Abstract
High temperature steam (H2O) electrolysis via a solid oxide electrolysis cell is an efficient way to produce hydrogen (H2) because of its high energy conversion efficiency as well as simple and green process, especially when the electrolysis process is combined with integrated gasification fuel cell technology or derived by renewable energy. However, about 60%–70% of the electricity input is consumed to overcome the large oxygen potential gradient but not for electrolysis to split H2O to produce H2 due to the addition of safe gas such as H2 in the fuel electrode. In this work, Sr2Fe1.5Mo0.5O6-δ-Ce0.8Sm0.2O1.95 (SFM-SDC) ceramic composite material has been developed as fuel electrode to avoid the use of safe gas, and the open circuit voltage (OCV) has been effectively lowered from 1030 to 78 mV when the feeding gas in the fuel electrode is shifted from 3%H2O–97%H2 to 3%H2O–97%N2, reasonably resulting in a significantly increased electrolysis efficiency. In addition, it is also demonstrated that the electrolysis current density is greatly enhanced by increasing the humidity in the fuel electrode and the working temperature. A considerable electrolysis current density of − 0.54 A/cm2 is obtained at 800 °C and 0.4 V for the symmetrical electrolyzer by exposing SFM-SDC fuel electrode to 23%H2O–77%N2, and durability test at 800 °C for 35 h demonstrates a relatively stable electrochemical performance for steam electrolysis under the same operation condition without safe gas and a constant electrolysis current density of − 0.060 A/cm2. Our findings achieved in this work indicate that SFM-SDC is a highly promising fuel electrode for steam electrolysis.
Highlights
The integrated gasification fuel cell (IGFC) system, which combines the coal gasification and solid oxide fuel cells (SOFCs), has been considered as one of the most promising technologies in the coal utilization for power generation because of superior electrical efficiency and efficient carbon dioxide capture and sequestration (CCS) (Lanzini et al 2014; Li et al 2014; Wang et al 2020a)
Mass flow rates of N 2 and H 2 gases in the fuel electrode side were precisely controlled by using digital mass flow controller (MC-100SCCM-D/5M, Alicat Scitific Inc), while water vapor was added to the gas stream via a humidifier by heating liquid water to a certain temperature, and the steam content was measured by using a humidity sensor (HTM 338, Vasala)
It can be clearly seen that the including current density-cell voltage (i-V) curve preformed in 3% H 2O humidified N 2 atmosphere is far below that for the conventional solid oxide steam electrolyzer operated in 3% H 2O humidified H 2 atmosphere, indicating that a much lower applied potential is required to produce the same amount of electrolysis current and hydrogen gas
Summary
The integrated gasification fuel cell (IGFC) system, which combines the coal gasification and solid oxide fuel cells (SOFCs), has been considered as one of the most promising technologies in the coal utilization for power generation because of superior electrical efficiency and efficient carbon dioxide capture and sequestration (CCS) (Lanzini et al 2014; Li et al 2014; Wang et al 2020a). Because of the high rate of greenhouse gas emissions, alternative technology is being sought to further reduce the
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal of Coal Science & Technology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
