Hydrogen production from the ambient air

Abstract

Green hydrogen, produced by water splitting using renewable energy, is the most promising energy carrier for a low-carbon economy. However, a significant challenge arises from the geographic mismatch between the distribution of renewables and freshwater availability. Apart from liquid water, the water vapor in the atmosphere weighs approximately 12.9 trillion tons. Therefore, utilizing this atmospheric moisture as an alternative water source for water splitting represents a promising avenue for green hydrogen production. In this research: An innovative DAE module was designed and developed. This module could continuously produce hydrogen from atmospheric moisture, operating within a range of 4–100% RH. It enables hydrogen generation without any geographic constraints or freshwater supply. Subsequently, this DAE module was combined with a system for CO2 reduction designed to prevent CO2 from entering the DAE's electrolyzer. Specifically, we investigated CO2RR, generating formic acid/formate with over 99% Faradaic efficiency, exhibiting stability over 80 hours. Additionally, we identified strategies to manage humidity transfer while preventing CO2 intrusion. Using a hygroscopic solution as a barrier, the CO2 concentration was maintained below 110 ppm in a closed environment for over 12 days, enhancing the module's cost-effectiveness and long-term stability. In conclusion, the results of this thesis demonstrate that the DAE module can produce green hydrogen using atmospheric water continuously. When integrated with the CO2RR system and a hygroscopic solution for humidity transfer and CO2 blocking, DAE systems offer a scalable, cost-effective solution for hydrogen generation in arid and semi-arid regions with minimal environmental impact.

Date of Award	31 Dec 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Xiaolei Fan (Supervisor)