Concentrated Solar Power

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Concentrated Solar Power : Future Energy Solutions

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Concentrated Solar Power
Course: Management Information Systems Instructor: Prithwis Mukerjee Vijay Kumar Prajapati Vinod Gupta School Of Management, IIT Kharagpur

Abstract
Concentrated solar power (CSP) is a method of electric generation, fuelled by the heat of the sun, an endless source of clean and free energy. Concentrated solar power could account for up to 25% of the world's energy needs by 2050. This technology is emerging as commercially viable and quickly expanding. Also, with this expansion of concentrated solar power, thousands of new jobs would be created and millions of tonnes of carbon dioxide would be prevented from being released. It would also results in drastic price reduction of around 30%. This type of solar technology requires strong, direct solar radiation and can be primarily used as a large, centralized source of power for utilities.

Source: http://upload.wikimedia.org/

Introduction
Solar Power an intermittent natural energy resource, utilizes the concept of conversing sunlight into electricity. There are various methods or procedures to generate this energy sources like photovoltaic cells (PV) i.e. direct or concentrated solar power which is indirect method. Previously, people generally uses photovoltaic which were used to power small and medium size applications but now as the needs of the person increases their demands will also increase so they thought to go for bigger platform which is “Concentrated Solar Power”. This basically uses lens or mirrors and different

tracking systems to focus a large area of sunlight into a small beam which is then further used as a heat source for a conventional power plant.

Why Concentrated Solar Power?
We can see that current trends in energy supply and use are unsustainable as economically, environmentally and socially. Without any decisive action, energy-related emissions of CO2 and many more gases will get more than double by 2050. We must and can change the current scenario. We must and can change our current scenario; we must leads to an energy revolution in which low carbon energy technologies play a major role. If we need to reach greenhouse-gas emission goals, me implement and promote deployment of energy efficiency, different types of renewable energy, carbon storage, transport technologies and nuclear power. To do so, we must insure to include every major countries and sector of economy. These types of emerging technologies hold many promises for countries with plenty of sunshine and clear skies. The electrical output of these power systems matches well with the shifting daily demand for electricity at different places of world. These technologies when backed up by thermal storage facilities and combustible fuel offer utilities electricity which can be dispatched whenever required. We can see the future as within one to two decades it will be able to easily compete with different other energy resources plants that emit high levels of carbon dioxide. The world can concentrate on the high scale of sunny regions like North Africa which is sunniest region and may be able to export surplus solar electricity to different neighbouring regions such as Europe where we can see a strong demand of electricity from renewable sources. In the medium to longer term, concentrating solar facilities may also be used as a producer of hydrogen which can be blended with natural gas and provide low carbon liquid fuels for transport and other enduser utilities sectors. Also with the expansion of concentrated solar power, thousands of new jobs would be created and millions of tonnes of carbon dioxide and wastes would be prevented from being released. It would also results in drastic price reduction of around 30%.

A study found that concentrated solar power could capitalize 25% of world’s energy demands by 2050 and also results in drastic price reductions of electricity around 30%. Future development of this technology forced EU to invest in solar power plant recently few projects like “Desertec” and “carbon

free network link between Europe, north America and the middle east” have been started using CSP technology.

Current status of Concentrated Solar Power System


Spain is currently leading the Concentrates solar power technology, currently they have more than 50 solar power projects in channel to be implemented and approved by the government in the works.



As of in 2010, the global stock of CSP plants neared 1 GW capacity and are expected to touch 15 GW with the projects in development or under construction in different countries including India, China, Morocco, Spain and the United States.

• • •

In India first concentrating solar power is about to be build in Mathania, State of Rajasthan. International energy association (IEA) is developing a series of roadmap for key energy technologies. Parabolic troughs are mostly holding the market share of current CSP productions. Few plants are now adding different technologies like thermal storage.

Segments of Concentrated Solar Power Systems
Concentrated Solar Power systems can be divided into following Concentrated Solar Thermal This unit is produced to produce renewable heat or solar thermoelectricity usually generated through steam. This system use lenses or mirrors and tracking systems to concentrate a large area of sunlight onto a small area. The focused light is then further used as heat source for a conventional power plant. These systems use a wide range of concentrating technologies including dish Stirling, parabolic trough, solar chimney, concentrating linear Fresnel reflector, solar power tower. Each method is capable of producing high temperatures and high thermodynamics efficiencies varied in the way that they track the sun and focus light.

Concentrated Photovoltaic This is one of the newest forms of solar energy technology. CPV systems basically focus a large amount of sunlight onto a small region of solar photovoltaic materials to produce solar electricity. CPV systems are found to be much less expensive to produce, because the concentration produces a much smaller area of solar cells. A CPV system efficiency mostly depends on the solar cells is cool through use of heat sinks. To achieve their maximum efficiency, these systems must be located in places which receive plentiful direct sunlight.

CPV system has some advantage also in terms of costs of solar collectors than an equivalent area of solar cell.

