Contact Us  |  Search  
 
The National Academies of Sciences, Engineering and Medicine
Partnerships for Enhanced Engagement in Research
Development, Security, and Cooperation
Policy and Global Affairs
Home About Us For Grant Recipients Funded Projects Email Updates
PARTNERSHIPS FOR ENHANCED ENGAGEMENT IN RESEARCH (PEER)
Cycle 7 (2018 Deadline)


Off-grid, clean energy cooling for affordable storage of perishables for bottom-of-the-pyramid farmers

PI: Sangeeta Chopra (dhingra.sangeeta@gmail.com), Indian Council of Agricultural Research-Indian Agricultural Research Institute (ICAR-IARI)
U.S. Partner: Norbert Mueller and co-partner Randall Beaudry, Michigan State University
Dates:  January 2019 - June 2023

Project Website: http://www.coolsunproject.com

Project Overview


 
 

A stand-alone, batteryless, off-grid, solar-refrigerated evaporatively-cooled (SREC) structure for storage of perishables has not previously been field evaluated by smallholder base-of-the-pyramid (BOP) farmers. The SREC chamber can easily achieve daytime temperatures as low as ~5-10 °C when the daily maximum temperature outside is approximately 45 °C. This technology promises a meaningful contribution to the capacity and stability of the BOP farmer. The innovations incorporated into the SREC structure are many: a design that can be largely self-built and permits staged construction and investment; the use of passive evaporation of water from the chamber walls for partial cooling both day and night, thereby reducing refrigeration load and cost; the use of a split evaporator coil system to shunt cooling to a thermal reservoir; the deployment of a new inverter technology with a secure power supply and integrated controls to maximize solar collector efficiency; the use of a cold water reservoir to provide low-cost thermal storage instead of using batteries for overnight cooling (reducing environmental impact, operational risks, initial capital, and maintenance costs); the deployment of an extremely large surface in the chamber to maximize cooling with a minimal temperature differential, thereby increasing humidity and minimizing perishable desiccation; the use of a dedicated relay circuit to ensure automatic start-up following overnight shutdown; and no dependence on electrical grid for cooling. Despite the novelty of the structure, it can be self-built by farmers with inexpensive locally available materials, minimizing extra labor costs and initial investment requirements. The specialized components required, like solar panels, inverters, and refrigeration systems, are readily available in India. This project is aimed at replicating initial technical successes by transitioning to field trials by farmers. The researchers will evaluate the amount of energy collected and converted to refrigeration, measure impact on the quality of perishables stored, determine the value to farmer households, and assess the impact on local and regional markets.

Deploying innovative off-grid batteryless SREC structures/chambers at farmers’ fields in villages in three hot and dry states of India will have several important impacts. This innovation will help India's transition to a low emission economy by adding decentralized solar PV capacity. Having access to on-farm cold storage will increase incomes for BOP farmers by avoiding distress sales, reducing spoilage, and enabling pre-processing of perishables. Adopters of SREC technology will keep produce cool without grid electricity, which frequently fails. Market panic following grid failures is avoided and market confidence and control improved. Higher profits will improve quality of life, increase purchasing power, support higher education for women and children and improve household affluence. Education is another important part of this work. Farmers and local tradesmen will be trained to build SREC chambers themselves, thereby improving community capabilities and opening up new opportunities for financial growth. The farmers will be educated on opportunities for light processing of perishables (e.g., pod stripping, pea or bean shelling, packaging) and will be able to run small processing machinery directly from solar panels. Additionally, extension professionals will be trained on the fundamentals of construction and use of this technology and will be encouraged to act as agents of change.


7-360 Chopra SREC Picholiya
The fully constructed and operational SREC chamber in the village of Picholiya (Photo Cred: Dr. Chopra).

Final Summary of Project Activities

Dr. Chopra and her colleagues successfully designed an off-grid, batteryless solar refrigerated and evaporative cooled (SREC) structure, also called the Farm SunFridge, that can be self-built by smallholder farmers. Several innovative features have been incorporated, including a "water battery" (a thermal reservoir) to provide nighttime cooling, a dual-use refrigeration coil to cool the thermal reservoir and interior air simultaneously, and a solar adaptive controller to regulate power demand by refrigeration compressor based on available solar energy. Two SREC designs were built with frames of concrete (c-SREC) and iron (i-SREC) and evaluated for their ability to regulate temperature and humidity. The Farm Sunfridges were constructed and evaluated in the northern part of India (Delhi, Haryana, and Rajasthan) from 2017 to 2022, and the design proved able to reduce the interior temperature relative to ambient between 5 and 35 °C, varying throughout the day and across the seasons. During the hot, dry season of the year, the temperatures inside the i-SREC structures were lower than those in c-SREC structures; however, when solar insolation declined during the monsoon season, the two structure types performed similarly. The i-SREC out-performed the c-SREC during periods of high solar radiation, likely a result of the much reduced thermal mass of the roofing materials in the i-SREC. A significant reduction in storage temperature and improvement in storability of perishables can be achieved, relative to ambient and relative to evaporative cooling alone, in SREC (Farm Sunfridge) structures, and it has been proven as feasible for perishables storage by smallholder farmers and farmer organizations.

