Final Report Summary - INTERSOLAR (Development and demonstration of intelligent non-contact inspection technology for concentrated solar power plants)
Executive Summary:
The demand for energy is continuously increasing in the European Union. Thus, there is an urgent need to develop renewable energy sources which are capable of meeting the demand for economic growth across the continent further. Concentrated Solar Power (CSP) plants are a promising means of large-scale sustainable energy production.
In Europe as of 2014 there are 32 CSP utility-scale plants producing more than 2GW of power. The European CSP capacity represents approximately 50% of the total global capacity currently installed amounting to a total of 4GW. Outside Europe there were eleven operational CSP plants in the US with four of the biggest ones having been completed in 2014, three in China and twelve in the rest of the world. In early 2015 there were twenty-two CSP plants under construction around the world which will add another 2.5 GW of capacity by 2015 (265 MW installed in Europe). Several more CSP projects have been announced around the world. If all of them materialise they will add another 9 GW of CSP capacity by 2025. A number of CSP project are planned for construction within the Middle Eastern-North African (MENA) region, an area of direct relevance to Europe as it lies South and East of the Mediterranean Sea. At the moment, Spain is the European and world leader in the exploitation of CSP technology with the U.S. and China following. In the U.S. the total installed CSP capacity saw a significant increase in 2014 with more than 1 GW connected to the grid. By 2020 it is anticipated that the U.S. and China will have narrowed the gap with Europe considerably but Spain will probably retain its global leadership in total installed CSP capacity until then [1].
CSP is the renewable energy source with the highest potential for growth [2]. From a strict techno-economic aspect, the three CSP technologies which are currently commercially viable are those based on parabolic trough, solar power tower and Linear Fresnel Reflector (LFR) designs. Parabolic trough concentrators are so far the most widely deployed type of solar thermal power plant although solar towers are gradually catching up [3]. The number of solar power tower plants is predicted to increase significantly in the next decade as the main technical challenges are gradually overcome. LFR plants are not expected to grow as fast as the other two technologies, largely due to the lower efficiency of power production achievable in LFR configurations [4].
Most of the existing parabolic trough plants operate up to 400°C, but with recent technological advances the maximum operating temperature of newly commissioned parabolic plants can reach 550°C [5]. Comparable and higher operational temperatures up to 1000°C are feasible for solar tower plants resulting in higher energy production efficiency and capacity factor than possible in parabolic trough power plants. LFR plants are designed to operate at temperatures which do not normally exceed 300-325°C and therefore their energy production efficiency is significantly lower in comparison to parabolic trough and solar power tower-based plants.
CSP plants suffer from operational reliability issues which depending on the plant type can be related to failure of the solar absorbers, coolant system piping, heliostats or central tower receiver [5-9]. Existing parabolic trough plants suffer at least one week of forced outages per year whilst solar receiver tube failure rates alone can be as high as 0.09 per tube per year [7].
Failure of solar absorbers and coolant system pipes can disrupt production and result in significant maintenance costs. Mahoney of Sandia National Laboratories reported a failure rate of 30-40% in solar absorbers at the Solar Energy Generating Systems within a decade of operation [7]. The price of replacement is estimated to be €1000 per solar receiver replaced resulting in a significant extra maintenance cost on an annual basis. This cost is currently estimated to exceed 0.5 Million € per annum for an average-sized CSP plant [8]. Failures can also result in significant leaks and fires due to combustion of the oil commonly used as working fluid in the majority of CSP plants resulting in significant infrastructure damage [9-10]. Therefore there is an urgent need to increase the reliability of CSP infrastructure and optimise maintenance procedures by using efficient and cost-effective monitoring methods.
Although there is low technical and financial risk associated with the implementation of new trough plants in the near term, the long-term development projection has a substantially higher risk due to the technology advances needed in the fields of solar absorber efficiency, structural reliability of key plant components, thermal storage, selection of optimum working fluid and structural health assessment to enable the safe operation of the plant at temperatures above 400°C.
Solar power tower plants due to several technical challenges carry a more significant operational and financial risk. The main technical problems faced in solar power tower plants are somewhat different in nature from those in parabolic trough and LFR plants since they are predominantly related to structural deterioration of the central receiver due to creep, overheating, corrosion, and failure of heliostats. Nonetheless, the solar power tower plant piping is affected by the same damage mechanisms as in parabolic trough and LFR-based plants.
CSP plants consist of several kilometres of solar absorber tubes and insulated pipes. The inspection of CSP tubing and piping is currently very challenging. In the case of solar absorbers the tubes are inside a glass envelope under vacuum and covered by cermet coatings which enable a high amount of solar energy to be absorbed. The rest of the piping is insulated in order to minimise the heat losses in the CSP plant and increase energy conversion efficiency. Therefore in order to carry out any inspection the insulation needs to be removed.
Removal of the pipe insulation is a time-consuming process which can also result in damage to the pipes and the insulation itself. At the moment there is no reliable methodology for the inspection or structural health monitoring (SHM) of in-service solar receivers and insulated pipes and therefore CSP plant maintenance procedures are corrective rather than preventive. In the case of solar tower CSP plants, although off-line inspection is more straightforward, there is currently no way to continuously monitor the central receiver for the evolution of damage during normal in-service operation.
Within INTERSOLAR, the consortium has developed a low cost non-contact long range ultrasonic technique based on the application of Electromagnetic Acoustic Transducers (EMATs). A bespoke test facility has also been developed as part of this project and has been used for development as well as demonstration purposes of the technology developed within the project. EMATs can be applied to detect corrosion in solar receivers and insulated pipelines or solidification problems where molten salts are used as working fluid as well as other types of damage such as thermomechanical fatigue cracking, creep, etc. over long distances.
