Reefer (container)

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A reefer is a refrigerated container used in intermodal freight transport for transportation of temperature sensitive cargo.

While a reefer will have an integral refrigeration unit, they rely on external power to power them, from electrical power points at a land based site, a container ship or on quay. When being transported over the road on a trailer they can be powered from diesel powered generators ("gen sets") which attach to the container whilst on road journeys.

Some reefers are equipped with a water cooling system, which can be used, if the reefer is stored below deck if the vessel does not have adequate ventilation to remove the heat generated by the reefers.

Water cooling systems are expensive so modern vessels rely more on ventilation to remove heat from cargo holds: therefore the use of water cooling systems is declining.

Another refrigeration system uses liquid carbon dioxide (CO2) as a cooling agent. This cryogenic concept was developed in response to rising fuel costs, and was an attempt to find an alternative to the standard mechanical refrigeration systems that required periodic maintenance fuel and create emissions. The CO2 reefer system can keep the containers cargo frozen solid for periods as long as 30 days plus, if necessary.

New "cryogenic" reefers are in service transporting frozen foodstuffs, but they have yet to gain wide acceptance (due, in part, to the supply and cost of liquid carbon dioxide). Since cryogenic refrigeration is a proven technology and environmentally friendly, the rising price of fuel and the increased availability of carbon dioxide from Kyoto Protocol-induced capturing techniques may lead to common usage of cryogenic containers, especially in intermodal trade lanes.

The cryogenic reefer container can be stored anywhere on any vessel that can accommodate "dry" (un-refrigerated) ocean freight containers. This is vitally important to the vessel operator because a typical dry freight load does not generate anywhere near the revenue of a refrigerated shipment. They can use many modes of transportation without the concern of an outside power source or a mechanical breakdown; this is a major advantage to this type of refrigeration technology. Because a cryogenic reefer container doesn't need to be plugged in to a power source, it can be shipped anywhere, without the need for electricity or fuel. This basic CO2 refrigeration technology has been in operation in railcars for years. The system has proven to be safe and extremely reliable.

The impact on modern society of reefer containers is vast, allowing consumers all over the world to enjoy fresh products at any time of the year and experience fresh produce from parts of the world previously not available.