In Ladakh, one of the harshest places in the world, prone to extreme winter temperatures of minus 20 degrees, farmers still need to do what they do for a living, but in a renewable way. They rely on the power of the sun for Apricot drying and room heating systems. 

Senthil, our next pathbreaker, NISE Engineer, develops innovative and real world solar products to preserve food and agricultural produce, mostly suitable for farmers and rural users in a completely renewable way.  

Senthil talks to Shyam Krishnamurthy from The Interview Portal about  always wanting to bridge the gap between theoretical work and actual on the ground requirements through real products.

For students, there is no greater motivation than solving a problem for our most vulnerable population, the farmers, who bear the brunt of hostile climate.

Senthil, tell us about your background?

My name is Senthil Kumar and I am presently working as a project engineer at National Institute of Solar Energy (Govt. of India), Gurugram Haryana. I would like to tell you a little bit about my background, interest and my goals. 

I was born in a district named Salem in Tamilnadu. It is located at foot hills of Eastern Ghats & approximately 160KM from Coimbatore. It is famous for Industries and food. I was born in a small family that includes my father, mother, younger sister and me. My father was involved in a textile business and while growing up my entire childhood revolved around all textile oriented machines like Power looms and dyeing machines. I have completed my schooling in Salem and undergraduate in mechanical engineering at Namakkal.  During my school and college days I used to have a special interest in playing basketball and cricket with my friends.

Being very familiar with looms since childhood i developed a special interest in machines and technologies which propelled me to choose to study Mechanical Engineering. 

Presently I am working in the renewable energy sector, mainly in Solar Energy at National Institute of Solar Energy for the past 4 years. 

What did you do for graduation/post graduation?

Having completed my undergraduate in Mechanical Engineering, I am presently pursuing Masters in Energy & Environment technologies and management from Indian Institute of Technology, Delhi (IIT, Delhi) part-time along with my Job. 

What made you choose such an offbeat, unconventional and rare career?

During my undergraduate I had studied subjects like Thermodynamics, Thermal engineering, Heat & mass transfer. These subjects introduced me to the way we are dealing with the various forms of energy. Further, during my final semester a subject called “Non conventional power plants” introduced me to renewable energy technologies. This is when I began to develop interest & fascination for a career in this field. Renewable energy basically refers to the energy from nature and non-depletable sources such as solar, wind, hydro energy, etc. The systems that harness the energy from these sources and convert them into useful forms such as electricity & heat are called renewable energy technologies. Each renewable resource has various types of technologies under its roof. Being a mechanical engineer and having a good understanding in thermal energy related subjects I chose to work on solar thermal technologies. This solar thermal field deals in capturing heat energy from the sun using various devices and converting it into a useful form.  

I started my undergraduate project titled “Designing, and developing solar based refrigeration system using Vapour Absorption Chiller (VAM)”. The objective of my project was to design and develop a lab scale Solar Thermal technology for hot water using Vapour Absorption Chiller for cooling. I got interested in this topic when I came across a technology called “Solar based Refrigeration” while I was reading a research journal. It was quite impossible for me to understand how solar heat can be used for cooling because, in general, all our household air conditioners and refrigerators run only using electricity. This increased my curiosity to know more about it and I sourced many materials related to this. This introduced me to a technology called Vapour Absorption Chiller, which, unlike conventional refrigerators, consumes heat energy and with some chemical reactions in a cycle, delivers cooling effect.  

I was doing my project under my supervisor Prof G.K.Manikandan who taught me all thermal energy related subjects. He was my inspiration and a very kind person who helped me complete the project on time. Without him it may not have been possible for me to have a breakthrough in this field.  

How did you plan the steps to get into the career you wanted? Or how did you make a transition to a new career? Tell us about your career path

Due to my active participation and interest in Solar Energy, I got an internship offer at M/s. Stellar Energy, Erode, a manufacturer of solar thermal technologies. This was for carrying out my undergraduate project during my final year of engineering. 

I had a great learning experience there and successfully completed my project and UG degree. After that I got an offer from the same company as a project engineer to carry forward my research work. Later I got involved in designing, developing and manufacturing Solar Thermal Collectors.  

