Driven by the "dual-carbon" goals, the power industry is accelerating its transformation from "high-carbon power generation" to "low-carbon operation". As the core power equipment of power plants, generator rotors operate at high speeds of 1500-3000 rpm. Due to electromagnetic losses and mechanical friction, they generate a large amount of heat. If not cooled in a timely manner, excessive temperature of the rotor windings will cause aging of the insulation layer (for every 10°C increase in temperature, the insulation life is shortened by 50%), and may even lead to major failures such as rotor deformation and shafting vibration. Among traditional rotor cooling methods, air cooling is only suitable for small units below 100MW; internal water cooling carries the risk of water leakage and short circuits; while conventional hydrogen cooling relies on hydrogen production from fossil fuels (e.g., coal-to-hydrogen, natural gas-to-hydrogen), which produces approximately 10-15kg of carbon emissions per 1kg of hydrogen, conflicting with low-carbon goals.
Water electrolysis for hydrogen production uses water as raw material and decomposes water into hydrogen (with oxygen as a by-product) driven by electrical energy. When combined with off-peak electricity from power plants or renewable energy sources (wind power, photovoltaics), it can achieve "zero-carbon hydrogen production". Integrating this technology with rotor cooling systems not only leverages the advantages of hydrogen, such as high thermal conductivity (7.1 times that of air and 1.5 times that of water) and low density (reducing rotor windage loss by approximately 30%), but also solves the carbon emission problem of traditional hydrogen production, making it a key technical path for power plants to "reduce carbon and improve efficiency".
I. Analysis of Core Technical Principles
(1) Technical System of Water Electrolysis for Hydrogen Production
Based on the type of electrolyte, water electrolysis for hydrogen production is divided into three main technical routes, each with distinct characteristics suitable for different power plant scenarios:
- Alkaline Electrolysis (AE)
It uses KOH/NaOH solution as the electrolyte and nickel-based materials (e.g., nickel mesh, nickel alloy) as electrodes, operating at a temperature of 60-80°C. The hydrogen production efficiency is 70%-80%, and the purity of produced hydrogen exceeds 99.8%. Its advantages include low equipment cost (approximately 1500-2000 CNY/kW) and stable operation, making it suitable for large-scale fixed hydrogen production scenarios in power plants. However, it has a slow start-up response (requiring 30-60 minutes), making it difficult to adapt to the fluctuating electrical energy from wind power/photovoltaics.
- Proton Exchange Membrane Electrolysis (PEM)
It uses a perfluorosulfonic acid proton exchange membrane as the electrolyte and platinum/iridium-based catalysts, operating at 60-80°C. The hydrogen production efficiency is 80%-85%, and the hydrogen purity reaches 99.99%. Its strengths lie in fast start-up (<10 seconds) and high current density, enabling flexible tracking of fluctuations in renewable energy power. It is suitable for peak shaving in power plants or renewable energy consumption. The downside is the high cost of membrane materials and catalysts (equipment cost is approximately 4000-6000 CNY/kW).
- Solid Oxide Electrolysis Cell (SOEC)
It uses ceramic oxides as the electrolyte and operates at a high temperature of 700-900°C. The hydrogen production efficiency is 85%-95%, and it can utilize waste heat from power plant boilers to reduce power consumption (power consumption per 1kg of hydrogen is reduced to below 40kWh, 15%-20% lower than that of AE/PEM). Currently in the demonstration stage, it is suitable for "electro-thermal synergistic hydrogen production" scenarios in high-parameter power plants in the future.
Regardless of the technical route,water source pretreatmentis a critical link: if fresh water is used, multi-media filtration (to remove suspended solids) and ion exchange (to reduce hardness and prevent scaling) are required; if circulating water or reclaimed water from the power plant is used, additional units such as activated carbon adsorption (to remove organic matter) and reverse osmosis (for desalination) are needed. This ensures the inlet water has a turbidity <1 NTU and total hardness <5mg/L, preventing electrode contamination or electrolyzer blockage.
(2) Coupling Principle of Rotor Cooling System and Water Electrolysis for Hydrogen Production
The coupling process of water electrolysis for hydrogen production and the rotor cooling system forms a closed loop of "hydrogen production - cooling - circulation - utilization", as detailed below:
- Hydrogen Production Stage: Pretreated water enters the electrolyzer, and electrolysis is driven by off-peak electricity from the power plant (with an electricity price of 0.2-0.3 CNY/kWh) or wind power/photovoltaic electricity. The produced hydrogen undergoes water washing (to remove water mist), molecular sieve drying (to reduce dew point to below -40°C), and pressure swing adsorption (to purify to 99.99% purity), meeting the hydrogen purity requirements for rotor cooling (GB/T 4706.1-2005 stipulates that the purity of hydrogen for cooling shall be ≥99.9%).
