In the preparation process of hydrogen production by electrolysis of water, electricity, water and hydrogen production equipment are indispensable. At present, most people tend to focus on the price of electricity and the cost of electrolyzers, while the question of the source of water is often overlooked. However, without a stable supply of water, large-scale hydrogen production will not be sustainable.
Recently,'s first set of mild saline-alkali water in-situ electrolytic prototype successfully passed the expert review; Dalian Institute of Chemical Physics Coal Chemical Wastewater Hydrogen Co-production Freshwater Pilot Plant was successfully started; Dongfu Research Institute has completed a series of news such as the field test of hydrogen production from produced water in gas fields without purification, which allows people to see the possibility of hydrogen production from "wastewater", which may solve the water shortage crisis of large-scale hydrogen production from renewable energy in the future.
How to solve the "water shortage" crisis of large-scale hydrogen production
According to the statistics of the High-tech Hydrogen and Power Industry Research Institute (GGII), as of May 2024, the total installed capacity of domestic water electrolysis hydrogen production demonstration projects under construction and planning exceeded 72GW, and the number of green hydrogen projects under construction and planning exceeded 72GW/(5.46 million tons). Green hydrogen projects account for 99%, of which wind-solar coupling hydrogen production accounts for about 70%.
Ideally, the minimum consumption of electrolyzed water is about 9 kg of water per kilogram of hydrogen. In the future, these green hydrogen projects, once completed, will require tens of millions of tons of freshwater supply. However, most of these wind-solar coupled hydrogen production projects are concentrated in areas with relatively scarce water resources, such as Xinjiang, Gansu and Inner Mongolia, and the mismatch between the geographical distribution of renewable energy and freshwater resources in mainland China, as well as the shortage of freshwater resources, have become challenges hindering the development of the green hydrogen industry.
In view of the abundant scenery resources but the lack of water resources in the northwest region of the mainland, the research team in the mainland thought of making full use of the local "wastewater" resources such as brackish water, salt lake water, industrial wastewater and domestic sewage to reduce the cost of hydrogen production, so as to promote industrial development and ensure national energy security.
In terms of the use of saline-alkali water, on June 22 this year, the in-situ electrolyzer of mild saline-alkali water jointly developed by Xinjiang Energy and Chemical Co., Ltd., State Nuclear Power Planning and Design Institute Co., Ltd. and Jiangsu Trina Hydrogen Technology Co., Ltd. successfully passed the on-site operation test and expert review. During the test, the hydrogen output of the prototype reached the rated value, the DC power consumption per unit hydrogen production was 3.935kWh/Nm³, the current density reached more than 5000A/㎡, and the load of 30%-110% was continuously and stably. Compared with the traditional alkaline water electrolysis hydrogen production system, the system link is shortened, and a new breakthrough in the in-situ hydrogen production technology of saline-alkali water has been achieved.
In terms of the utilization of industrial wastewater, on June 20, Dalian Chemical Institute made new progress in the resource utilization of coal chemical wastewater, developed a new technology for preparing high-purity hydrogen co-production freshwater from coal chemical wastewater as raw material, and completed the test and verification of a 25 kilowatt pilot plant based on this technology. The chemical oxygen demand (COD), total nitrogen and salinity of the wastewater were 51,000 mg/L, 2,892 mg/L, and 32,000 ppm. The operation results of the pilot plant show that the high-efficiency hydrogen production and co-production of freshwater from coal chemical wastewater have been realized, with a hydrogen production capacity of 30,000 cubic meters per year, a hydrogen purity of ≥ 99.999%, and the freshwater produced is 6 tons/year of freshwater on the basis of meeting its own electrolysis needs, which proves the feasibility and advancement of the new technology of hydrogen production and co-production of freshwater from coal chemical wastewater.
In May this year, the team of Dongfang Electric (Fujian) Innovation Research Institute Co., Ltd. (hereinafter referred to as "Dongfu Research Institute") successfully completed the field test of hydrogen production by purification electrolysis of produced water from PetroChina Changqing Oilfield Gas Field in Ordos, Inner Mongolia. During the test, the hydrogen production of the demonstration prototype reached the rated value, and the field measurement showed that the hydrogen purity reached 99.999%. The project will provide a route reference for hydrogen production from industrial wastewater such as petrochemical wastewater and steelmaking wastewater.
