Author – Arushi Prakash
My first interaction with solar cookers happened many years ago when a friend of mine displayed a model at our school’s science fair, which was pretty much novel for us then. When I reminisce about that barely working model, I wonder how this technology has progressed in India. India is a country where more than 60% of population earns its living from agriculture. These subsistence farmers and their families rely heavily on the sun for plant growth, to dry husk and manure for fuel, and to drying clothes. Fortunately, they reside in a tropical country like India that receives 5-7 kWh per squared-meter of solar energy for around 300-330 days in a year.
In fact, innovators have tried to make the most use out of solar energy by using it to cook food directly with the help of solar cookers. A major advantage of this move is that the use of polluting fuels such as manure, coal and firewood that emit toxic fumes while burning is reduced. Solar cookers do not pollute and cause respiratory diseases like the ‘traditional chulhas’ (check our story on low smoke chulhas) in most Indian villages. Further, LPG and kerosene fuel are not easily available to many rural communities in remote areas.
With the advent of solar cookers, women in rural areas need not spend most of their day collecting firewood or creating manure cakes. Another economic benefit is that solar cooking has a wide customer base in India, since it targets the rural population. In fact, the Ministry of New & Renewable Energy (MNRE) also enthusiastically supports the cause of solar cookers and endorses the manufacture and distribution of energy-efficient solar cookers.
Mainly, there are three types of solar cooker technology that exist in the Indian market. Among them, the box type is the most common and commands most of the revenue in the solar cooker market.
Box-type solar cooker
This is the simplest type of solar cooker that consists of a box with a transparent glass top, in which food items are kept for heating. A single reflecting mirror reflects the Sun’s rays onto the food. The glass prevents light rays (or heat) from escaping the apparatus and allows the food to be cooked. It is appropriate for making small meals, the size of which is limited by the size of the box. However, to cook food in a box-type solar cooker, you need to keep the apparatus outside, under direct sunlight.
Community solar cooker
True to its name, a community solar cooker can be used to serve a small crowd (40-50 people). Two large reflectors placed outside the kitchen collect and concentrate the sun’s rays onto a black metal surface. Traditional cooking vessels, with just their bottoms blackened, can be used to cook on this surface. There is no need to cook in the open.
Dish-type solar cookers
Dish-type cookers have a large parabolic reflector that concentrates the Sun’s rays at a focal point where a pressure cooker is place. The parabolic dish is held by a large steel frame, which enables the reflector to track the sun.
Other technologies include dish-type, Arun and indirect solar cookers. The Arun technology incorporates a ‘Fresnel parabolic’ mirror that works in the same way as a dish. It also has the unique capability of automatically tracking the Sun in the sky for absorbing the maximum sunlight possible. Indirect solar cookers have reflectors that heat a pipeline of water and this water is routed around a box containing the food. The food takes up the heat from the pipe and gets cooked slowly.
A limitation of the solar cooker technology is that it takes a very long time to cook food. Box-type cookers may take 3-4 hours, while the community-type may consume only 2 hours. More efficient cooker technologies seek to minimize the cooking time and increasing the heating temperature at the point of focus of the sun’s rays.
Recent trends indicate that the solar cooking segment expanding seriously across the country and this idea is being propagated in schools, offices and villages.
• India’s Current Five Year Plan (2012) dedicates a INR30,000 million for teaching solar cooking in 500,000 schools nationwide.
• Orphanages are being supplied with solar cookers by state governments.
• 2,044 students at the JES College in Jalna were trained in January 2013 about solar cookers, who went on to assemble cookers and cook lunch on their own.
• Schools in Coimbatore and Ladakh have adopted solar cookers to cook their mid-day meals. Their performance and savings in fuel have set a precedent that is likely to be followed by schools across the nation.
• Large scale implementation of solar cooking technology is being promoted for large kitchens in pilgrimage places across India
A number of Indian companies have also started manufacturing solar cooker. To list a few of them:
- Solar Energy Systems, Coimbatore
- Shiva Solar Systems, Delhi
- The Bharat Engineering Company, Delhi
- RK Solar Systems, Bangalore
- Aruna Solar Energy Devices, Bangalore
- Cook & Cool, Bhopal
- Classic Solar Devices, Panna
- National Engineering Works, Jabalpur
- Technical Research & Engineering Company, Solapur
- Surya Jyoti Devices India Private Limited, Ropar
- Surya Fibres, Lucknow
Case Studies on Solar Cooking in India
Solar cooking in India has received steady support from the Indian government, non-profit organizations and several international organizations too. This has led to its increased adoption in various cities, communities and villages across India. Community solar cookers are an inexpensive way of cooking hundreds of meals for the whole community. Due to their distinct advantages, Community solar cookers have garnered positive response from most communities of India. Let us look at some success stories that tell us how this technology has been adapted to suit various needs in India:
Solar Cooking at pilgrimage places
The solar cooking system at the Shirdi Saibaba Temple serves 20,000 devotees daily. Its large 73 parabolic mirrors are manually tuned to face the sun each morning. After that the automatic tracking system takes over and follows the sun in the sky in order to capture maximum heat. This system priced at INR133 lakh, has 16 antennas of 16 square meters each. This large apparatus boils water into steam which is used to cook food. Solar cooking replaces traditional LPG-based cooking and saves nearly 100,000 kg of LPG, which translates to INR20 lakh in savings every year.
The concept of solar cooking for devotee meals was first started at the Brahma Kumari Spiritual Trust, Mount Abu in 1997. Their initial capacity was 1,000 people, which grew to 10,000 in just two years. With the support of the Government of India, The Tirupati Temple in Andhra Pradesh and the Shirdi Saibaba Temple then followed suit. These community solar cooking systems are based on Scheffler Technology, which was innovated and implemented by Deepak Gadhia.
Solar Cooking in Ladakh
Ladakh, situated in the extreme north of India, is a cold desert with very low temperatures, negligible rainfall and scanty vegetation. The region may not be fit for farming, but it is ideal for harnessing solar energy since it receives more than 300 sunny days in a year. Voluntary organization SECMOL’s Phey Campus has two massive parabolic mirrors for solar cooking. Each mirror is made of small household mirrors. A secondary reflector under the cooking vessel receives the reflected rays from these mirrors and concentrates it on the bottom surface of the utensils in order to cook food. This arrangement has been functional since 1997, when a group of SECMOL students installed this setup under Swiss direction.
Solar Cooking in Auroville
Auroville is the earliest success story for solar cooking in India that began as an experiment way back in 1970s. A medium-sized solar kitchen was setup at Auroville global village in Tamil Nadu to serve the local community. A large bowl-shaped mirror is used to harness the sun’s energy on sunny days. On cloudy days, a diesel-fired boiler replaces the solar cooker. This system has been active and delivering regular meals, seven days a week, since 1997. The kitchen delivers 1,000 meals a day, lunch and dinner, out of which 600 are delivered to schools, 300 are served in the dining hall and 100 are packed as tiffin.