Concentrating Solar Power: A Promising Technology For India’s Energy Mix

ENGY7000 Energy Principles and Renewable Energy

Solar Power and Its Importance in Daily Life

The sun in conjunction with its excess solar energy is used in meeting numerous diverse functions in the daily lives of human beings across the world. Be it air circulation, supporting the growth of plants or heating of water, the sun and its solar energy of utmost importance. A study conducted on the technologies and uses of solar energy established that the most common and prevalent applications of the solar energy are a generation of electricity and heating. Just like coal, natural gas and petroleum, the sun is cheap and readily a viable source of energy with an exceptional feature of being renewable and clean. Thin film, photo-voltaic, CPV are some of the technologies in solar energy render solar power in India least prominent but a very important contributor of power generation (Sridevi, 2014, p.320).

India, just like any other countries in the world is struggling to meet the sustainable development goals despite the numerous challenges and obstacles that it finds on its ways to the achievement of such goals (Thangavel, 2014, p.265). From the abundant reserves of fossils fuels available in the country, achievement of the sustainable energy foals that have been set out by national and international agencies remains a major challenge that calls for diverse ranges of options. To lower its dependence on imported coal as the greatest chunk of India’s primary energy is from coal, the country is making remarkable progress when it comes to introducing renewable energy power techniques and facilities.

Various issues among them environmental concerns, scarcity of fuel and availability of site are the challenges and hurdles that conventional power plants suffer. These problems are overcome using alternate technologies which borrow from renewable energy sources such as biomass, wind and solar. From the numerous options available in solar technology, generation of power through Concentrating Solar Power, CSP, is one of the most promising in India for the days to come (Blanco, 2016, p.269). There has been an upsurge in the amount of electricity produced by concentrated solar power in India every year. This illustrates the commitment of the country towards attaining sustainable, reliable and affordable energy for its citizens. India has huge potential for solar power for the generation of solar electricity per watt that is built. This is attributed to its solar radiation that ranges between 1700 and 1900kW per kilowatt peak. The potential is also attributed to the numerous clear sky days in the year which is about 300 days.

Challenges Faced by India in Meeting Sustainable Development Goals

India has more than enough land that can be used in the implementation of concentrating solar power technologies (Philibert, 2011, p.237). The land areas are not only in abundance but also ideal for direct normal radiation levels which are important in making Concentrating Solar Power an integral contributor to the energy mix of India.

In its efforts to realizing Concentrating Solar Power, India introduced a ley of Rs 50 per ton of coal that was either produced domestically or imported. The levy was to be used in funding a National Clean Energy Fund of which Concentrating Solar Power is among them.

Concentrating Solar Power revolves around accumulating heat from the rays of the sun to a specific point on a surface for heating oil, water or any other material that is intended to be heated. Concentrating Solar Power works by concentrating and focusing the sun rays on a very small area which would otherwise be spread over a large area. This small area can be composed of water that is flowing through some pipe or any other fluid is it liquid or gas containers. Due to its ability to retain heat efficiently and for a long time, molten salt is often considered as the best fluid in this technology. The molten salt is able to dissipate heat during the cloudy days while there is no sun. This heat can then be used in the generation of electricity (Tyagi, 2017, p.170).

Concentrating Solar Power technology is based on focused sunlight. Power is generated by CSP plants by using mirrors that concentrate or focus the energy from the sun and change it into a heat of very high temperature. The heat is then passed through a conventional generator. CSP plants have two parts: the part responsible for collecting solar energy and changing it to heat and the other part that changes the heat energy to electricity. Any of the CSP technologies approaches need very large areas for collection of the solar radiation when production of electricity is to be done on a commercial scale.

The technology of conversion of heat to power is normally applied in power plants that produce electricity through steam turbines. In these plants, water heated by the heat from solar energy is changed into steam which is then used in operating a turbine that in turn produces electricity. In larger power plants, the supply of the heat is supplemented by burning of coal as coal has a high capability of generating large amounts of heat. Concentrating Solar Power is used instead of coal so as to lower the harmful impacts of using coal among them air, water and land pollution (Palenzuela, 2015, p.312).

Concentrating Solar Power: A Promising Alternative

A mirror used in reflecting light to the point of focus is the main component of Concentrating Solar Power. India has three main technologies used for Concentrating Solar Power based on the types of mirrors that have been in the system. The types of technologies include parabolic trough system power tower system and dish Stirling system.

