Morocco, as an important country in Africa, has attracted much attention for its energy development. The country is relatively scarce in energy resources, with 85% of energy products relying on imports every year. This has prompted Morocco to vigorously develop various types of power plants to meet its electricity demand and actively explore efficient and sustainable energy utilization methods. Among the numerous power plants, some coastal power plants use seawater as circulating cooling water. However, the abundant microorganisms, algae, and marine organisms in seawater have caused serious biological fouling problems in the cooling systems, which have greatly affected the normal operation and efficiency of the power plants. Seawater electrochlorination technology, as an effective means to prevent biological fouling, has been applied in Moroccan power plants, providing a feasible solution to this problem.
I. Overview of the Development of Moroccan Power Plants
Morocco's electricity production covers various forms such as hydropower, thermal power, and wind power. At present, there are 20 hydropower stations with a total installed capacity of 1.16 million kilowatts; 30 thermal power stations, including oil-fired and coal-fired ones, with a total installed capacity of 3.16 million kilowatts. In addition, Morocco has actively deployed in the field of renewable energy power generation, such as the Noor Solar Thermal Power Station, which, as one of the world's largest solar thermal power station projects, is of great significance for the optimization of Morocco's energy structure. However, both traditional thermal power stations and emerging solar thermal power stations and other types of power plants face problems related to cooling systems during operation. Especially for power plants using seawater for cooling, biological fouling has become a key factor affecting their stable operation and efficiency improvement.
II. Principle of Seawater Electrochlorination Technology
The core of seawater electrochlorination technology is to generate strong oxidizing substances through the electrolysis of seawater, mainly sodium hypochlorite (NaClO) or chlorine gas (Cl₂), so as to kill or inhibit the growth of organisms in seawater, prevent them from attaching to the surfaces of pipelines and equipment in the power plant's cooling system, and thus avoid a series of problems caused by biological fouling. The basic chemical reaction process is as follows:
In the electrolytic cell, seawater (mainly composed of NaCl solution) undergoes an electrolysis reaction under the action of direct current. An oxidation reaction occurs at the anode, where chloride ions (Cl⁻) lose electrons to generate chlorine gas (Cl₂), and the reaction formula is: 2Cl⁻ - 2e⁻ → Cl₂↑; a reduction reaction occurs at the cathode, where water (H₂O) gains electrons to generate hydrogen gas (H₂) and hydroxide ions (OH⁻), and the reaction formula is: 2H₂O + 2e⁻ → H₂↑ + 2OH⁻. The generated chlorine gas (Cl₂) will further react with the hydroxide ions (OH⁻) produced at the cathode to form sodium hypochlorite (NaClO), and the reaction formula is: Cl₂ + 2OH⁻ → Cl⁻ + ClO⁻ + H₂O. Finally, the generated sodium hypochlorite (NaClO) or unreacted chlorine gas (Cl₂) enters the seawater cooling system of the power plant through a specific dosing method. These strong oxidizing substances can destroy the cell structure of microorganisms and marine organisms, denature their proteins, thereby achieving the purpose of killing or inhibiting their growth, effectively preventing organisms from attaching and reproducing in the cooling system, and ensuring the normal operation of the cooling system.
III. Application Examples of Seawater Electrochlorination in Moroccan Power Plants
(I) Jorf Phosphate Chemical Complex Steam Power Station
This power station was constructed by China Electric Power Construction Group and is equipped with a seawater cooling system for turbine condensation. Although it has not been explicitly reported that it specifically adopts seawater electrochlorination technology, in view of China Electric Power Construction Group's rich experience in applying electrochlorination technology to control biological fouling in seawater cooling systems in domestic projects, it is speculated that a similar seawater electrochlorination scheme is very likely to be introduced in the Jorf Phosphate Chemical Complex Steam Power Station project. In some similar domestic projects, sodium hypochlorite generated by seawater electrochlorination systems can stably control the number of microorganisms in seawater, significantly improve the biological fouling phenomenon of the cooling system, and ensure the efficient operation of power station equipment. By analogy, in this project in Morocco, seawater electrochlorination technology may also play a similar key role in ensuring the normal operation of the seawater cooling system and improving the overall operating efficiency of the power station.
