The field of electric buses is growing like hotcakes, but in complex urban environments, the weight of bus-sized battery packs adds a limiting element. There are a variety of solutions to that, of course, and on last week’s technology tour* of Switzerland, CleanTechnica visited the automotive company Carosserie Hess, to see what’s cooking over there.
The Lego Solution
Hess has a running jump on urban transportation electrification, having jumped into field about 75 years ago when war-related petroleum shortages drove a renewed interest in electric buses and trolleys.
Head of Technics Hans-Jörg Glaser showed us around the company’s small-scale manufacturing facility in Bellach (larger ones are located overseas), and highlighted a few points about the company’s approach to manufacturing.
One significant point is that the frames of Hess electric buses and other vehicles are put together from lightweight aluminum pieces that are interchangeable. Cross a particularly advanced Lego kit with IKEA-style interlocks and you’re on the right track.
Here’s one such frame snapped together:
This proprietary system, called CO-BOLT, has some clear advantages for sustainable manufacturing, partly because it enables more efficient breakdown and recycling at the end of the vehicle’s life.
This approach also enables Hess to tailor its products to a client’s needs without the expense (and rippling energy effect) of retooling and retraining.
Another thing we noticed was an “Internet of things” approach to factory logistics. Below is a row of blue bins for small nuts, bolts, and other parts. Each bin sits on a simple scale that is wired to a computer. Re-supply alerts are sent on a weight basis, which avoids under- and over-ordering:
A Simple Solution
Before we move on to the various electrification solutions, check out this bus without a driver:
Actually, it’s a trailer that can virtually double the capacity of a regular bus (you can see the hitch at the bottom of the photo). Rather than having one large-capacity bus drag unused weight around all day, the trailer can be hooked up to a regular bus during peak use periods or special events.
Electric Buses, Electric Trolleybuses
As for electric buses, one solution of course is to supply power from a central source by overhead wires, as in the familiar trolley system. In Switzerland, the deal is sweetened by the country’s vast hydropower resources (60% of generating capacity), which provide trolley systems with a head start on renewable electricity.
The rest of Switzerland’s grid mix comes mainly from its five nuclear power plants (all of which were inoperable during our visit for various reasons), and/or from neighboring Germany and France, which are beginning to send more wind and solar to the grid.
That’s all well and good for existing light rail lines, but installing track is an expensive proposition for new or expanding systems. That’s where the Hess line of trolleybuses comes in — essentially, a trolley with bus wheels.
You can check out the company’s full line of trolleybuses here. During our tour of the Hess facility, Mr. Glaser pointed out one weakness in the trolley system that the company has addressed.
As with large sailboats, which rely on motors to steer in and out of harbor, trolleys typically rely on heavy (as in more than 1,000 pounds) diesel engines to get in and out of the trolley yard. In addition to generating emissions at the trolley yard, the heavy engine has to be hauled around all day without contributing anything to the operation.
Hess has subbed in a proprietary battery pack called EP for Energy Pack. Aside from eliminating emissions at the yard, it can act as a range extender during the bus route (the EP has a 30 kWh capacity and a 4-kilometer range). The EP can also be used to start up a trolleybus in at the beginning of the day instead of drawing from the grid, which helps to shave the morning peak.
Hess also pays close attention to one major non-technology issue, which is how to attract travelers onto buses and out of their cars. The solutions include keeping the bus floor as low to the ground as possible for convenient low-entry, which means that the battery pack and other equipment have to go on top. That arrangement has a side benefit of helping to keep the battery pack cool.
Comfortable seats and free Wi-Fi are additional attractants.
One final note before we go on to the next topic: As Hess sees it, under the current state of technology, full battery-electric buses are inefficient compared to other solutions at hand. If you think otherwise, drop us a note in the comment thread.
Electric Buses, Hybrid Buses
Hess is also involved in some interesting demo projects, one of which is AHEAD, a diesel-electric project that we caught wind of when we previewed the tech tour. In partnership with the leading technological university ETH, this prize-winning project deploys optimal control theory to design an energy management system for hybrid electric buses, particularly as applied to negotiating the country’s hilly terrain.
So far, road tests yielded a 27.5% fuel savings over a standard diesel bus. A three-week run on an actual bus route came in slightly less, at 20–25% savings.
All photos by Tina Casey; schematic (hybrid bus, cropped) via Hess.
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