During those days I started understanding that there were very few industries who were manufacturing such technologies and there is a huge scope for research in this field, which further propelled me to take up more research activities. So, myself and my teammates started working on various research initiatives in solar thermal technology. One of our important works was the development of a secondary reflector for Parabolic Trough Concentrators (PTC). PTCs are one of the solar thermal technologies which are made of parabolic shaped mirrors/reflectors to concentrate solar radiation in a particular point where a fluid flows to absorb heat energy (heat collecting element). This can be understood with the following image 


We were having our own PTC, developed by us at that time in our factory and we noticed that the performance was not as good we had expected due to some deviation in parabolic shape. Manufacturing a perfect parabolic structure is very challenging and more expensive, because this technology is completely new for the Indian market and no facilities were available at that time. Majority of components were complexly customised or imported. This problem motivated us to develop an alternative to solve this issue, so we started designing secondary reflectors which can be fitted above the heat collecting element which will redirect the escaping radiation back to the receiver. After making this product, we were eager to test its performance at any national research centre. This is when we came to know about my present organization M/s National Institute of Solar Energy (NISE), an apex Research & Development institute on Solar Energy under the Ministry of New & Renewable energy at Gurugram, Haryana. With the support from our boss, we brought our invention to get it tested at NISE and I got an opportunity to stay there for more than six months to test and carry out our research. 

I would say this was a golden time for me, because, being from a small town and a budding company, I had an opportunity to meet the greatest minds in the Solar field where I wanted to make my career. I got introduced to various scientists, research fellows, and technical staff during this period. A notable person from NISE who i would like to mention here is Mr. S.K.Singh, Ex-Director General of NISE and a renowned scientist in the Solar field. During my interaction with him he showed me a completely different angle to what I was working on, which further helped me to advance in this field. 

One thing I noticed during those days was, whenever I studied, I was able to understand several good concepts and ideas that were published by reputed scientists in various journals, but was not able to see any of those ideas reflecting in any real life products. So I always wanted to fill this bridge between theoretical work and actual ground requirements.

How did you get your first break?

My first break was when I got an opportunity to work as Junior Research Scientist at NISE.

After i returned from NISE I was again involved in my work at stellar energy. During that time I came across an advertisement for the post of Junior Research Scientist at NISE in the Solar Thermal field. My inner voice told me to grab this opportunity and I immediately packed my bags and came to Gurugram. I stayed at my friend’s home two months before my interview and started preparing for it. Luckily I cracked it and joined NISE. 

After joining, me and my team were actively involved in core Research & Development activities and we were able to successfully develop three solar based technologies in the last three years. 

The first system we developed was a solar based dryer cum space heating system. Drying is one of the most important processes for preservation of food and agricultural produce. Majority of agricultural products undergo the process of drying before reaching our table. Drying is most widely used in industries for various processes. We started our project when the Jammu & Kashmir horticulture department approached us to develop a solar based drying technology to help their farmers in drying apricot fruits with unique requirements. They wanted to dry a huge quantity of apricot fruits being harvested by many famers living in the Ladakh region. The challenges in apricot farming are, it is a seasonal fruit, means it grows only in the month of July – September. Secondly, fresh apricot shelf life is only 7- 10 days. The shelf life of this fruit can be extended with the drying process, therefore local farmers employed open sun drying methods to dry apricots. Open sun drying method took around 5-7 days, but there was some compromise on the quality of drying which impacted the fruits and their economy. The Horticulture department wanted a way to overcome this challenge by reducing the drying time and deliver a better quality fruit so the farmers will be benefited largely. To resolve this issue and to develop an innovative solution, the J&K horticulture department had approached our division at NISE. 

Solar based drying technology was not new in the market and it was partially helping in improving the quality of the product by reducing drying time to 5 days. However the challenge was that it would work only during solar hours. To tackle this issue our team worked on developing a solar drying system which shortened drying time further from commercially available solar drying systems.  We used the concept of Thermal Energy Storage (TES) using Phase Change material (PCM) to store heat energy. This technology helps in storing the excess heat energy from sun during morning time and uses it during non solar hours, therefore our system was able to dry apricot in 24-36 hours on sunny days when compared to 7 days through the open sun drying method.  

We also made additional provision in the system to use it for room heating during the winter period. Ladakh is one of the coldest regions in India and during winter the temperature reaches around minus 20 Deg C. As our system provides heat energy and during winter there will be no farming of apricot, we made a provision in the same system so that the farmer can use the hot air from solar system to heat room space. This further helps farmers in saving the money they are investing in fire wood. 