Concentrated photovoltaic and thermal Concentrating photovoltaic and thermal technology (CPVT) integrates the production of both electricity and thermal in the same system module. This technology system therefore

involves a large investment as compared to other units but the generation of solar electricity and thermal heat will overcome this disadvantage. Thermal heat produced by this unit can be used at different scale as per requirements like solar process heat, hot tap water, desalination or solar cooling.

How the sun can drive a Power Plant
In a very simple way: the solar radiations can be collected at different power units to provide high temperature heat which is then further used to operate a conventional power cycle or any turbine or engine. Solar energy can be stored during day time to meet the requirements at night; this can be done by storing it in concrete, molten salt, phase change media or ceramics. In a broader scale we can classify Concentrated Solar Power technologies into four families depending upon the way they focus and receive the sun’s energy

Receiver\Focus

Line Focus

Point Focus

Linear Fresnel Reflector Fixed

Towers (CRS)

Parabolic Troughs Mobile

Parabolic Dishes

Linear Fresnel Reflector (Line Focus, Fixed receiver)

Source: http://solarenergytopics.com/parabolic_trough.html

Linear Fresnel Reflectors (LFRs) uses long rows of slightly curved or flat mirrors to reflect the sun’s rays onto a downward facing linear, fixed receiver through approximating the parabolic shape of trough systems. Their simple design, flexibly bent mirrors and fixed receivers requires lower investment cost and also facilitates direct steam generation eliminating the need and cost of heat exchangers and heat transfer fluids.

Solar Towers (Point Focus, Fixed Receivers)

Source: http://jcwinnie.biz/wordpress/?p=1979

It is also known as central receiver system which uses hundreds to thousands of small reflectors called Heliostats to concentrates sun rays on a central receiver kept atop of a fixed tower. The main advantage of this system is that the concentrating power of the tower achieves very high temperatures, thereby increasing the efficiency at which heat is converted into electricity and reducing thermal storage cost. In addition, the concept is highly flexible which helps to integrate wide numbers of heliostats, receivers, transfer fluids and power blocks. Also, sometimes we can have several towers feeding one power block.

Parabolic Troughs (Line Focus, Mobile receiver)

Source: http://www.nrel.gov/csp/troughnet/solar_field.html

Parabolic troughs act like a collector and is constructed as a long parabolic mirror and a dewar tube running it length to the focal point. Sunlight is reflected by the mirror and gets concentrated on the dewar tube. Depending upon the change in seasons these device generally designed with low solar concentration ratio. Dewat tube is filled with heat transfer fluid to absorb the concentrated sunlight which significantly increases the temperature of the fluid to high level. This fluid is then used to heat steam in a standard turbine engine. The whole process is economical and the overall efficiency is around 15% which is round about equivalent to photovoltaic cells.

Parabolic Dishes (Point Focus, Mobile Receiver)

Parabolic dishes concentrate sun’s radiations at a central focal point above the centre of the dish. The entire apparatus tracks the sun, with the receiver and dish moving in tandem. It eliminates the need for cooling water and heat transfer fluids. This design offers highest solar-to-electric conversion

performance compared to other concentrated solar power system. These features also put parabolic dishes in competition with photovoltaic modules like concentrated photovoltaic’s (CPV) and other CSP technologies. The main disadvantage is that they are limited in size and each independently produces electricity so for huge production requirements we need hundreds or thousands of them to be colocated to create a large-scale thermal plant.

Source: http://newenergyportal.wordpress.com

Enhancing values of Concentrated Solar Power
Human activities, sunlight availability at different places, thermal inertia of buildings maintain high demand for electricity after sunset also development areas for CSP production and sunlight exhibits a good match with electricity demand and its peak. CSP plants needs to provide a larger share of clean electricity and maximise CO2 emission reductions and to provide base load power. To address these issues of CSP technology different processes has been adopted like thermal storage and backup or hybridisation.

Source: Geyer, 2007, SolarPACES Annual Report. Thermal Storage This theory is basically defined to balance the energy utilization between day and night time. Mostly CSP plants have some ability to store solar energy even for short period of time providing buffering capacity allowing smooth electricity production. The solar field is somewhat larger in the locations with good sunlight so that they can have more production and further storage capacity as compared to locations with low sunlight. Thermal storage also contributes largely to the cost of the plant therefore currently industries are focusing to significantly increasing temperature and to improve overall efficiency.

Backup and hybridisation Mostly all CSP Plants are equipped with fuel-powered backup systems which help to regulate production and guarantee capacity especially in different time periods. The fuel powered backups almost completely guarantee the plant’s production capacity at a lower cost comparing to the plants that depends only on the thermal and solar fields. CSP can also be combined in hybrid by adding a solar power field with fossil fuels plants such as coal plants or along with natural gas plants as in integrated solar combined cycle plants. These hybridisation methods really help to conserve fuels also their relatively low cost is an overall positive aspect.