(II) Jerada Coal-fired Power Station
Jerada Coal-fired Power Station is located in an arid area. If seawater is used for cooling (it is necessary to further confirm whether its actual cooling water source is seawater), it not only has to face the problems of equipment corrosion and scaling caused by the high salinity and high hardness of seawater but also needs to solve the problem of biological fouling. Seawater electrochlorination technology has important application value in such environments. Combined with the circulating fluidized bed dry desulfurization technology already applied in this power station, if seawater electrochlorination technology is adopted at the same time, it can solve the problem of flue gas desulfurization and effectively control the biological fouling of the cooling system. For example, in similar power stations in other regions, the content of microorganisms in seawater has been reduced to an extremely low level through seawater electrochlorination systems, which has significantly reduced the blocking frequency of cooling pipelines and improved the service life of equipment and power generation efficiency. In Jerada Coal-fired Power Station, the application of seawater electrochlorination technology is expected to provide a strong guarantee for the stable operation and efficient power generation of the power station, and also help reduce the maintenance cost and downtime caused by biological fouling.
IV. Technical Implementation Details
(I) System Configuration
- Electrolytic Cell and Power Supply: The seawater electrochlorination systems in Moroccan power plants usually use titanium-based coated electrodes (DSA) as key components of the electrolytic cell. This type of electrode has excellent corrosion resistance and can work stably for a long time in the highly corrosive environment of seawater. At the same time, it has high current efficiency, which can effectively improve the efficiency of the electrolysis reaction and reduce energy consumption. For example, the seawater electrochlorination system adopted by a large Moroccan power plant has an electrolytic cell with a chlorine production capacity of 2×45kg/h, which can meet the anti-fouling needs of large-scale seawater cooling systems. The power supply part is generally equipped with a special DC power rectifier, which converts alternating current into direct current to provide a stable current for the electrolytic cell. The rectifier can accurately adjust the output current and voltage according to the needs of the electrolytic cell to ensure that the electrolysis reaction is carried out under optimal conditions.
- Dosing Methods: In practical applications, the dosing methods of seawater electrochlorination systems mainly include continuous dosing and shock dosing. The continuous dosing method refers to continuously adding a certain concentration of sodium hypochlorite solution to the seawater cooling system to maintain the residual chlorine concentration in the system at 0.5-1mg/L. This method can continuously inhibit the growth of microorganisms and marine organisms, preventing them from multiplying in large numbers in the cooling system, thereby effectively preventing the occurrence of biological fouling. Shock dosing is to regularly increase the concentration of sodium hypochlorite solution to about 3mg/L for high-intensity sterilization treatment of the cooling system. This method can remove organisms that have attached to the surfaces of pipelines and equipment, prevent further growth and accumulation of organisms, and is usually adopted during periods of high risk of biological fouling or when a certain degree of biological attachment occurs in the system.
(II) Synergistic Treatment Technology
- Pretreatment: To ensure the normal operation of the seawater electrochlorination system, Moroccan power plants carry out pretreatment before seawater enters the electrolytic cell. A self-cleaning filter is usually used, with a filtration accuracy of up to 2mm. This filter can effectively remove suspended particles in seawater, preventing these particles from entering the electrolytic cell, causing blockage of the electrolytic cell, and affecting the normal progress of the electrolysis reaction. At the same time, the pretreatment process can also reduce the wear of impurities in seawater on the electrodes, prolong the service life of the electrodes, and improve the stability and reliability of the entire seawater electrochlorination system.
- Chemical Agents: In addition to seawater electrochlorination technology, Moroccan power plants also use chemical agents to further ensure the normal operation of the cooling system. For example, adding corrosion inhibitors (such as polyphosphates) can form a protective film on the surface of metal equipment, effectively reducing the corrosion rate of seawater on metals and prolonging the service life of the equipment. Scale inhibitors (such as organic phosphonates) can prevent calcium, magnesium, and other ions in seawater from forming scale on the surfaces of pipelines and equipment, avoiding the reduction of heat exchange efficiency and pipeline blockage caused by scale accumulation. Seawater electrochlorination technology and these chemical agents work synergistically to ensure the efficient and stable operation of the seawater cooling system of the power plant from multiple aspects such as preventing biological fouling, corrosion, and scaling.