Due to the power needed by EMAT sensors to operate wireless function is not possible. However, since long-distance measurements can be carried out only a few strategically selected positions need to be instrumented in order to cover the entire area of interest. The selection of EMATs has been based on the fact that they are a non-contact NDT transducer capable of being used for inspection of high temperature pipes. Physical contact between the transducer and the specimen under test is not required and hence there is no requirement for couplant either. Also, the component's surface does not generally require preparation.
The key objectives of the project have been to: a) develop a non-contact structural health monitoring technique for CSP coolant system application based on EMATs, b) design and implement a bespoke test facility suitable for simulating CSP conditions used for testing, validation and demonstration of the system, c) demonstrate the complete prototype system under realistic operating conditions, d) transfer the technical knowledge developed from the RTDs to the SMEs leading the INTERSOLAR project, e) support the further growth of the CSP industry, and f) assist the SMEs of the INTERSOLAR consortium increase their market share in CSP inspection and maintenance and enhance their prospects for strong growth in the medium to long term. These objectives have been achieved in full and the project has been concluded successfully and on time.
During the second reporting period covering Months 10 to 24 (1/06/14-31/08/15) of the project, the consortium carried out technical work as planned in six different Workpackages (WPs 2-8). WP-1 was successfully concluded and reported during the first reporting period. WP-1 concerned the system requirements and specification of the INTERSOLAR system. WP-1 was completed and all associated deliverables were submitted on time as anticipated in the project’s DOW under the leadership of INGETEAM Service S.A. The construction of the INTERSOLAR bespoke test facility was also completed on time and the relevant deliverable report (D1.3) submitted.
Work concerning the development and evaluation of the transducer arrays started during the first reporting period, and one of the deliverables was reported then. More specifically, D2.1 concerning the simulations and modelling results, was submitted on time on Month 8. The remaining deliverables of WP-2 (D2.2 and D2.3) have been reported during the second reporting period.
Work in WP-3 also commenced in the first reporting period but D3.1 was due for reporting during the second reporting period. This deliverable was also submitted on time and concerned the signal processing and analysis tools for flaw sizing. Similarly work in WP-4 had commenced during the first reporting period and was successfully completed on time during the second reporting period.
The two deliverables associated with WP-4 were D4.1 regarding the development of the control system and software and D4.2 concerning the remote SCADA unit. Subsequently, WP-5 concerning integration, validation and troubleshooting commenced and was completed on time during the second reporting period. D5.1 on the integration of software and hardware and D5.2 on simulated trials and troubleshooting were completed and reported successfully and on time.
WP-6 associated with the demonstration of the complete INTERSOLAR system was also carried out during the second reporting period and completed on time. The results of the demonstration were included in Deliverable D6.1 An interim Exploitation and Dissemination plan was prepared and reported during the first reporting period as part of
D71. The Exploitation and Dissemination plan was further updated during the second reporting period and its final version reported in D7.2. Workshops, training, certification and contribution to standards taking place during the project were reported in D8.1. Transfer of the knowledge gained by the RTDs during the last 15 months of the project to the consortium has taken place as part of WP-8.
Research results have already been published in international conferences (4 papers published in the proceedings of various international conferences), a journal paper has been published in the International Journal of Renewable Energy (Impact Factor: 3.456) whilst two more journal papers have been submitted to other journals with similar impact factors. In addition, the consortium members have been asked to contribute a chapter on NDT in Concentrated Solar Power Plants to a book on NDT in Renewable Energy that will be published by Elsevier in 2017 and is currently under preparation.
A project poster and leaflet have also been prepared by the consortium. Finally, a project website (www.intersolar-shm.com) has been designed and created for the wider dissemination of the project’s main results. An interim exploitation plan has also been prepared by the consortium and the relevant deliverable submitted (D7.1). The exploitation plan will be finalised at the end of the project on Month 24.
References
1. Cheng, L., Mohimi, A., Kerkyras, S. C., Constantinou, L., Hatzigeorgiou, C., Marquez, F. P. G., Cuesta, J. E. C., “Report on condition monitoring requirements, system and sample specifications”, Deliverable 1.1 Report, INTERSOLAR FP7 project, 30th November 2013.
2. Del Chiaro et al., “Solar thermal power and the fight against global warming”, Environment America Report, 2008.
3. Gunther, M., Joemann, M., Csambor, S., “Chapter 5: Parabolic trough technology”, Advanced CSP Teachign Materials, DLR, 2011.
4. Marker, A., “Concentrating Solar Power-Trough Technology”, Schott North America Presentation, November 17, 2008.
5. Heller, P., Haberle, A., Malbranche, P., Malbranche, P., Mal, O. Cabeza, L. F., “Scientific assessment in support of the Materials Roadmap Enabling low carbon energy technologies, Concentrating Solar Power Technology”, JRC Report, European Commission, 2011.
6. Philibert, C., “Barriers to technology diffusion: the case of solar thermal technologies”, IEA Report, 2006.
7. Mahoney, R., “Trough Technology Heat Collector Element (HCE) Solar Selective Absorbers”, Presentation at Trough Workshop ASES 2000m, June 18, 2000.
8. Torresol Internal CSP Plant Operation and Maintenance Report 2011.
9. Why not think about operational plant optimization financial closure, CSP Today Press Release, March 2011.
10. Cohen, G. et al., Final report on the operation and maintenance programme of CSP plants, SANDIA report, June 1999, U.S.
Project Context and Objectives:
The main objectives of the INTERSOLAR project have been to develop and demonstrate an innovative and intelligent structural health monitoring system for CSP plants based on EMATs which is capable of being installed in the field for long term online operation.
The development work has been carried out with reference to: a) EMATs modelling and manufacturing of sensors for monitoring solar receivers and insulated pipelines, b) data acquisition, pulser-receiver, and control unit, c) software and signal processing, d) SCADA unit and e) test rig.
A key aspect of the project is the demonstration of the integrated system as well as its individual subcomponents in the field followed by successful commercialisation. In order to achieve this the consortium has carried out extensive trials on the bespoke test facility developed by the consortium as part of the INTERSOLAR project.
