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Solar-Biomass Hybrid Cold Storage-cum-Power Generation system for Rural Applications

Background
In a tropical country like India, with about 70% of population of India is engaged in agriculture, the importance of refrig-eration can hardly be over-emphasized. India is the 2nd largest producer of fruits and vegetables in the world. Horticulture provides 6.5% of the country's GDP, 13% of employment and accounts for more than 9% of Indian exports with only 9% crop acreage. However, while India's agricultural production base is quite strong; wastage of agricultural produce is massive. It is estimated that, due to a lack of proper storage and transit facilities, about 22% of agricultural produce, especially fruit and vegetables, is spoiled. The wastage in fruit and vegetables is estimated to be worth about Rs.330 billion. India, therefore, has tremendous growth potential with respect to rural-based food processing.

However, poor infrastructure, including the lack of integrated cooling facilities (cold chain), has retarded the growth of the food processing industry. The Ministry of Food Process in India has identified refrigeration and cold storage facilities as the weakest link in the whole value chain.

The lack of proper storage facilities has led to the following consequences:

  • Excess produce either floods the market and results in an oversupply or is totally wasted; and
  • An artificial scarcity is created during non-harvesting periods.
The cold storage facilities for India's agricultural produce are falling short by more than 10 million tonnes. Moreover, the conventional cold storages, which are being set up mostly in semi urban areas, are of 100TR (Tons of Refrigeration) and above capacity making them unviable for small village level applications. Additionally, these cold storages consume 30,000 MW of the installed power capacity and energy expenses account for 28% of costs in cold storage.

Also, very often farmers have to resort to distress selling due to limited shelf life of the produce in absence of access to even short-term cold storage facilities. As a result marginal and small farmers face difficulty in getting good returns from sales of their produce. Furthermore, a majority of India's villages are unelectrified and even the electrified ones have erratic power supply. Hence there is need for small cold storage facilities that are not dependent on the grid electricity, to temporarily store the farm produce till market prices are more amenable to small farmers.

Since India is blessed with perennial solar energy and a lots of surplus biomass resources, developing a solar-biomass powered cold storage can help meet this shortage using abundantly available renewable energy that is best suited for rural/decentralized deployment.

TERI's initiative
Against this backdrop, way back in 2006, TERI started working on a concept whereby indigenously available biomass and solar resources could be used to operate small, decentralized cold storage right at the village level (as opposed to commercial, large-capacity cold storages at centralized locations). In addition to providing the cold storage facility to the farmers, such a system - it was envisaged- would also supply grid-quality power to the village; thereby offering a holistic solution to some of the key problems facing agrarian India.

Finally, in 2009, TERI started the development work with support from the Ministry of New and Renewable Energy (MNRE), Government of India under the aegis of Asia Pacific Partnership on Clean Development and Climate: in partnership with Solar Energy Centre, MNRE; Commonwealth Scientific & Industrial Research Organization, Australia, and Thermax Ltd., India. For finalizing the design, TERI held wider consultations with stakeholders such the National Horticulture Board, District Horticulture Offices, and Central Food Technological Research Institute in addition to undertaking an elaborate exercise to understand the field requirements.

The cold storage system so developed, comprises a 15 kW (~5 TR) Vapor Absorption Machine (VAM) coupled with a 50 kWe Biomass Gasifier system and a field of solar concentrating collectors. The bio-mass gasifier produces synthesis gas using locally available woody biomass, which is then used to run an engine-generator to produce electricity. The waste heat from the biomass gasifier along with the heat energy from the solar concentrating collectorsis utilized by the VAM to cool the cold storage chamber. Since the cold storage can be cooled to temperature as low as 0°C, a wide variety of fruit, vegetables, and horticulture produce can be stored there. The electricity generated by the system is enough to power domestic, community, as well as productive loads in a typical village.

The pilot plant has been set up in Solar Energy Centre, Gurgaon and is now operational.

Successful implementation of this system can open up avenues for its replication in other regions of India, thereby helping in both saving valuable agricultural produce and village electrification. Besides providing cold storage facilities as a mean for rural economic development, the system would also be providing electricity to the rural households and communities.The socio-economic impacts of this would be multifold, namely:

  • Electricity for lighting, resulting in (a) clean environment, (b) increased hours for study and social interaction, and (c) improved quality of life
  • Electricity for essential community applications like primary health centre and ICT based rural knowledge centres
  • Electricity for commercial activities like village market place
  • The use of electricity during the day time for income-enhancing activities like local entrepreneurship development and irrigated farming.

Tags: solar cooling, village electrification, cold storage, biomass gasifier

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