Reported from CSPPLAZA: Since completed on March 17, 2013, Shams1 CSP plant with 100MW has been running for about four years and six months. As one of the largest solar thermal power projects in the Middle East, the plant is designed to generate 210 million kilowatt hours of electricity per year, while its actual electricity generation has always exceeded expectations over the past three years.
Figure: Annual electricity production of Shams1 during 2014~2016 (source: Shams power company)
In line with previous years, 2017 generation is once again exceeding the expectations, as the plant has been able to export 148 GWh during the first 8 months of the year.
This excellent performance is inseparable from previous good design, construction and debugging, however, the operation and maintenance work in later development which lasted for more than twenty years as a “protracted war” is almost occupied power station throughout its life cycle, its success not only relates to the final produced electricity of the power plant, also relates to the actual effect of all the antecedent work.
Therefore, there must be some great experience other CSP projects can benefit from Shams 1 plant about the optimized ways of debugging, operation and maintenance. Besides, most China first CSP plant owners are plunging theirselves in to constructing their plants, and naturally the next challenge they need to face is the commission as well as O&M. CSPPLAZA journalist interview Borja Sanz, Plant Manager in Shams Power Company.
Borja Sanz started in the solar business in 2006. He has been involved in all phases of projects from their design to the operational phase, being this last stage where he has grown from the bottom to the top of the organization. He was first involved in the Solucar Platform, a complex with 5 solar power plants, where he led the engineering team for few years. He then moved to Abu Dhabi, where he took the responsibility of operating Shams One, one of the largest CSP plants in the world and the first of its kind in Middle East. Initially in the Operation Manager role and ultimately as Plant Manager, position he currently holds.
CSPPLAZA: How will you appraise the importance or value of Operation & Maintenance (O&M)?
Borja Sanz: The O&M is a critical and key factor in the success of any project. A proper O&M of an asset is what make a well designed, built and commissioned plant to finally generate the expected electricity and revenues for the stakeholders and shareholders. Even more, O&M team also contributes to the successful development of the project during the construction and commissioning phase as can anticipate potential problems that are easier to be resolved before starting the commercial operation.
O&M activities are even more important when a project is handed over still with some deficiencies compared to the design, which is normally the case. In those cases, O&M activities adequately handled can make a project to still perform within certain expectations until problems are fixed. In fact, O&M plays a key role in the resolution of these problems, as well as in the optimization of the project once during the commercial operation phase.
Some companies tend to underestimate the importance of the O&M activities. For instance, some often try to find savings during the mobilization period of the O&M staff, which normally results into a terrible hand over from the EPC contractor, ending up into low generation and performance during the initial phase of the commercial operation, normally much more costly than those savings during the mobilization period.
CSPPLAZA: What is the total cost of O&M (its percentage in CSP plants’ total investment)? What are the main parts of O&M cost?
Borja Sanz: Different studies typically consider 0.02-0.03 USD/kWh as a good reference for O&M costs. However, the O&M cost will strongly depend on the particularities behind each project (location, design, size, storage, synergies, etc.).
CSPPLAZA: What are the daily tasks of O&M in a CSP plant?
Borja Sanz: The responsibility of the O&M team is to ensure that the plant is operated with optimum efficiency, availability and safety, generating the expected amount of electricity and corresponding revenues. This should be done in an appropriate manner: controlling expenses, building good stakeholders relationships, ensuring that safety initiatives are implemented, etc. Therefore, there are a great number of activities of a completely different nature around the O&M of an asset.
On the technical side, O&M teams usually work in a way similar to conventional power plants. Despite being a renewable technology, many of the equipment are similar to those used in conventional power plants (turbine, pumps, motors, compressors, etc.), and therefore the required O&M is similar.
The operation team leads the daily start-up and operation of the plant both from a control room and in field, monitors the status of equipment by doing rounds and reporting abnormalities to the maintenance team, and is in charge of the preparation of the equipment when any maintenance is required and before handing over the equipment (Operation is normally the leader of the “Permit to Work” and “Lock-out Tag-out” systems). Equipment log-sheets, isolation certificates, service requests… are tools that operators use on daily basis to perform their job.
On the other hand, the maintenance team takes care of any required corrective maintenance, as well as the maintenance plan as per OEM and industry best practices. Leading the scheduling and planning of maintenance activities based on the work load and priorities is one of the key areas behind any maintenance department. When receiving a service request (or notification) from the operation team, and after the required coordination, maintenance will plan the resolution of any activity, for which it will be also required to deal the procurement department and, eventually, with vendors. Normally under the maintenance team, the cleaning activities are also presented as key tasks as the performance of the plant will directly depend on the cleaning conditions. A number of other important activities such as inspection of equipment, reliability programs… are also required as part of the O&M. These activities, depending on each company and potential synergies between projects, can be organized differently.
Operation and maintenance teams must be supported by an HSE and an Engineering team. They provide a key support to ensure that activities are performed safely and that the performance of the plant is monitored using models, defining any required actions.
CSPPLAZA: What are the differences between parabolic trough and tower projects’ operation and maintenance procedures?
Borja Sanz: Each technology has its own particularities, and therefore a number of procedures will differ between them. The principles in terms of O&M will be similar: operation will lead the daily start-up, will use log-sheet to monitor the status of equipment raising abnormalities to maintenance, etc., while maintenance will take care of performing corrective actions, when required, will ensure the fulfillment of the maintenance plan as required, etc. However, many procedures around the operation and maintenance of trough and tower plants differ significantly.
