“It’s a very complex piece and very expensive. And they’re very new to the market, but the lithium in them is recyclable. So, let’s say the battery pack lasts us six years, the battery can then be recycled by — and we don’t know what the process is because it's brand new — but the lithium does not degrade and can be used in a new battery by repackaging it.”
To offset weight and to give the new buses a little more durability they are built using a composite structure. Karbowski says they hope this will also extend the bus life for a number of reasons.
“It’s non-conductive. It reduces weight, which all have impact on how we operate, but we can probably run [these buses] for 18 years without compromising the quality of the structure. And that’s critical in getting the lifecycle cost down,” Karbowski says.
“And we say composite, and in reality it’s probably about 11 different types of fiberglass resin combinations. In areas that require high strength [there is] some carbon fiber, but it’s predominantly fiberglass, so it’s really easy to repair internally.
“In fact, the company that is manufacturing the bodies for Proterra is a company that manufactures upscale yachts and prowler fishing boats which are pretty common in the fishing industry.”
Foothill Transit does all of its own bodywork, which can be costly and time-consuming. Karbowski says the composite structure of the new buses, though, helps mitigate that.
“It absorbs and distributes a lot of energy throughout the structure, so bodywork is one of the other factors with this composition structure that helps reduce lifecycle costs,” Karbowski says.
Weight is always an issue when it comes to transit buses. This is especially the case when it comes to something like Foothill Transit’s new electrically powered buses. Karbowski says the composite structure is probably 20 to 40 percent lighter than a conventional steel bus.
Whiles some past composite structure vehicles had a monocoque construction, Foothill’s new bus adopts a slight change to that design.
“While the stuff is all still bolted to the structure itself, they have some steel stiffener pieces built into it just to give it a little added strength,” Karbowski says.
“More importantly, it makes replacing suspension components later on in the life of the bus a little bit less of a challenge because they bolt up and on and off pretty simply.”
Karbowski says though the new vehicles have a ground-breaking electric drive system, they make maintenance easier by keeping things simple wherever possible.
“First of all, when you look at the bus itself, it is a very conventional bus. There is not a lot of fancy stuff on it that is going to require unique maintenance,” Karbowski says.
“I mean it has standard suspension, standard steering, standard electrical system, and lighting. Now some of the components, like the air conditioning/heating system, is all electrical, but those are still products that are understood from trolley buses and rail.”
Karbowski says even the new drive system isn’t overly complicated when you compare it to hybrid systems that are popular in transit agencies across the nation because they have an impact on lowering the emissions, but they don’t have a huge infrastructure impact.
“A hybrid bus is really similar to the electric bus, it has an electric drive system and a battery system, but the hybrid buses add an auxiliary power unit, a genset of some sort, which makes it more complicated than an electric bus,” Karbowski says.
“And when you go to a fuel cell bus, you make it even more complicated, so what we’re envisioning is that bus costs will be very similar to any other bus in our fleet.”
Karbowski says the technology is very simple, “Obviously it's different, and you know that is a challenge for today’s maintenance technicians, but I just have high hopes for this being a very cost-effective vehicle to maintain.”
Karbowski says one of the hidden profitability elements about these new buses may be time. Most transit fleets run throughout the day and when they come in at night they line up to be fueled and cleaned, which means that any maintenance for a bus must wait for a couple hours while it is fueled and cleaned. But Foothill’s new electric buses can skip to the head of that fueling line.