Advanced solar thermal technologies to address the challenges of Indian markets

Analyzing the role of solar thermal in strengthening bilateral relationship
In India, the industrial sector is the main contributor to GHG emissions with ~560 Mt CO2 annually as in 2020. The sector showcases a heavy reliance on conventional fuel options, such as petroleum products, oil, coal and natural gas. Increasing efficiencies of renewable energy technologies like wind and solar, coupled with supportive policy and regulatory landscapes have resulted in a rapid scaling up of clean energy measures in India, several of which can help industries reduce dependence on conventional fuels. The estimated potential for solar is about 5,000 trillion kWh per year considering the solar insolation that India is endowed with. The Government of India also recognizes the potential and benefits of solar thermal technologies, particularly concentrating solar thermal (CST) technologies and has been supporting them through a capital subsidy mechanism. The sector calls for strong value proposition to entice the industry stakeholders to participate and meet significant quantum of demand through solar thermal, rather than focusing on competing resources. The developments in the clean
energy sectors are creating opportunities for collaboration and renewed interest from international players operating in India. In this context, plugging the gaps in the sector to improve the overall business case requires increased research and innovation (R&I) and coordination between key stakeholders.

Viewing solar thermal in the light of developments in solar PV
In India, solar thermal technology has not witnessed the same traction as solar PV, which has garnered far greater interest. However, a direct comparison would be inaccurate as the applications for both technologies are different in India in terms of heat vs power generation. The market for solar PV has developed and the economies of scale have resulted in reduced overall costing and competitive solar tariffs and overall greater acceptance by the industry, owing to development of a much-improved ecosystem in the last 10 years. But the same cannot be said for solar thermal sector where the progress has been rather slow, as the price economics has not been very conducive. Unlike solar PV, solar thermal requires large amount of upfront CAPEX, and the running costs are low as there are no operational fuel requirements. The sector in general has not been able to attract substantial financing,
which has been restricted to support from programmes run by UNDP, UNIDO, GEF and MNRE.
Another major challenge with solar thermal is to suit the viability specific to applicability in a given industry. High degree of customization efforts is required, which is not the case with solar PV, where the systems are standardized and modular in nature. The operations of solar thermal in India has usually been restricted up to 250˚C temperature range and only those industrial processes, which have heat requirements below that temperature can be catered to by such systems.

n terms of supply chain also, solar PV has a well-developed value chain, with a heavy focus on stimulating domestic manufacturing of critical components such as modules and cells. On the other hand, for solar thermal the supply chain is not fully developed, and critical operations such as mirror manufacturing, receiver tube manufacturing, etc. are not being performed in India (70-80% domestic value capture is presently happening in India). In terms of requisite testing infrastructure as well, solar thermal technologies are lagging behind from solar PV technologies with very few research labs having the capacity to conduct various performance tests and certify product.

Solar thermal market overview in India
Overview of Indian markets
Solar thermal technologies in India form a critical facet of overall energy planning and are classified as ‘viable solutions for meeting specific heat delivery requirements, at specific time at a given temperature’. The market, which initially began with non-concentrating technologies, typically designed for solar water heating applications has gradually evolved into a much more R&I driven market (with the advent of concentrating solar thermal (CST) technologies), focussing on multitude of applications at industrial and commercial level. India presently has 16 million sqm of collector area under solar water heating (SWH) or non-concentrating technology, which is anticipated to reach 20 million sqm (14 GWth) by FY 2022 as per the Ministry’s long-term vision. The growth of SWH sector can largely be attributed to more mature technology, more awareness, ease of deployment and even mandatory obligations in some cases for certain categories of buildings (states such as
Karnataka, Chandigarh, Haryana had mandatory obligations to install SWH based on floor area/site area). In terms of non-concentrators, both flat plate and evacuated tube technologies are prominent in India, with recent trend more biased towards evacuated tube collectors.

As aforementioned, the concentrating technology came into existence only a decade back and hence its share in terms of total collector is small (less than 0.5% in terms of collector area). However, over the last 5-10 years the CST market in India has been flourishing at a rapid pace, with solar thermal installations in the country rising every year, in alignment with country’s ambitious goals. The commercialization of CSTs across different segments in India has been predominantly achieved through support programmes in the form of capital subsidies offered by MNRE. MNRE initiatives have further been supported by UNDP and UNIDO led programs on promotion of CSTs through support from GEF. Currently within CST technology space, India has solar thermal installed capacity of ~ 70,000 sqm17 (48 MWth) which is projected to reach 200 MWth by 2022, as per the ‘India’s CST roadmap-2022.

