Transport Partnership
Hybrid Powertra in  Technology
    A Glance at Clean Freight Strategies
                                  Hybrid vehicles that use two or more distinct power sources to operate can
                                  provide fuel savings in both long-haul combination trucks and stop-and-qo
                                  freight applications as well as cut greenhouse gas emissions. The amount of
                                                 savings is highly dependent on the drive cycle.

                               What is the challenge?

                                  When a truck decelerates or brakes, the kinetic energy of the moving vehicle is typically
                                  lost. This energy loss is particularly large for trucks operating in urban areas, where vehicles
                                  make frequent starts and stops. If the kinetic energy of a braking truck can be captured and
                                  harnessed, the truck can achieve better fuel economy and lower emissions.
                               What is  the solution?

                                  Hybrid powertrain technology is a method to capture this energy and improve fuel econo-
                                  my. Hybrid technology uses two power sources to move the vehicle, a main source and a
                                  secondary source. The secondary power source provides an extra boost to the main power
                                  source (usually an internal combustion engine) when the vehicle needs extra power, such
                                  as when climbing a hill or accelerating to pass. This usually makes it possible to use a main
                                  power source that operates more efficiently and could be downsized. When the main engine
                                  is downsized, other powertrain components, such as the radiator, can be downsized as well.

                                  One of the primary benefits of hybrid powertrain technology is the ability to reclaim a portion
                                  of the energy otherwise lost to braking or deceleration. A variety of options exist to capture
                                  and store this kinetic energy for later use. One option relies on the kinetic energy of the
                                  vehicle to generate electricity, which can be stored in a battery. Another option is to store the
                                  electricity in ultracapacitors, which charge quickly but are costly. Athird option stores energy
                                  as hydraulic pressure. Hydraulic fluid inside a sealed cylinder pushes  against a "bladder" of
                                  inert nitrogen gas, which is compressed and thus stores energy. Flywheels have also been
                                  used to store the extra energy.

                                  While the first commercial applications of hybrid powertrain technology have been passen-
                                  ger vehicles, it is actually more efficient to place hybrid technology in heavier vehicles like
                                  trucks. Since a vehicle with greater mass requires more power to stop, more potential energy
                                  can be recaptured during braking or deceleration.  Larger vehicles also tend to have  more
                                  available space for packaging the hybrid power train components. Heavy-duty trucks typically
                                      I Use hybrid powertrain
                                     technology in a fleet set-
                   2 Set up an evalua-
                   tion process to assess
                   hybrid power train
                   technology with differ-
                   ent fleet drive cycles.
             SmartWay Transport |  EPA420-F09-035 | | 734-214-4767 |  smartway_transport@epa.go

Hybrid Powertrain Technology
  Stop & Go
Fuel Savings
   Gallons Saved

    394 gallons
   CO2 Savings
   4 Metric tons
  Fuel Consump-
  tion Reduction
  (original MPG 8.54
   Fuel Economy
  Fuel Cost Sav-
  cost more than passenger vehicles, so the additional cost for the technology can be a smaller
  percentage of total vehicle cost.
Savings and benefits
  In pick-up and delivery service, it is estimated that truck fuel consumption can be reduced
  from 25 to 50 percent using hybrid powertrain technology. Fuel savings depend on the type
  of hybrid technology, the amount of regenerative braking energy, and the amount of engine
  efficiency improvements .Atypical long-haul combination truck could save about $5,000 in
  fuel costs and reduce greenhouse gas emissions by over 13 metric tons per year. Benefits
  for a typical stop-and-go truck include fuel savings of about $1,000 and 4 metric tons of
  greenhouse gases each year. At least three major parcel delivery companies are exploring
  the use of hybrid technology for step vans. Preliminary results from some parcel delivery
  companies  indicate hybrid trucks expect about a 40 percent improvement in fuel economy.
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      SmartWay Transport |  EPA420-F09-035 | | 734-214-4767 |  smartway_transport@epa.go