To achieve the objectives set in the project, the consortium has followed a step-by-step approach in order to implement the key project deliverables.
The principle objectives for the second reporting period (last 15 months of the project or M10-M24 reporting period) have been to:
• Complete the design of EMAT sensors and test them.
• Assess the performance of the EMATs sensors under realistic operational conditions.
• Develop an appropriate signal processing methodology and associated algorithms.
• Develop the control software for the operation of the INTERSOLAR system.
• Develop the control and SCADA units of the INTERSOLAR system.
• Validate and troubleshoot the integrated INTERSOLAR system.
• Demonstrate the complete INTERSOLAR system under realistic operational conditions.
• To publish key results and participate in conferences.
• To prepare dissemination material (leaflets, posters).
• Disseminate the project’s achievements and main results to the CSP industry and to the rest of the scientific community.
• Transfer knowledge developed from the RTD performers to the SMEs.
• Develop training procedures.
• Complete the final exploitation plan for the appropriate use of the technology and foreground knowledge developed and demonstrated during the project leading to the successful commercialisation of the INTERSOLAR system and subcomponents.
• Determine the optimum route for commercialisation.
Project Results:
During the first reporting period covering Months 1 to 9 (1/09/13-31/05/14) of the project, the consortium carried out technical work as planned in four different Workpackages (WPs 1-4). WP-1 concerning the system requirements and Specification of the INTERSOLAR system was completed and all associated deliverables submitted on time as anticipated in the project’s DOW under the leadership of INGETEAM Service S.A. The construction of the bespoke INTERSOLAR test rig was also completed on time and the relevant deliverable report (D1.3) was submitted.
During the second reporting period covering Months 10 to 24 (1/06/14-31/08/15) of the project, the consortium carried out technical work as planned in six different Workpackages (WPs 2-8). WP-1 was successfully concluded and reported during the first reporting period. WP-1 concerned the system requirements and specification of the INTERSOLAR system. WP-1 was completed and all associated deliverables were submitted on time as anticipated in the project’s DOW under the leadership of INGETEAM Service S.A. The construction of the INTERSOLAR bespoke test facility was also completed on time and the relevant deliverable report (D1.3) submitted.
Work concerning the development and evaluation of the transducer arrays started during the first reporting period, and one of the deliverables was reported then. More specifically, D2.1 concerning the simulations and modelling results, was submitted on time on Month 8. The remaining deliverables of WP-2 (D2.2 and D2.3) have been reported during the second reporting period.
Work in WP-3 also commenced in the first reporting period but D3.1 was due for reporting during the second reporting period. This deliverable was also submitted on time and concerned the signal processing and analysis tools for flaw sizing. Similarly work in WP-4 had commenced during the first reporting period and was successfully completed on time during the second reporting period.
The two deliverables associated with WP-4 were D4.1 regarding the development of the control system and software and D4.2 concerning the remote SCADA unit. Subsequently, WP-5 concerning integration, validation and troubleshooting commenced and was completed on time during the second reporting period. D5.1 on the integration of software and hardware and D5.2 on simulated trials and troubleshooting were completed and reported successfully and on time.
WP-6 associated with the demonstration of the complete INTERSOLAR system was also carried out during the second reporting period and completed on time. The results of the demonstration were included in Deliverable D6.1 An interim Exploitation and Dissemination plan was prepared and reported during the first reporting period as part of
D71. The Exploitation and Dissemination plan was further updated during the second reporting period and its final version reported in D7.2. Workshops, training, certification and contribution to standards taking place during the project were reported in D8.1. Transfer of the knowledge gained by the RTDs during the last 15 months of the project to the consortium has taken place as part of WP-8.
The main objectives of the INTERSOLAR project have been to develop and demonstrate an innovative and intelligent structural health monitoring system for CSP plants based on EMATs which is capable of being installed in the field for long term online operation.
The development work has been carried out with reference to: a) EMATs modelling and manufacturing of sensors for monitoring solar receivers and insulated pipelines, b) data acquisition, pulser-receiver, and control unit, c) software and signal processing, d) SCADA unit and e) test rig.
A key aspect of the project is the demonstration of the integrated system as well as its individual subcomponents in the field followed by successful commercialisation. In order to achieve this the consortium has carried out extensive trials on the bespoke test facility developed by the consortium as part of the INTERSOLAR project.
To achieve the objectives set in the project, the consortium has followed a step-by-step approach in order to implement the key project deliverables.
The principle objectives of the project have been to:
• To develop the specifications for the INTERSOLAR system and condition monitoring requirements.
• To specify and procure samples.
• To design and construct the INTERSOLAR test rig.
• To complete the simulations and modelling for the EMAT sensors.
• Complete the design of EMAT sensors and test them.
• Assess the performance of the EMATs sensors under realistic operational conditions.
• Develop an appropriate signal processing methodology and associated algorithms.
• Develop the control software for the operation of the INTERSOLAR system.
• Develop the control and SCADA units of the INTERSOLAR system.
• Validate and troubleshoot the integrated INTERSOLAR system.
• Demonstrate the complete INTERSOLAR system under realistic operational conditions.
• To publish key results and participate in conferences.
• To prepare dissemination material (leaflets, posters).
• Disseminate the project’s achievements and main results to the CSP industry and to the rest of the scientific community.
• Transfer knowledge developed from the RTD performers to the SMEs.
• Develop training procedures.
• Complete the final exploitation plan for the appropriate use of the technology and foreground knowledge developed and demonstrated during the project leading to the successful commercialisation of the INTERSOLAR system and subcomponents.
• Determine the optimum route for commercialisation.
