U.S. Department of Energy - Energy Efficiency and Renewable Energy
Vehicle Technologies Office
Parasitic Loss Reduction
Heavy vehicles lose a tremendous amount of energy to wind resistance and drag, braking, and rolling resistance. Such non-engine losses can account for an approximate 45% decrease in efficiency. Other sources of energy loss include: friction and wear in the power train, thermal (heat) loads, operation of auxiliary loads (air conditioning, heaters, refrigeration, etc.), and engine idling.
The parasitic loss activity identifies methodologies that may reduce energy losses, and tests those in the laboratory. Promising technologies are then prototyped and tested onboard heavy vehicles. Once validated, technologies must be tested on-road to obtain durability, reliability, and life-cycle cost data for the developmental component and/or design strategy.
This process for validating performance, component robustness, operational reliability, and cost-competitiveness — conducted in conjunction with prominent participants in the heavy vehicle industry through cost-shared research and development with the U.S. Department of Energy — is most likely to provide a basis for timely introduction of a technology into the marketplace and acceptance by industry.
Current areas of focus for the parasitic loss reduction activity include:
- Aerodynamic drag reduction research, to characterize and respond to energy losses caused by wind and rolling resistance.
- Friction and wear-reduction research, to understand and address the multiple surface interactions that occur in heavy vehicle systems.
- Regenerative shocks primarily for trains, which can recover energy that is dissipated by conventional shock absorbers.
- Predictive cruise control that can control vehicle speed for optimal fuel efficiency.
- Idle reduction devices and systems that enable truckers to turn off their engines when stopped and still be comfortable while sleeping.
- Locomotive systems that reduce emissions and increase fuel efficiency.
- Off-highway systems for construction and farm vehicles.
- Diesel reformers to transform diesel fuel into carbon monoxide and hydrogen for use with auxiliary systems.
- Thermal management to counter some of the negative heat-producing consequences of emissions control techniques.