In terms of the use of domestic sewage, at the 25th IE Expo China this year, Shanghai Fujie Environmental Protection demonstrated the "Pilot Test Application Research Project of the Whole Chain of 'Hydrogen Production-Hydrogen Storage-Combined Heat and Power' of Urban Sewage Plants". Relying on the Shanghai Municipal Sludge Treatment and Resource Utilization Technology and Equipment Research and Verification Base, the project realizes the full-chain application and circular economy demonstration of "green hydrogen preparation-solid-state hydrogen storage-cogeneration" in sewage plants for the first time in the world by electrolysis of reclaimed water from photovoltaic power generation in sewage plants, and hydrogen production from biogas produced by anaerobic digestion of sludge, and then connected to safe hydrogen storage technology and equipment, hydrogen fuel cells and high-efficiency hydrogen use scenarios (such as solid-state hydrogen storage sightseeing vehicles).
In the past, "wastewater" resources such as saline-alkali water, industrial wastewater and domestic sewage were treated in a complex manner, and the costs of the entire treatment process were much higher than the benefits. However, the resource endowment dictates that renewable energy hydrogen production projects must make good use of precious water resources. Exploring hydrogen production from wastewater not only solves the problem of water for hydrogen production, but also saves billions of environmental protection investment costs for the local area, so it is of great significance to develop new methods and technologies for hydrogen production using wastewater as raw materials.
The future of large-scale "wastewater" hydrogen production is promising
In fact, in the research project of hydrogen production using "wastewater" resources, the shadow of hydrogen production from "seawater" can be seen. The new technology of Dalian Chemical Institute in the resource utilization of coal chemical wastewater is a further expansion and application of the new technology of seawater hydrogen co-production and freshwater co-production developed by the research team of Deng Dehui of the university.
In addition, the field test project of hydrogen production by purification of produced water from gas field of Dongfu Research Institute was transformed by the team of Xie Heping, academician of the Chinese Academy of Engineering and dean of the Institute of Deep Earth Science and Energy of Shenzhen University, on November 30, 2022, in Nature. On December 16, 2022, Dongfang Electric signed a contract with the team of Academician Xie Heping to carry out joint technological innovation, and Dongfang Electric Group is responsible for the transformation and industrialization of achievements. In November 2023, Dongfu Research Institute signed a project cooperation agreement with PetroChina Changqing Oilfield Branch to apply the in-situ direct electrolysis hydrogen production technology of undesalined seawater to Changqing Oilfield.
As the technical source of "wastewater" hydrogen production, seawater hydrogen production technology is currently exploring the effective combination with renewable energy power generation. On June 21 this year, Nature Communications published that the team of Academician Xie Heping and the team of Dongfang Electric Group cooperated to realize the integration of offshore wind power renewable energy and seawater direct electrolysis hydrogen production for the first time, and used offshore wind power to drive seawater hydrogen production in the sea. In the future, this achievement is also expected to be widely used in more fields, and it is foreseeable that the integration process of large-scale onshore renewable wind and solar resources and "wastewater" hydrogen production will be accelerated.
In terms of the cost of direct electrolysis of seawater hydrogen production, it is estimated that when the electricity price is lower than 0.15 yuan/kWh, the hydrogen production from seawater is equivalent to that of gray hydrogen from coal; When the electricity price is lower than 0.11 yuan/kWh, the cost of hydrogen production from seawater will be completely lower than the cost of coal to ash hydrogen. If the cost of hydrogen production from wastewater is comparable to the cost of direct hydrogen production from seawater in the future, then compared with the cost of water treatment that often invests hundreds of millions, hydrogen production from industrial wastewater will not only help enterprises reduce emissions, but also be more economical.
In the context of global carbon neutrality, hydrogen must be an important direction for future energy development. However, green hydrogen production is more important and requires a corresponding supply of clean energy and water. If hydrogen production from "wastewater" can be applied on a large scale, then water sources will not be a problem, and the green hydrogen industry from renewable energy will go further and further on the road to sustainable development.