Economic Potential of Concentrated Solar Power
Investment costs of 50MW plant trough plant with 7 hour storage

Source: Technology roadmap concentrating solar power. International Energy Agency • Till last year i.e. 2009 the cost of building a CSP System was typically about $2.5 to $4 per watt with free fuel i.e. the sun’s radiation. Therefore a 250MW station would have cost $6001000 million to build working out to be 12-18 cents per KWh. • • Currently requires high capital investments as compared to other energy sources, but it offers a good long term benefits. The economics of this technology will remain favourable for peak load and intermediate loads than for base loads. Also plants having large storage area and higher load factor are on higher side of investment. • • • • Advanced technologies, economies of scale, mass production and improved operations allow reducing electricity cost to a lower level in upcoming 10 to 15 years. Hybrid Solar and fossil fuel plants along with different finance schemes are already delivering competitive priced electricity these days. Investment cost is slightly higher than photovoltaic devices i.e. PV but CSP is higher in generation of power per MW. Investment can be reduced to 30 to 40% by implementing effective power blocks in turbine and DSG systems instead of trough plants.

Environment and Social Sustainability of CSP
• • •

This technology is best suited for the reduction of greenhouse gases and other polluting gases without creating environmental risks. The collector materials used in CSP can be recycled and again used in the plant as the energy payback time of this technology is in the order of 5 months. Concentrated solar power not only creates many jobs and boost economy it also reduce the risk of conflict between energy, water and climate change.

Challenges in CSP technology
• • • • • •

High start-up cost, the cost of photovoltaic panels will remain expensive despite of any advancement in technologies. Very much dependent on climate conditions, also power can only be harnessed when there is sunshine so no energy collection is possible during night. Installation of solar power systems accounts for large storage space to ensure its effectiveness. CSP is usually not competitive in bulk wholesale electricity market. Financing a CSP plant may find difficulties in long term is investor in different technology companies do not supply any equity capital. For a new CSP plants, obtaining permit and grid access is a main challenge, also access to gas or water networks may be difficult in some locations.

Way ahead for CSP


If solar electricity is exported to regions with high solar demand and low solar energy resources then the potential of sunbelt countries could be harvested for the protection of climate change.

• •

India needs to step into fresh initiatives to asses these viable technologies and its feasibility in Indian context. A study done by Greenpeace International and European solar thermal association investigated the future aspects of CSP results in the investment and capacity in different time horizons. Time 2015 Investment 21 billion Euros a year 2050 174 billion Euros a year 1500 Gigawatts Capacity 420 Megawatts

Opportunities for CSP in India
• •

Rural electrification using different solar technologies can play important role in meeting the demand supply gap for electricity. Integrating solar thermal power plants with existing industries such as paper, dairy or sugar industries. This approach can reduce the capital investment on steam turbines and other associated power house infrastructures resulting in decrease of cost.



Integrating CSP unit with existing coal thermal power plant which leads to saving of up to 24%during high isolation periods for feed water heating to 240 C
0

Future role of stakeholders
National Governments • • • • Enable and ensure increased and sustained funding for Concentrated Solar Power projects. Provide an equitable environment for CSP development through joining different renewable energy portfolios to build large-scale plants. Encourage state-controlled bodies and rich community to participate in CSP capacities bidding. Permit procedures and access lines should be streamlined for better development of project.

Concentrated Solar Power Industries • • • • Utilities • • • • • • • • Rewarding CSP plants that provide firm capacities. In future add the CSP plant in own asset portfolio by owning, operating and maintain the plant. Provide certainty to different investors through long- term power purchase agreements or different procedures. Actively participate in whole project development. Enhance cost reduction system through different innovative method like improving line-focus system, new transfer fluids and components. Collaboratively work with other power generation system like turbine to generate new turbines to match the capacity for CSP plant with greater efficiency. Implement new concepts for different segments need of plant like small, mid-scale plant for isolated end-users or remote area. Develop central receiver system, for molten salt, superheated steam and air receivers and further increase temperature levels for good efficiency and reduce storage cost.

Organizations and Agencies Implement international mechanisms to increase the development of CSP plants for different consumption requirements. Provide help in organising the network of HVDC lines across the borders mainly associated with CSP expansion. Establish relations and call for negotiations between potentially importer and exporter of CSP electricity between countries. Help in gaining local public acceptance of CSP plants through balancing the different pros and cons.

Conclusion
Developing countries in Africa, Asia, Latin America where more than half of population is currently is living without electricity and sunlight is fully abundant may have the potential for biggest and fastest growing market for solar energy source. The running projects are now opening the doors for other bigger development projects in developing countries. To make this technology a huge success, international collaborative efforts, policies and new technology developments needs to be taken into account. Correct future milestones need to be set for international community so that they can use to track the CSP development efforts to achieve the reduction in emission of green house gases. These technologies have the potential to bring economic, environmental and social sustainability on a large scale throughout the world.

References:
[1] Making solar thermal power generation in India a reality – Overview of technologies, opportunities and challenges. The Energy and Resources Institute (TERI), India [2] [3] Exploiting the heat from the sun to combat climate change. Greenpeace International Concentrating solar power now. The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) [4] [5] Technology roadmap concentrating solar power. International Energy Agency Concentrated Solar Power. http://www.concentratedsolarpower.com

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