Successful Use of Solar Power in Food Processing Industry
The Society for Energy, Environment and Development (SEED) was founded in 1987 by a few professionals with expertise in engineering, management, solar energy, law, and social work. The purpose of the NGO is to draw upon the expertise of these fields of study to create awareness about environment and energy issues and creating devices to enhance the quality of life. SEED works in the areas of green energy applications, solar food processing, and rural women and youth empowerment. SEED believes in taking a holistic approach to achieve rural employment, food and nutrition security, and environmental sustainability.
SOLAR-POWERED AIR CABINET DRYERS
SEED has designed and developed solarpowered air cabinet dryers based on solar radiation with greenhouse effect (solar thermal) and with the introduction of solar fan for the first time. In the experimental set-up, they have used heaters operated by solar photovoltaic energy. This has given a good impetus to solar food processing technology. The cabinet dryer processed 96 solar-dried products based on fruits, vegetables, and forest produce, and the processing data is preserved under the headings of loading capacity kg/m2, yield (%), finished product moisture (%), drying hours, cabinet temperature (oC), and ambient temperature (oC).
Even though solar power is introduced in SEED’s innovative solar cabinet dryer to drive the fans, but solar power is not completely utilized in the operation of the machinery for food processing industry. Hence, the objective of their investigation is to interface solar power with the operation of food processing machinery.
FOOD PROCESSING EQUIPMENT: LOAD ESTIMATION
Subsequently, SEED calculated the load estimation of different units in food processing industry for the application of solar power. The following are the equipments (Table 1):
DESIGNING AND DEVELOPMENT OF 10- kW ROOFTOP SOLAR POWER SYSTEMS
With the previous experience in building up solar power systems, the SEED R&D has designed and developed a model solar power system for application in food processing technology. It is a rooftop 10- kW Solar Power System. It was divided into two parts—5 kW is connected battery backup and another 5 kW is connected on grid. This mode facilitates the machinery to operate with solar power only when the grid is on and also when the grid is off. In other words, it is connected with the string invertor and also hybrid (or) dual input inverter. The machinery will draw power from the battery bank. The cost of 10-kW Rooftop Solar Power System Rs. 10 lakh and the savings are Rs. 1.44 lakh per year and its payback period is 7 years.
INTERFACING FOOD PROCESSING EQUIPMENT
The machinery will draw the total solar power generated, which is distributed through three sections namely, R&D Section, Food Processing Section, and Solar Hybrid Dryer—SDM-50. It successfully operates micro food processing machinery so that the total solar power is drawn and used with varying series of operations. The system was tested with load at variable times so that the total solar power drawn is equivalent to about 10 kW limit. The detailed diagram is given as Figure 1.
The 10-kW solar photovoltaic system generates about 50–55 units per day in a single phase. During the research period, SEED made great progress and was successful in introducing new innovations in solar food processing technology. Alongside using solar-based cabinet dryer for dehydration of fruits and vegetables, SEED successfully integrated solar energy to operate the downstream and upstream small-scale food processing equipment, such as pulpers, transfer pumps, pulverizers, and heat sealing equipment. etc., in conjunction with the dehydration process. The solar power distribution system interfacing with other smaller capacity food processing equipment was installed as a demo model with 10-kW rooftop solar power system. This innovative working prototype is working successfully at SEED R&D Center. These efforts will continue in future as well to further scale up to solar power generation system and utilize the solar energy for fullscale operation of small- and medium food enterprises. All the practical purposes to complete the process of the product from pulping stage to finished product are tested successfully.
EXPERIMENTS ON PROCESSING OF SAPOTA AND MANGO FRUIT BARS USING SOLAR POWER
The SEED researchers chose Solar Hybrid Dryer–SDM-50 model for experimentation during non-sunny hours of operation for processing of fruit bars from fruit pulps drying. The full load of the pulp is 24 kg including all ingredients and loaded in solar cabinet dryer’s trays for drying. The drying process is completed within 10 hours during nonsunny hours operation, that is, exclusively on solar power and the yield is 11 kg per batch. The equipment that are used in production of fruit bars is food processing machinery, which includes dryer, pulper, mixer, and packing machine.
The required power for the whole operation is 25 kWh and drawn from integrated PV system of 10 kW which gives us 50–55 kWh power per day. The rest of the power is supplied to laboratory equipment, general lighting for factory, and office maintenance. Balance power, if any, is supplied to grid.
In this experiment, a total of 10-kW rooftop solar power system is connected in three sections, that is, R&D Section, Food Processing Section, and Solar Hybrid Dryer – SDM-50, and 12,700 watt hours are required for this operation as already mentioned above.
THE WAY FORWARD
SEED successfully completed the introduction of solar energy in the food processing industry for the first time. It is an uninterrupted source of energy for sustaining the food industry. The solar cabinet dryer is operated with zero energy cost and zero carbon emissions. The income for the farmers and rural women through processing of the food products will be sustainable in the long run. This additional income will be an excellent means for the welfare of the farmers’ families involved in the agrihorticulture produce in villages.
Prof. M Ramakrishna Rao and G Harikrishna, Society For Energy, Environment & Development (SEED); www.seedngo.com