By Patrick M. McKelvey, AIA, PQP
Across the country, transit agencies face a growing need to adopt more sustainable operations and maintenance practices, including the use of environmentally friendly products and transportation methods. Air pollution in major cities from Los Angeles to New York, caused in part by fossil fuel-burning vehicles, is a growing issue of concern that many transit agencies and municipalities simply cannot ignore. In fact, according to the Federal Transit Administration, transportation accounts for 29% of greenhouse gas emissions in the U.S. One approach transit agencies can take to address their impact: battery-electric buses.
Electric buses are quickly becoming the vehicle of choice for transit agencies looking to reduce their carbon footprint. Some major transit agencies are already putting stakes in the ground to go completely electric. Both the Los Angeles County Metropolitan Transportation Authority (LA Metro) and West Covina, Calif.-based Foothill Transit have committed to using 100% zero-emission electric bus fleets by 2030. LA Metro currently operates 2,200 buses; Foothill operates over 300. The impact could be significant. From 2010 to 2016, Foothill’s 15 electric buses eliminated 2,616 tons of greenhouse gases and helped the agency save 200,405 gallons of natural gas. Other agencies, such as Madison Metro in Wisconsin, have opted to slowly replace their existing fleet over time through annual replacement programs.
Electric buses are designed to operate with more efficiency and at a lower cost than buses that use diesel or compressed natural gas (CNG), a lower-emission alternative that many agencies have started using over the past decade. Liquified natural gas briefly was in favor in the previous decade, but didn’t gain the market share of CNG. While there are many arguments in favor of electric buses, including reducing air pollutants, such as carbon monoxide, nitrogen dioxide, particulate matter, and other volatile organic compounds, the decision to use them isn’t quite as simple as a yes or no.
Transit agencies must first identify and create the infrastructure needed to maintain and operate this new kind of vehicle. Agencies that made the transition from diesel to CNG bus fleets might cringe at the thought of going through another change, but fortunately, incorporating electric is not quite as difficult. It simply requires different considerations.
Operation, charging electric buses
When bus fleets in major metro areas made the transition from diesel to CNG, the infrastructure upgrades were significant. Agencies had to create new fueling stations, meet new exhaust, ventilation and monitoring standards, and educate crews on maintaining the vehicles.
In switching to electric buses, crews will still need to be educated on maintenance and operations (including charging protocol), but there is no need to change fuel stations or update exhaust systems because a zero-emissions bus fleet simply does not require it. Electric charging stations can be easily located inside new or existing vehicle storage areas.
However, the operating limitations of electric buses do require consideration. Diesel and natural gas-powered buses can run up to 400 miles on one tank of gas. While it may not be the best option for the environment, these buses can make continuous routes without refueling breaks.
The current technology in electric buses does not provide that same flexibility. While manufacturers and models vary, today’s electric buses can typically run up to 120 miles on one charge — and only 35 miles on certain models. With that in mind, it’s important to consider the location of the transit agency’s operations and maintenance facility in relation to routes.
If electric buses need to operate outside their range, transit agencies will need to consider charging vehicles en route, either by developing charging stations along longer routes or by using on-bus charging systems. Manufacturers such as Proterra offer a 10-minute full-charge technology that can be used for buses in transit. These can be “in-line” charges, or an ideal location would be in transit centers. Typically, bus schedules call for a “layover” at the transit center, providing a perfect opportunity to charge the buses while they wait. Another option is to limit the use of electric buses to shorter routes with close proximity to the facility. However, as electric bus technology continues to advance, the need for multiple charges throughout the day will most likely dissipate.
Electric buses can also be charged overnight, which comes with its own set of advantages. Since buses are already stored overnight in facilities, there is minimal infrastructure needed to support electric buses. Besides creating charging stations, the overnight storage will not look very different from today’s set-ups.
Relationship with Utility Companies
One of the biggest changes to the infrastructure of a transit facility using electric buses is ensuring the correct amount of power is available. Electric buses require more electric energy to operate than their diesel counterparts — energy that would need to come from the region’s electrical grid or generated on-site. Utility companies, then, are one of the most important relationships for any transit agency because they are the gatekeepers of that power.
Recognizing the future role of electric vehicles, many utility companies are already figuring out ways to support city-wide and state-wide energy goals. Some states, like Wisconsin, have efficiency programs in place that provide rebates to cities for designing highly efficient operating facilities. By partnering with these companies, a transit agency can begin to assess the level of electricity needed to charge 15, 150, or 1,500 electric buses, and when the best time to do that is, depending on what the grid can handle.
As electric bus technology advances, transit agencies will have increasingly viable options for improving the sustainability of their operations. Looking at the whole picture, from bus technology to infrastructure needs, is one important step in ensuring this move is done as effectively and efficiently as possible.
Patrick M. McKelvey, AIA, PQP is a senior principal at RNL (www.rnldesign.com), now part of Stantec.