As municipal transit agencies continue to move away from fossil fuels, they are increasingly tasked with figuring out which of the more environmentally friendly options is the best choice for them.
(TNS) — Public transit agencies are often among the first customers for vehicles that run on new types of fuel, whether it was cleaner-burning diesel in the 1990s or natural gas more recently.
Today, eco-conscious agencies looking to switch to electric fleets face a big choice: power them with rechargeable batteries or with hydrogen fuel cells?
There isn't an obvious answer. Both are more environmentally friendly than fossil-fuel buses, and both can be cost-effective options.
Two transit systems in Illinois offer a case in point. The transit agency for Quad Cities is going with battery electric buses for the hilly terrain along the Mississippi River. Elsewhere in the state, the agency servicing the college towns of Champaign-Urbana is set to become one of the first systems in the country that uses hydrogen fuel cells to propel its 60-foot buses when they arrive next summer.
The Quad Cities agency -- officially called the Rock Island County Metropolitan Mass Transit District but commonly known as Metrolink -- just received five battery-powered buses last month, bringing its total to eight.
Metrolink has long been a leader in the greening of local fleets. It was one of the first systems to buy engines that were built specifically to run on natural gas -- rather than retrofitted diesel engines. The tractor manufacturer John Deere, which is based in the area, pioneered the technology that made those vehicles efficient. Deere has stopped making those engines, but the transit agency is now better equipped to adopt new technologies.
When Metrolink decided to move to electric vehicles, it was initially considering diesel-electric hybrids. But the procurement process was delayed by 18 months. In that short span of time, battery-powered buses became a lot more attractive.
“The technology has changed so rapidly,” says the agency's general manager, Jeff Nelson. “One of the key drivers to me is money. What can you stretch your dollar to do? We knew adding better electric to our fleet was not going to have a high cost for us.”
Metrolink paid for the new buses with a $3.2 million federal grant. The new buses required Metrolink to spend $70,000 on electric work to be able to handle the chargers, plus seven new chargers that cost $45,000 each. The new configuration will be able to handle up to 30 battery-powered buses.
One concern for the agency was how the batteries would perform over the long haul. The battery technology is so new that the agency has had to rely on engineers’ estimates about battery life rather than real-world testing.
To minimize that risk, Metrolink opted to lease the batteries for six years, rather than buying them outright. If the batteries deteriorate too much, the manufacturer will replace them.
So far, the buses have out-performed the agency's expectations.
Metrolink had originally planned to use the buses for eight hours a day on a single charge. But, except for the cold winter months, drivers have found they can usually keep the bus operating for 10 or more hours. The buses can recharge their batteries with regenerative braking.
In fact, Metrolink drivers have something of a competition among themselves to see how efficiently they can keep their buses running. The record so far, Nelson says, was set on a 60-degree day with no wind, over the weekend, when the buses’ loads are light. The bus went for more than 14 hours on a single charge.
Travel range was a bigger concern in Champaign-Urbana.
“We want to plan our service to serve our community. We don’t want to plan our service to serve our equipment,” says Karl Gnadt, the CEO and managing director of the Champaign-Urbana Mass Transit District (MTD). “The battery-electric buses do not have the range that allow you to just put a bus out and have it run for 18 hours. A hydrogen bus has a range that is equivalent to a diesel bus, so it’s a one-for-one replacement.”
Champaign-Urbana’s transit system may operate in a relatively small market, but with 13 million passenger trips a year, it provides more rides than much larger markets, such as Nashville, Tenn. The MTD services the University of Illinois’ flagship campus, and student fees pay for a significant amount of its budget. In turn, the campus community expects buses to come frequently and run late into the night.
“The beauty of the fuel-cell electric is that, operationally, there are no alterations to our system that we need to make,” Gnadt says.
The cost of acquiring the two new buses, a fueling station and fuel storage equipment will be about $3.5 million, of which $1.5 million will be covered by federal grants.
Gnadt says the hydrogen fuel cell technology meets MTD’s environmental goals better than batteries. The electric batteries have to be recharged, usually at night, when solar power is not available, so they’re plugged into the electric grid, he says.
“While we wouldn’t be burning fossil fuels on the vehicle, the grid is not zero-emission. Not only is it burning coal, it’s burning Illinois coal, which is particularly dirty,” he says. (In the Quad Cities, the electricity comes from a mix of solar, wind, coal-fired and nuclear sources.)
MTD plans to produce the hydrogen for its fuel-cell buses itself. It could use solar power, wind turbines or, if need be, gas from the local landfill to separate the hydrogen from oxygen in water molecules for the buses.
The transit agency will soon be accepting bids for the equipment it will use for that conversion. It plans to add a total of 12 hydrogen fuel-cell buses by 2023, or about one-tenth of its fleet. By that time, the rest of its buses will be diesel-electric hybrids.
Although transit agencies are taking different approaches toward their next fuel sources, Gnadt says hydrogen fuel cells will be a viable option for the foreseeable future. Any fuel source comes with some risks, he says.
There’s only one company left making diesel engines for buses, so if something happens with that company, transit agencies could be left in the lurch. Battery-powered buses require expensive batteries that aren’t recyclable. The upfront costs of hydrogen fuel cells scare off some potential customers, he acknowledges.
“We believe the test case has been successfully completed for the hydrogen fuel cells,” he says. “We believe that it is a viable option and that there will be other systems that get on board with this the way that we have.”
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