On the operation side, for instance, an important difference is the inertia during transients if we compare trough with steam tower plants. Although it will depend on the design of each project, inertias are normally lower in tower technology than in trough, so the operation strategy and reaction to transients should be defined accordingly. When comparing trough to molten salt tower plants, however, the main differences are probably around the receiver, which should be drained every night.
On the maintenance side, it is important to notice that, while some equipment are common between trough and tower technologies and even when comparing with conventional power plants, many others such as mirrors, receivers, molten salts heat exchangers, pumps, etc. differ between technologies and therefore require certain level of expertise and specialization. Corresponding O&M procedures therefore differ significantly.
Finally, it should be highlighted that particularities behind the fluid used as HTF (normally oil in trough and molten salts in tower) make a great difference in many operation and maintenance procedures.
CSPPLAZA: Thermal storage systems are equiped in some CSP stations, while other projects especially those early ones don’t use storage system. What are the differences when operate and maintain the two kinds of projects?
Borja Sanz: The storage system is one of the key systems in CSP plants. It is in fact the system that makes the difference when it comes to compare CSP with other technologies in new developments. One could say that the storage system, including its different equipment (pumps, tanks, exchangers…) should be simply operate and maintained following OEM recommendations. However, the experience in some projects shows that this system in particular should be monitored extremely carefully. Storage systems normally use molten salts, which solidify at a really high temperature. Mistakes in this system can result into huge expenses for the projects. Heat exchangers should be operated and maintained properly, as it could otherwise result into damages with major impact in the whole storage system and therefore the whole project. Dedicated staff with specific knowledge is probably a great approach especially during the early stage of operation.
CSPPLAZA: People also wonder how many staff need in O&M. Take the 50MW solar thermal power station equipped with energy storage system for example, how many person will be needed in daily O&M in total, (what are their duties) and how many people are respectively required in solar field, thermal-storage land and power block 3parts?
Borja Sanz: Different companies have different approaches to the O&M activities. The stage of the project is also an important factor when defining the required resources. In this sense, a project just handed over will normally require more resources than a mature project in stable conditions. Although it depends on the particularities behind each project, I believe that, as reference, a 50 MW plant with storage would require during its first years of operation following resources: 1 operation supervisor always present at site, 2 control room operators during day time and only 1 during night hours, 3 power block operators always present at site, 2 solar field operators always present at site, 4 maintenance supervisors, 12 maintenance technicians (incl. mechanical, electrical and I&C), cleaning staff in a number that would depend on the environmental conditions, warehouse staff and additional resources for HSE and engineering support.
The total number of employees for positions in shift will obviously increase in order to be able to cover the established rotation patterns.
CSPPLAZA: What kind of shift system is usually adopted? How many people in each shift?
Borja Sanz: This differs between countries and companies. Depending on the labor law, the maximum working hours per week will vary. Accordingly, the total number of operators required to cover the same necessities per hour will vary. That is the reason why the important step is the definition of necessities at every moment (for instance, 2 control room operators during day and only 1 during night time). The total number of control room operators required to satisfy that necessity will be later on easily calculated depending on the labor law (maximum working hours per week and minimum leaves per year) and company HR policy. Typically, shifts patterns are of 12 hours shift (day and night) and 8 hours shift (morning, afternoon and night) when some positions are required during 24 hours. However, even several shift patterns can be used for different positions within the same O&M team depending on the necessities.
CSPPLAZA: What are the main major challenges or problems happening during O&M process?
Borja Sanz: I would say that the first challenge takes place during the construction and commissioning of the plant, as it is then when the O&M team mobilization takes place. During this phase, attracting and later on developing staff to be ready to take over the operation of the plant is a challenge. Being late in these tasks can end up into an inappropriate handover of the plant by the O&M team, which would definitely result into costly operation mistakes or even accidents. Also during this phase, it is critical that the O&M procedures, strategies and philosophy are well defined.
Once the O&M team takes over the operation of the plant, a number of technical challenges are usually faced in different systems. Reliability should be one of the key objectives, for which an adequate reliability program must be implemented. Also during this phase, the O&M team starts to experience how all procedures and coordination tools defined during the commissioning phase work. It often happens that these tools need to be adjusted based on real experience depending on the particularities of the project. Creating the adequate environment to adjust all these procedures and tools while still performing the daily O&M activities is a great challenge that management should address effectively to keep the asset and activities under control.
CSPPLAZA: Could you please share some suggestions for China CSP project owner based on your several years of experience in O&M?
Borja Sanz: I strongly suggest defining and implementing an adequate mobilization plan, ensuring that personnel is on board early enough to get familiar with the project and be trained on it. For this training, it is of extreme importance to receive training from the different vendors on the different systems and also around the integration of all of them together. Having in place a training matrix is a must.
An action plan for the development of O&M documentation should be one of the key activities during the commissioning phase. Some companies rely on the OEM manuals when it comes to O&M procedures, or even in documentation as a deliverable from the EPC contractor. While this is correct, I believe this is not complete. The O&M team should develop its own procedures in line with the OEM manuals. This will in fact also serve as training for the staff during this period. Related with the documentation, the O&M team should ensure that the O&M philosophy and strategies are developed during the commissioning period, and that required actions are put in place. For instance, it is in this philosophy where the activities to be subcontracted or software to be used will be defined. Accordingly, the required service agreement with third parties should be put in place well in advance to ensure they are available since the completion of the plant to avoid surprises. Some service agreements with certain experts on specific systems are definitely recommended as it is really challenging to expect to cover all required technical knowledge within the O&M team.
Last but not least, safety should not be underestimated. CSP plants are similar to chemical plants in many aspects, and therefore a number of risks can be encountered. A proper analysis and implementation of required action to ensure safe operation is extremely important.