Summary
India has an abundance of solar radiation, making Concentrated Solar Thermal Technologies
an economical option to complement, if not replace, fossil fuels for various industrial
applications.
Some of the most viable applications are space and water heating/cooling, process heat, water
desalination, and effluent treatment. When hybridised with biofuels these thermal energy
solutions can deliver 24 x 365 renewable energy.
India has great potential for solar industrial process heating and cooling. Recent studies have
shown an addressable market potential of 6.5 GW-thermal for CST technologies out of a total of
13 GW thermal technical potential for industrial applications requiring heat of temperature up to
300°C. Higher temperature applications in industry sectors such as cement, steel, and chemical
production add further to this potential.
This article describes a three-phase project that is being implemented where the world’s largest
and most efficient Solar Concentrator is being deployed to generate steam with solar energy in
the first phase a single “BIG DISH” Concentrator has been successfully installed and being
tested.
In phase two further 8 BIG DISHES are going to be installed to provide chilled water to cool a
450-bed cancer hospital with a capacity of 1000 TR and in phase three more BIG DISHES will
be added along with a turbine to generate power too.
Sunrise CSP’s Big Dish solar concentrator, developed in collaboration with the Australian
National University, is a modular 400kW thermal CST platform capable of delivering the steam
requirements for the industry at temperatures currently ranging from 150°C to 600°C and
pressures up to 160 bar, with new heat transfer fluids lifting temperatures to 800°C planned.
The Big Dish is specifically designed for local manufacture and its modularity supports staged
and scalable solar field deployment that enables socio-economically appropriate solutions
spanning factory-scale to national utility-scale with a Levelized Cost of Steam (LCoS) 14% –
25% lower than fossil fuel alternatives in India.
The Solar Concentrator – Big Dish
Big Dish is a 500 m 2 solar parabolic concentrator designed by the Sunrise CSP Australia Team
members in collaboration with the Australian National University. Big Dish has an accurate dual-
axis tracking, that focuses the sun to achieve an average concentration of approximately 2200
suns. At the focal point of the parabolic dish structure is a High-Efficiency Solar Boiler
(Receiver) with high solar-to-heat efficiency measured up to 97.1% by the ANU, which is a world
record on its own.
Big Dish drew upon 30 years of research in solar thermal concentrating technologies at the
ANU. It is the third-generation solar concentrator after a 20 m 2 and 400 m 2 dish, developed by
the ANU, being a major improvement over both.
Every component of the concentrator, from Mirrors to the Receiver, Tracking Control System to
the Manufacturing Technique has been refined and improved over the years, with a continuous
cost reduction and capability enhancement program underway. Table 1 lists down key design
specifications of the Big Dish Solar Concentrator
Table 1. Big Dish key specifications
| Particular | Value |
| Reflector/shape Tracking | Paraboidal Dish/Dual Axis |
| Contruction | 25 m/13.4 m |
| Mirror/Aperture Area | 520 m2/485 m2 |
| Thermal Power | 413 kWth @ 900 W/m2 DNI |
| Concentration Ratio | 2,240 suns for 95% capture |
| Mirror Reflectivity/Slope Error | >94%/<1.5 mrad |
| Receiver/Overall Thermal Efficiency | >94.9%/>80% |
A prototype of the Big Dish was developed and installed at ANU Campus in 2009, while the first
commercial project was commissioned at and for a Cancer Hospital run by the NGO Muni Seva
Ashram, Vadodara, Gujarat.
Figure 1. Big Dish commissioned at Muni Seva Ashram Campus, in standing position (left) and sleeping position (right)
Project Site and its steam requirements
Muni Seva Ashram (MSA) is an NGO near Goraj village in Gujarat, Vadodara which is a mother
organization to many social activities. The Ashram houses Kailash Cancer Hospital & Research
Center (KCHRC), known for its subsidized cancer treatments for patients who cannot afford
them. The Ashram has been validated as an organization from the CAF International.
MSA has two 200 TR and a single 400 TR Vapour Compression Refrigeration System that
caters to the space cooling requirements of KCHRC. MSA also has an industrial Biomass
Briquette Boiler of 1 TPH that supplies steam to KCHRC for cooking in their canteen, cleaning
clothes in their laundry, and sterilizing surgical equipment.