- Cooling Stage: The purified hydrogen is pressurized to 0.3-0.5MPa by a hydrogen compressor (matching the pressure requirements of the rotor cooling system) and sent to the air gap between the generator stator and rotor. The hydrogen flows through the rotor ventilation ducts, absorbs heat from the windings (temperature rises from 40°C to 60-70°C), and then enters the hydrogen cooler (cooled by the power plant's circulating water). After being cooled to 35-40°C, it re-enters the air gap, realizing hydrogen circulation (with a circulation rate of approximately 8-12 cycles per hour).
- By-Product Utilization: The oxygen produced by electrolysis (with a purity of over 99.5%) is dried, and part of it is used for secondary air combustion support in boilers (which can reduce the excess air coefficient and decrease flue gas heat loss by approximately 1.5%). The remaining oxygen is compressed, stored, and sold externally (with strong demand in medical and chemical fields, at a price of approximately 0.8-1.2 CNY/m³), improving resource utilization efficiency.
II. Application Feasibility and Core Advantages
(1) Feasibility Demonstration: Three Supporting Conditions
- Water and Energy Security
Power plants themselves have stable water sources (e.g., circulating water, reclaimed water, municipal fresh water), eliminating the need for additional long-distance water pipelines. Meanwhile, power plants experience "peak-valley electricity differences" (off-peak electricity utilization rate is only 70%-80%), and using off-peak electricity for hydrogen production enables "electric energy storage", avoiding waste from abandoned electricity. Taking a 2×1000MW power plant as an example, the surplus power during off-peak hours (22:00-6:00) is approximately 300MW, which can meet the demand of a 1500Nm³/h hydrogen production unit, producing 36,000Nm³ of hydrogen per day—fully covering the cooling hydrogen demand of two units (each unit consumes approximately 300Nm³ of hydrogen per hour).
- Mature Technical Readiness
Domestic water electrolysis for hydrogen production technology has achieved industrialization: the single-unit capacity of AE hydrogen production equipment exceeds 2000Nm³/h, the service life of PEM hydrogen production equipment reaches 60,000-80,000 hours, and the hydrogen purity is stably above 99.99%—fully meeting the hydrogen quality requirements for rotor cooling. In addition, the sealing technology of the rotor hydrogen cooling system (e.g., labyrinth seal, floating ring seal) is mature, with the hydrogen leakage rate controllable below 0.5% per day, meeting safety standards.
- Policy and Standard Support
The national "14th Five-Year Plan for the Development of Advanced Energy Storage" clearly proposes to "promote the coordinated operation of water electrolysis for hydrogen production with the power system". Local governments provide subsidies for low-carbon transformation projects of power plants (e.g., Shanghai and Guangdong offer subsidies of 10%-15% of the total investment for water electrolysis hydrogen production projects). Meanwhile, standards such as "Technical Specifications for Generator Hydrogen Cooling Systems (DL/T 1570-2016)" provide normative basis for the application of this technology.
(2) Core Advantages: Four Value Dimensions
- Low-Carbon Emission Reduction: From "Carbon Source" to "Carbon Sink"
Compared with traditional natural gas-to-hydrogen, water electrolysis for hydrogen production (using clean energy electricity) can achieve "zero-carbon hydrogen production". Taking a 1000MW unit as an example, its annual hydrogen demand for cooling is approximately 26,000Nm³. Using natural gas for hydrogen production results in annual carbon emissions of about 280 tons, while using photovoltaic electricity for water electrolysis only produces 15 tons of annual carbon emissions (mainly from equipment manufacturing), achieving a emission reduction rate of 94.6% and helping power plants achieve their "carbon neutrality" goals.
- Cost Optimization: Significant Long-Term Economic Benefits
In terms of initial investment, a 1500Nm³/h AE hydrogen production system (including pretreatment and purification) costs approximately 30 million CNY, and 15%-20% of this cost can be covered by policy subsidies. In terms of operating costs, hydrogen production using off-peak electricity costs about 18-22 CNY/kg, which is 40%-50% lower than externally purchased hydrogen (35-40 CNY/kg), saving approximately 5-6 million CNY in annual costs. Additionally, oxygen sales can bring an annual additional income of 800,000-1 million CNY, with an investment payback period of 5-6 years—superior to other low-carbon transformation projects (e.g., carbon capture projects have a payback period of 8-10 years).