(III) Environmental Protection and Compliance
- Residual Chlorine Control: Morocco has strict standards for industrial wastewater discharge, especially for residual chlorine content. If the residual chlorine generated during the operation of the seawater electrochlorination system is directly discharged, it may have a negative impact on the marine ecological environment. Therefore, Moroccan power plants need to carry out dechlorination treatment on the discharged seawater. Usually, a method of adding reducing agents such as sodium bisulfite (NaHSO₃) is adopted to reduce the residual chlorine in seawater to harmless chloride ions, ensuring that the discharged seawater meets Morocco's "Industrial Wastewater Discharge Standards". By accurately controlling the dosage of dechlorinating agents, it can ensure compliance with discharge standards while avoiding excessive treatment costs due to excessive dechlorination.
- Energy Efficiency: To reduce the energy consumption of seawater electrochlorination systems, Moroccan power plants are actively exploring various energy-saving measures. Some power plants have tried to adopt self-powered systems, such as combining renewable energy technologies such as triboelectric nanogenerators and solar cells. For example, a system developed in a research can use wind energy and solar energy to drive the electrolytic chlorine production process, which not only realizes the function of seawater electrochlorination but also greatly reduces the dependence on traditional grid power, with a sterilization rate of more than 95%. This way of using renewable energy not only helps to improve energy utilization efficiency and reduce operating costs but also conforms to Morocco's sustainable energy strategy, reduces carbon emissions, and has positive significance for environmental protection.
V. Chinese Enterprise Technology Export and Cooperation
(I) Technology Introduction Path
Many Chinese enterprises such as China Electric Power Construction and Shanghai Electric have played an important role in the EPC (Engineering, Procurement, Construction) projects of Moroccan power plants. Relying on their rich experience in seawater electrochlorination technology accumulated in China, these enterprises have integrated mature technologies into the design of seawater cooling systems of Moroccan power plants. For example, Shandong Electric Power Construction No.3 Engineering Co., Ltd. has successfully applied molten salt heat storage technology in the Noor Solar Thermal Power Station project, and its supporting cooling system is very likely to draw on advanced domestic seawater electrochlorination anti-fouling schemes. Shanghai Electric has demonstrated advanced membrane technology in the Safi seawater desalination project, which also indirectly reflects its profound technical accumulation in the field of seawater treatment, providing support for the introduction of related technologies in Moroccan power plant projects. Through cooperation with local parties in Morocco, Chinese enterprises have comprehensively introduced seawater electrochlorination technology from design, equipment supply to installation and commissioning into Moroccan power plants, helping Morocco improve the operation and management level of power plants.
(II) Localization Adaptation
Due to the characteristics of high salinity of Moroccan seawater (about 38‰ in the Mediterranean Sea), Chinese enterprises have carried out localization adaptation of the technology when introducing seawater electrochlorination technology. In view of high-salinity seawater, it is necessary to adjust the electrolysis parameters, such as appropriately increasing the current density to improve the electrolysis efficiency, ensuring that enough sodium hypochlorite can be generated to meet the anti-fouling needs; reasonably adjusting the electrode spacing to optimize the electric field distribution in the electrolytic cell and improve the uniformity and stability of the electrolysis reaction. In addition, some projects have adopted containerized modular design. This design method is convenient for quick installation and maintenance and can adapt to the construction conditions and operation management needs in Morocco. For example, the containerized modular design adopted in the Sino-Moroccan jointly developed seawater desalination plant has greatly shortened the project construction period, improved the maintainability of the equipment, and provided a good example for the successful application of seawater electrochlorination technology in Moroccan power plants.
