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Idle Reduction Research and Development

Long-haul trucks in the United States use 838 million gallons of fuel annually while idling six hours per day. This idling provides power for heating, air conditioning, and other amenities used by truck drivers during rest periods. The U.S. Department of Energy (DOE) is leading research and development on technologies that reduce the need for truck idling while maintaining or improving driver comfort.

CoolCab Project

Climate control is the primary reason truck drivers keep their engines running during rest periods. In warm weather, engine idling powers the air conditioner to offset heat from the sun and from the truck's engine and exhaust. In cold weather, idling heats the cab against low outside air temperatures. Truckers experience a wide range of hot and cold conditions throughout their day and year.

Some idle reduction systems introduced in recent years have lacked the capacity to maintain driver comfort under these varying thermal conditions. DOE and the National Renewable Energy Laboratory (NREL) initiated the CoolCab project to improve the effectiveness of idle reduction systems. The CoolCab project is a government-industry collaboration focusing on the design and integration of advanced thermal management technologies for long-haul trucks.

Diagram of a long-haul truck with the names of thermal management technologies connected by arrows to various parts of the truck: Exhaust Heat Recovery (pointing to exhaust pipe), Advanced Seating - Low Mass (seating), Advanced Glazings or Shades (windshield), Efficient HVAC Equipment (engine compartment), Comfort-Based Air Distribution (driving cab), Infrared Reflective Materials (sleeper cab), Insulation (sleeper cab).

Some of the advanced thermal management technologies being explored by the CoolCab project.

The CoolCab project has partnered with companies such as Schneider National, Volvo, and International Truck and Engine Corporation to quantify truck thermal loads, identify areas for improved thermal management, and evaluate thermal management technologies. An evaluation of the thermal load reduction benefits of privacy curtains and window coverings is detailed in the paper Thermal Load Reduction of Truck Tractor Sleeper Cabins (PDF 862 KB). Download Adobe Reader. Ongoing CoolCab work includes developing computer models of truck cab heat transfer and climate control and working with truck and idle reduction technology manufacturers to define idle reduction system requirements.

Three photos of a Volvo long-haul truck. The photo in the middle is in the normal visible light spectrum. The other two photos have colors showing the infrared spectrum: the photo at left (uninsulated windows) is mostly blue and purple with yellow and red on and around the truck's windows; the photo at right (insulated windows) is almost entirely blue and purple (including on and around the truck's windows).

As part of the CoolCab project, NREL quantified the heat transfer characteristics of a Volvo truck (middle). These infrared images show higher heat transfer from the truck with uninsulated windows (left) versus the truck with insulated windows (right).

Idle Reduction Technology Demonstrations

DOE initiated a study of diesel truck engine idle reduction technologies in 2002 through the Advanced Vehicle Testing Activity (AVTA). The study identified several barriers to widespread use of existing idle reduction technologies, including initial cost, driver education and receptiveness, reliability, and maintenance considerations. The study results were used to develop a plan to implement idle reduction technologies.

As part of this study, AVTA sponsored four idle reduction demonstration projects, which consist of teams of a truck fleet, truck manufacturer, and idle reduction technology manufacturer. The following reports contain project details and results (Download Adobe Reader):

Other Government-Sponsored Idle Reduction Activities

The U.S. Environmental Protection Agency's SmartWay Transport Partnership sponsors idle reduction projects. DOE's Clean Cities Program lists funding sources for transportation projects, including idle reduction; see the Clean Cities Financial Opportunities page. National Idling Reduction Network News is also an excellent source of information on idle reduction activities and funding opportunities.