Dish Stirling system

Dish Stirling system makes use of mirrors that are of the shape of a bowl or dish and resemble the satellite TV dishes even though they are normally larger, about ten times larger. These dish mirrors work by concentrating the rays of the sun to the point of focus that is located at the epicenter above the surface of the mirror (Blanco, 2016, p.452). At this point of reception, there is a complex receiver which absorbs all the concentrated energy and drives the Stirling engine which has gases such as hydrogen or helium. The gases undergo expansion upon receiving sufficient amount of heat. The expansions results in motion of the engine’s piston just like are the case with the engine in cars. This movement results in the generation of electricity.  

The efficiency of the machine is increased through tracking of the positions of the sun in the sky by the mirror. This leads to capturing of maximum solar energy that would mean generation of more electricity (Rather, 2018, p.289). The advantage of Dish Stirling system is that it is economical in terms of occupation of space being a stand-alone project. Dish Stirling system provides the highest efficiency of conversion of solar energy to electricity at about 30-32%. It is sufficiently modulus to lower the numerous complex steps that need to be followed to obtain electricity. High initial capital and maintenance cost have formed the hurdles to the implementation and commercial applications of the Sterling engine in India.

Parabolic Trough System

The Parabolic Trough System is made up of a large parabolic focusing mirror that is u-shaped.  The mirror works by reflecting light when sun ray falls on it towards a pipe that is fixed at the center of the system. The pipe has been blackened to enhance its absorption efficiency. The concentrated light from the sun in conjunction with the blackened pipes lead to heating of the oil inside the pipe to a temperature that can go as high up as 350?C. the heated oil which is at high temperature then flows through a pipe and is used in heating water which then converts to steam and in effect operate the turbines that are used in generating electricity (Heller, 2017, p.122).

Efficiency and Advantages of Concentrating Solar Power

The Parabolic Trough System was the initial technology of concentrated solar power and the first one to achieve commercial viability hence a lot of information is at disposal as well as skilled personnel in the manufacture of parabolic trough systems. The Parabolic Trough System is disadvantageous in terms of space economization and the cost of the parabolic mirrors. The trough systems need a very large space to be set up. Manufacturing of the parabolic mirrors is a costly undertaking that most of the investors are shying away from engaging in (Bhaskar, 2013, p.187).

Power Tower Systems

This system adopts flat mirrors called heliostats which rotate as the position of the sun changes in the sky. The rotation ensures that as many rays as possible are reflected throughout the day. The system uses numerous of such mirrors which are placed around a tall tower which acts as the receiver and has a very big container of fluid such as molten salt that is to be heated. These mirrors precisely and accurately concentrate the sun rays onto the container which heats up to a temperature of between 500?C and 1000?C (Sunderasan, 2014, p.268). Power tower systems have managed to address some concerns such as cost since the flat mirrors used in these systems are cheaper than the parabolic mirror that is needed in the parabolic trough systems. The power towers have also proved to be more efficient in terms of storage of energy. Despite these advantages, power tower systems require very large and flat areas in order to meet its efficiency objectives of high power generation.

Technical specifications of concentrated solar power systems

Parameter	Parabolic Trough	Power tower	Stirling Engine/Dish
Mirror	U-shaped	Flat	Dish-shaped
Object to be heated	Pipe	A large container	Small engine
Point of concentration	Center of the mirror	Separate high tower	Center of the mirror
Temperature achieved	750?F	1050?F	2000?F
Mechanism of generation of electricity	Heating of oil which in turn heats water that generates steam	Heating molten sand that in turns heats water to produce steam	Heating gas that operates electricity turbine
Main advantage	Properly and well-established technology	Flat mirrors are more affordable	Require small surfaces that can be located on any terrain

Only 52.5 MW of the available Concentrated Solar Power is operational in India despite the total number of projects which is seven and has a generation capacity of 470 MW upon completion of the construction under the first phase of the Jawaharlal Nehru National Solar Mission. The Jawaharlal Nehru National Solar Mission, launched in 2010, was set up as an ambitious plan to implement 20 GW solar capacities across India by 2022 (Kohl, 2010, p.333). This mission was segmented in three phases: the first phase that was to run up to 2013, the second phase running between 2013 and 2017 and the third and the last phase that was to operate from 2017 to 2022.  The first phase involved the selection of seven proposals on Concentrated Solar Power plants that cumulatively would generate 470 MW with bids that ranged between Rs 10.49/kWh and Rs 12.24/kWh. The projects were kicked off and were expected to have begun operating by May 2013. The deadline for the commissioning was however extended by months until March 2014 as a result of delays in the supply of equipment which affected most of these projects (Sridevi, 2014, p.230).