VI. Challenges and Optimization Directions
(I) Main Challenges
- Electrode Corrosion: During the long-term operation of the seawater electrochlorination system, electrode corrosion is a problem that cannot be ignored. Although titanium-based coated electrodes (DSA) are used, due to the strong corrosiveness of seawater and the complex chemical environment during electrolysis, the electrode coating may gradually fall off. Once the coating is damaged, the corrosion resistance and electrolysis efficiency of the electrode will be affected. Usually, the service life of the electrode is about 3-5 years, after which it needs to be replaced, which increases the equipment maintenance cost and system downtime.
- Energy Consumption Cost: The energy consumption of seawater electrochlorination systems is relatively high, especially for large power plants, the continuous electrolysis process requires a lot of electric energy. With the fluctuation of electricity costs, this may have a greater impact on the operating costs of power plants. How to reduce the energy consumption of seawater electrochlorination systems while ensuring the anti-fouling effect has become one of the important challenges faced by Moroccan power plants.
- Regulatory Requirements: Morocco's regulatory requirements for industrial wastewater discharge are increasingly strict. In addition to clear restrictions on residual chlorine content, requirements for other related indicators have also been put forward. Power plants need to continuously optimize the operation and management of seawater electrochlorination systems to ensure that the discharged seawater fully meets the regulatory standards, which increases the complexity and management difficulty of system operation.
(II) Technical Optimization Trends
- Intelligent Control: To meet the above challenges, the seawater electrochlorination technology in Moroccan power plants is developing towards intelligent control. By installing online monitoring equipment, such as residual chlorine sensors that can real-time monitor the residual chlorine concentration in the cooling system, and biological slime monitors that can timely grasp the situation of biological fouling. Based on these real-time data, the control system can dynamically adjust the dosage to achieve precise dosing. When it is monitored that the residual chlorine concentration is low or the risk of biological fouling increases, the dosage of sodium hypochlorite is automatically increased; otherwise, the dosage is reduced. This intelligent control method can not only improve the anti-fouling effect but also avoid resource waste and environmental risks caused by excessive chlorination.
- Green Processes: The development of chlorine-free anti-fouling technologies is an important development trend in the future. At present, some research institutions and enterprises are exploring the application of green anti-fouling technologies such as ultrasonic waves and ultraviolet rays in power plant cooling systems. Ultrasonic technology can destroy the cell structure of microorganisms and marine organisms through high-frequency vibration, making them unable to attach to the pipeline surface; ultraviolet rays can achieve sterilization and disinfection by destroying the DNA structure of organisms. These chlorine-free anti-fouling technologies have the advantages of environmental protection and no secondary pollution. If they can be successfully applied in Moroccan power plants, they will provide a more sustainable solution to the problem of biological fouling and better meet Morocco's increasingly strict environmental protection regulatory requirements.
The application of seawater electrochlorination technology in Moroccan power plants is of vital significance for ensuring the efficient operation of seawater cooling systems and improving the power generation efficiency of power plants. Through practical applications in multiple power plant projects, this technology has effectively solved the problem of biological fouling and ensured the stable operation of cooling systems. Chinese enterprises have actively exported seawater electrochlorination technology in Moroccan power plant projects and carried out localization adaptation according to local conditions, providing strong support for the development of Moroccan power plants. However, this technology still faces challenges such as electrode corrosion, high energy consumption costs, and strict regulatory requirements during application. Chlory Company has been committed to the development and application of seawater electrochlorination technology. In the future, with the continuous development and application of technologies such as intelligent control and green processes, seawater electrochlorination technology is expected to achieve more efficient and environmentally friendly operation in Moroccan power plants, making greater contributions to the development of Morocco's energy industry. At the same time, continuously paying attention to and researching the optimization directions of related technologies is of great practical significance for further improving the operation management level and sustainable development capabilities of Moroccan power plants.
Chlory Company, with its advanced seawater electrochlorination technology, has successfully promoted its mature system to many countries such as Algeria, Spain and Morocco, and it is widely applied in key fields such as water plants, power plants and sewage treatment plants. With its outstanding performance and stable performance, this system has received high praise and unanimous approval from end users.