Alternative Energy Sources for Agriculture

MAHENDRA S. SEVEDA PRADIP D. NARALE SUDHIR N. KHARPUDE SUNIL L. NARNAWARE Central Agricultural Unive

PART-I

 Agriculture is highly dependent on energy for irrigation, machinery operation, crop processing, storage, and transportation. Traditionally, this energy has been derived from fossil fuels such as diesel and coal, which contribute significantly to greenhouse gas emissions and climate change. Renewable energy sources provide a sustainable alternative that can reduce environmental impacts while improving farm productivity, rural livelihoods and relief from the present energy crisis. With rapid technological advancements and declining costs, renewable energy is increasingly integrated into agricultural systems worldwide. The major renewable energy sources used in agriculture are solar, biomass, hydro power, wind and hydrogen.

Solar Energy

Solar energy is the most widely used and fastest-growing renewable energy source in agriculture. Photovoltaic (PV) modules convert sunlight into electricity, which can power irrigation pumps, lighting systems, greenhouse climate control, and farm machinery. Solar-powered irrigation systems are particularly beneficial for farmers in remote areas where grid electricity is unavailable. Applications of solar energy in agriculture include: Solar water pumping, Solar agri-voltaic, Solar drying, Solar cooking, and Solar water heater.

Solar Water Pumping Technology

Water pumping is one of the simplest and most appropriate uses for photovoltaic. From crop irrigation to stock watering to domestic uses, photovoltaic-powered pumping systems meet a broad range of water needs. A solar photovoltaic water pumping system consists of a photovoltaic array mounted on a stand and a motor-pump set compatible with the photovoltaic array. It converts the solar energy into electricity, which is used for running the motor pump set to draw water from the open well, bore well, streams, ponds, canal, etc.

Solar Agri-voltaic Technology

Solar Agri-voltaic Technology (Agrivoltaics) is a system in which solar photovoltaic (PV) panels and agricultural crops are produced on the same land simultaneously. Agri-voltaics involve installing solar photovoltaic (PV) panels above or alongside crops, allowing farming activities to continue underneath or between the modules. This technology is an innovative approach that combines renewable energy generation with agricultural production, improving land efficiency, farmer income, and environmental sustainability.

Solar Drying Technology

The solar dryers have many applications in industries and agriculture. Traditionally, drying of agricultural products is done on the open ground directly under the Sun, that leads to losses due to uncontrolled drying, besides causing contamination of the product. The College of Agricultural Engineering and Post Harvest Technology, Central Agricultural University, Ranipool, Gangtok, Sikkim has developed many solar dryers as follows:

Mixed Mode Photovoltaic Powered Forced Convection Solar Dryer: It is a combination of direct and indirect solar dryers. Product may dry with both direct exposure to solar radiation and hot air supplier on it. The dryer had capacity to dry10 kg of drying product, and is suitable for drying all kinds of agricultural and horticultural products like turmeric, ginger, leafy vegetables, fruits, cherry pepper, large cardamom etc. The drying time varies from 18 to 24 Solar hours (i.e., 2-3 days).

Solar Biomass Hybrid Dryer for Large Cardamom Drying: The solar biomass hybrid dryer (10-15 kg capacity) consisting of a solar collector, a down draft biomass gasifier and a drying chamber was designed and developed with drying capacity of 20 kg per batch of large cardamom within 12-15 hours of operation.

Portable PV Powered Forced Convection Solar Dryer: This dryer (capacity 5-10 kg) has four main components viz. flat plate collector, drying trays, exhaust fan and solar PV module. Being light weight, this dryer is highly suitable for high altitude and portability supports hilly region utility, and can dry products within 20-24 solar hours (i.e.,2-3 days).

Direct Type Natural Convection Solar Dryer for Drying of Large Cardamom: The solar dryer (capacity 7-10 kg) designed and developed for large cardamom is capable of producing the optimum temperature in the range of about 55^oC to 60^oC for drying of large cardamom within 20-24 solar hours (i.e., 2-3 days).

Solar Tunnel Dryer: The solar tunnel dryer consists of solar air collector cum drying chamber. The drying chamber is divided into multiple trays. It can accommodate drying of 75 to 200 kg product within 10-22 solar hours (i.e., 1.5-3.0 days), and supports all sorts of agricultural and horticultural products.

Solar Cooking Technology

Solar cooker is a device which uses solar energy for cooking and thus saving petroleum resources (LPG & Kerosene), fuel wood, and electrical energy to a large extent. It is a simple cooking unit, ideal to domestic cooking during most part of the year except during the monsoon season, cloudy days and winter months. The box type solar cooker with a single reflecting mirror is most popular in India. It works as an airtight box with double glass covers. A reflector is placed over it for boosting the solar radiation thus increase in temperature. Box type solar cookers are capable for cooking different types of food including rice, vegetables, pulses, chicken and fish, etc. A family size box type solar cooker is sufficient for 4 to 5 members, that save about 3 to 4 cylinders of LPG every year.

Solar Water Heater Technology

Most solar water heating systems have two main parts: a solar collector and a storage tank. The most common solar collector is called a flat plate solar collector. It consists of a thin flat, rectangular box with a transparent cover that faces the sun, mounted on the roof of building or home. Small tubes run through the box and carry the fluid-either water or other fluid, such as an antifreeze solution to be heated. The tubes are attached to an absorber plate, which is painted with special coating to absorb the heat. The heat builds up in the collector, which is passed to the fluid passing through the tubes. An insulated storage tank holds the hot water. Presently, the solar water heater is used for domestic, commercial and industrial applications. A temperature of 60^oC is sufficient for domestic use. Most domestic solar water heaters are capacity ranging from 100-500 litres per day. A typical solar water heater can save up to 1500 units of electricity every year, for every 100 litres per day of solar water heater. A solar water heater of 100 litres capacity can prevent emission of 1.5 tons of carbon dioxide per year. Solar water heater has a life of 15 to 20 years and pays back the cost in 3 to 4 years when electricity is replaced. Solar water heaters ranging from 100 to over 20,000 litres per day capacity at 85^oC to 90^oC have been installed in hostels, guest houses, hotels, industries, etc.

TO BE CONCLUDED