Technical Specifications of Concentrated Solar Power Systems

A delay in the supply of the equipment resulted in the extension of the commissioning of most of these Concentrated Solar Power projects. It is projected that there will be a rapid increase in the demand for electricity in India in the coming decade following the rapid economic growth being experienced in the country. This calls for the need to make heavy investments in a bid to increase its present installed capacity and to foster the stability of its electricity grid. The first Concentrated Solar Power plant in India was having an installed capacity of 2.5 MW and was commissioned in 2011 at Bikaner, Rajasthan (Shome, 2015, p.215). This plant was established by the ACME Group and made use of eSolar power technology in the generation of electricity. Plans are underway to scale up the plant to 10 MW.

Karnataka state has recently launched a request proposal that would be used in coming up with up to 130 WM of solar power projects in the state. The bidders are expected by law to apply a discount to the tariff which has been set at Rs 11.35 /kWh for Concentrated Solar Power.  Other Concentrated Solar Power projects in India include:

• Megha Solar Plant
• Diwakar
• National Solar Thermal Power Facility
• Abhijeet Solar Project
• Dhursar
• KVK Energy Solar Project
• Godawari Solar Project
• Gujarat Solar One among other projects

The details of each of the plants are discussed below:

Dhursar

This is a project that has been completed and is fully operational. Located in Rajasthan, Dhursar the Dhursar Solar Project adopts the linear Fresnel reflector type of technology. It covers 340 hectares of land and started generating electricity in 2014. The tariff rate of the project is 11.97 Rs per kWh and is a project of a commercial scale. Rajasthan Sun Technique Energy is the developer of the solar plant owned by Reliance Power and being constructed by Areva. The gross and net capacity of the turbine is 125 MW, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines (Thangavel, 2014, p.152).

ACME Solar Tower

This is a fully operational project. Located in Rajasthan, Bikaner the ACME Solar Tower adopts the power tower system type of technology. It covers 12 acres of land and started generating electricity in 2011. The tariff rate of the project is 12.24 Rs per kWh and is a project of a commercial scale. ACME Group is the developer as well as the owner of the plant that is being constructed by ACME Group Chennai. The gross and net capacity of the turbine is 2.5 MW, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines. Water/steam is the heat-transfer fluid type used in ACME Solar Tower.

Current Status of Concentrated Solar Power in India

Godawari Solar Project

This is a project that is fully operational. Located in Rajasthan, Nokh the Abhijeet Solar Project adopts the parabolic trough system type of technology. It covers 150 hectares of land and started generating electricity in 2013. The tariff rate of the project is 12.20 Rs per kWh and is a project of a commercial scale. Godawari Green Energy Limited is the developer as well as the owner of the plant that is being constructed by Lauren-Jyoti. The gross and net capacity of the turbine is 50 MW, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines (Vogel, 2010, p.369). The SCA manufacturer model of the plant is Euro Trough (ET 150), while the HCE manufacture is the Schott (PTR-70). Dowtherm A is the heat-transfer fluid type used in Godawari Solar Project.

Megha Solar Project

This is a project that is fully operational. Located in Andhra Pradesh, Anantapur the Megha Solar Project adopts the parabolic trough system type of technology. It covers large tracks of land and started generating electricity in November 2014. The tariff rate of the project is 11.31 Rs per kWh and is a project of a commercial scale. Megha Engineering and Infrastructure is the developer as well as the owner of the plant that is being constructed by MEIL Green Power. The gross and net capacity of the turbines is 50 MW, manufactured by Siemens (Rather, 2018, p.230). Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines. The SCA manufacturer model of the plant is Albiasa (AT-150), while the HCE manufacture is Siemens (UVAC 2010). Xceltherm®MK1 is the heat-transfer fluid type used in Megha Solar Project.

National Solar Thermal Power Facility

This is a project that is fully operational. Located in Gurgaon city of India the National Solar Thermal Power Facility adopts the parabolic trough system type of technology. It covers large tracks of land and started generating electricity in 2014. The tariff rate of the project is not defined and is a project of a commercial scale. IIT Bombay is the developer as well as the owner of the plant that is being constructed by Abengoa Solar. The gross and net capacity of the turbines is 1 MW, manufactured by Shrijee Structures. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines. The SCA manufacturer model of the plant is Euro Shrijee Structures, while the HCE manufacture is Schott (PTR 70) (Dixit, 2017, p.355). Therminol VP-1 is the heat-transfer fluid type used in Gujarat National Solar Thermal Power Facility Project.