Potential Impact:
Research results have already been published in international conferences (4 papers published in the proceedings of various international conferences), a journal paper has been published in the International Journal of Renewable Energy (Impact Factor: 3.456) whilst two more journal papers have been submitted to other journals with similar impact factors. In addition, the consortium members have been asked to contribute a chapter on NDT in Concentrated Solar Power Plants to a book on NDT in Renewable Energy that will be published by Elsevier in 2017 and is currently under preparation.
A project poster and leaflet have also been prepared by the consortium. Finally, a project website (www.intersolar-shm.com) has been designed and created for the wider dissemination of the project’s main results. An interim exploitation plan has also been prepared by the consortium and the relevant deliverable submitted (D7.1). The exploitation plan will be finalised at the end of the project on Month 24.
Patents, copyrights, registrations of trademarks or other IPR exploitation activities are under consideration or already in place for several subcomponents of the INTERSOLAR system. For the integrated system IPR activities are under discussion between the consortium members. Discussions regarding commercialisation have also been initiated.
One of the main ideas in terms of commercial exploitation is the creation of a new joint venture between the SMEs which will sell the INTERSOLAR system in its integrated form to CSP operators and maintenance companies. The new company will also provide services and will redistribute the profit arising according to the shares owned by the original companies participating in the new venture.
The final exploitation and dissemination of knowledge document has been drafted and approved by the consortium partners. This document details the past, current and future efforts undertaken for exploitation and dissemination.
The potential impact of the final INTERSOLAR product following its commercialisation can be profoundly positive to the CSP industry since a much more improved predictive maintenance strategy minimising downtime can be achieved. This would increase the productivity and consequently the profitability of CSP plant operators.
The constantly growing global energy demand coupled with the increasing effects of climate change have resulted in an urgent need for more widespread use of stable renewable sources of energy. Concentrated Solar Power (CSP) is a rapidly growing renewable energy source. It can be used for predictable utility-scale power generation facilitating more efficient integration of larger amounts of renewable energy to the grid. As of 2015, there are more than 35 CSP plants of various sizes producing more than 2.5 GW of power in the EU. This represents more than 55% of the total global CSP capacity being produced by more than 70 CSP plants currently amounting to 4.8 GW. Outside Europe, there are 14 CSP plants in the U.S. with 4 of the biggest ones having been completed in 2014, 5 in China and more than 16 over the rest of the world. In late 2015, 25 new CSP plants have been reported to be under construction worldwide that will add another 2.5 GW of capacity with 265 MW installed in Europe. Several more CSP projects have been announced in several countries. If all of them materialise they will result in further 15 GW of CSP capacity being connected to the grid by 2020. According to the International Energy Agency’s SolarPACES group CSP has the potential to cover up to 25% of the global energy demand by 2050 . The investment in new CSP project increased from €1.65 billion in 2009 to over €6.5bn in 2013 . By 2050 the total investment in CSP could exceed €150 billion. The annual turnover of the solar thermal power industry and its added value to the European economy was estimated to be €15 billion for 20113. Moderate estimations indicate that the global CSP market will worth more than €50 billion by 2020 . The Operational and Maintenance (O&M) costs are currently estimated at 13-25% of the overall CSP market or €700 million in 2011. Moderate estimates predict that the global CSP market will worth more than €50 billion by 2020 .
Solar receiver and coolant system failures are the most significant single cost factor in O & M expenditure of CSP plants, representing 25-30% of the Levelised Cost of Electricity (LCOE)8 which at the moment is estimated at €0.15-€0.23/kwh with the current cost of maintenance being €0.04-€0.08/kwh. Reducing the cost of maintenance without compromising operational reliability would improve the value for money for the European CSP industry as a whole which aims to reduce LCOE down to at least €0.10-€0.14/kwh by 2020. It would also release substantial capital for new investments contributing to the further rapid expansion of CSP and renewable energy in general within the EU.
The non-destructive testing (NDT) market is highly competitive sector where SMEs also have a significant presence . NDT equipment suppliers and inspection service providers form an important part of the overall supply chain either directly to the end-user CSP plant operators and constructors or to their main mechanical engineering/asset management suppliers. There are hundreds of companies throughout the EU, most of them SMEs, involved in direct and indirect commercial activities within the CSP market with several having activities in maintenance, inspection and consultancy engineering for CSP plants . CSP plant operators rely on NDT equipment providers in order to develop the necessary systems and techniques for traditional inspection activities and components. Also, companies which provide inspection services normally carry out on-site NDT inspection of inspectable plant infrastructure on behalf of the operator during pre-determined outages. It has been estimated that the total CSP plant European inspection market is currently in the range of €100 million with a potential of increasing up to €0.5 billion by 2020. The CSP plant inspection and maintenance market is expected to rise in line with the growth of the CSP market until at least 2050.
List of Websites:
As part of the INTERSOLAR project management and dissemination activities, CIT hosts a website on behalf of the consortium with the domain name www.intersolar-shm.com.
The purpose of the website is two-fold:
1. A public area for the dissemination of information about the INTERSOLAR project. A project page provides an introduction to the project. In addition, a contact page on the website provides telephone and form access to CIT’s scientists, and specific enquiries will be automatically forwarded to all relevant project partners. The website also supports the exploitation of the key project deliverables.
The following figure shows the homepage of the website as it appears on a standard web browser. Certain project pages currently provide an overview of the project. As the project advanced, more information relating to the project activities, including project work descriptions and publications, has been added to the website. The website will also host an electronic leaflets and a poster giving an overview of the project.
2. A secure member area to act as a repository for project related information and to allow easy transfer of electronic information between consortium partners. This secure area is only accessible with the correct username and password specific to each consortium partner.
Partners have been asked to make links from their websites to the INTERSOLAR project website in order to help improve the website’s ranking in search engines. Currently the following partners have established links from their company websites:
1. CIT
2. Engitec
3. UCLM
4. BU
Project posters and leaflets
A number of A0 posters have been designed and created by the consortium and a leaflet has been designed and created. Posters, leaflets and brochures are planned until the end of the project as dissemination material.
