Accountable for 18% to 25% of all US vehicle emissions, diesel semi-trucks are linked to many serious health issues, including lung cancer and heart disease. Although electric semis eliminate these harmful emissions, automotive manufacturers must overcome several significant challenges before their long haulers can complement or replace diesel trucks.
This article discusses the benefits of electric semis, reviews critical barriers to mass adoption, and spotlights zero-emission long haulers on the road today.
The advantages of electric semis
Representing only 4% of vehicles in the US, medium and heavy-duty trucks consume more than 25% of total highway fuel and emit nearly 30% of heat-trapping carbon on highways (Figure 1). Replacing diesel long-haulers with zero-emission semis will significantly help reduce greenhouse gases (GHGs) and create a greener, cleaner future.
Figure 1. A smog-filled highway illustrates harmful GHG emitted from diesel-powered trucks. (Image: EV Engineering)
Beyond the environmental benefits, a 2021 Lawrence Berkeley National Lab study estimates an electric semi with a 375-mile range could eventually cost $1.51 per mile versus $1.73 per mile for diesel. Over 15 years, these savings would total approximately $200,000. Notably, electricity is typically cheaper than diesel fuel, while regenerative braking helps extend vehicle range. This contributes directly to the lower cost per mile and overall savings.
Similarly, the North American Council for Freight Efficiency (NACFE) projects a 40 to 70% reduction in maintenance costs for electric semis compared to diesel long haulers. Zero-emission semis are equipped with electric motors and systems containing fewer moving parts than diesel internal combustion (ICE) engines and components. Regenerative braking further minimizes maintenance requirements by reducing the wear and tear of friction-based (braking) mechanisms during normal driving conditions.
Moreover, electric drivetrains boost efficiency by converting energy directly into motion with minimal heat loss, decreasing thermal stress, and extending component lifespans.
Unlike diesel heavy haulers, electric semis instantaneously deliver torque from a standstill, efficiently accelerating and decelerating during stop-and-start traffic. Electric semis also perform optimally on steep inclines and hills, maintaining consistent power output and torque.
Additionally, zero-emission long haulers reduce rollover risks by positioning batteries at the base (or bottom) of the vehicle, effectively creating a lower center of gravity. Diesel trucks, in contrast, raise the center of gravity by locating engines and fuel tanks higher in the chassis.
The long-haul challenges of a zero-emissions future
Several major challenges, including limited range, must be addressed before zero-emission long haulers are widely adopted. The Tesla Semi (Figure 2), for example, offers an impressive 300-mile to 500-mile range on a single charge.
However, Class 8 diesel trucks equipped with two 150-gallon tanks can travel up to 1,800 miles without refueling, which takes minutes rather than hours. Notably, even the most powerful 350-kilowatt chargers require at least 90 minutes to fully replenish an electric semi battery.
Figure 2. A Tesla Semi leaving a warehouse after an early-morning delivery. (Image: Tesla)
There are also less than 7,000 public dc fast-charging stations across the US, and most of these are designed to accommodate smaller electric vehicles (EVs) rather than heavy-duty long haulers.
The economics of electric semis present another serious challenge. Massive battery traction packs can weigh up to 16,000 pounds, nearly a quarter of the total legal weight limit for a semi and its cargo. Far exceeding the weight of diesel tanks, this added load can seriously limit profit margins.
Lastly, electric semis are currently priced up to 2.8 times more than diesel trucks, with battery costs representing most of the differential. Battery prices, however, are widely expected to decline over time. According to the National Renewable Energy Laboratory (NREL), electric-diesel cost parity may be achieved by 2030 for smaller zero-emission trucks and 2035 for heavier long-haulers.
Electric semis on the road today
Nearly 13,000 electric trucks, ranging from Class 2B to Class 8, operate across the US. Local government incentives, such as those offered by California, are accelerating the adoption of zero-emission vehicles by companies such as Amazon, FedEx, PepsiCo, and Schneider. Amazon services thousands of cities with Rivian electric vans, while FedEx and Schneider use electric semis for various types of deliveries.
Some of the most popular electric semis in North America and Europe include:
- Tesla Semi: Traveling 300 to 500 miles on a single charge, Tesla’s zero-emissions truck covers 800 miles in 24 hours using 750kW interim charging — recovering 70% range in 30 minutes with its fast-charging capability. With three motors delivering instant torque, the Tesla Semi accelerates from 0 to 60 mph in 20 seconds under full load and maintains optimal speed on inclines. Pre-ordered by multiple companies, Tesla’s flagship electric truck, which consumes less than 2 kWh per mile, was recently trialed by PepsiCo.
- Freightliner eCascadia: Integrating motor, transmission, and electronics around an eAxle, Daimler’s electric semi supports a 230-mile range and recharges to 80% in 90 minutes. Driven by Schneider and other companies, the eCascadia has a dual motor (470 hp) or single motor (320 hp), offering battery options of 194, 291, or 438 kWh.
- Volvo VNR Electric: Featuring four 375 kWh or six 565 kWh batteries, the VNR Electric delivers a 275-mile range and an 80% recharge in 60 to 90 minutes. The VNR Electric is currently used by Canadian coffee franchise Tim Horton, accommodating local and regional fleet operations for various customers.
- Mercedes Benz eActros: Boasting dual motors and an electric axle, the eActros generates continuous 330 kW and peak 400 kW power output with three or four 112 kWh batteries. Selected by Germany’s DB Schenker corporation, the eActros supports a range of 205 to 248 miles and 20% to 80% charging in 60 to 90 minutes.
- Nikola Tre: Offering a 330-mile maximum range and a continuous power output of 645 hp, the Tre boasts a nine-pack 733 kWh battery configuration that supports fast charging, reaching 80% at 350 kW in just 90 minutes.
Summary
Diesel semi-trucks are accountable for 18 to 25% of all US vehicle emissions. Although electric long haulers effectively eliminate harmful diesel emissions, automotive manufacturers must overcome several significant challenges, including limited range and up-front costs, before their zero-emission vehicles complement or replace ICE trucks.
References
- The Future of the Trucking Industry: Electric Semi-Trucks, EESI
- Electric Big Rigs are Going Farther and Charging Faster, Canary Media
- 6 Problems with Electric Semi Trucks, MUO
- Where EV Trucks are Going to Hit the Road First, CNBC
- NACFE Helps the Industry Navigate to Zero Emissions, NAFCE
- For Truckers Driving EVs, There’s No Going Back, Washington Post
- Electric Truck Deployments by U.S. Companies Grew Five Times in 2023, EDF
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