Passive Refrigeration Technology

Place: Lucerne, switzerland, Europe
Quantitative & qualitative enhancement of crop products Quantitative & qualitative enhancement of crop products
Total Budget: € 0,00 | Period: From September 2014 To


The scope of development of PRS technology was to provide a unique refrigeration equipment meeting the following Fundamental Requirements:
1) Thermal autonomy: sufficient to cover typical intermodal and mid sea door to door transit times.
2) Energy consumption and CO2 emission: significant reduction both as direct and indirect thanks to the change of mode of transportation.
3) Enhancement of quality of preservation: the reduction of product losses and the enhancement of quality provide strategic opportunities for the producing Countries.
The field tests have proven that PRS equipment exceed all 3 Fundamental Requirements and the continuous effort of optimization has allowed to develop technical solutions which are economically competitive vs. conventional refrigeration equipment with a significantly shorter Return of Investment.
The introduction to the market has been more difficult than expected due to the conservative approach and resistance to change of the Clients.


PRS - Passive Refrigeration Solutions S.A. - Swaziland

Lead applicant

Development of innovative technologies in the field of thermodynamics, energy saving and environmental impact reduction.

Mediterranean Agronomic Institute of Bari - Italy

Initiative partner

L'Istituto Agronomico Mediterraneo di Bari-IAMB è la struttura operativa italiana del CIHEAM, istituito con Legge 932/1965 ed opera in 4 aree tematiche: - Gestione del suolo e delle risorse idriche; - Protezione integrata delle colture frutticole mediterranee; - Agricoltura biologica mediterranea; - Agricoltura, alimentazione e sviluppo rurale sostenibili. La formazione continua prevede corsi di aggiornamento anche a distanza rivolti a giovani dell’Area Mediterranea, Balcanica e del Vicino Oriente. L’Istituto svolge inoltre attività di ricerca applicata per migliorare la qualità della formazione con il coinvolgimento diretto dei corsisti nella ricerca e garantire un valido supporto alla progettazione e realizzazione di iniziative di partenariato. L’IAMB assiste le istituzioni, sia a livello centrale sia locale, per l’identificazione, la formulazione e l’esecuzione di progetti di cooperazione nei Paesi mediterranei al fine di promuovere la sicurezza alimentare e lo sviluppo sostenibile.

EMS – Seven Seas - Norway

Initiative partner

Ship and off-shore supply

Enormous investments spend to increase production but up to 50% of crop is lost in post-harvest due to insufficient preservation related to missing knowledge or missing infrastructures in particular relevant to refrigeration. The Best Refrigeration Practice consisting of field tested Passive Refrigeration System (PRS) guarantees optimal preservation conditions and the continuity of the fresh chain from the field to the final destination without continuous dependence on energy sources. The investment is lower than conventional refrigeration equipment and the logistic flexibility is similar to dry cargo. Fresh commodities cover the largest export market share of Developing Countries and their production costs, quality, are affected by conventional refrigeration. The non compliance with the key preservation requisites consisting of high relative humidity, no forced ventilation and constant temperatures result in poor preservation with consequent complicated and expensive logistics.

Food Safety: healthy and environmental friendly PRS technology extends fresh food storage life and avoid the use of chemical preservatives.
Main innovation consists of the capacity of storing the thermal energy sufficient to cover the required temperature controlled period without re-plug-in and its use to maintain the optimal relative humidity and temperature without using forced ventilation, which affects the quality of preserved commodities. PRS does in the thermal field what battery cars perform in transport.

PRS containers cover with the same equipment all cold chain functions from in-field postharvest to the final warehouse such as cold stores trucks and containers.

Effects: longer storage life means the possibility of reducing loss of product due to deterioration and creating additional export markets actually difficult to reach while low energy consumption and thermal storage allow the use discontinuous power supply typical of Developing Countries and renewable energies.

20’ PRS container used for preservation and thermal autonomy test 20’ PRS container used for preservation and thermal autonomy test
Award of termal tecnology This innovative teohnology enables produoersto maintain the freshloold chain from farms to rnarket independent of continuous power supply. it thus reduces post-hansest, post-slaughter and port-milking warte and provides safer food to consumers
Table grape in PRS Grape in October 2013 after 28 days without SO2
Temperature and RH recording Temperature and RH recording from Sept. 12 to Oct. 10, 2013 with a single initial thermal charge

Developing Countries are generally has hot climates, insufficient infrastructures and need of large investments rarely affordable by local producers.
Limited and discontinuous power supply as well as long distances from production to destination require complex logistics, which further complicate the export operation.
PRS containers solve the Problems by covering the complete fresh chain from in-field postharvest to destination at a cost similar to dry cargo, giving the possibility export of competitive high quality products from South Mediterranean Countries to European, American and Far Eastern Countries which will be beneficial for consumers and rewarding for the local producers.
Reducing the investments for fixed assets and creating higher revenues will enable to expand the local production and employment while today the high deterioration hampers the possibility of export and the very low prices affect the motivation for agriculture work abundance and migration.

PRS container full of bush onion crates PRS container full of bush onion crates – no space is left for air circulation
Temperature of the container Temperature of the container at the end of loading at the farm
Truck loading after the pull down Truck loading after the pull down under the tent – transport to packing center produces another weight loss At the arrival the products are washed with water to recover the lost humidity

Extension to the field of cold chain, reduction of field-to-destination weight loss and waste due to deterioration, simplification of operations with direct load of non-pre-refrigerated product to PRS container with elimination of vacuum/blast cooling, reduction of packaging and preservatives, reduction of ocean freight from reefer fares to dry box ones, improvement of quality, possibility of shipping high added value products which today can’t be shipped due to deterioration rate.
Disruptive change of the business model, which drastically enhances the grower profitability and enables the export of competitive products from Countries with limited infrastructures and limited financial resources.
The reduction to a fraction of power consumption-CO2 emission of PRS containers vs. conventional reefers and the use of environment friendly transport modes, ship-rail instead of road and intermodal vs. road, further reduce the energy consumption-CO2 emissions, reducing contamination.