- Efficiency Improvement: Extending Equipment Service Life
The high thermal conductivity of hydrogen can reduce the maximum temperature of rotor windings: in a certain power plant, the maximum temperature of rotor windings decreased from 110°C to 98°C after adopting water electrolysis hydrogen production for cooling, which is below the insulation grade limit (120°C). The insulation life is expected to be extended by 6-8 years, reducing the frequency of unit overhauls (from once every 3 years to once every 5 years), with each overhaul saving approximately 8-10 million CNY.
- Flexible Adaptation: Compatibility with Multiple Scenarios
The water electrolysis hydrogen production system can be coordinated with renewable energy power generation in power plants: when wind power/photovoltaic output is high, surplus electricity is used for hydrogen production; when output is low, hydrogen production is reduced to prioritize unit power supply. Furthermore, the hydrogen production equipment adopts a modular design (single module capacity: 500-1000Nm³/h), which can be flexibly increased or decreased according to the number of units, making it suitable for power plants of different scales (300MW-1000MW units).
III. Analysis of Practical Application Cases
(1) Renovation Project of an Inland Coal-Fired Power Plant in China
Located in Central China, this power plant has an installed capacity of 2×600MW. Originally, it used externally purchased hydrogen for cooling, with an annual hydrogen procurement cost of approximately 7.2 million CNY and carbon emissions of about 320 tons. In 2023, it implemented a water electrolysis hydrogen production renovation, adopting AE hydrogen production technology. The water source is the power plant's reclaimed water (undergoing "filtration - reverse osmosis - ion exchange" pretreatment), and the energy source is nighttime off-peak electricity (22:00-6:00, electricity price: 0.22 CNY/kWh). The hydrogen production scale is 800Nm³/h, with two supporting hydrogen drying and purification units (purity: 99.99%).
The operating data after renovation shows:
- The maximum temperature of rotor windings decreased from 108°C to 95°C, reducing the insulation aging rate by 40%;
- The hydrogen production cost is 19.5 CNY/kg, saving 4.2 million CNY annually compared to externally purchased hydrogen (36 CNY/kg);
- The by-produced oxygen (purity: 99.6%) is used for boiler combustion support, reducing standard coal consumption by 850 tons per year and carbon emissions by 230 tons;
- The system operates stably, with a hydrogen leakage rate of 0.3% per day and no safety accidents.
(2) Demonstration Project of a New Energy Power Plant Abroad
Located in Europe, this power plant has an installed capacity of 1×800MW (500MW photovoltaic + 300MW wind power). It adopts a coupled system of PEM water electrolysis for hydrogen production and rotor cooling, with a hydrogen production scale of 1200Nm³/h. The energy is fully sourced from photovoltaics/wind power, realizing a "zero-carbon hydrogen production - zero-carbon cooling" closed loop.
Innovation highlights of the project:
- Adoption of "hydrogen production - hydrogen storage - cooling" coordinated control: when photovoltaic/wind power output is high, surplus hydrogen is stored in a 100m³ high-pressure hydrogen storage tank (pressure: 35MPa); when output is low, hydrogen from the storage tank is released to supplement cooling demand, avoiding hydrogen supply interruptions.
- In-depth oxygen utilization: part of the oxygen is integrated with the power plant's photovoltaic panel cleaning system, using high-purity oxygen to improve cleaning efficiency and reduce the usage of cleaning agents (saving approximately 200,000 CNY in annual chemical agent costs).
One-year operation data: the renewable energy consumption rate increased from 82% to 95%, the failure rate of the rotor cooling system decreased from 3.2% to 0.8%, and the annual carbon emission reduction reached 1200 tons, making it a benchmark project for "new energy + hydrogen energy" coordination in Europe.
IV. Application Challenges and Countermeasures
(1) Existing Challenges: Three Core Pain Points
- Differentiated Difficulty in Water Source Pretreatment
For inland power plants using high-hardness groundwater, pretreatment requires additional softening units (e.g., lime softening), resulting in a cost 20%-30% higher than that of reclaimed water; for coastal power plants using seawater, additional chlorine removal units are needed (to prevent electrode corrosion), further increasing pretreatment costs.
- Cost and Service Life Bottlenecks of Electrolysis Equipment
The proton exchange membranes for PEM hydrogen production (service life: approximately 3-5 years, replacement cost accounts for 30% of the total equipment price) and platinum catalysts (with volatile prices) still rely on imports, with a localization rate of less than 40%; the ceramic electrolytes for SOEC hydrogen production are prone to cracking due to temperature fluctuations, with a service life of only 20,000-30,000 hours, making it difficult to meet the long-term operation needs of power plants.
