Lesson learnt in class 4 can help save lakhs
Ashok Paranjape writes how rising fuel costs are forcing the industries to the advantage of solar energy technology
Ashok Paranjape, Managing Director, Clique Solar
Lessons last a lifetime and some of them help you make money too. This one is a little different. This becomes an industry and helps others make money (through savings) and saves the environment too.
The lesson is when sun rays are focused at a certain area, the concentration of these rays generates high temperatures at the focal point. And if this heat is generated on a large scale, from morning to evening by tracking the sun, it can be used in industrial processes for catering to their thermal energy requirements.These concentrated sun rays can generate steam that can be augmented with the existing conventional boilers in the industry, converting them into solar boilers for a fair part of the year. It is called Concentrated Solar Thermal (CST); and yes, we call it an industry.
The heat generated through steam and thermal oil finds applications across industries. Industrial sectors such as food processing industries (dairy industry, beer industry, sea food processing industry and sugar industry), textile processing industry, pharmaceutical industry, pulp and paper industry, chemical industry, auto component industry etc. have large requirement of thermal energy in their manufacturing plants. Table 1 will give some idea of the processes which use thermal energy in these industries.
Applications in community cookingMany religious places as well as schools and colleges across the country provide meals to devotees and students respectively. Many of them have community cooking facilities which use high-cost fuels like LPG. Solar energy can be used to substitute the use of these fuels.
Comfort cooling applicationsSolar-assisted cooling systems use the thermal energy of solar radiation captured through solar concentrators to power thermally driven cooling machines. As many cooling loads — such as air conditioning — have a high coincidence with the availability of solar irradiation, the combination of solar thermal and cooling obviously has a high potential to replace conventional cooling machines based on electricity. Cooling and air conditioning is one of most energy intensive processes amongst the various energy consuming applications. Any technology that can help save energy in the cooling and air-conditioning applications can help reduce India’s power shortage burden to a great extent.
What facilitates this application?The answer lies in the question: what is important to clients?
The important factors boil down to a good all inclusive word called relevance. The definition of relevance from clients’ perspective can have many meanings: cost, technology, performance, location (space), other challenges etc.
With experience of over a decade and a half of engaging with clients, I can comfortably define the relevance for the clients in the following categories:•Performance •Addressing practical challenges •Cost.
Performance Applicability of CST technologies is directly dependent on two factors:•Can the CST technology deliver temperature or pressure required by the process?•Can it do so accurately and consistently?
Majority of the thermal energy requirement in industrial processes ranges between 80 C and 250 C. Many industries require accurate and consistent delivery of thermal energy for their processes.
Practical challenges A technology can only be widely adopted when it can successfully balance functional needs, economic demands and practical constraints. Some of these practical constraints for the adoption of solar technologies are mentioned below:•Space: One of the most common constraints is space. If a company lacks space, even the economics is in favour, the client can’t buy it. This is not a technological constraint, but a practical challenge. •Economics of a system: Supplementing existing source of fuel, ease of maintenance and faster return on investment hold key in economics of the system.•Integration with existing system: The task of integration of solar thermal system with the existing boiler system must not be underestimated. A schematic shown here for one of the CST technologies ARUN installed at ITC Maurya in Delhi, and how it has been efficiently integrated with the existing boiler.
The basic aim of the control system in this scheme is to deliver steam to the existing boiler header.
The ARUN dish automatically tracks the sun from morning to evening on two axes (N-S and E-W). The solar radiation falling on the reflecting collector surface is concentrated at a single point at which the receiver is placed. The receiver coil at the focus of the dish transfers the heat of the sun to the heat transfer medium (water).
“The steam generation system” will consist of ARUN 160 dish system, steam separator, pumps, valves etc. Once the system starts generating steam, the pressure in the line starts increasing. Once this pressure matches with the pressure in the existing boiler header (8 bars), a valve opens and steam is delivered to the common header. This process will continue whenever the sun is available. When the sun is not available, the existing boiler will turn on. This switchover between the solar and existing boiler is automatic.
How does it save lakhs?If cost is a consideration, the type of fuel being used directly affects the motivation to adopt solar energy technology. If the fuel, used to generate thermal energy, is LPG, furnace oil, diesel or PNG, it makes for a highly favourable case for the adoption of a solar thermal technology. On top of that, companies get MNRE subsidy and tax benefits by way of 80 per cent accelerated depreciation. Payback period generally ranges from 2-4 years while life of the system is more than 20 years (for ARUN). On the other hand, solar systems require very little maintenance.
If clients want to evaluate any system for investment returns, they should consider the following •Capital cost of the solar energy system•Government subsidies•Financing options•Value of energy generated over the lifetime of the solar system•Non-financial factors that influence the economics.
What are the technology options?There are a number of CST technologies. These are:•Scheffler dish•Parabolic trough concentrator •Concentrated Fresnel linear reflector •ARUN dish: two-axis automatically tracking parabolic solar concentrator.
ARUN is commercially proven for industrial process heat requirements. It has been installed in diverse industries for various applications across the country. Industry leaders like Mahindra, ITC, NTPC, TVS Group, BARC, Chitale Dairy etc. have adopted the ARUN technology.
Why is it not being spoken about?The biggest hurdle in the adoption of solar thermal technologies is awareness and confidence amongst adopters (clients and technical consultants to the industry). This is compounded by financing challenges as banks across the country are still evaluating the risks to fund projects in this area.
However, much of it is changing. The government has undertaken the MNRE-UNDP programme to spread awareness about the industry by asking for proposals for demonstration and replication projects. The government will provide additional subsidy for these projects and make these reference projects for the industry. Solar energy policies of the Indian states are also helping immensely in raising awareness and promoting adoption of solar energy technologies that are commercially viable.
Companies across industries are facing a big challenge because of rising fuel costs. It is only a matter of time before industries will take the advantage of such a technology.
Lesson learnt in class 4 can help save lakhs