Haibo Zhai
A research team at the University of Wyoming recently published two peer-reviewed
sister articles exploring different life cycle impacts related to hydrogen production
pathways and their applicability to an emerging hydrogen industry.
Both studies were led by Haibo Zhai, the Roy and Caryl Cline Distinguished Chair in
Engineering and a professor of environmental engineering at UW. The studies were supported
by the Wyoming Innovation Partnership (WIP), with additional funding from the UW School
of Energy Resources for blue hydrogen development.
The first paper, “Comparative Life Cycle Water Use Assessment of Diverse Hydrogen
Production Pathways,” was published in the prestigious Environmental Science and Technology
journal. Led by Dengfeng Qin, a Ph.D. student in environmental engineering, the paper
focuses on the life cycle of water use for hydrogen production.
In the paper, water consumption across the entire life cycle from feedstock extraction
to facility operation for hydrogen production is compared between two pathways: electrolysis
using renewable power, and reforming or gasification using fossil fuels with carbon
capture. The study identifies two main drivers of water use: the operation of the
hydrogen plant itself and the water required for the external electricity supply.
A major concern when discussing upscaling hydrogen production is water scarcity.
“Our analysis shows that the choice of feedstock and electricity sources, and the
cooling method are the major determinants of a pathway’s total water footprint,” Zhai
says. “By comparatively examining the impacts and challenges for water use in different
scenarios, we can better assess a pathway forward and be strategic in the types of
fuel sources used to generate hydrogen in arid locations.”
The authors recommend dry cooling and the use of alternative water sources, such as
reclaimed or brackish water, be adopted to significantly reduce the use of precious
freshwater resources in the growing hydrogen economy.
In addition to water considerations, emissions are at the forefront of hydrogen production
discussions. The second paper, co-written with Qin and Zitao Wu, a postdoctoral research
associate in Zhai’s group, addresses these concerns.
Titled “Life Cycle Emissions of Diverse Fossil-Based Hydrogen Production Pathways
for Transportation Application,” the second publication appeared in IOP Publishing’s
journal, Environmental Research Letters.
The paper comprehensively evaluates the life cycle greenhouse gas emissions of fossil-based
hydrogen production methods for fuel cell vehicle use. It further analyzes major pathways
for fossil-based hydrogen production, including steam methane reforming, autothermal
reforming, gasification and chemical looping. All pathways incorporate carbon capture
and storage to lower their carbon intensity.
According to Zhai, it’s an oversimplification to look at hydrogen’s potential for
climate mitigation only through reduced greenhouse gas emissions.
“To truly validate hydrogen as a sustainable solution, we must employ a full life
cycle analysis that rigorously evaluates both the carbon footprint and resource dependencies,
particularly water usage,” Zhai says. “We are grateful to both the WIP program and
the School of Energy Resources for supporting this research and helping to provide
a clearer picture for the sustainable hydrogen industry moving forward.”
To learn more, download the respective papers at pubs.acs.org/doi/10.1021/acs.est.5c14837 and iopscience.iop.org/article/10.1088/1748-9326/ae0fac/pdf.