Two options to reduce emissions and fuel use with electrified trailers!
Tightening environmental regulations are pushing carriers to purchase zero-emission vehicles. However, battery-electric power units may not be cost-effective without substantial government incentives. A battery-electric Class-8 truck can cost three times more than a traditional diesel-powered vehicle.
Trailers are usually 30-50 percent less expensive than trucks. Two trailer-based options to consider to achieve lower emissions and fossil fuel consumption are:
- Battery-electric trailer refrigeration units (TRUs), and
- Electric-drive trailers.
Transitioning from diesel refrigeration units and diesel-powered tractors may take some time. However, electrified trailer options can be part of a carrier’s plan to reduce dependency on fossil fuels.
Diesel-powered TRUs
The current trailer refrigeration units, commonly called a reefer unit, has a small diesel engine powering a TRU on the trailer's front wall. The TRU has a compressor, evaporator, and condenser. The TRU automatically controls the trailer temperature based on the products hauled, such as minus 10 degrees Fahrenheit (F) for ice cream and above 32 degrees (F) for fresh vegetables or other unfrozen products.
Battery-electric TRUs
Leading manufacturers have developed battery-electric powered TRUs that have reached refrigeration capacities similar to those only previously achieved by diesel-powered systems. This breakthrough allows carriers to consider reefer trailers as another opportunity to reduce emissions and meet company decarbonization goals.
These electric TRUs are especially well-suited for businesses in states that have or are looking to introduce zero-emission requirements for trailers. There are also hybrid versions of TRUs that use an internal combustion engine for backup power and may be appropriate for states without zero-emissions mandates in the next few years.
Another emerging technology, turbine auxiliary generators (TAG), mount to a trailer chassis' and generate electricity for liftgates, refrigeration units, lighting, and auxiliary batteries. A TAG can also be mounted on the underside of a box truck chassis.
CARB has not yet mandated electric TRUs for standalone reefer trailers. However, for straight trucks with TRUs, CARB statute 2477.5(b)(1) requires:
"Beginning December 31, 2023, no owner or owner/operator shall operate or cause to be operated in California, any (straight) truck TRU in the owner's truck TRU fleet, unless the fleet meets or exceeds the required zero-emission (ZE) truck TRU fleet percentages specified" as follows:
By December 31 of: | ZE Truck TRU Fleet Percentage |
2023 | 15 |
2024 | 30 |
2025 | 45 |
2026 | 60 |
2027 | 75 |
2028 | 90 |
2029 | 100 |
Electric-drive trailers
When the words "electric vehicle" are heard in transportation, an image of a battery-powered truck pulling a trailer comes to mind. However, an innovative solution that could be ready as early as 2025 involves electric-powered trailers that could increase fuel efficiency by 35-40 percent. Paired with a battery-electric truck, it could add 100 miles to the range on a single charge.
These trailers have an electric-motor-driven axle with regenerative braking that recharges a battery pack and slows the tractor when going downhill or stopping. The kingpin (secure connection to the tractor) senses how hard the tractor is pulling. The electric motor engages to lighten the truck's load, thereby reducing tractor fuel consumption and component wear.
The downside is about 4,000 pounds of additional weight, so less freight by weight can be hauled. Light and bulky products (like potato chips) may suit this trailer. Electric tractors are allowed an extra 2,000 pounds weight due to an exception, but not electric trailers, so far.
Key to remember: Carriers should consider electrified trailer options as part of an emissions reduction plan.