MSA is renowned for its strong commitment to sustainability and renewable energy. The
organization has intensively invested in organic farming and animal husbandry. The
organization has also invested in Renewable Energy Projects of Biogas and Solar.
In 2006, MSA commissioned India’s first Solar Thermal Powered Space Cooling System that
comprised 100 Scheffler Dishes and a 100 TR Vapour Absorption Machine (VAM).
Replacing 100 Scheffler Dish Concentrator with a Big Dish Concentrator
Sunrise CSP Australia established a subsidiary, Sunrise CSP India Pvt Ltd in 2018 to bring
cost-competitive thermal energy solutions to the Indian sub-continent.
The current core business focus is to deliver process heating and cooling, co- and tri-generation
solutions, delivered either on an EPC basis where the customer will finance and own the plant
or an energy services basis where the customer enters into a steam/heat/power purchase
agreement, as applicable and Sunrise CSP finances and owns the plant. Grid-scale
dispatchable electricity generation will be a future growth stage expected to commence within 3
years.
MSA desired to reduce their dependence on biomass briquettes for their existing steam demand
and to thereby lower their cost of steam used for both process heating and space cooling
applications, described below. Sunrise CSP proposed an energy services-based solution to
MSA and entered into a Steam Purchase Agreement (Phase 1), which is to be extended into a
Chilled Water Purchase Agreement (Phase 2) and a Power Purchase Agreement (Phase 3).
Phase 1 – Replacing the 100 Scheffler Dishes with a Single Big Dish
The Solar Field of 100 Scheffler Dishes was decommissioned in 2019 and a Big Dish has been
installed in the same field. The area occupied by the Big Dish was 1/3 rd of that of the Scheffler
Solar Field but had the same thermal output. Table 2 provides a brief comparison of the two
technologies. The mirror facility to produce the 380 Solar Mirror Panels was also set up in the
MSA campus.
Table 2. Comparison of Solar Field of 100 Scheffler Dishes and Big Dish
Particulars Scheffler Dishes Solar
| Particulars | Scheffler Dishes Solar Field | Big Dish |
| Number of Dishes | 100 Scheffler Dishes | 1 Big Dish |
| Total Mirror Area | 1,250 m2 | 520 m2 |
| Output | 400 kg/hr steam @ 10 bar, 180°C | 400 kg/hr steam @ 40 bar, 450°C |
| Footprint Area | 2,000 m2 | 625 m2 |
Even though the Big Dish was already constructed once before on the ANU campus, re-constructing it in India was a challenge due to different regulations, different availability of steel grades, and different local manufacturing practices. Modifications to the Big Dish Receiver and steam piping were made as per IBR and availability of materials.
Before the installation of the Big Dish in India, IBR had not permitted the use of moving boilers and flexible joints. This presented a significant challenge for the Big Dish project in India, as the design involves a boiler (Receiver) that moves throughout the day while the dish tracks the sun.
In addition to the mobile boiler, the pipes that carry water and steam needed to be flexible to accommodate the sun-tracking functionality of the dish. The requirement for dual-axis tracking necessitated flexibility at two points in the piping.
Recognizing the innovation and potential of the Big Dish, IBR expressed interest in supporting the project’s progress while upholding safety regulations. Both concerns were thoroughly deliberated with IBR, leading to the introduction of new regulations following extensive engineering discussions. Notably, the Receiver of the Big Dish has achieved the distinction of being India’s inaugural IBR Certified Solar Boiler and India’s first Certified moving boiler.
To address the issue of flexibility in the pipelines, rotary joints that were originally used on ANU’s previous SG3 400 m2 Solar Concentrator were adapted, produced, and subjected to testing, all under the approval of IBR – once again India’s first – IBR Certified Rotary Joints.
The novelty of the system concerning India’s IBR meant that from the early designing stage to the final commissioning stage, the IBR was involved at every step. The result is that every system component and the end-to-end solution are IBR compliant – a first in the CST industry in India.
The feedwater for the Big Dish is also required to comply with the IBR Norms, hence a De-Mineralised Water (DM) Plant of 10 Kl/day capacity was installed. This facility operates in batch mode to treat water from the adjacent Dev River and store enough water for the Big Dish to run for one day.
