.
Local Failure at a Garage
As part of optimising the cost of charging, each garage should have a battery bank that can take the load of the garage for a couple of hours. This might also include a backup generator to stretch the capacity of the batteries. This system would be capable of dealing with short power outages with no issues. For longer outages, rental generators could be sourced. Larger generators are capable of charging about 200 buses per day.
To further reduce the possibility of a power outage, power can be supplied to the garage on two separate feeds from the grid to reduce the chance of one failure taking out the site as a whole.
In the case of a catastrophic event such as a fire or major weather event such as last year’s tornados, the buses could be moved to other garages for charging. This would have some impact on service but should not be a major disruption as each bus will take about 4 hours to charge and by cycling buses through the chargers the entire fleet should be able to be charged overnight. It is likely that parking the buses would be the major problem, not charging them.
Weather Disruption of the Power Grid
The Tornados in 2018 and the ice storm of 1998 disrupted power across Ottawa. In both cases power was not out across the city. Depending on the severity of the damage to the grid, buses could be moved between garages for charging or in the case such as the widespread destruction caused by the ice storm, OC Transpo could reduce service as they did in 1998.
In the summer of 2003 there was a grid failure that impacted much of Ontario and many states on the east coast of the US. This outage lasted a few hours in most places, however in Ontario it took about 5 days for the grid to recover fully. This type of event is thankfully rare world wide but still a possible issue that OC Transpo would have to deal with.
The battery systems and generators at garages could maintain some service and if sized for a long term outage the generators could keep the system operational. This solution would be very expensive and likely not justified as the demand for transportation would be much reduced as all workplaces would be closed.
Cooperation with STO in Gatineau
Ottawa does have one interesting option. Quebec’s grid is not vulnerable to the grid issues that were seen in 2003 and Gatineau was not affected by the outage. Similarly, power issues in Quebec are very unlikely to cascade into Ontario. STO, the Transit Authority for Gatineau and OC Transpo could have a reciprocal agreement to charge buses in each others garages in the case of a power failure. This could allow both systems to have cost effective backup plans in the case of a major failure.