Gujarat Solar One

This is a project that is still under construction. Located in Gujarat, Kutch the Gujarat Solar One Project adopts the parabolic trough system type of technology. It covers large tracks of land and started generating electricity in 2014. The tariff rate of the project is 10.25 Rs per kWh and is a project of a commercial scale. Cargo Solar Power is the developer as well as the owner of the plant that is being constructed by Lauren CCL (Palenzuela, 2015, p.368). The gross and net capacities of the turbines are 28 MW and 25 MW respectively, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines. The SCA manufacturer model of the plant is Euro Trough (ET 150), while the HCE manufacture is Schott (PTR 70). Diphyl is the heat-transfer fluid type used in Gujarat Solar One Project.

KVK Energy Solar Project

This is a project that is still under construction. Located in Askandra Rajasthan the KVK Energy Solar Project adopts the parabolic trough system type of technology. It covers large tracks of land and started generating electricity in March 2013. The tariff rate of the project is 11.2 Rs per kWh and is a project of a commercial scale. KVK Energy Ventures Ltd is the developer as well as the owner of the plant that is being constructed by Lanco Solar. The gross and net capacity of the turbines is 100 MW, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines. The SCA manufacturer model of the plant is SENERtrough (SNT0) while the HCE manufacture is Siemens (UVAC 2010). Synthetic Oil is the heat-transfer fluid type used in KVK Energy Solar Project (Lovegrove, 2018, p.158).

The scope of work for this project is composed of a concentrating solar power plant that operates on parabolic trough type of technology. It is a 100 MW project located in Askandra, Rajasthan. Among the specifications of the field in the project include

• 290 loops
• Synthetic Oil as the heat transfer fluid type
• SENER trough (SNTO) model of the SCA Manufacturer
• The following specifications define the power block of the project
• Gross turbine capacity of 100 MW
• Net turbine capacity of 100 MW
• SST 700 turbine description
• Wet cooling as the cooling method adopted for the engines

The following specifications define the thermal storage in the project

• 1010 MWh of Molten salt thermal storage description
• Indirect storage types of 2 tanks
• A storage capacity of 4 hours

Dadri ISCC Plant

This is a project that is still under construction. Located in Uttar Pradesh, Dadri the Dadri ISCC Plant adopts the linear Fresnel reflector type of technology and has an electricity generation capacity of 14000 MW per year. It covers 33000 m² of solar field aperture area and started generating electricity in 2017. The tariff rate of the project is 12.24 Rs per kWh and is a project of a commercial scale. Frenell is the developer of the plant that is owned by NTCP and being constructed by Thermax (Kohl, 2010, p.225). The gross capacity of the turbine is 14 MW, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines.

Abhijeet Solar Project

This is a project that is still under construction. Located in Rajasthan, Phalodi the Abhijeet Solar Project adopts the parabolic trough system type of technology. It covers 388 acres of land and started generating electricity in 2015. The tariff rate of the project is 12.24 Rs per kWh and is a project of a commercial scale. Corporate Ispat Alloys Ltd is the developer as well as the owner of the plant that is being constructed by Shriram EPC Ltd Chennai (Heller, 2017, p.205). The gross and net capacity of the turbine is 50 MW, manufactured by Siemens. Steam Rankine is the output type of the plant which using wet cooling method in cooling of its engines. The manufacturer mode of the plant is Enter-t International Ltd, while the HCE manufacture is the Siemens (UVAC 2010). Therminol VP-1 is the heat-transfer fluid type used in Abhijeet Solar Project.

Concentrating Solar Power energy in India is one of the renewable and clean sources of energy in the country. Through its development, the country does not only add on top of its generation capacity and thus meeting the demands of the electricity of her citizens but also tend towards achieving zero carbon emission energy. If properly harnessed Concentrating Solar Power energy has the capability to meet a significant fraction of the electricity needs of Australia.

Concentrating Solar Power energy offers a source of energy to India that can easily be predicted and maximized. This forms one of the greatest advantages of Concentrating Solar Power energy against numerous other alternative sources of energy and hence can be used in estimating the amount of energy it can generate. The consistency of the Concentrating Solar Power energy following the numerous sunshine days in India throughout the year has made it a better source of energy as compared to the other sources which depend on wind and exposure to the sun. In this light, a more reliable source of energy thus gets its ways into the energy system and supplementing the already existing sources that are perceived to be reliable as well (Dixit, 2017, p.230). Most of the strongly perceived reliable sources of energy are fossils which emit carbon dioxide. By introducing Concentrating Solar Power energy, the fear and anxiety of having a less reliable and consistent source of energy are eliminated. This then makes it easy to adopt renewable energy sources and the overall impact on the energy system would be a significant reduction in the levels of emissions of greenhouse gases.

