Tracking Green Hydrogen Projects: Shenzhen Institute and Changqing Oilfield Break Through Hydrogen Production Technology from Oil and Gas Wastewater, 100kW System Operates Stably for Over 60 Days in Sulige Gas Field

Recently, a 100kW-level oil and gas associated wastewater electrolysis hydrogen production system, jointly developed by China National Petroleum Corporation Safety and Environmental Protection Technology Research Institute (Shenzhen Institute) and Changqing Oilfield, has achieved stable operation for over 60 days in the Sulige Gas Field, China's largest integrated gas field by reserves. This breakthrough signifies a critical leap from laboratory research to engineering application in the full-chain resource utilization of oil and gas wastewater for "pollution reduction and hydrogen production" in China, providing an innovative technological pathway for the green transformation of the oil and gas industry and the efficient utilization of water resources.

Addressing the industry challenges of high difficulty and cost in treating high-salinity, high-organic-pollutant wastewater from oil and gas extraction, the Shenzhen Institute team, after years of dedicated research, established a bipolar synergistic catalysis theoretical system and successfully overcame the technical bottleneck of insufficient electrode material stability in high-salinity, high-pollution environments. The project team completed the full-chain development from a 20kW engineering prototype to a 100kW-level integrated system. The system is compatible with various treatment scenarios, including produced water, fracturing fluid, flowback fluid, and refining wastewater, while also possessing the potential for expansion into hydrogen production from seawater and municipal wastewater.

This system innovatively adopts a modular design with atmospheric/pressurized dual-configuration electrolyzers, forming a technical route of "graded treatment - synergistic hydrogen production": the atmospheric square electrolyzer module, equipped with self-developed highly salt-tolerant and pollution-resistant electrode materials, can simultaneously achieve electrocatalytic oxidation of wastewater and preliminary production of green hydrogen; the pressurized tank module uses low-concentration clean saline water after deep treatment as raw material to produce high-purity hydrogen. To date, the system has completed industrial trials with 5 types of fracturing fluids and flowback fluids, and 6 types of gas field produced water, cumulatively treating 24 mt of wastewater. The maximum hydrogen production rate reached 40 Nm³/h, with hydrogen purity stably maintained at 99.99%. The system's comprehensive hydrogen production energy consumption is controlled at 4.5 kWh/Nm³ H₂, an advanced level in the industry. According to third-party detection, the chemical oxygen demand (COD) removal rate of the treated wastewater reached 99%, achieving efficient coupling of deep pollutant degradation and clean energy production.

An economic feasibility analysis shows that under a green electricity cost of 0.3 yuan/kWh, the levelized cost of hydrogen for this technology is approximately 20.6 yuan/kg, representing a 25% reduction in comprehensive cost compared to the traditional "wastewater treatment + separate hydrogen production" model, laying the foundation for large-scale commercial application. As a demonstration project for CNPC's implementation of the "Four Waters and Four Determinations" principle, the successful operation of this system in the Sulige Gas Field not only provides a clean hydrogen energy supply for the gas field site but also resolves the dual challenges of "difficult wastewater treatment and tight energy supply" in oil and gas production areas.

According to the project leader from the Shenzhen Institute, the next step is to accelerate the development and engineering verification of a megawatt (MW)-level system, with plans to complete the construction of a 3 MW-level demonstration project by 2026. The goals are to further reduce the treatment cost per metric ton of wastewater by 15% and lower the hydrogen production energy consumption to below 4.2 kWh/Nm³ H₂. This technological pathway is expected to be replicated and promoted in large oil and gas production areas such as the Changqing Oilfield and Tarim Oilfield in the future. By 2030, it is projected to help PetroChina's oil and gas fields reduce wastewater discharge by 12 million mt per year and produce over 50,000 mt of green hydrogen annually, equivalent to reducing carbon dioxide emissions by 650,000 mt per year, providing important technical support for the energy industry's "dual carbon" goals.