During a conference in Center City Philadelphia in August, transit professionals from all over the country piled into a sleek new Southeastern Pennsylvania Transportation Authority (SEPTA) bus for a tour of some of the transit authority’s facilities.
As the bus idled at a SEPTA transportation center in Northeast Philly, it produced a quiet hum. Water dripped from beneath its rear bumper. Bold letters along the top of the bus spelled the words “ZERO EMISSION.”
The bus is one of 10 hydrogen fuel cell buses that SEPTA plans to roll out this fall in a pilot program to help determine what role hydrogen could play in a future zero-emissions fleet.
“We’re going to see what it’s going to be like actually operating the buses,” said Donzell Dunston, project manager of SEPTA’s power department. “So we actually can test it out to see ‘okay, it can handle this route.’”
A hydrogen fuel cell bus that will carry passengers as part of a SEPTA pilot project. Photo: Sophia Schmidt / WHYY
Hydrogen is a fuel that can power vehicles without releasing pollution from a tailpipe. But how clean it is depends on how it’s made.
Hydrogen can be produced using a variety of energy sources, from solar to coal. Most hydrogen today is made with natural gas, and its production contributes to climate change because it releases carbon dioxide, along with other air pollutants. When hydrogen is combusted in an industrial setting, the process can release some unhealthy air pollution, but when used in a fuel cell to power a vehicle, the only emission is water. While some see “green hydrogen” — produced with renewable energy — as a false climate solution, others see it as a way to decarbonize hard-to-electrify industries.
During SEPTA’s year-long pilot project, 10 New Flyer hydrogen fuel cell buses will carry passengers along a variety of routes in both Philadelphia and the surrounding suburbs, helping SEPTA officials gauge how the buses perform over different terrain and in different weather conditions.
The transit authority plans to transition its more than 1,300-bus fleet to zero-emissions by 2040 — and officials expect hydrogen to be part of the picture.
“We will be a mixed fleet, between … battery electric and hydrogen fuel cell,” said Tyler Ladd, director of power engineering at SEPTA. “What we’re doing now with these pilot projects is determining what that percent mix is going to be.”
The first phase of the pilot will involve comparing the performance of the hydrogen fuel cell buses with SEPTA’s current diesel hybrid buses. Then the transit authority will pilot new battery electric buses to compare with the fuel cell hydrogen buses.
The transit authority sidelined around two dozen battery electric buses just months after deploying them in 2019, when the buses developed cracks and other defects (the manufacturer, Proterra, has since filed for bankruptcy). SEPTA also found the buses’ actual range to be lower than what was initially advertised.
“What we saw in that six months let us know that we need to explore some other options,” Dunston said.
Still, the transit authority predicts that battery electric buses will be able to support the majority of its service within the city of Philadelphia. But in the suburbs, where bus routes are longer and the terrain is hillier, officials say hydrogen fuel cell buses may make more sense.
Hydrogen fuel cells vs. battery electric
On the one hand, battery electric buses make more efficient use of renewable energy than hydrogen fuel cell buses do, said Timothy Lipman, co-director of the Transportation Sustainability Research Center at the University of California, Berkeley.
“Anytime you convert one fuel to another … there will be losses,” Lipman said. “Solar, wind, whatever — it is more efficient to take that renewable electricity and put it into a battery bus and run it on batteries, than to make hydrogen and run it through a fuel cell and have a hydrogen bus. So from a pure efficiency perspective, the batteries are a better solution.”
But energy efficiency isn’t the whole picture, Lipman said. Transit authorities also need to balance operational considerations, like fueling time and range.
Hydrogen fuel cell buses gain some efficiency in cold weather, Lipman said, and can outperform battery electric buses on hilly terrain and over long distances. Hydrogen fuel cell buses typically have a longer range than battery electric buses and can refuel faster than battery electric buses can recharge, he said.
“I think a mix [of bus types] could make a lot of sense for a lot of places,” Lipman said.
SEPTA’s 10 hydrogen buses will be fueled at the Midvale station in Nicetown. SEPTA signed a three-year contract for hydrogen from Plug Power, which opened a liquid green hydrogen production plant in Georgia this year. The fueler, its maintenance and three years worth of fuel delivery will cost SEPTA over $5.6 million.
SEPTA installed a hydrogen fueler at its Midvale Depot for the year-long pilot project. Photo: Sophia Schmidt / WHYY
The issue of safety
While the goal of the hydrogen bus pilot project is to clean up SEPTA’s fleet, it’s drawn criticism from the environmental advocacy organization Delaware Riverkeeper Network over concerns about transparency, safety and greenwashing.
Tracy Carluccio, the organization’s deputy director, argues the project is being launched without adequate public input. SEPTA officials held one community engagement event about the pilot in the spring near the Midvale Depot, but Dunston admitted turnout was small.
Carluccio also worries the buses will not be truly zero-emission, since one of the sources of electricity that Plug Power uses to make its hydrogen is hydroelectric power, which is considered renewable and zero-emission by the EPA but can release greenhouse gasses when it involves reservoirs.
Plug Power describes its hydrogen as “green” and did not respond to questions from WHYY. According to its website, the company also uses wind and solar energy to power its hydrogen production.
Hydrogen is famously explosive and leaks easily. The gas is colorless and odorless, and its flames can be nearly invisible in daylight. Carluccio worries hydrogen being trucked to, stored and handled at the Midvale Depot in Nicetown could endanger nearby residents.
“We don’t believe that SEPTA has proven that this is safe for the community, and they certainly have not shared that information publicly,” Carluccio said.
SEPTA says it is ensuring the safety of its workers and the communities in which it operates. Employees will receive “extensive on-site safety training” from Plug Power around safe usage of the fuel, and the transit authority is following all applicable codes, including National Fire Protection Association codes, the International Fire Code and OSHA and U.S. Department of Transportation regulations, said spokesperson John Golden.
SEPTA spent roughly $500,000 on a temporary maintenance bay at the Midvale Depot with hydrogen sensors and special ventilation systems. It also plans to upgrade the site’s permanent maintenance depot with ventilation and fire protection to accommodate hydrogen fuel cell buses.
A temporary maintenance bay for fuel cell electric buses at SEPTA’s Midvale Depot, equipped with specialized sensors and ventilation. Photo: Sophia Schmidt / WHYY)
Lipman said the applicable hydrogen safety codes are now “very well-developed,” and as long as SEPTA follows them, neighbors don’t need to be particularly concerned about the presence of hydrogen at the Midvale Depot.
“I don’t think they should be any more concerned than if it was a large diesel storage tank, which also has safety issues,” he said. “They just need to be managed.”
