Onboard Idle Reduction Equipment for Heavy-Duty Trucks
Onboard equipment options can easily be installed on heavy-duty trucks and can help reduce idle time at truck stops, roadsides, ports, terminals, and delivery sites. The cost-effectiveness of each technology depends on the climate in which it is used and the amount of idling to be offset. See the fact sheet, Long-Haul Idling Burns Up Profits, for more information.
Auxiliary Power Units
Auxiliary power units (APUs) are portable, vehicle-mounted systems that provide engine-off power for climate control and electrical devices in trucks, locomotives, and marine vehicles. These systems may be powered by diesel, electricity, or other alternative fuels.
Cab or Bunk Heaters
Cab or bunk heaters, usually diesel-fired, supply warm air to the cab or bunk. An engine block heater to eliminate "warm up" idling can also be included. Diesel heaters use only small amounts of fuel and have low emissions because they supply heat directly from a small combustion flame to a heat exchanger. Natural gas-fired heaters are also available. Cab or bunk heaters can be coupled with air conditioners if the trucker's service area includes both cold winters and hot summers.
Coolant heaters use the truck's integrated heat-transfer system. The heater is mounted in the engine compartment, draws gasoline or diesel from the fuel tank to heat the vehicle's coolant, and pumps the heated coolant through the engine, radiator, and heater box. Coolant heaters keep the engine warm, reducing the impact of cold starts and the need for "warm-up" idling.
Energy Recovery Systems
Energy recovery systems use the vehicle's heat-transfer system, much like a coolant heater, but without a separate piece of equipment. A very small electric pump is connected to the water line, which keeps the truck's cooling system and heater operating after the engine is turned off, using engine heat that would otherwise dissipate. Energy recovery systems, however, typically do not provide enough warmth to be a sole source of overnight heat.
Storage Air Conditioners
Thermal storage and battery-electric air conditioners (storage cooling) derive energy to recharge the device from the truck's engine during operation or from plugging in to external power sources at truck stops. For on-road recharging, the engine uses a small quantity of extra diesel. The emissions from burning this fuel are controlled by the engine's emissions control system and occur on the highway rather than at the truck stop or depot.
Automatic Engine Stop-Start Controls
Automatic engine stop-start systems keep sleeper compartment temperature within a preset range. When sensors dectect that the temperature is out of range, the engine is automatically turned on to run climate control for a set period. Similar controls can also keep locomotive engines warm. This technology reduces but does not eliminate idling, and fuel savings may be minimal in extreme temperatures. The extra starts may also disturb the driver's sleep.
The U.S. Environmental Protection Agency’s (EPA) Clean Diesel Program provides financial support for some idle reduction projects. The program includes grants and rebates funded under the Diesel Emissions Reduction Act (DERA). EPA's SmartWay program offers a list of Verified Idle Reduction Technologies.