A distinctive advantage with CSTs is their versatility in terms of producing heat delivery at a range of
temperatures, between 50°C and up to over 250°C, which can be used in a variety of industrial process- heating and space cooling applications. Industries showing good potential for implementation of solar concentrators are food processing, dairy, paper and pulp, chemicals, textiles, fertilizer, breweries, electroplating, pharmaceutical, rubber, desalination and tobacco sectors. Any industrial/commercial establishments currently using steam/hot water for process applications can also employ CSTs with a minimum tinkering to the existing setup. For industrial processes where lower temperature range (less than 120 °C) is required, technologies such as the non-imaging concentrators are common and for higher temperature range applications, technologies based on tracking mechanisms with a higher sun concentration ratio such as parabolic trough, Linear Fresnel and paraboloid dish are preferred.

Non concentrating technologies
Flat Plate Collectors
Flat plate collectors are probably the most fundamental and most studied technology for solar-powered domestic hot water systems. The Sun heats a dark flat surface, which collect as much energy as possible, and then the energy is transferred to water, air, or other fluid for further use
• Working Temperature: Upto 80oC
• Concentration Ratio: 1 sun
• Tracking: Not Necessary
Evacuated tube collectors Evacuated tube collectors work in a manner in which heat loss to the environment, inherent in flat-plates, has been reduced. Since heat loss due to convection cannot cross a vacuum, it forms an efficient isolation mechanism to keep heat inside the collector pipes.

Non-Imaging technologies
Non Imaging Concentrators (NICs)
Also known as Compound Parabolic Collectors (CPC), NICs consist of specially coated absorber tubes that are enclosed in concentric vacuum glass covers to reduce
convection losses. The fluid to be heated passes through these tubes and is transferred via a header to the central receiver tube on top.
• Working Temperature: Upto 150oC
• Concentration Ratio: 5-25 suns
• Tracking: Not Necessary.

Thermal energy storage
Thermal energy storage (TES) is a technology that stores thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation. TES systems are used particularly in buildings and in industrial processes where batches are often the norm. Advantages of using TES in an energy system include an increase in overall efficiency and better reliability, and it can lead to better economics, reductions in running costs, and less pollution of the environment, i.e., fewer carbon dioxide (CO2) emissions. Solar thermal systems, unlike photovoltaic systems with striving efficiencies, are industrially mature and utilize a major part of the sun’s thermal energy during the day. TES is becoming particularly important for electricity storage in combination with concentrating solar power (CSP) plants where solar heat can be stored for electricity production when sunlight is not available. New materials are selected, characterized, and enhanced in their thermo-physical properties to serve the purpose of a 24 hour operation in an efficient TES system. In Europe, it has been estimated that around 1.423 million GWh/year can be saved, and 400 million tons of CO2 emissions avoided, in buildings and in industrial sectors by more extensive use of heat and cold storage.

R&I areas
Sensible heat is applicable to domestic systems, district heating, and industrial needs. The most popular and commercial heat storage medium is water, which has a number of residential and industrial applications. Underground storage of sensible heat in both liquid and solid media is also used for typically large-scale applications. However, TES systems based on SHS offer a storage capacity that is limited by the specific heat of the storage medium. Furthermore, SHS systems require proper design to discharge thermal energy at constant temperatures. PCMs can offer a higher storage capacity that is associated with the latent heat of the phase change. PCMs also enable a target-oriented discharging temperature that is set by the constant temperature of the phase change. Melting temperature, latent heat of fusion, and PCM thermo-physical issues are three basic factors influencing the selection of PCMs in any application. A high heat of fusion and a precise melting/solidification temperature (without subcooling) are two primary requirements in the selection approach. Numerous mechanical and nano-level enhancements have been achieved to increase the heat transfer rate, which is promising. Micro-encapsulation increases the heat transfer surface area and is also a solution for phase segregation in salt

Numerous technologies, including unglazed, flat-plate, evacuated tube and concentrating collectors, are
available on the market to provide the temperatures and efficiency needed by different applications. The three distinct temperature ranges in which solar thermal collectors operate and their corresponding applications and technologies are defined below.

In this regard, the key intervention areas for Indian context w.r.t collector technologies have been analyzed below.

In India, for a very long time there has been limited focus on mapping performance attributes of solar thermal systems such as quantum of heat delivery, quality of heat delivery, efficiency, steam (pressure and temperature), timing of heat availability, etc., resulting into generation of ‘no specific data insights’ with respect to different solar thermal technology performance over longer periods. Hence, firstly data collection techniques need to be made more concrete, so that all data points are captured in a comprehensive manner.