The demand for energy is continuously increasing in the European Union. Thus, there is an urgent need to develop renewable energy sources which are capable of meeting the demand for economic growth across the continent further. Concentrated Solar Power (CSP) plants are a promising means of large-scale sustainable energy production.
In Europe as of 2014 there are 32 CSP utility-scale plants producing more than 2GW of power. The European CSP capacity represents approximately 50% of the total global capacity currently installed amounting to a total of 4GW. Outside Europe there were eleven operational CSP plants in the US with four of the biggest ones having been completed in 2014, three in China and twelve in the rest of the world. In early 2015 there were twenty-two CSP plants under construction around the world which will add another 2.5 GW of capacity by 2015 (265 MW installed in Europe). Several more CSP projects have been announced around the world. If all of them materialise they will add another 9 GW of CSP capacity by 2025. A number of CSP project are planned for construction within the Middle Eastern-North African (MENA) region, an area of direct relevance to Europe as it lies South and East of the Mediterranean Sea. At the moment, Spain is the European and world leader in the exploitation of CSP technology with the U.S. and China following. In the U.S. the total installed CSP capacity saw a significant increase in 2014 with more than 1 GW connected to the grid. By 2020 it is anticipated that the U.S. and China will have narrowed the gap with Europe considerably but Spain will probably retain its global leadership in total installed CSP capacity until then [1].
CSP is the renewable energy source with the highest potential for growth [2]. From a strict techno-economic aspect, the three CSP technologies which are currently commercially viable are those based on parabolic trough, solar power tower and Linear Fresnel Reflector (LFR) designs. Parabolic trough concentrators are so far the most widely deployed type of solar thermal power plant although solar towers are gradually catching up [3]. The number of solar power tower plants is predicted to increase significantly in the next decade as the main technical challenges are gradually overcome. LFR plants are not expected to grow as fast as the other two technologies, largely due to the lower efficiency of power production achievable in LFR configurations [4].
Most of the existing parabolic trough plants operate up to 400°C, but with recent technological advances the maximum operating temperature of newly commissioned parabolic plants can reach 550°C [5]. Comparable and higher operational temperatures up to 1000°C are feasible for solar tower plants resulting in higher energy production efficiency and capacity factor than possible in parabolic trough power plants. LFR plants are designed to operate at temperatures which do not normally exceed 300-325°C and therefore their energy production efficiency is significantly lower in comparison to parabolic trough and solar power tower-based plants.
CSP plants suffer from operational reliability issues which depending on the plant type can be related to failure of the solar absorbers, coolant system piping, heliostats or central tower receiver [5-9]. Existing parabolic trough plants suffer at least one week of forced outages per year whilst solar receiver tube failure rates alone can be as high as 0.09 per tube per year [7].
Failure of solar absorbers and coolant system pipes can disrupt production and result in significant maintenance costs. Mahoney of Sandia National Laboratories reported a failure rate of 30-40% in solar absorbers at the Solar Energy Generating Systems within a decade of operation [7]. The price of replacement is estimated to be €1000 per solar receiver replaced resulting in a significant extra maintenance cost on an annual basis. This cost is currently estimated to exceed 0.5 Million € per annum for an average-sized CSP plant [8]. Failures can also result in significant leaks and fires due to combustion of the oil commonly used as working fluid in the majority of CSP plants resulting in significant infrastructure damage [9-10]. Therefore there is an urgent need to increase the reliability of CSP infrastructure and optimise maintenance procedures by using efficient and cost-effective monitoring methods.
Although there is low technical and financial risk associated with the implementation of new trough plants in the near term, the long-term development projection has a substantially higher risk due to the technology advances needed in the fields of solar absorber efficiency, structural reliability of key plant components, thermal storage, selection of optimum working fluid and structural health assessment to enable the safe operation of the plant at temperatures above 400°C.
Solar power tower plants due to several technical challenges carry a more significant operational and financial risk. The main technical problems faced in solar power tower plants are somewhat different in nature from those in parabolic trough and LFR plants since they are predominantly related to structural deterioration of the central receiver due to creep, overheating, corrosion, and failure of heliostats. Nonetheless, the solar power tower plant piping is affected by the same damage mechanisms as in parabolic trough and LFR-based plants.
CSP plants consist of several kilometres of solar absorber tubes and insulated pipes. The inspection of CSP tubing and piping is currently very challenging. In the case of solar absorbers the tubes are inside a glass envelope under vacuum and covered by cermet coatings which enable a high amount of solar energy to be absorbed. The rest of the piping is insulated in order to minimise the heat losses in the CSP plant and increase energy conversion efficiency. Therefore in order to carry out any inspection the insulation needs to be removed.
Removal of the pipe insulation is a time-consuming process which can also result in damage to the pipes and the insulation itself. At the moment there is no reliable methodology for the inspection or structural health monitoring (SHM) of in-service solar receivers and insulated pipes and therefore CSP plant maintenance procedures are corrective rather than preventive. In the case of solar tower CSP plants, although off-line inspection is more straightforward, there is currently no way to continuously monitor the central receiver for the evolution of damage during normal in-service operation.
Within INTERSOLAR, the consortium has developed a low cost non-contact long range ultrasonic technique based on the application of Electromagnetic Acoustic Transducers (EMATs). A bespoke test facility has also been developed as part of this project and has been used for development as well as demonstration purposes of the technology developed within the project. EMATs can be applied to detect corrosion in solar receivers and insulated pipelines or solidification problems where molten salts are used as working fluid as well as other types of damage such as thermomechanical fatigue cracking, creep, etc. over long distances.