Economical analysis relevant to a typical major high quality horticultural Economical analysis relevant to a typical major high quality horticultural producer operating in West Africa with yearly export of 30.000 tons of product. Weight loss saving: is related to the elimination of vacuum cooling Transport saving: the use of PRS containers allows to use dry box ocean freight at 1.800 €/container instead of reefer ones at 2.800 €/container.
Environmental impact function of transport mode Environmental impact function of transport mode, the superior quality of preservation of PRS equipment allow to use environment friendly modes such as ship and rail instead of faster ones such as trucks

Growers: reduction of weight and product loss, direct load of non-pre-refrigerated product to PRS container, reduction of ocean freight, improvement of quality, possibility of shipping new high added value products.
Logistic companies: reduction of deterioration factor and related risks, widening of the range of transported products, creation of additional markets.
Shipping lines: elimination of on board fuel consumption for reefer power supply, increase of traffic due to the shipment of larger quantities of products, elimination of               port/on-board/port power supply and elimination of plug-in genset necessary for  upstream and downstream operation.
Railways: solution of on-train critical energy supply problem, acquisition of new markets alternative to road.
Insurances: reduction of risk due to PRS reliability.
Consumers: better products at lower cost with higher nutritional content, reduction of environmental impact.
Traders: widening the area of operation.

• Scientific Research:
o Scope: software development for computer simulation of system behavior, development and analysis of eutectics, prototype modeling.
o Participants: professors of University of Milano, Genova and Bologna.
• Prototype realization, testing and performance assessment:
o Scope: realize the prototypes from models up to full size cold stores and containers to assess the compliance of test results with specs.
o Participants: Euopean Union, IFOS-Lincoln University, d’Apollonia, RINA, CISCo, ISA, CIHEAM-IAMB.
• Field testing:
o Scope: in-field postharvest cooling, transports of pre-cooled and non pre-cooled products, energy consumption, product preservation, thermal autonomy.
o Participants: CIHEAM-IAMB, Ortonatura, Tonolo, Van Ours United, EMS, Agris Sardegna.
Profiles and no. of people involved in the Project: physicists, mathematicians, chemists, agronomists, veterinary, logistics, ocean shipping and manufacturing experts for a total > 100 peoples.

• Initial feasibility analysis: the initial main difficulty to develop a completely new and economically attractive technology was the feasibility assessment, which required a preliminary sophisticated analysis.

• Development of proprietary mathematical model: it was necessary to create proprietary algorithms able to cover all parameters of the system reproducing the behavior of each and all components.

• Applicability to a great variety of products: each food product has its own characteristics, for economical reasons it was not possible to create a version for each product. The possibility of using a standard version for all products required extensive testing.

• Physics constraints: the system is based on phase change involving volume variations which generate destructive pressures, the possibility of absorbing it with sealed modules has been a major challenge which was solved using proprietary know how.

Energy saving: has been verified during 28 day test of CIHEAM on a 20’ PRS with the following result:
• PRS container energy consumption for 28-day thermal charge: 450 kWh, 0.66 kWh per hour, with a total production of 443 kg of CO2.
• Conventional reefer container energy consumption specified by Germanischer Lloyd in chilled mode: 4.704 kWh, 7 kWh per hour, with a total production of 5.736 kg of CO2.
CO2 emission saving related to transport mode: PRS allows the use of environment friendly transport modes as ship and intermodal instead of road. Result of test by Van Ours United from Agadir-Morocco to Holland with ship as alternative to truck transport over 3.535 km:
• Ship CO2 emission: 1.190 kg
• Truck CO2 emission: 22.960 kg
Fundamental characteristics of PRS containers are total lack of moving parts and full aluminum alloy construction, which result in a much longer life and very recyclable material.

Sustainability: PRS the refrigeration technology have the lowest environmental impact and lowest operating cost among all refrigeration equipment.
PRS units are suitable for operation in any location including remote ones with critical access to infrastructures, can be supported by any renewable energy sources and transported by any mode.
The possibility of realization in any size allows its use also for vaccine transport and distribution in remote areas.
Transferability: while PRS technology are readily and easily transferable thus enabling production under license in locations close to the areas of operation.
Duplicability: the standardization of shop drawings, production and QA/QC procedures as well as of all components allow to duplicate PRS equipment with consistent and repeatable performances for pull down, preservation, storage and transport of any type of food productions in all continents. 

Innovative methodology: it consists of giving a certain quantity of PRS containers to a limited number of selected Clients for each market segment (horticultural, fruits, ornamentals, meat, poultry and dairy products). The units was used in real operation in accordance with the procedures preferred by the Clients.
The field tests are repeated at least twice to be sure that the results are consistent and, after the conclusion of each series, we jointly define a comparative business cases for that application where all steps of the activity are analyzed and cover food safety, refrigeration equipment direct environmental impact, transport mode environmental impact, man power and economical perspectives.
Spread of the results: the comparative analysis is made with the “problem solving approach” and used to communicate to Clients what can be achieved and the competitive advantages of PRS equipment.