Electric trucks are becoming a reality, in California, with electrified overhead power cables providing the power to trucks delivering to the ports. Diesel News’ US Correspondent, Steve Sturgess, reports.
German industrial giant Siemens and California’s South Coast Air Quality Management District (SCAQMD) are conducting a one-mile, zero-emission eHighway demonstration in Carson, California, near the ports of Los Angeles and Long Beach. Three heavy-duty trucks hauling freight are running along the stretch of roadway that uses Siemens technology to electrify select highway lanes via an overhead catenary system.
According to SCAQMD, heavy-duty trucks are the number-one source of smog-forming emissions in Southern California. Developing a zero- or near-zero goods-movement system in and out of the ports will reduce smog formation and toxic and greenhouse gas emissions in communities around the ports, which are some of the areas most heavily impacted by air pollution.
“Every day, Americans rely on the goods and services that are carried by road freight,” said Andreas Thon, head of Turnkey Projects & Electrification, Siemens North America, in the press release issued by the air quality district. “But with that transportation predicted to double by 2050, only one-third of this additional travel can be handled by trains, despite expansion of rail infrastructure. Experts expect global CO2 emissions from road freight traffic to more than double by 2050.
“This electrified truck system, what we call eHighway, can modernise the existing infrastructure using the latest technology to accommodate the growing amount of [truck] freight travel, reduce harmful emissions, and keep these ports – one of our country’s major economic drivers – competitive.”
Siemens noted it launched the world’s first eHighway system on public roads in June 2016, using a two-kilometre section of a highway north of Stockholm, Sweden. Three field trials of the eHighway technology on German highways are planned to take place in 2019.
The South Alameda Street demonstration is a one-mile ‘test track’, with the left lane coned off in both directions in Carson, California. A small construction-site mobile office sits approximately at the mid-point, under the Sepulveda Boulevard overpass. Here, another very short section of catenary allows for experimentation on or service of the installations on the trucks.
The electrical infrastructure is called a catenary because the conductor wires hang from and are clipped to a ‘messenger’ wire. This delivers the electrical power to the conductor wire, which has to be at a constant height above the roadway. The messenger wire is anchored at the many supporting structures along the route and hangs in a catenary, the arc that any line or chain describes when it is hung from its ends. A chain to prevent entry to a gateway, for instance, hangs in a catenary arc, which is a quite different arc than a segment of a circle.
All three trucks can operate quite satisfactorily on electrical power supplied via the catenary power lines through the pantograph contact arms mounted behind the cabs. Both the catenary infrastructure and the on-board electronics and power controls to reduce the catenary voltage of 500–750 volts DC down to the 350 volts required to drive the trucks are owned and installed by the German Siemens.
The electrical installation took about six months to complete, according to Kay Rasch, Technical Project Manager for Siemens’ Mobility Division and on-site engineer. He added that the infrastructure part of the demonstration accounted for about 25–30 per cent of the total $17 million investment. “It could have been more, but to keep within budget we had to eliminate some of the features,” he said.
Where this demonstration is unique in the US in providing power to transport trucks, the overhead supplied power is fairly common in people-moving trams, trolleybuses and railways. Railways and trams have the advantage of steel wheels on steel rails providing one of the power lines. Since trucks and trolleybuses have rubber tires on roads, this option is not available and there have to be two overhead wires and two pantographs on the trucks to complete the electrical circuit.
Since the pantographs can be raised and lowered from the dashboard touchscreen, in a more lengthy demonstration or even a practical application, a truck could disconnect from the overhead power to pass another catenary user, reverting to the lane and reconnecting to the overhead power again when the manoeuvre is complete. In this way, a catenary installation could serve other users such as trolleybus or electric transit bus lines, refuse trucks, school buses, even intercity coaches, if such an installation were to run from Los Angeles to Las Vegas, for example.