Due to the power needed by EMAT sensors to operate wireless function is not possible. However, since long-distance measurements can be carried out only a few strategically selected positions need to be instrumented in order to cover the entire area of interest. The selection of EMATs has been based on the fact that they are a non-contact NDT transducer capable of being used for inspection of high temperature pipes. Physical contact between the transducer and the specimen under test is not required and hence there is no requirement for couplant either. Also, the component's surface does not generally require preparation.
The key objectives of the project have been to: a) develop a non-contact structural health monitoring technique for CSP coolant system application based on EMATs, b) design and implement a bespoke test facility suitable for simulating CSP conditions used for testing, validation and demonstration of the system, c) demonstrate the complete prototype system under realistic operating conditions, d) transfer the technical knowledge developed from the RTDs to the SMEs leading the INTERSOLAR project, e) support the further growth of the CSP industry, and f) assist the SMEs of the INTERSOLAR consortium increase their market share in CSP inspection and maintenance and enhance their prospects for strong growth in the medium to long term. These objectives have been achieved in full and the project has been concluded successfully and on time.
During the second reporting period covering Months 10 to 24 (1/06/14-31/08/15) of the project, the consortium carried out technical work as planned in six different Workpackages (WPs 2-8). WP-1 was successfully concluded and reported during the first reporting period. WP-1 concerned the system requirements and specification of the INTERSOLAR system. WP-1 was completed and all associated deliverables were submitted on time as anticipated in the project’s DOW under the leadership of INGETEAM Service S.A. The construction of the INTERSOLAR bespoke test facility was also completed on time and the relevant deliverable report (D1.3) submitted.
Work concerning the development and evaluation of the transducer arrays started during the first reporting period, and one of the deliverables was reported then. More specifically, D2.1 concerning the simulations and modelling results, was submitted on time on Month 8. The remaining deliverables of WP-2 (D2.2 and D2.3) have been reported during the second reporting period.
Work in WP-3 also commenced in the first reporting period but D3.1 was due for reporting during the second reporting period. This deliverable was also submitted on time and concerned the signal processing and analysis tools for flaw sizing. Similarly work in WP-4 had commenced during the first reporting period and was successfully completed on time during the second reporting period.
The two deliverables associated with WP-4 were D4.1 regarding the development of the control system and software and D4.2 concerning the remote SCADA unit. Subsequently, WP-5 concerning integration, validation and troubleshooting commenced and was completed on time during the second reporting period. D5.1 on the integration of software and hardware and D5.2 on simulated trials and troubleshooting were completed and reported successfully and on time.
WP-6 associated with the demonstration of the complete INTERSOLAR system was also carried out during the second reporting period and completed on time. The results of the demonstration were included in Deliverable D6.1 An interim Exploitation and Dissemination plan was prepared and reported during the first reporting period as part of
D71. The Exploitation and Dissemination plan was further updated during the second reporting period and its final version reported in D7.2. Workshops, training, certification and contribution to standards taking place during the project were reported in D8.1. Transfer of the knowledge gained by the RTDs during the last 15 months of the project to the consortium has taken place as part of WP-8.
Research results have already been published in international conferences (4 papers published in the proceedings of various international conferences), a journal paper has been published in the International Journal of Renewable Energy (Impact Factor: 3.456) whilst two more journal papers have been submitted to other journals with similar impact factors. In addition, the consortium members have been asked to contribute a chapter on NDT in Concentrated Solar Power Plants to a book on NDT in Renewable Energy that will be published by Elsevier in 2017 and is currently under preparation.
A project poster and leaflet have also been prepared by the consortium. Finally, a project website (www.intersolar-shm.com) has been designed and created for the wider dissemination of the project’s main results. An interim exploitation plan has also been prepared by the consortium and the relevant deliverable submitted (D7.1). The exploitation plan will be finalised at the end of the project on Month 24.
References
1. Cheng, L., Mohimi, A., Kerkyras, S. C., Constantinou, L., Hatzigeorgiou, C., Marquez, F. P. G., Cuesta, J. E. C., “Report on condition monitoring requirements, system and sample specifications”, Deliverable 1.1 Report, INTERSOLAR FP7 project, 30th November 2013.
2. Del Chiaro et al., “Solar thermal power and the fight against global warming”, Environment America Report, 2008.
3. Gunther, M., Joemann, M., Csambor, S., “Chapter 5: Parabolic trough technology”, Advanced CSP Teachign Materials, DLR, 2011.
4. Marker, A., “Concentrating Solar Power-Trough Technology”, Schott North America Presentation, November 17, 2008.
5. Heller, P., Haberle, A., Malbranche, P., Malbranche, P., Mal, O. Cabeza, L. F., “Scientific assessment in support of the Materials Roadmap Enabling low carbon energy technologies, Concentrating Solar Power Technology”, JRC Report, European Commission, 2011.
6. Philibert, C., “Barriers to technology diffusion: the case of solar thermal technologies”, IEA Report, 2006.
7. Mahoney, R., “Trough Technology Heat Collector Element (HCE) Solar Selective Absorbers”, Presentation at Trough Workshop ASES 2000m, June 18, 2000.
8. Torresol Internal CSP Plant Operation and Maintenance Report 2011.
9. Why not think about operational plant optimization financial closure, CSP Today Press Release, March 2011.
10. Cohen, G. et al., Final report on the operation and maintenance programme of CSP plants, SANDIA report, June 1999, U.S.
Project Context and Objectives:
The main objectives of the INTERSOLAR project have been to develop and demonstrate an innovative and intelligent structural health monitoring system for CSP plants based on EMATs which is capable of being installed in the field for long term online operation.
The development work has been carried out with reference to: a) EMATs modelling and manufacturing of sensors for monitoring solar receivers and insulated pipelines, b) data acquisition, pulser-receiver, and control unit, c) software and signal processing, d) SCADA unit and e) test rig.
A key aspect of the project is the demonstration of the integrated system as well as its individual subcomponents in the field followed by successful commercialisation. In order to achieve this the consortium has carried out extensive trials on the bespoke test facility developed by the consortium as part of the INTERSOLAR project.