The Big Dish delivers steam to a pressurized hot water system, where feed water of ambient temperature from the DM Plant is mixed with the Dish steam at 250°C, which results in the accumulation of steam in the upper vessel and water in the bottom.
The water from the bottom (250°C) is flashed into another vessel at the time when steam is required by MSA. The steam is provided to the application via a header shared by the MSA existing boiler, while the hot water condensate is stored in a third vessel that is used for bathing the next day.
The pressurized hot water system works in two modes of operation:
- Storage Mode: The storage tank is filled with steam from the dish and then emptied by supplying steam and hot water to the ashram on demand
- Continuous Mode: The storage tank is set at a constant level during dish operations (i.e., charging and discharging at the same time). This is used when the storage tank is full and there is a demand for heat during dish operating hours
Figure 2. Big Dish Schematic for MSA Phase 1 Project Phase 1
Big Dish Performance
The following Figure 3. shows the estimated performance of the Big Dish
Phase 2 – 1000 TR Vapour Absorption Refrigeration System
The next phase of the project is to implement a 1000 TR Vapour Absorption Refrigeration System using 8 Big Dishes.
Proposed Site for Phase 2:
Figure 4. Schematic for MSA Phase 2 Project
The area selected for the project is 800 meters away from the point of application in MSA. It is decided to install the Vapour Absorption Machine (VAM) near the solar field and pump the cold water to the MSA, as it will be more energy efficient than transporting steam.
A Double-effect VAM capable of delivering 1000 TR cooling requires 3.6 TPH of saturated steam at 8 bar(g) pressure.
As the Big Dish is designed for pressure and temperature well above the requirement, a Pressure-reducing and Desuperheating System (PRDS) will be used.
The PRDS will inject low-temperature water into the steam flow to reduce its temperature to 180°C and a Pressure Reducing Valve (PRV), an internal component of PRDS, reduces the pressure to 8 bar(g). A steam accumulator is also installed after PRDS to stabilize the flow inlet to the VAM.
Figure 5. Estimated Performance of MSA Phase 2 Project
Levelized Cost of Refrigeration
Levelized Cost of Refrigeration (LCoR), was calculated to be ₹6.76/TR for 25 Years of operation. 0.5% degradation in the Steam Production was assumed for each year. The cost of 1 TRh with Solar Big Dish was compared with the fossil fuel scenario, assuming a 1% escalation in fuel costs. The comparison is shown in Figure 6.
The cost of fossil fuels considered is for the Muni Seva Ashram.
Figure 6. Comparison of LCoR with Big Dish powered VAM with Fossil Fuel Power VAM
2.3 Phase 3 – 1 MWe Trigeneration Power Plant
The last phase of the project is to implement a 1 MWe Trigeneration Power by adding 12 more dishes to the Phase 2 Big Dish Solar Field. These 20 dishes will run a condensing turbine, and a bleed from this will be used for VARS and other applications at MSA.
The Trigeneration System aims to utilize the maximum amount of energy from solar steam while fulfilling multiple applications of an organization or an industry.
Figure 7. Conceptual Layout of Trigeneration System for MSA Phase 3 Project
Phase 3 Project Overview
The concept of the Trigeneration Project is at the design stage. The project aims to demonstrate how solar electricity, space cooling, and steam for process heating can be provided with the same solar field. Figure 7. shows 400kg/hr of low-pressure steam which is sufficient for various applications like cooking for almost 2500 people per day, laundry, sterilization, 20000 ltr hot water, etc.
Conclusion
The project to replace 100 Scheffler Dishes with a single Big Dish at Muni Seva Ashram has successfully concluded, overcoming various technical and commercial challenges.
Over the next few months, the Big Dish will undergo several tests while meeting the thermal demands of the KCHRC.
The experience gained during the manufacturing of the Big Dish has highlighted opportunities for enhancing both the manufacturing process and the design to optimize the cost and performance of the solar concentrator. Additionally, insights into the dish’s performance will be obtained from operational tests.
The Sunrise CSP team plans to refine the design based on their manufacturing experience and operational data. These enhancements will be implemented into the Space Cooling (Phase 2) and Trigeneration (Phase 3) projects at MSA.
Author
Deepak Gadhia
Chairman at Sunrise CSP India Pvt. Ltd.
