Robust bipolar-membrane electrolyzers for high-purity compressed H2 generation from unpurified water
Abstract
Abstract, approved for public release. The direct, efficient, generation of pressurized H2 from variable and unpurified water sources using intermittent renewable electrical energy sources is an attractive route to power DoD assets in remote and strategic regions, while also having civilian applications. However, unpurified water, e.g. river or seawater contain ions (e.g., Cl-, Mg2+, Ca2+) can drastically reduce the energy efficiency, durability, selectivity of standard electrolyzer designs. In this proposed project, we aim to provide the key fundamental insights necessary to design water electrolyzers capable of durable, efficient operation with unpurified water and intermittent power sources using a bipolar membrane (BPM) based design. Supported by ONR, our team has recently demonstrated bipolar membrane water electrolyzers (BPMWE) able to produce O2 for life support applications directly from seawater. Thisis in contract to proton-exchange membrane water electrolyzers (PEMWEs), which provide efficient direct electrochemical H2 generation under pure water conditions but can generate corrosive, dangerous oxidized chlorine products in the presence of Cl-. The BPMWEs selectively generated O2 even in the presence of Cl- and also demonstrated unique control of the ion transport properties at the device level. In this project the collaborative team across UC Berkeley, Stanford, and Stanford Linear Accelerator Laboratory will understand the limits of performance of BPM-based electrolysis when supplied with variable purity water feeds, inform operational characteristics, optimized hydrogen production rates, and increase durability to meet Navy needs. The team will integrate next-generation anodes to prevent oxidative damage of the ionomer/catalyst interface and provide stable H2 production. Understanding ion and water transport will provide pathways to prevent performance loss due pH gradients and dehydration of the bipolar junction. The team will also develop accelerated stress tests which to simulate long-term field operation when coupled to intermittent power sources (e.g., solar and wave energy) and maximize durability. The science and engineering principles targeted in the work are central to enable the development of a combined, electrochemical H2 generation and compression unit using a BPM-based water electrolyzer leveraging electrochemically generated pressure gradients to drive water transport and improve material resilience regarding membrane dehydration, stability at high currents, and catalyst stability in the presence of impurified water. This knowledge is broadly useful inform the opportunity to deploy BPM technology to drive resilient energy infrastructure under the complex and varying conditions expected for Navy and eventual civilian deployment.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 08, 2024
- Source ID
- N000142412433
Entities
People
- Shannon W. Boettcher
Organizations
- Office of Naval Research
- United States Navy
- University of California Regents