Analysis of PEM Membrane Electrode Assemblies Impact on the Levelized Cost of Hydrogen
Authors: Valdez Thomas I. , Takatsuji Koshu , Yang Fan , Jia Qingying , Mittelsteadt Cortney 
Published: February 2024

Plug is building an end-to-end green hydrogen ecosystem to help its customers meet their business goals and decarbonize the economy. This hydrogen ecosystem is inclusive of production, storage, delivery, and energy generation. As the largest user of liquid hydrogen globally, Plug Power plans to build and operate green hydrogen production plants across North America and Europe. Plug’s hydrogen production plants are based on electrolyzer systems featuring internally developed proton exchange membrane (PEM) based water electrolysis membrane electrode assemblies (MEAs). This paper will review the state of commercial PEM water electrolysis MEAs and provide insight as to what advances in MEA technology are needed to produce hydrogen at a levelized cost of $1/kg.

The cell polarization curves for two modeled PEM MEAs are shown in Figure 1. They represent the performance of both commercial and future PEM water electrolyzer technology. As the applied current density to the cell increases, so does the cell voltage, and thus the energy required to produce a kilogram of hydrogen. As the MEA technology in the stack matures, the applied current density, and thus, the hydrogen production rate can increase at a set efficiency. A 155 cell, 1,000 cm2 active area, electrolyzer stack featuring commercial MEAs would produce approximately 220 kg-H2/day at an efficiency of 49 kWh/kg-H2. With the future MEAs, this same stack, operating at the same efficiency, could produce as much as 1,200 kg-H2/day.

A hydrogen plant with a production capability of 45 metric tons per day, featuring commercial MEAs, would produce hydrogen at a cost of approximately $6/kg when powered by energy at a price of $35/MWh. The MEA cost represents only a few percent of the total capital expenditure required to build a 45 metric ton hydrogen plant. Thus, MEAs would only contribute a few cents to the estimated $6/kg levelized cost of hydrogen (LCOH). They, however, are responsible for most of the energy consumed at a hydrogen plant. Therefore, the MEAs could account for 50%, or more, of the total cost to produce hydrogen. A savings of $328M to $410M can be realized or every $1/kg reduction in LCOH over the lifetime of a hydrogen plant. Thus, performance improvements in the MEA are paramount to making hydrogen production competitive with other energy carriers.

The oxygen evolution catalyst featured in a future MEA would be required to achieve a greater than four-fold increase in activity. The PEM of the future MEA would also be required to support a substantial increase in proton transfer while maintaining its integrity for greater than 100,000 hours. These advances, as well as savings in hydrogen plant capital expenditures, are required to achieve a LCOH of approximately $1/kg at a fixed energy cost of $35/MWh. Even at the lowest projections for capital expenditures, most of the cost of hydrogen will be dominated by power consumption, further highlighting the importance of maturing PEM water electrolysis MEA technology.

Figure 1