Similarly, we were also involved in developing other products such as solar powered cold storage technology and bulk milk cooling with thermal storage system for 24×7 operations in remote locations and solar powered cooking technology.  We have filed patents for these innovations, which use novel thermal storage systems, in our name, on behalf of NISE. We are also publishing our research work in reputed research journals.

What were the challenges? How did you address them?

Challenge: Language

As my entire childhood was in Tamilnadu I was not familiar with Hindi language. When I came to Gurugram the language barrier was the crucial thing I faced. Hindi was the predominant language in all the meetings and seminars that I have attended. It was difficult for me to travel outside campus without the support of my friends. It also impacted my work and learning. 

But later on, with time and with involvement I started learning Hindi from my friends and coworkers. It took me 1 complete year to get familiar with this language. 

Where do you work now? 

After my tenure as Junior Research Scientist for three years I joined as project engineer at the same organization in a different project. Along with my job I am also pursuing my masters from Indian Institute of Technology, Delhi (Energy & Environmental Technologies & Management) Part time.

What problems do you solve?

My job nature at NISE can be categorized into three verticals, 

  1. Testing and certification. 

In NISE we have a state of the art laboratory facility where we conduct tests and certify the solar products for its performance and quality.  Manufacturers who develop new solar products will approach NISE for testing and validation before commercializing it. 

  1. Research & Development (R&D).

My R&D activities can be classified into two types –  First one is development of innovative technologies/solutions. When we have an objective to solve any new issue for which solution is not available currently, then this type of research will be initiated. This type needs extensive theoretical study, literature survey, validating need of the industries, study about existing development status etc,

The second type is improvising and optimizing the existing technologies /solutions. In this, numerical solving, data resourcing, testing and validation process will be involved.

  1. Skill Development

This part involves conducting training programs and delivering lectures to various levels of participants. 

What skills are needed for your job? How did you acquire the skills?

Analytical skill is the primary requirement for research and one should have strong basic knowledge of his field. Through regular studying and updating oneself of recent trends anyone can build their knowledge.  

What’s a typical day like?

My day starts at 5AM in the morning and I leave my home by 6.30AM to my college. Since my masters at IITD is a part time course my classes start at 8 AM in the morning. After the classes I rush back to my work around 11.00 AM and I work till 7 PM at office. Later I spend 2 hours with family and two hours for study before retiring for the day by 11.00PM. During weekends I spend time with family and go out for dinner. 

What is it you love about this job? 

One thing I love about this job is the versatility. This job allows me to involve myself in all types of activities, from top to bottom and we have great support from our reporting officer. We have all the freedom to learn and express ourselves which has helped us achieve these milestones at a young age. 

How does your work benefit society? 

The products we have developed are 1) solar drying cum space heating technology, 2) solar power cold storage and 3) solar powered bulk milk chiller. All the three products are used to preserve food and agriculture products and mostly suitable for farmers in a completely renewable way. That means the farmers don’t have to depend on any fossil fuels like kerosene, firewood or electricity. And due to this, their food preservation costs have been reduced which helps them in their business and they are able to grow and sell more products to the market.

In the last year alone we have got an order for manufacturing and supplying 800 numbers of Solar Dryer cum Space Heating systems to be delivered to 800 farmers in Ladakh region at a subsidised rate.  Due to the subsidy from the government (@90% subsidised rate) farmers have to pay only 10% of the actual cost.  This system is helping them in drying apricots and various other fruits and they are using the same system for room heating during winter months. 

Similarly 7 of our solar powered cold storage systems have been installed across India, in various horticulture departments and for private beneficiaries for preserving their agricultural produce. 

In addition to this I used to take lectures and training programs on Solar Thermal technologies and our developed products to various levels of participants, So far I have taken sessions for government officials from foreign nations and lectures for officials at PSU’s like GAIL, ONGC, NTPC, and NPTI. I have also given expert talks to various college students, and Training programs to industrials etc., 

Tell us an example of a specific memorable work you did that is very close to you!

The development of our first Solar Dryer cum Space Heating system in June 2018 was the most memorable experience I had. After finalizing our designs we started manufacturing the first Solar Dryer system. In those days we used to spend days and nights for almost a month in industries and that experience taught us many new things and those feelings are indescribable. 

Your advice to students based on your experience?

  • Make a habit of studying
  • Be determined
  • Have short term and long term goal 

Future Plans?

My future plan is to continue my research in developing newer technologies for my countrymen and farmers.