To illustrate the impact the FSF is having on its users, the young farmer Abhishek and his local farmer producer organization (FPO) near the project site at Cullakpur, New Delhi, use the FSF to store cabbage, tomatoes, and spinach. They have constructed a collection center and light processing platform adjacent to the FSF, and the farmer is buying, storing, and selling his produce from the FSF facility. The farmer and other members of the FPO said that FSF was working better than their expectations. The SunFridge at Cullakpur is working very well, with low temperatures ranging from 0 to 5 °C, when there was no loading/unloading of produce, and 10 to 15 °C when there was significant product movement. The SunFridge and cold room environment has permitted growers to enter the premium market segment for sale of spinach (washed, trimmed, and bound in bunches) and red cabbage (long-term storage), and they are making increased profits thanks to the FSF. The other units built at Chamrara, Haryana, and at the exhibition ground of IARI are working well also, with the latter also serving as a demonstration unit for policy makers, growers, and students visiting IARI. The latest FSF has been built at the village of Choti Bhitarwali, Dehradun, using IARI funds.

The Farm SunFridge has garnered a lot of attention and popularity among growers and policy makers in India. The Director of IARI has provided funds to build two of the structures, and in response to the rising demand for FSF technology, IARI has selected FSF to be built under its revolving fund scheme. Under this scheme, the tenders are floated and based on the bids received, the contractors are identified for construction of the FSF, wherever and wherever there is a demand. The innovative technologies incorporated into the FSF have also attracted attention from other researchers. Two groups of scientists have contacted Dr. Chopra and her group, and together they have prepared three proposals to USAID for the construction of FSF units in Kenya and Ethiopia for smallholder farmers.

Although the PEER grant has now ended, the PI and her colleagues will be continuing their work on further enhancements to the FSF design, including to expand its storage capacity in response to feedback from its users. They will also be supervising students studying the use of the FSF with other mangoes, marigolds, and milk. Further publications on their work are expected, and they have filed for a patent in India. Dr. Chopra and her U.S. partners feel the future for upscaling the FSF looks bright, given that users of the pilot units have demonstrated strong and rapid return on investment and industry and government agencies at various levels have expressed interest.

Supplemental Funds

With funding provided through a PEER Research to Action supplement, Dr. Chopra and her colleagues prepared an FSF construction manual, something that has been requested by farmers and policy makers alike. In addition, they have written a detailed project report with relevant economic analysis that will help interested parties obtain bank loans for building the structure.

Publications

S. Chopra, N. Mueller, D. Dhingra, P. Pillai, T. Kaushik, A. Kumar, and R. Beaudry. 2022. Design and performance of solar-refrigerated, evaporatively-cooled structure for off-grid storage of perishables, Postharvest Biology and Technology 197, 112212. https://doi.org/10.1016/j.postharvbio.2022.112212

S. Chopra, N. Mueller, D. Dhingra, I. Mani, T. Kaushik, A. Kumar, and R. Beaudry. 2022. A mathematical description of evaporative cooling potential for perishables storage in India. Postharvest Biology and Technology 183:111727 https://doi.org/10.1016/j.postharvbio.2021.111727

P.S. Mahangade, I. Mani, R. Beaudry, N. Mueller, and S. Chopra. 2020. Using amaranth as a model plant for evaluating imperfect storages: assessment of solar-refrigerated and evaporatively-cooled structures in India. HortScience 55, https://doi.org/10.21273/HORTSCI15249-20.

Sangeeta Chopra and Randolph Beaudry. 2018. Innovative composite wall designs for evaporative cooled structures for storage of perishable. Indian Journal of Agricultural Sciences 88 (11):1692-95. https://doi.org/10.56093/ijas.v88i11.84895

Sangeeta Chopra and Randolph Beaudry. 2018. Redesigning evaporatively cooled rooms to incorporate solar powered refrigeration in India. Acta Horticulturae 1194, 609-616. https://doi.org/10.17660/ActaHortic.2018.1194.88


Back to PEER Cycle 7 Grant Recipients