"Idling" means the operation of an engine in the operating mode where the engine is not engaged in gear, where the engine operates at a speed at the revolutions per minute specified by the engine manufacturer, or when the accelerator is fully released and there is no load on the engine. Most of us just think of it as “leaving your engine running” while you run into a store or while you wait for a train to pass.
Negative Impacts Associated with Idling
The U.S. Environmental Protection Agency (U.S. EPA) estimates that long duration idling consumes over one billion gallons of diesel fuel annually, at a cost of over $5 billion. Further, idling emits approximately 200,000 tons of nitrogen oxides, 5,000 tons of particulate matter, and significant quantities of other harmful air toxics. Idling also increases engine operation and maintenance costs and shortens engine life. Idling emissions have been found to leak into the truck cab creating health and safety concerns for the truck driver. When trucks idle near residential neighborhoods, the pollution and noise level raise serious quality of life concerns.
Idle Reduction Alternatives
There are many alternatives to engine idling and they range from no-cost options to options costing several thousand dollars. Much depends on the extent of the idling problem and the ability to convince the truck operator to adopt the alternative.
Behavioral change is the simplest route. Education and driver incentives play an important role in behavioral change. Informing the driver or operator about the fuel consumption, emissions, and the potential health risks plays an important part in changing behavior. Another powerful tool in changing driver behavior is offering financial incentives to reduce idling. Many large trucking companies already offer these incentives and they have reported success in reducing idling times below national averages.
A number of technologies are currently available to help companies and drivers reduce truck engine idling:
- Automatic engine shut down/start up
- An automatic engine shut down/start up system controls the engine start and stop based on a set time period or ambient temperature, and other parameters (e.g., battery charge). For trucks, these devices are available from some of the engine manufacturers. Estimated costs: $900 - $1,200.
- Direct Fired Heater
- These are small, lightweight diesel units available both as coolant heaters and as air heaters. Using the same fuel supply as the vehicle, they can be utilized to eliminate warm-up idling or to heat the truck cab and/or sleeper cab while stationary. However, since they do not provide air conditioning, they are a partial seasonal solution. Estimated costs: $900 - $3,000. Estimated 6% fuel savings assuming 1,200 hours idling per year.
- Auxiliary Power Units/Generator Sets
- Small diesel powered generator (5 to 10 horsepower) mounted on the truck to provide air conditioning, heat, and electrical power to run appliances. Estimated costs: $6,000 - $8,000. Estimated 10% fuel savings assuming 2,400 hours idling per year.
- Advanced Truck Stop Electrification
- Advanced truck stop electrification systems services include: heating and air conditioning, internet, local phone service, satellite television, and movies on demand. It can be a stand-alone system or it can include a combined on-board and off-board system. Estimated costs to the driver: $1.25 - $1.50 per hour/ $10 adapter. One gallon of diesel fuel is saved for every 75 minutes spent at an advanced truck stop electrification system as opposed to idling. Estimated installation cost: $7,000 - $15,000 per space.
- U.S. DoE Idle Reduction:
- Provides information on idle reduction technologies, available equipment, and links to additional resources.
- Diesel Emissions Reduction Act (DERA):
- This program funds grants and rebates that protect human health and improve air quality by reducing harmful emissions from diesel engines.
- U.S. EPA SmartWay Transport Partnership:
- A voluntary collaboration between U.S. EPA and the freight industry to increase energy efficiency and reduce emissions.