Cost reduction measures
To understand the cost effectiveness of solar thermal system and to understand the potential for cost reduction, it is crucial to analyse various components that constitute a solar thermal system. A component wise cost distribution for a larger solar thermal system has been plotted below24. Though it must be noted that the price can vary based on the technology, application, sizing and location of the concentrating solar thermal system.

Concentrating solar technologies in India have not been able to grow at a large scale, inter alia as a result of the following challenges.

Mapping of potentially relevant EU stakeholders
Key R&D solar thermal institutes in EU
There are numerous institutes that have been working in Solar thermal over the last decade in conducting targeted research in innovative areas such as thermal storage, polymeric materials, solar industrial heat applications, solar district heating, collector materials and performance, solar thermal integrated building designs and cost reduction strategies across the value chain. Some of these research areas overlap with the intervention areas proposed in the Indian context (preceding sections) and thus serve as perfect opportunities for increased collaboration between Indian stakeholders and relevant EU counterparts (R&D institutes and technology players offering these solutions). Key solar thermal research institutes and universities active in EU, along with their research focus areas have been presented below29 (The highlighted innovation areas indicate overlap).

Solar heat Europe
Solar Heat Europe (formerly European Solar Thermal Industry Federation (ESTIF)), with around 40 members, represents 90% of the industry across the value chain striving for growth of solar heat solutions in Europe.Solar Heat Europe’s mission is to achieve high priority and acceptance for solar heat as a key element for sustainable heating and cooling in Europe and, with immediate effect, to work for the implementation of all necessary steps to realize the high potential of solar heat.32 Solar Heat Europe is particularly involved in contributing to the solar heat research and innovation by being the Secretariat’ of a dedicated platform on solar heat technology as well as being involved in Renewable Heating and Cooling platform. One of the notable contribution of Solar Heat Europe was drafting the ‘Solar Heating and Cooling Roadmap for Europe’, identifying strategic priorities for research over short, medium and long term, in order to influence decisions of European Commission, regarding solar thermal research. Some of these R&D areas have large degree of overlap with the Indian context in the areas of ‘solar thermal collector technologies, thermal storage, system control performance assessment and standards and quality assurance’, which can provide relevant guidance and exposure to developing R&I solutions for Indian markets.

R&D collaboration between academia and industry from EU and India
To develop a robust market for solar thermal technologies, it is necessary to invest in research and development activities to make the technology economically viable and more efficient. Several R&D developments related to solar thermal heating and cooling systems have taken place in the EU, leading to improved designs and reduced manufacturing costs. These learnings can be accessed and adopted through research and commercial collaborations between the EU and India. A few areas of collaboration between the EU and India have been discussed below.

Projects like the European Technology Platform on Renewable Heating and Cooling (RHC-Platform) now known as European Technology and Innovation Platform (ETIP)35, which are helping accelerate research and innovation in renewable heating and cooling for commercial and industrial purposes should be encouraged and replicated in India to further R&D activities in solar thermal technologies.

Demand creation through policy and regulatory mandates
Policy and regulatory mandates are crucial drivers for creating a sustained demand for technologies like
concentrated solar thermal. Long term demand can be realized through conducive policy mandates that can improve the adoption of solar thermal technologies in the commercial and industrial sectors. The solar thermal roadmap for India, while emphasizes on the targets in the near term i.e. till FY 2022, it does not necessarily focus towards long term trajectory till FY 2030 and associated demand creation measures to achieve those targets. To stimulate the adoption of solar thermal technologies India must focus on the following key attributes:

Similar to the Strategy on Heating and Cooling released by the European Commission, India must also set a long term vision for the development of the solar thermal industry in the sub-continent.

Attract investors and technology companies through conducive policy formulation
Solar thermal technologies, while having relatively low operational costs are still capital intensive. Regulators and policy makers may offer financial incentives which will be critical in improving the commercial viability of these technologies. This is also essential for attracting large scale investment into this sector. The support could be in the form of investments/incentives in manufacturing for solar thermal technologies and its components, project deployments, machinery building, manpower training or other related avenues, which will aid in driving more investors in the ecosystem. The incentives could also increase opportunities for partnership between firms from the EU and India to form joint ventures (JVs) through collaboration/tie-ups to scale up solar thermal technologies in India. Many firms operating in the solar thermal sector in the EU possess expertise and proprietary design knowledge of these systems that India can benefit from, technology partnerships and knowledge transfer agreements between such firms would further drive deployment of solar thermal technologies in India.

Source:CECP EU

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