All of the reefers in the world consume as much energy as a small state. Since most reefers use fossil fuels to run the refrigeration system’s compressor, fan and electronics, the specialized containers emit millions of tons of CO2 each year. Is there a way to reduce reefers’ CO2 emissions? Can reefer-owners “green” their reefers to lower dependence on fossil fuels?
Most of the energy sources used to power the reefers use fossils fuels: On ships, energy comes from the ship’s electrical system, powered by steam or diesel generators; in container yards the energy comes from the local grid; and on long-haul trucks or railcars, energy comes from generators attached to the box.
Reefer’s CO2 emissions tend to be pretty high. The Container Handbook suggests the average energy consumption per reefer amounts to 3,600 W, though it should be noted that said energy consumption varies for each container depending on factors such as set-point temperature for the cooled space, ambient conditions, system efficiency, etc.
Each day a regular reefer consumes 43,000 W per hour; assuming that each 1,000 W per hour emits 1.27 kg of CO2, the average reefers’ CO2 emissions ascend to 54.61 kg.
Mitigate reefers’ CO2 emissions with alternative energy
Is there a way to reduce this carbon footprint? Well, reefer-owners can use alternative green sources of energy to power reefers. Given the nature of the environment in which reefers develop, a solar-based energy source seems ideal.
Solar panels come to mind when thinking of solar powering the reefers cooling system. It is a renewable energy source which would reduce reefers’ CO2 emissions. But is it a viable option?
Given the average reefer energy consumption per day, the solar array on the solar reefer would need to output 10,000 W per hour assuming an average insolation of 5 peak sun hours falling over the container (explanation of peak-hour concept).
Using a 300 W rated solar panel and since each panel is 1.6 m by 1 m, the reefer would need 34 panels and 54.4 square meters of sun receiving surface to function solely on solar energy. A single TEU container has an available surface area of 58.8 square meters excluding the bottom, but it is impossible for the sun to hit every side of the container at once, so it is not viable to power a reefer solely on solar energy.
Since there is no sense in covering the entire container with solar panels, and knowing there is no possible way to power the reefer with solar energy, we’ll consider using just the top of the TEU for solar energy production.
A TEU container has roughly 14 square meters of surface available on its top, meaning eight 300 W panels can fit in. Assuming 5 hours of peak sun hours, the panels can generate 12,000 W, which represents almost 28% of the energy a reefer consumes in a day. This energy can relieve the reefers’ CO2 emissions by 15.24 kg.
Of course this is all a rough calculation and subject to variables such as efficiencies, temperatures, insulation, shading, and weather. I’m also not considering the battery storage system that we’d want to incorporate as well.
Solar reefers could be a viable way to reduce reefers’ CO2 emissions as of today, even more as its performance and strength improves. Soon a solar reefer may shift from a mere novelty to a new standard.
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