To achieve the objectives set in the project, the consortium has followed a step-by-step approach in order to implement the key project deliverables.
The principle objectives for the second reporting period (last 15 months of the project or M10-M24 reporting period) have been to:
• Complete the design of EMAT sensors and test them.
• Assess the performance of the EMATs sensors under realistic operational conditions.
• Develop an appropriate signal processing methodology and associated algorithms.
• Develop the control software for the operation of the INTERSOLAR system.
• Develop the control and SCADA units of the INTERSOLAR system.
• Validate and troubleshoot the integrated INTERSOLAR system.
• Demonstrate the complete INTERSOLAR system under realistic operational conditions.
• To publish key results and participate in conferences.
• To prepare dissemination material (leaflets, posters).
• Disseminate the project’s achievements and main results to the CSP industry and to the rest of the scientific community.
• Transfer knowledge developed from the RTD performers to the SMEs.
• Develop training procedures.
• Complete the final exploitation plan for the appropriate use of the technology and foreground knowledge developed and demonstrated during the project leading to the successful commercialisation of the INTERSOLAR system and subcomponents.
• Determine the optimum route for commercialisation.
Project Results:
During the first reporting period covering Months 1 to 9 (1/09/13-31/05/14) of the project, the consortium carried out technical work as planned in four different Workpackages (WPs 1-4). WP-1 concerning the system requirements and Specification of the INTERSOLAR system was completed and all associated deliverables submitted on time as anticipated in the project’s DOW under the leadership of INGETEAM Service S.A. The construction of the bespoke INTERSOLAR test rig was also completed on time and the relevant deliverable report (D1.3) was submitted.
During the second reporting period covering Months 10 to 24 (1/06/14-31/08/15) of the project, the consortium carried out technical work as planned in six different Workpackages (WPs 2-8). WP-1 was successfully concluded and reported during the first reporting period. WP-1 concerned the system requirements and specification of the INTERSOLAR system. WP-1 was completed and all associated deliverables were submitted on time as anticipated in the project’s DOW under the leadership of INGETEAM Service S.A. The construction of the INTERSOLAR bespoke test facility was also completed on time and the relevant deliverable report (D1.3) submitted.
Work concerning the development and evaluation of the transducer arrays started during the first reporting period, and one of the deliverables was reported then. More specifically, D2.1 concerning the simulations and modelling results, was submitted on time on Month 8. The remaining deliverables of WP-2 (D2.2 and D2.3) have been reported during the second reporting period.
Work in WP-3 also commenced in the first reporting period but D3.1 was due for reporting during the second reporting period. This deliverable was also submitted on time and concerned the signal processing and analysis tools for flaw sizing. Similarly work in WP-4 had commenced during the first reporting period and was successfully completed on time during the second reporting period.
The two deliverables associated with WP-4 were D4.1 regarding the development of the control system and software and D4.2 concerning the remote SCADA unit. Subsequently, WP-5 concerning integration, validation and troubleshooting commenced and was completed on time during the second reporting period. D5.1 on the integration of software and hardware and D5.2 on simulated trials and troubleshooting were completed and reported successfully and on time.
WP-6 associated with the demonstration of the complete INTERSOLAR system was also carried out during the second reporting period and completed on time. The results of the demonstration were included in Deliverable D6.1 An interim Exploitation and Dissemination plan was prepared and reported during the first reporting period as part of
D71. The Exploitation and Dissemination plan was further updated during the second reporting period and its final version reported in D7.2. Workshops, training, certification and contribution to standards taking place during the project were reported in D8.1. Transfer of the knowledge gained by the RTDs during the last 15 months of the project to the consortium has taken place as part of WP-8.
The main objectives of the INTERSOLAR project have been to develop and demonstrate an innovative and intelligent structural health monitoring system for CSP plants based on EMATs which is capable of being installed in the field for long term online operation.
The development work has been carried out with reference to: a) EMATs modelling and manufacturing of sensors for monitoring solar receivers and insulated pipelines, b) data acquisition, pulser-receiver, and control unit, c) software and signal processing, d) SCADA unit and e) test rig.
A key aspect of the project is the demonstration of the integrated system as well as its individual subcomponents in the field followed by successful commercialisation. In order to achieve this the consortium has carried out extensive trials on the bespoke test facility developed by the consortium as part of the INTERSOLAR project.
To achieve the objectives set in the project, the consortium has followed a step-by-step approach in order to implement the key project deliverables.
The principle objectives of the project have been to:
• To develop the specifications for the INTERSOLAR system and condition monitoring requirements.
• To specify and procure samples.
• To design and construct the INTERSOLAR test rig.
• To complete the simulations and modelling for the EMAT sensors.
• Complete the design of EMAT sensors and test them.
• Assess the performance of the EMATs sensors under realistic operational conditions.
• Develop an appropriate signal processing methodology and associated algorithms.
• Develop the control software for the operation of the INTERSOLAR system.
• Develop the control and SCADA units of the INTERSOLAR system.
• Validate and troubleshoot the integrated INTERSOLAR system.
• Demonstrate the complete INTERSOLAR system under realistic operational conditions.
• To publish key results and participate in conferences.
• To prepare dissemination material (leaflets, posters).
• Disseminate the project’s achievements and main results to the CSP industry and to the rest of the scientific community.
• Transfer knowledge developed from the RTD performers to the SMEs.
• Develop training procedures.
• Complete the final exploitation plan for the appropriate use of the technology and foreground knowledge developed and demonstrated during the project leading to the successful commercialisation of the INTERSOLAR system and subcomponents.
• Determine the optimum route for commercialisation.
Potential Impact:
Research results have already been published in international conferences (4 papers published in the proceedings of various international conferences), a journal paper has been published in the International Journal of Renewable Energy (Impact Factor: 3.456) whilst two more journal papers have been submitted to other journals with similar impact factors. In addition, the consortium members have been asked to contribute a chapter on NDT in Concentrated Solar Power Plants to a book on NDT in Renewable Energy that will be published by Elsevier in 2017 and is currently under preparation.
