Mini containers, an energy-efficient solution for small farmers?
To benefit small growers, a team of researchers investigated the concept of mini containers that would consume less energy and produce fewer GHG emissions than conventional full-size reefers.
In an article published in Climate, a team of researchers introduced the concept of mini containers for transporting fresh fruit and vegetables with lower GHG emissions, especially for partial loads compared to conventional refrigerated transport (reefers).  The smaller size would benefit small growers, as they wouldn’t have to use an entire reefer for a relatively small harvest. According to the Food and Agriculture Organization of the United Nations (FAO), farms smaller than 2 hectares produce around one third (35%) of the world's food.
The mini containers are 4 × 4 × 4 ft3 (about 1.2 x 1.2 x 1.2 m3) insulated boxes that maintain traceable, controlled environments corresponding to the fresh produce stored in each mini container. Refrigeration and other environmental conditions are maintained by a separate central driving unit powered by batteries that can be charged by renewable energy.
Since mini containers are small, thermally insulated boxes, a non-refrigerated vehicle can be converted into refrigerated transport. Furthermore, when stationary, the mini containers and their central driving units become a scalable refrigerated warehouse.
The heat loads on the mini container were calculated for four different types of insulation to help optimise their design. A comparison of the energy intensity and corresponding GHG emissions for two climates, Phoenix, Arizona, USA (hot climate) and Chicago, Illinois, USA (cold climate), was made for mini containers and conventional reefers transporting tomatoes. Their results showed that, for partial reefer loads less than 72% and 85% for Phoenix and Chicago, respectively, the use of mini containers reduces energy consumption and GHG emissions because of the reduced volume requiring refrigeration. Above those thresholds, their calculations indicated that there was no longer a benefit to using a mini container rather than a conventional reefer.
For more information, the research article is available on FRIDOC, thanks to an agreement with MDPI.
Read our Informatory Note on the carbon footprint of the cold chain
 Syam, M.M.; Cabrera-Calderon, S.; Vijayan, K.A.; Balaji, V.; Phelan, P.E.; Villalobos, J.R. Mini Containers to Improve the Cold Chain Energy Efficiency and Carbon Footprint. Climate 2022, 10, 76. https://doi.org/10.3390/cli10050076
 Lowder, S. K., Sánchez, M. V., & Bertini, R. (2021). Which farms feed the world and has farmland become more concentrated?. World Development, 142, 105455. https://doi.org/10.1016/j.worlddev.2021.105455
 FAO. Small family farmers produce a third of the world’s food (23 April 2021). https://www.fao.org/news/story/en/item/1395127/icode/
Credits image: U.S. Department of Agriculture (public domain/free image)