On September 4, it was learned from Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences that the prototype of a 5kW CO2 electrolysis and its reversible all-in-one machine jointly developed by the fuel cell technology team of the Institute and Zhejiang Hybond Technology Co., Ltd. recently went offline in Ningbo, Zhejiang Province. The equipment can convert 1.5 cubic meters to 2.1 cubic meters of CO2 per hour.
“Efficient recycling of carbon dioxide cycle is an important way to achieve the goal of” double carbon “.” Researcher Wan Bing, officer of the fuel cell technology team of Ningbo Institute of Materials, Chinese Academy of Sciences, introduced that the team continued to iterate and optimize the flat tube solid oxide electrolytic cell independently developed. The equipment developed has great application potential in energy storage and carbon cycle, has the level of promotion and demonstration, and is at the international leading level.
Analysis of parameter characteristics to improve battery performance
The existing technologies for CO2 electrochemical synthesis of fuel mainly include low-temperature solution battery, molten carbonate battery and solid oxide battery. Among them, the solid oxide battery can efficiently convert CO2 into CO and O2 under high temperature for the preparation of ethylene and ethanol, and can also be coupled with renewable electricity and cheap heat sources, with the lowest overall cost.
In addition, since the solid oxide battery can be divided into power generation mode and electrolytic cell mode, it can also convert fuel chemical energy such as hydrogen and natural gas into electrical energy in reverse reaction, so it has great application value in the field of efficient utilization of CO2 cycle.
“‘Coupling’ means that the electrical energy required for the operation of solid oxide battery is provided by the electrical energy generated by renewable energy.” Guan Wanbing explained that with these characteristics, the team developed the key technology of CO2 electrochemical synthesis fuel with practical application capability based on the flat tube solid oxide battery independently developed.
For example, in 2020, the team studied the long-term operation stability and efficiency of flat tube solid oxide battery for CO2 electrolysis by improving the battery performance. The results show that at 750 ℃, in an atmosphere with 75% and 25% CO2 and H2 concentrations, the electrolysis of CO2 at a specific constant current density runs for nearly 2000 hours, refreshing the longest running time previously described in the open literature, with a decay rate of 4.9% per thousand hours.
“In this state, in the process of electrolysis of CO2, the conversion rate of CO2 can reach 42%, and the comprehensive energy conversion efficiency of electrolysis can reach more than 95%.” Guan Wanbing said that, on this basis, the team has taken the lead in the research on CO2 electrochemical synthesis fuel technology coupling the characteristics of renewable electricity in the past two years, in close combination with the energy storage needs of renewable electricity.
Through several years of basic research work, the team was able to master the change characteristics of the key technical parameters of the solid oxide cell electrolysis CO2 synthesis fuel technology.
Guan Wanbing said that the research on the preparation process, performance, efficiency, stability and attenuation mechanism of the battery was mainly based on a single battery. After the performance of the single battery was improved to a certain standard, the team began to develop the preparation and packaging process of kilowatt class solid oxide stacks. After the technology of kilowatt class stacks was mature, the scale of the stack was gradually expanded.
Step by step challenge power preparation multifunction machine
At the end of last year, the fuel cell technology team of Ningbo Institute of Materials, Chinese Academy of Sciences, together with Zhejiang Hydrogen State Technology Co., Ltd., started the research and development of the integration of CO2 electrolysis and its reversible discharge, which was initially successfully developed in March 2022.
“On this basis, the development plan of the 5kW power prototype has also been put on the agenda.” Guan Wanbing introduced that the so-called “integration of electrolysis and reversible discharge”, as the name implies, means that the equipment prototype can realize the alternate operation of two modes by setting the program mode, so as to realize the alternate transformation of electric energy, chemical energy and electric energy.
It is worth mentioning that due to the multi fuel applicability of nickel based electrode in solid oxide battery, the fuel includes CO2, CO, CH4, NH3 and other gases. This equipment can not only catalyze the electrolysis of CO2, but also be used for the electrolysis of water to produce hydrogen.
In order to electrolyze CO2 in the prototype and realize wet reforming of water and methane, the team independently developed a vaporizer suitable for fuel cell power generation mode, and developed a heat exchanger with ultra-low flow resistance, low cost and high performance, which is mainly used for the recovery and treatment of exhaust gas energy.
It is reported that the cost of the 5-kilowatt reversible all-in-one machine is about 1 million yuan. The expected service life of the core part of the electrolytic cell is 20000 hours. Because of its low cost, it is a consumable part and can be replaced regularly. The overall service life of the equipment can reach more than 10 years.
Speaking of promotion and application, Guan Wanbing believed that to achieve commercialization of the 5-kilowatt solid oxide battery reversible all-in-one machine in a short period of time, problems such as high equipment costs need to be overcome. The team hopes that the life of the electrolytic cell can further break through to more than 40000 hours.
Guan Wanbing said that in the future, the team will conduct in-depth research on the volatility and reversibility of the battery to improve the performance of solid oxide batteries in all aspects. In terms of electrolysis equipment, we will try to add more functions to realize intelligent operation, and then start to develop a 100 kilowatt CO2 electrochemical synthesis fuel integrated machine, providing a new technical route reference for domestic CO2 resource recycling.
(Source: Ningbo Science and Technology Bureau)