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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

The construction of the first solar refrigerated evaporatively cooled (SREC) chamber in India was completed in October 2019 in the village of Picholiya, Ajmer, Rajasthan with the NGO partner Krishak Vikas Sansthan (KVS) providing assistance to Dr. Chopra and her team. The building materials were procured from the market at Pisanganj near Picholiya and the field staff was sent from IARI to build the chamber and fabricate and install the water battery. Local laborers from Picholiya were employed for the construction work. During the construction of the SREC chamber, Dr. Chopra and project consultant Dr. Randolph Beaudry visited the site, where they organized a special workshop to teach the laborers and local farmers to utilize professional tools properly and increase their work efficiency. Dr. Beaudry’s hard work and passion for this project inspired the laborers, who are now capable of following instructions and reading technical drawings to do efficient work. U.S. partner Dr. Norbert Mueller has also helped the PEER team understand the refrigeration system and troubleshoot any problems that arose during continuous operation. With his guidance they improved the system, and the final model is much more efficient and easier to use and install.

With the kinks ironed out during construction of the first SREC, the team is eager to continue their installation. As of the last quarter of 2019, the team was in the process of sending solar panels, the specially-designed refrigeration system, control panel and aramid needle felt fabric to Picholiya where they intend to make the chamber operational and ready to use by farmers in February or March 2020. They will also monitor the new chamber to receive daily data of temperature/ relative humidity both inside and outside of the chamber along with voltage/ current being drawn by the refrigeration system and the energy being generated by the solar panels.

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

A group of farmers around Picholiya, Rajasthan expressed an interest in building the SREC chamber on their own by getting partial loans from the bank. The team committed to help them with the design details and the construction guidelines. They expect that once the chamber is made operational it will be visited by many famers/ entrepreneurs and the team will see significant interest from them. A retired bureaucrat from the government of Haryana and an official from National Bank for Agriculture & Rural Development (NABARD) visited the chamber being built in Rajasthan.

In addition to the construction, the team continued its research work on the proof of concept SREC chamber at IARI, New Delhi. The students stored tomatoes, spinach and amaranth in the SREC chamber and compared their quality with the produce stored in the mesh fabric evaporatively cooled (EC) chamber, uncooled laboratory and refrigerator. The quality parameters of the produce stored in these structures were measured and analyzed with respect to cumulative respiration that the produce had undergone during storage period. Based on gather data, the technical performance of the solar inverter was improved by Tushar Kaushik by redesigning the configuration of solar panel strings connected to it. This enabled the inverter to generate sufficient energy even during low solar insolation days and on cloudy days. The team has also designed a compact and low-cost control panel which is easy to understand/ monitor by the local users. This control panel will be fitted to the SREC chamber at Picholiya. A new SREC structure is being designed using iron pipes, with the intention of further reducing both the cost and the time taken to build the chamber. It is being constructed at IARI, New Delhi

In the coming months, the team will work to design and construct an SREC chamber with iron pipes, which should take less time to build and be cheaper. They will survey villages in Delhi to identify a suitable site for an SREC chamber and visit the village where the chamber can be constructed and data can be collected. Construction of the structure at the village of Haryana will finish and the SREC chamber in Picholiya will be made operational.

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