- High Complexity of System Coordinated Regulation
The pressure and flow of the hydrogen production system and the rotor cooling system need to be accurately matched: if hydrogen production is excessive, the system pressure will increase (exceeding 0.6MPa will trigger the safety valve); if hydrogen production is insufficient, the cooling effect will decrease (resulting in overheating of the rotor). Existing regulation systems are mostly "separate control" and lack integrated intelligent scheduling capabilities.
(2) Countermeasures: Driven by Technology and Policy
- Targeted Optimization of Water Source Pretreatment Technology
- For inland high-hardness water sources: develop a combined process of "membrane softening + scale inhibitor" to reduce pretreatment costs by 15%;
- For coastal seawater sources: adopt "nanofiltration desalination + titanium-based coated electrodes" (chlorine corrosion-resistant) to extend the electrode service life to over 50,000 hours;
- Promote the "direct supply of power plant circulating water" technology: circulate water is directly sent to the electrolyzer after simple filtration, suitable for power plants with good water quality, reducing pretreatment costs by 40%.
- Promoting Localization and Upgrading of Electrolysis Equipment
- Policy level: Establish a "special fund for water electrolysis hydrogen production equipment" to support domestic enterprises in developing proton exchange membranes (targeting a localization rate of 80% by 2026) and SOEC ceramic electrolytes (extending service life to 50,000 hours);
- Technology level: Develop an "AE-PEM hybrid hydrogen production system", using AE for hydrogen production during off-peak periods (low cost) and PEM for hydrogen production during periods of renewable energy fluctuations (flexible response), balancing cost and flexibility.
- Building an Integrated Intelligent Regulation Platform
Based on digital twin technology, build an integrated "hydrogen production - cooling - hydrogen storage" platform:
- Real-time monitoring of over 200 parameters, including rotor temperature, hydrogen pressure, and electrolyzer current;
- Using AI algorithms to predict renewable energy output and cooling demand within 1 hour, and automatically adjust hydrogen production power;
- Setting up multi-level safety redundancies (automatic shutdown for excessive pressure, automatic alarm for hydrogen leakage) to ensure system stability.
V. Outlook for Future Development
The application of water electrolysis for hydrogen production in power plant rotor cooling systems will develop in three directions: "technological upgrading, multi-energy coordination, and industrial integration".
- Technological Upgrading: Breakthroughs in Both Efficiency and Cost
Short-term (before 2025): Increase AE hydrogen production efficiency to 85%, and reduce PEM hydrogen production equipment costs to below 3000 CNY/kW; Long-term (by 2030): Realize commercial application of SOEC hydrogen production, utilizing waste heat from power plant boilers (300-400°C) to drive electrolysis, reducing hydrogen production power consumption to below 35kWh/kg and breaking the cost barrier of 15 CNY/kg.
- Multi-Energy Coordination: Building an "Electricity-Hydrogen-Heat" Integrated Energy System
In the future, power plants will form a closed loop of "renewable energy power generation - water electrolysis for hydrogen production - rotor cooling - waste heat utilization": the electricity consumed by electrolytic hydrogen production can be counted as "green electricity consumption"; the waste heat generated by hydrogen cooling can be used for plant heating; the by-produced oxygen can be supplied to chemical parks. This realizes "one plant with multiple functions" and increases the overall energy utilization efficiency to over 90%.
- Industrial Integration: Promoting the Extension of the Hydrogen Energy Industry Chain
Large-scale power plants can rely on their water electrolysis hydrogen production capabilities to build "hydrogen energy hubs": on one hand, providing hydrogen for their own rotor cooling and boiler combustion support; on the other hand, supplying hydrogen to surrounding hydrogen refueling stations, hydrogen fuel cell buses, and chemical enterprises. This forms an industrial chain of "hydrogen production - storage - transportation - utilization" and drives the development of regional hydrogen energy economies.
The integration of water electrolysis for hydrogen production with power plant generator rotor cooling systems is not only a technological innovation but also a crucial path for power plants to transform from "single power generation" to "comprehensive energy service providers". With the decrease in technology costs, strengthened policy support, and improved industrial chain, this technology will achieve large-scale application during the "14th Five-Year Plan" period, providing key support for the power industry to achieve its "dual-carbon" goals. In the future, when water electrolysis for hydrogen production is deeply integrated with renewable energy and energy storage technologies, power plants will truly realize "zero-carbon operation" and become a core force in the energy transition.
Chlory's seawater electrolytic chlorination technology has been successfully applied in many countries, including Iraq, the United Arab Emirates, Iran, Malaysia, Singapore, the United States, and Canada, and is widely used in fields such as power plants, seawater desalination plants, andMunicipal waterworks. Based on this solid foundation, the introduction and application of water electrolysis for hydrogen production technology will inject new impetus into the sustainable development of power plants.