Keeping electric trucks charged to work continuously remains one of the most vexing problems of green shipping and logistics.
Air quality officials in California believe they might have found a possible solution for the twin ports of Los Angeles and Long Beach. They recently launched testing of a trolley-like catenary system from German automation company Siemens on a short stretch of road near the port complex.
Nearly 16 million shipping containers moved through the gateway last year, making it the largest port in the U.S. But in addition to transporting goods, the complex creates millions of tons of pollutants that regulators want to scrub from the air.
The mayors of Los Angeles and Long Beach have set a goal to have near-zero or zero emissions at the complex by 2035.
Regulators and the trucking industry are exploring a variety of technologies to reach that target, including ultra-low emission natural gas engines, hydrogen fuel-cell vehicles, battery-electric trucks and hybrids.
Catenary is yet another approach that can supplement hybrid and battery-electric trucks.
Catenary systems work by equipping electric-powered trucks with metal devices called pantographs. When a truck drives under overhead catenary wiring the pantographs on a truck’s roof provide power for the electric motor.
This solves the downtime problem for electric trucks when they stop working for long periods to charge or swap batteries. But such systems still require considerable investment in the overhead wiring along roadways.
In Europe, it costs about 3 million euros per kilometer to implement a catenary system, including upgrades to the grid, according to Roger Bedell, founder of Opbrid Fast Charge Systems in Switzerland. That works out to about $5.6 million per mile.
The $13.5-million demonstration project directed by California’s South Coast Air Quality Management District has built a 1-mile catenary system – 2 miles counting both directions – along Alameda Street in Carson, near the ports of Long Beach and Los Angeles.
There are three trucks in the heaviest Class 8 weight segment testing out the system, pulling loads of 60,000 pounds back and forth along the roadway, said Sam Atwood, a spokesman for the district.
Two of the trucks are made by TransPower of Escondido, Calif. One is a battery-electric vehicle, and the other is a hybrid that runs on compressed natural gas and electricity. The third is a diesel-electric hybrid built by Mack Trucks.
Testing started in July and is expected to run at least six months, Atwood said.
There’s potential for catenary in an environment “where you are running a mile or a mile and a half to a specific point and back and forth,” said Jonathan Randall, senior vice president of North American sales for Mack Trucks, a division of Volvo Trucks. Once off the wire, the truck could easily switch to diesel power and continue on its way.
With so many different technologies undergoing tests at the port and elsewhere, it’s hard to know which will work best.
“We know there will be some form of electric truck, compressed natural gas remains viable, liquefied natural gas is interesting, and then there are the fuel cells we are working on,” Randall said. “Everything is open to see what the industry will accept and what is commercially viable.”
The catenary test has not been without hiccups.
The project faced significant delays caused by attempting to build the demonstration system in what is a highly industrialized section of Southern California next to a major refinery.
“There were a lot of problems to be worked out with the infrastructure,” Atwood said.
The builders had to deal with underground natural gas pipelines. The electrical structure requires a large transformer to convert AC power to the DC used by the electric powertrains in the trucks. There were a host of safety regulations to meet.
Longer catenary systems are already in service in Europe, championed mostly by Siemens. After testing the technology on a 2-kilometer public road in 2016 in Stockholm, Sweden, Siemens built a longer eHighway across Germany, outfitting 10 kilometers of the autobahn with a catenary wire.
Southern California's South Coast Air Quality Management District will try to determine whether the technology is scalable for a U.S. highway system.
“In Germany and Sweden, the track is much longer, but it’s also in a kind of greenfield. There’s nothing out there,” said Matt Miyasato, deputy executive officer in the science and technology advancement office at the air quality agency. “In our case, it was in a very busy industrialized area already surrounded by refineries and tank farms.”
The challenge of building an effective catenary above a busy California highway is one that needs to be built into the design strategy if such systems are to come to the U.S.
“We’ve been pitching it to [Siemens] as, now you have a solution you could put anywhere,” Miyasato said. “It doesn’t have to be in a greenfield or out in the middle of nowhere — you could do it in a highly industrialized area like SoCal.”
Still, experts said it has proven harder to install a catenary over existing roadways, especially where infrastructure is outdated.
“I wonder if [catenaries] would work better if we start building new roadways or expansions of existing roadways,” said Bill Van Amburg, senior vice president at Calstart, a green trucking and transport technology incubator.
It might work best on a dedicated lane for trucks as opposed to trying to retrofit it on an existing, older roadway, he said.
One way to reduce cost is to limit the length of a catenary. The trial is examining how far a system could extend.
“In California right now most people are looking at catenary projects to allow an electric, regional heavy-haul truck to extend its range,” Van Amburg said. “Because it can connect to power periodically within a zone.”
That means prioritizing powering trucks that travel shorter distances rather than long-haul tractor-trailers making cross-country trips.
Companies could also combine the most efficient form of traditional charging methods, DC fast-charging, with the catenary track, an idea Miyasato calls “opportunity charging.”
“You could put DC fast chargers on either end of the route — somewhere down at the marine terminals and somewhere up in the rail yard,” Miyasato said. “That’s one of the comparisons we want Siemens to make: Does it make more sense to charge on a catenary line or should you just have opportunity charging on each end?”
Either way, a catenary system is not likely to be used as a single solution.
“In Southern California, they’re thinking about how to use this for backbone corridors where the bulk of freight goes,” Van Amburg said. But they’re also realizing that in addition to “backbone routes” that could be outfitted with a catenary, trucks must get to distribution centers or other sites along secondary routes. In that case, they will need additional stored power on board.
“The catenary is not going to do the total job,” he said.