Concentrating Solar Power energy also adds to the energy system a source of energy that is in abundance and widespread availability (Lovegrove, 2018, p.188). This is attributed to the numerous sunshine days in India throughout the year. There are about 300 days of clear sky and sunshine in India making harnessing the sun rays very easy using the technologies which turn relative to the position of the sun. As a result of population growth and rapid migration of people into the cities, the cities tend to have a high population and these numerous people can have access to and use electricity generates from the waves using wave energy plants. This reduces costs that are involved with transportation of electricity from the point of generation to the point of consumption. Also reduced are the power losses that are normally associated with transmission of electricity over long distances (Blanco, 2016, p.162).

Concentrating Solar Power energy can be harnessed in using various types of technologies hence not limiting the harvesters to a single technology line. Currently, Concentrating Solar Power energy can be harnessed by using methods that range from Stirling Engine System, Parabolic Trough System to Power Tower Systems. These massive structures are positioned in such a way that they maximized collection of solar radiation. This means that harvesting of w Concentrating Solar Power energy is not purely dependent on one technology and hence the failure of a technology does not lead to total collapse of the generation of electricity through Concentrating Solar Power energy (Bhaskar, 2013, p.203). This adds more sense to the concept of the reliability of wave energy as long as the country puts in place an avalanche of technologies aimed at improving harnessing of the resource.

Still, just like any other renewable sources of energy, Concentrating Solar Power energy adds to the energy system environmental friendly sources of energy. The energy generated from Concentrating Solar Power energy is used in the generation of electricity that can serve numerous homes. Coming across a clean energy source in the energy-powered world of today is a bit of a challenge following the numerous barriers to adoption of clean energy.

Among the opportunities include

India has huge potential for solar power for the generation of solar electricity per watt that is built. This is attributed to its solar radiation that ranges between 1700 and 1900kW per kilowatt peak. The potential is also attributed to the numerous clear sky days in the year which is about 300 days (Kulichenko, 2012, p.147).

India has more than enough land that can be used in the implementation of concentrating solar power technologies. The land areas are not only in abundance but also ideal for direct normal radiation levels which are important in making Concentrating Solar Power an integral contributor to the energy mix of India.

On the other hand, the barriers to implementation of CSP in India are among them:

Numerous barriers have been pointed out to be derailing the process of transition to sustainable energy specifically concentrating solar power in India. Among the barriers include:

Unavailability of solar energy: The availability and reliability of solar radiation are determined by the weather conditions of a place at a particular time. It is rarely possible to categorically predict and state that solar will be available at a particular time (Philibert, 2011, p.256).

Unavailability of land: Land remains one of the secret reserves in India. Installation of concentrating solar power calls for very large areas of land which may at the time not be feasible. Currently, 1 km² of the area is required for solar power plants of utility-scale for every 20-60 MW production. Still on this point is the low availability of per capita income. 

Storage is yet another serious problem experienced in the implementation of Concentrating Solar Power in India. In cases where the demand for electricity does not go very high, there will be a need for storage capacities to keep the supply for meeting future demands. This leads to an increase in the overall cost of the project (Kulichenko, 2012, p.274).

India is aiming at generating 100 GW of solar. This would translate to approximately 10.5% of the total amount of power generated in India. Attaining such a large share of intermittent sources calls for very heavy investments by the country in the infrastructure of the power grid in order to achieve smart supply transmission and management of demand.

Achievement of the projected 60 GW utility-scale projects by 2022, an approximate of $40 billion is needed (Blanco, 2016, p.177). The government of India at the moment relies on international sources to acquire a large share of this money. The international funding of solar power in India is relatively low and hence raising this lump sum of money through such channels appears farfetched.

Conclusion

Concentrating Solar Power, CSP, is one of the most promising in India for the days to come. Through adopting the various types of techniques of Concentrating Solar Power, India is gravitating towards achieving the sustainable, reliable and affordable energy goals set by the various national and international agencies. There has been an upsurge in the amount of electricity produced by concentrated solar power in India every year. This illustrates the commitment of the country towards attaining sustainable, reliable and affordable energy for its citizens. India has huge potential for solar power for the generation of solar electricity per watt that is built as attributed to its solar radiation that ranges between 1700 and 1900kW per kilowatt peak. The potential is also attributed to the numerous clear sky days in the year which is about 300 days.

Cooperation with other countries is one of the surest ways that India can follow in order to achieve an enhanced rate of sustainable energy development. This cooperation may be in the form of joint missions in sustainable energy achievements, organizing workshops and events aimed at imparting knowledge and understanding on the various sustainable energy needs. Still, through donor funding, the financial burden that comes with these projects can significantly be reduced making them attractive to investors.

References

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