The global transition of diesel-powered bus fleets to electric vehicles may be in its early days, but all signs point to growth acceleration over the next decade. In Canada, current federal plans would have 5,000 zero-emission buses on the streets by the end of 2024.

This led energy researchers to a key question: how will this impact not just transit authorities, but utilities and power system operators? What are the factors that affect how much electricity each bus will actually use and at what points of the day will they need to charge up? And how can these factors be optimized to support transit and power grid operations? The IESO partnered with York University and Alectra Utilities to find out.

A few years ago, Dr. Hany Farag wanted to dig deeper into his study of bus transit electrification — moving beyond basic calculations and involving the real-life circumstances of how Ontarians travel. Ultimately, Farag sought to identify exactly what it would take — from a cost, logistical and electricity demand standpoint — to fully electrify a municipal bus system.

“It’s not only going to impact the grid in terms of the increase in demand for power, but also the cost of electricity is going to be significantly impacted by the location of the charger and the charging time for the municipalities,” said Farag, an associate professor at York University and research chair of Integrated Smart Energy Grids.

The idea was taking shape in 2018, but Farag needed a partner to support it. He submitted a project to the Grid Innovation Fund, where the IESO supports innovative projects that enable customers to better manage their energy consumption or that reduce the costs associated with maintaining reliable operation of the province’s grid.

“Electrifying cars and transit makes a lot of sense in Ontario, where the electricity system is 93% emissions free,” says Katherine Sparkes, IESO Director, Innovation, Research & Development . “While electrification can contribute to higher overall electricity use, studies like Dr. Farag’s can help us understand how to best optimize transit electrification, while ensuring the reliability and environmental benefits for transit systems and the electricity grid can be realized.”

With this funding, and with Alectra serving as the utility stakeholder, his team set out to work on an analysis of Brampton, Mississauga and York Region.

A Future of Electrified Bus Fleets

Farag and his team, in collaboration with Moataz Mohamed, assistant professor at McMaster University, have developed an integrated transit-utility optimization toolbox, including an engineering formula that considered transit modelling, simulation, optimization and design so that transit authorities could determine the most efficient transition from a diesel-fueled bus system to a fully-electrified one.

 “As transit electrification grows, when they charge is just as important as how much they charge – the IESO needs to ensure that we have enough generation and transmission capacity to meet needs at all times of the day,” said Ahmed Maria, IESO Director of Transmission Planning.

“This study will encourage more transit authorities and utilities to take a closer look at optimizing the operation of electric bus fleets that are coming online over the next decade. More accurate energy use forecasts will help IESO ensure a reliable supply of electricity, at the lowest cost.

The IESO’s forecasts released in 2020 show electric vehicles (which includes cars and buses) will make up roughly 10 per cent of Ontario’s demand growth over the next 20 years, or 4.06 TWh of demand by 2040.

Charging-Up Mass Transit

The real-life study showed how much actual electrical consumption a running bus can vary from the stated average electrical consumption rate from the bus manufacturer. For example, if a route has a long and extended incline it will need more energy – and planning from a utility perspective needs to take that into account. Researchers also found that that adding seven 600 kW chargers along one distribution line would mean a peak demand increase of 17 per cent. They also considered energy storage systems to help increase charging efficiency on heavily-used routes.

Informed by the research of Farag’s team as well as case studies, the toolbox can clearly determine all components of an electrified bus fleet, its recommended charging needs and the resulting impact on the grid.

“We’ll know the impact on the grid per route, per trip, per fleet, you name it,” Farag said.

For Neetika Sathe, VP of Alectra’s Green Energy and Technology Centre, the research represented a much broader overview for electric bus fleets.

“While we have done a lot of research related to individual passenger vehicles being electrified, we did not have a good report in hand, or a good sense of the impact of the mass transit, the bus electrification. So this report really filled that gap,” she said. “The devil is in the details and yet they were able to incorporate it and aggregate it and come back to us with a report that was relevant."

Farag believes the detailed summary of findings in the report also opens up other areas of study that can be relevant to utilities and municipalities as trends move in this direction.

“How this can be realized with the minimum cost possible, without significantly disrupting transit operation and practices, and overall power grid operation,” he said. “That is the importance.” 

Just as Alectra now has the details of bus electrification expectations and impacts in hand — tested in real-time, on real routes in Brampton, Mississauga and York Region — the formula prepared by Farag’s team is openly accessible for any Ontario municipality that is considering an electric transition to serve its community’s public transport needs. 

Learn more about the report called Optimization Toolbox for Public Bus Transit Electrification.