The Bright Future Of Bus Electrification

By John Hroncich, Director, North American Transit Sales at BAE Systems

John Hroncich

There is no denying that the transit industry is in the process of an electrifying transformation. Growing environmental concerns, coupled with advancing technology, are setting bus/coach companies firmly on the path toward increasingly electrified platforms.

Imagine what that would look like.

Transit authorities would benefit from fuel savings, easier maintenance, and lower operation costs. Riders would enjoy cleaner air, a quieter ride, and a lower carbon footprint. Larger communities would benefit from the reductions of those harmful emissions and traffic noise.

The future of transit is electric… but the road there has admittedly been long and bumpy.

The adoption of fully electric buses is complicated by several factors. Charging stations are a significant investment that often requires coordination with local governments and utility companies to ensure electric grids can handle increased demand. Cost is also a factor. While electric buses can lead to lower operating costs over time — thanks to reduced fuel and maintenance expenses — purchasing one is a much larger up-front investment over traditional diesel buses. The battery technology that powers electric buses is also a major concern. Careful planning is required around charging times to ensure electric buses can run their routes without interruption. The safe operation and storage of battery electric buses are concerns as well for transit operators.

Engineers are currently innovating solutions that will advance the technology of fully electric transit and its infrastructure. There are hybrid buses that operate on electric power, significantly reducing emissions, fuel consumption, and noise, without the added complexity and expense of additional infrastructure. Work associated with developing hybrid electric bus solutions has established the supply chain of batteries, electric accessories and software management solutions; all key elements for bus electrification. Key technologies — such as regenerative braking, energy storage system load balancing and variable power control for electric accessories — have been developed for hybrid buses and are now being utilized for battery electric and hydrogen fuel cell powered buses.

There are hybrid systems, for example, that power thousands of buses worldwide and are equipped with reliable electric drivetrain technology. This involves a smaller diesel engine running in its most emission-friendly mode, coupled with a generator, that powers the bus using a fully electric drivetrain. Using an on-board generator, hybrid buses utilize regenerative braking to capture energy (which is wasted in conventionally-powered buses) in their energy storage systems. These buses can reach their destinations without the need for expensive charging infrastructure or increased grid capacity. They are fueled once per day in minutes, versus hours.

In addition, hybrids allow workforce development by providing valuable training on high-voltage systems. This includes everything from integration to general operation and service, gradually allowing technicians to gain experience working on electrified systems. If a fleet technician can diagnosis a hybrid bus, he/she can do the same for battery electric and hydrogen fuel cell electric buses. Hybrid powertrain training teaches how to safely work with high voltage power, troubleshoot across an integrated system of inverters, batteries and software, and guides technicians in ground-fault diagnosis. These are skills essential for the future electrified bus fleet workforce.

More than 25 years of development in hybrid solutions has also allowed for the development of energy-saving technology and zero-emission features. The latest generation technology uses advanced materials such as silicon carbide (SiC) and gallium nitride (GaN) to improve fuel efficiency, allowing the energy to cover more distance and the bus to operate more efficiently. Such a system uses less fuel and produces fewer emissions due to a continuous management of power flow from the engine to the battery and wheels, while also maximizing the capture of regenerative breaking energy.

Another key feature of hybrids is that they can be equipped to operate within engine-off zones, enabling emission-free travel in designated areas called “green zones,” a great option for transit operators.

Green zones help cities eliminate emissions in targeted areas by turning a hybrid bus into a part-time zero emissions bus. Using GPS-enabled geofencing technology, the zero-emission capable hybrid buses will automatically switch to battery power when entering designated zero-emission zones. The green zones are in population-dense neighborhoods and confined areas most affected by air pollution. The bus then switches back to electric-hybrid mode when it exits the zone and then recharges the on-board battery before entering the next zone. Electric drive systems with green zone technology are currently operating on buses in major cities, such as Toronto and San Francisco, as well as smaller fleets including in Broome County, NY, and Rockford, IL.

In summary, hybrid buses bring the environmental benefits, operational flexibility, and cost-effectiveness that are core to bus electrification. As cities continue to seek innovative solutions to combat pollution and enhance public transit systems, the adoption of hybrid will ultimately pave the way to a transportation landscape with zero emissions.

BAE Systems’ electric drive solution builds on 25 years of innovation that powers low- and zero-emission heavy-duty vehicles including battery electric, fuel cell, and hybrid electric vehicles. The company has more than 19,000 propulsion systems operating worldwide in transit buses, military and industrial vehicles across the globe. Its electric propulsion technology is developed and serviced at its facilities in Endicott, NY, and Rochester, U.K. Visit baesystems.com.