A Hybrid Electrochemical and Catalytic Compression System for Direct Generation of High-Pressure Hydrogen at 700 Bar

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OPEN 2021
Pasadena, California
Project Term:
03/21/2022 - 03/20/2024

Critical Need:

Hydrogen (H2) is important to global de-carbonatization in multiple industrial sectors. H2 has the lowest volumetric energy density among commonly used fuels; however, storing gaseous H2 at high pressures in tanks is the most common approach. Current compression technology for high pressure gaseous H2 generation is prohibitively expensive and unreliable. The cost of H2 compression alone from 30 bar to 700 bar was estimated to be $1.54/kg via multi-stage mechanical compressors. Reciprocating and mechanical compressors are still the most common choice for H2 compression, but their multiple moving parts, risk of piston embrittlement, manufacturing complexity, and difficulty in managing thermal transfer and performing maintenance increase their costs.

Project Innovation + Advantages:

Low-cost H2 is the key to affordable long-term grid storage technologies that could work well with grid-scale battery storage to accommodate high penetration of wind and solar electricity generation in the next decades. The California Institute of Technology (Caltech) seeks to develop a hybrid electrochemical/catalytic approach for direct generation of high-pressure H2. Caltech’s proposed system has the potential to reach <$2/kg of H2 produced and compressed at 700 bar using renewable energy sources. The proposed catalytic compression is estimated to require lower capital expenditures and operating expenses and has much better scalability than incumbent technologies. The team estimates a cost of $0.19/kg H2 for compression to 700 bar, representing a >80% reduction compared with state-of-the-art.

Potential Impact:

Catalytic compression without any moving parts in the system for generation of highly pressurized H2 will be game-changing in the field of H2 generation and storage.


Low-cost high-pressure H2 will play a critical role in the future grid configurations for long-duration storage needed for improved energy resilience.


Low-cost H2 using renewable electricity will be a key enabling technology in the power-to-gas-to-power or windgas systems.


The hybrid electrochemical catalytic compression is estimated to require significantly lower capital expenditures and operating expenses and have much better scalability than the incumbent technologies.


ARPA-E Program Director:
Dr. Douglas Wicks
Project Contact:
Dr. Chengxiang ("CX") Xiang
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