A project poster and leaflet have also been prepared by the consortium. Finally, a project website (www.intersolar-shm.com) has been designed and created for the wider dissemination of the project’s main results. An interim exploitation plan has also been prepared by the consortium and the relevant deliverable submitted (D7.1). The exploitation plan will be finalised at the end of the project on Month 24.
Patents, copyrights, registrations of trademarks or other IPR exploitation activities are under consideration or already in place for several subcomponents of the INTERSOLAR system. For the integrated system IPR activities are under discussion between the consortium members. Discussions regarding commercialisation have also been initiated.
One of the main ideas in terms of commercial exploitation is the creation of a new joint venture between the SMEs which will sell the INTERSOLAR system in its integrated form to CSP operators and maintenance companies. The new company will also provide services and will redistribute the profit arising according to the shares owned by the original companies participating in the new venture.
The final exploitation and dissemination of knowledge document has been drafted and approved by the consortium partners. This document details the past, current and future efforts undertaken for exploitation and dissemination.
The potential impact of the final INTERSOLAR product following its commercialisation can be profoundly positive to the CSP industry since a much more improved predictive maintenance strategy minimising downtime can be achieved. This would increase the productivity and consequently the profitability of CSP plant operators.
The constantly growing global energy demand coupled with the increasing effects of climate change have resulted in an urgent need for more widespread use of stable renewable sources of energy. Concentrated Solar Power (CSP) is a rapidly growing renewable energy source. It can be used for predictable utility-scale power generation facilitating more efficient integration of larger amounts of renewable energy to the grid. As of 2015, there are more than 35 CSP plants of various sizes producing more than 2.5 GW of power in the EU. This represents more than 55% of the total global CSP capacity being produced by more than 70 CSP plants currently amounting to 4.8 GW. Outside Europe, there are 14 CSP plants in the U.S. with 4 of the biggest ones having been completed in 2014, 5 in China and more than 16 over the rest of the world. In late 2015, 25 new CSP plants have been reported to be under construction worldwide that will add another 2.5 GW of capacity with 265 MW installed in Europe. Several more CSP projects have been announced in several countries. If all of them materialise they will result in further 15 GW of CSP capacity being connected to the grid by 2020. According to the International Energy Agency’s SolarPACES group CSP has the potential to cover up to 25% of the global energy demand by 2050 . The investment in new CSP project increased from €1.65 billion in 2009 to over €6.5bn in 2013 . By 2050 the total investment in CSP could exceed €150 billion. The annual turnover of the solar thermal power industry and its added value to the European economy was estimated to be €15 billion for 20113. Moderate estimations indicate that the global CSP market will worth more than €50 billion by 2020 . The Operational and Maintenance (O&M) costs are currently estimated at 13-25% of the overall CSP market or €700 million in 2011. Moderate estimates predict that the global CSP market will worth more than €50 billion by 2020 .
Solar receiver and coolant system failures are the most significant single cost factor in O & M expenditure of CSP plants, representing 25-30% of the Levelised Cost of Electricity (LCOE)8 which at the moment is estimated at €0.15-€0.23/kwh with the current cost of maintenance being €0.04-€0.08/kwh. Reducing the cost of maintenance without compromising operational reliability would improve the value for money for the European CSP industry as a whole which aims to reduce LCOE down to at least €0.10-€0.14/kwh by 2020. It would also release substantial capital for new investments contributing to the further rapid expansion of CSP and renewable energy in general within the EU.
The non-destructive testing (NDT) market is highly competitive sector where SMEs also have a significant presence . NDT equipment suppliers and inspection service providers form an important part of the overall supply chain either directly to the end-user CSP plant operators and constructors or to their main mechanical engineering/asset management suppliers. There are hundreds of companies throughout the EU, most of them SMEs, involved in direct and indirect commercial activities within the CSP market with several having activities in maintenance, inspection and consultancy engineering for CSP plants . CSP plant operators rely on NDT equipment providers in order to develop the necessary systems and techniques for traditional inspection activities and components. Also, companies which provide inspection services normally carry out on-site NDT inspection of inspectable plant infrastructure on behalf of the operator during pre-determined outages. It has been estimated that the total CSP plant European inspection market is currently in the range of €100 million with a potential of increasing up to €0.5 billion by 2020. The CSP plant inspection and maintenance market is expected to rise in line with the growth of the CSP market until at least 2050.
List of Websites:
As part of the INTERSOLAR project management and dissemination activities, CIT hosts a website on behalf of the consortium with the domain name www.intersolar-shm.com.
The purpose of the website is two-fold:
1. A public area for the dissemination of information about the INTERSOLAR project. A project page provides an introduction to the project. In addition, a contact page on the website provides telephone and form access to CIT’s scientists, and specific enquiries will be automatically forwarded to all relevant project partners. The website also supports the exploitation of the key project deliverables.
The following figure shows the homepage of the website as it appears on a standard web browser. Certain project pages currently provide an overview of the project. As the project advanced, more information relating to the project activities, including project work descriptions and publications, has been added to the website. The website will also host an electronic leaflets and a poster giving an overview of the project.
2. A secure member area to act as a repository for project related information and to allow easy transfer of electronic information between consortium partners. This secure area is only accessible with the correct username and password specific to each consortium partner.
Partners have been asked to make links from their websites to the INTERSOLAR project website in order to help improve the website’s ranking in search engines. Currently the following partners have established links from their company websites:
1. CIT
2. Engitec
3. UCLM
4. BU
Project posters and leaflets
A number of A0 posters have been designed and created by the consortium and a leaflet has been designed and created. Posters, leaflets and brochures are planned until the end of the project as dissemination material.