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Cycle 7 (2018 Deadline)

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

PI: Sangeeta Chopra (, Indian Council of Agricultural Research-Indian Agricultural Research Institute (ICAR-IARI)
U.S. Partner: Norbert Mueller, Michigan State University
Dates:  January 2019 - December 2020 

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.

Summary of Recent Activities

7-360 SREC
A test SREC being finalized in a local town (Photo courtesy of Dr. Chopra).
From April 14 through 19, 2019, Dr. Chopra, her colleagues, and representatives from their project partner institution Krishak Vikas Sansthan (KVK) visited village clusters in Rajasthan and Delhi to survey and identify communities that need small-scale (2 tonne) off-grid battery-less storage facilities for keeping perishables and have the required capabilities for operation, maintenance, and record keeping. Farmers in the areas visited produce fruits and vegetables, such as lemon, peach, cucumber, bitter gourd, bottle gourd, watermelon, muskmelon, mushroom, cauliflower, tomato, beet, papaya, and rose. The PEER team explained the design and performance of SREC structures with the farmers and obtained their input regarding their needs and prospects for building these structures on their fields. The researchers also used questionnaires to get additional information from the attendees, including the size of their farms, types of fruits and vegetables grown, cropping systems used, local village demographics, distance from nearby markets, and needs for storage structures. Based on their field survey, the team identified two villages (i.e., Picholiya, District Ajmer, Rajasthan; and Chamrara, Tehsil Israna, District Panipat, Haryana) where SREC structures will be built. They then began procurement of building materials and hiring of labor for the installation of the first SREC structure. One item purchased was an innovative inverter that can be operated “off-grid” (i.e., not connected to the electrical grid), does not need batteries to operate, and can therefore deliver energy to the refrigeration system, lights, and pumps directly from solar energy influx. As far as the team is aware, there are only three such inverters made globally, and they will be purchasing the other two systems in the third quarter of 2019. The team has also tested the performance of the structure for storage of amaranth, a model crop. They are evaluating the possibility of using amaranth as a model crop for testing the efficacy of storage structures at all the planned locations.

Upcoming plans on the project include travel by the PI Dr. Chopra to the United States in late July 2019. She will present a paper entitled “Amaranth: a model crop for testing imperfect storages” at the annual conference of the American Society for Horticultural Science, to be held July 21-26 in Las Vegas. Following the conference, she will travel to Michigan State University to work with her U.S. partner Dr. Randy Beaudry. In the subsequent months, she and her team plan to start building the SREC structure in the village of Picholiya, Ajmer, Rajasthan, with the assistance of KVK and the local farmer producer organization. The researchers will also compile detailed documentation on construction materials and methods, including precise drawings with exact measurements so that the structure can be replicated easily at other villages.

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