Clean Diesel Funding Assistance
Program FY 2019Transport
Refrigeration Unit (TRU) Factsheet
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What is a "reefer?"
Refrigerated, insulated cargo trailers, straight trucks, intermodal shipping containers,
and rail cars can all commonly be referred to as "reefers." It originates from the word
"refrigerated."
What is a "TRU?"
A Transport Refrigeration Unit (TRU) is a refrigeration system installed on insu-
lated cargo trailers, straight trucks, intermodal shipping containers, and rail cars used
in transporting temperature sensitive goods. A conventional TRU is powered by a
small diesel engine.
Truck TRUs are used to refrigerate insulated cargo vans mounted on the frame of
a straight truck. Trailer TRUs are used to refrigerate insulated trailers mounted on
semitrailers. Railcar TRUs are used to refrigerate insulated railcars.
What is an "eTRU?"
Electric Transport Refrigeration Unit or "eTRU" is a term sometimes used to describe
different types of alternatives to conventional diesel powered TRUs including hybrid
electric TRUs, standby electric TRUs, and all-electric TRUs. In an eTRU, the
refrigeration system's compressor is driven by an electric motor all or at least part
of the time. eTRUs can be powered by a plug-in electrical connection from electri-
cal grid power (commonly referred to as shore power) while parked or being loaded.
eTRUs may be powered by a battery pack for shorter distances or a diesel-powered
TRU generator set for longer distances while operating on the road. Integral diesel
generators, engine-mounted or transmission power-take-off generators or other range
extenders may also be used to provide electrical power to the unit when in transit.
Jk United States
Environmental Protection
^1	Agency
Office of Transportation and Air Quality
EPA-420-F-18-028
December 2018

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Refrigerated shipping containers typically employ all-electric TRUs which are powered by
ocean-going ship electric power, dock-side shore power, or TRU generator sets for travelling
shorter distances. Often, insulated trailers with shore powered all-electric TRUs are used for
stationary operations to increase holiday and summer season cold storage capacity at grocery
stores.
Hybrid Electric TRU
In a hybrid electric TRU (also called a hybrid plug-in eTRU), the refrigerator's compressor
is driven by solely by an electric motor. When over-the-road, electric power is supplied
by an integral diesel genset located within the TRU housing; when stationary (e.g.,
loading at a distribution center), the hybrid electric TRU plugs-in to available electric
grid shore power.
Standby Electric TRU
In a standby electric TRU (also called a standby plug-in eTRU), the refrigerator's com-
pressor is both mechanically driven by an integral diesel engine and electrically driven
by an integral electric motor. When over-the-road, the unit is powered by the diesel
engine; when stationary, the electric standby feature allows the TRU to be plugged into
electrical power and the diesel engine to be turned off.
What is a TRU generator set (genset)?
A TRU genset provides electric power to an all-electric TRU when the unit is not plugged into
ocean-going ship electric power or dock-side shore power. "Pin-on" TRU gensets are pinned
onto the front of refrigerated shipping containers, just above the container's built in all-electric
refrigeration system. "Under-slung," or "belly mount" TRU gensets are clamped to the frame
rails of intermodal trailer chassis. A "powerpack" TRU genset consists of several diesel generators
installed into a shipping container, which then provides electric power to multiple refrigerated
shipping containers and are generally limited to railcar use and longer periods of transport.
What types of TRU projects are eligible under DERA?
Diesel powered TRUs and TRU gensets are eligible as nonroad equipment under DERA if the
existing engines meet the applicable nonroad eligibility criteria defined in Section III.D of the
Request for Applications (e.g. operating hours, horsepower, model year and tier).
Replacement may consist of removing the old, diesel-powered TRU from the truck or trailer,
scrapping it, and installing a new TRU, electric standby TRU, hybrid electric TRU, or all-
electric TR. EPA will fund up to 25% of the cost of an eligible piece of equipment powered by
an engine certified to EPA emission standards. EPA will fund up to 45% of the cost of an
eligible zero tailpipe emission piece of equipment. Please note that the 45% EPA funding is

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only eligible if the new unit will operate solely on grid, battery, solar, or other zero emission
power sources. eTRUs that will be powered by diesel engines or diesel gensets are only eligible
for the 25% EPA funding.
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