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This Week in Engineering

Tesla Launches the Semi

After five years of development, the Tesla Class 8 tractor is ready. Do the economics make it viable?

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In 2017, Elon Musk presented a prototype of a battery electric Class 8 highway tractor, predicting that electrification will fundamentally change the American trucking industry. Trucking in America is a 700-billion-dollar annual industry, and with 4 million Class 8 vehicles registered on American roads, the fleet is considerable. 

While electrification looks promising, current lithium-ion battery technology suggests that 500 to 600 miles is the reasonable range that can be expected from a battery electric highway tractor. For long-haul with a single driver, this range corresponds roughly to the allowable hours of service mandated by U.S. Federal regulations, suggesting that short and medium distance intercity transportation with electric heavy trucks is feasible with current technology. With the first units now in the hands of PepsiCo, it will be possible to get real-world data on Tesla Semi performance.

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Episode Transcript:

Everything Elon Musk does is newsworthy, and nothing more so than the rollout of a new product.  
 
The Tesla Semi, an all-electric Class 8 highway tractor, was shown in prototype form in 2017 with much fanfare, and last week, the formal rollout of a production Tesla Semi for customer use was held at a media event in Nevada.

Electrification of the passenger car fleet has been predicted for a decade or more, but the switch from diesel to battery electric in the trucking industry has been problematic. It’s a big industry. It generates over 700 billion dollars in annual revenue, hauling freight behind over 4 million Class 8 trucks. Annually, about three quarters of America’s freight, approximately 10 billion tons, is hauled by trucks.  

In America, the bestseller is Freightliner, with almost 40 percent of the market; that’s 190,000 vehicles. They are followed by Kenworth and Peterbilt, who together build 150,000 trucks.

Federal Motor Carrier Safety Administration hours of service rules limit American drivers to 11 hours behind the wheel, preceded by 10 consecutive hours off duty. In terms of consecutive hours after coming on duty, the driver may not spend more than 14 hours behind the wheel. That’s important for electrification of long-haul tractors, since the Tesla Semi advertises a 500-mile range, and typical average speeds for American intercity motor freight are approximate 55 miles per hour. If the Tesla Semi can be driven to its maximum range, and the driver can then plug-in during the downtime, then the Semi will be a practical proposition for long-haul trucking.

For driving teams. however, a stop for deep charge will be a definite disadvantage compared to the speed of refuelling a diesel truck—although the one-megawatt chargers that Tesla has announced are projected to allow a 30-minute charge to add 400 miles of range.
To date, Tesla has not announced the gross weight of the Semi, and test runs have been in the 80,000-pound gross weight range, so the total payload available is unknown at this time. With the delivery of the first units to PepsiCo, it will be possible soon to determine whether these units are practical for long-haul applications.
A study by the Carnegie Mellon School of engineering calculates that currently lithium-ion battery technology will result in vehicles with a payload capacity of under 10 tons, with a six-hundred-mile driving range, compared to an average current payload carried by U.S. Class 8 trucks of 16 tons, with an upper limit of 40 tons.
With lithium-ion battery technology, it appears that practical applications for the Tesla Semi will focus on carriers who ship volume more than weight, and who do so on line haul routes, rather than long haul. Electric vocational trucks already exist from major truck makers such as Freightliner, BYD, Renault and others, and in the stop-and-go service typical of buses, refuse haulers and other city trucks, electric drive may be immediately usable on a one-for-one replacement basis with diesel.
For tractor-trailers however, Tesla Semi is about to demonstrate whether lithium-ion batteries are ready for prime time.
Written by

James Anderton

Jim Anderton is the Director of Content for ENGINEERING.com. Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.