Liquid Alkaline Water Electrolyzers: Comparing Performance across Design, Operation, and End-of-Life Scenarios

Area of Science:

• Environmental Science
• Chemical Engineering
• Energy Systems

Background:

• Liquid alkaline water electrolysis (LAWE) is a key technology for hydrogen production.
• A comprehensive life cycle assessment (LCA) for LAWE deployment is currently lacking.
• Recent advancements in electrochemical stacks and dynamic operation modeling provide new data for evaluation.

Purpose of the Study:

• To conduct a detailed life cycle assessment (LCA) of two liquid alkaline water electrolysis (LAWE) facility designs.
• To evaluate the environmental impacts of hydrogen production using variable electricity sources (solar, wind).
• To analyze the effects of advanced stack designs, dynamic operation, and recycling strategies on sustainability.

Main Methods:

• Life cycle assessment (LCA) modeling using TRACI and ReCiPe impact categories.
• Evaluation of two LAWE facility designs: current state-of-the-art and advanced zero-gap electrode stack.
• Dynamic electricity use modeling incorporating solar, wind, and hybrid sources.
• Analysis of stack recycling strategies and hydrogen leakage.

Main Results:

• Electricity source is the primary driver of carbon intensity (83-94%) in LAWE.
• Wind electricity resulted in lower carbon intensity (1.03 kgCO2e/kgH2) and hydrogen leakage compared to solar (2.57 kgCO2e/kgH2).
• Advanced LAWE designs and stack recycling significantly reduce environmental impacts across all life cycle stages.

Conclusions:

• Wind energy offers a more sustainable electricity source for LAWE compared to solar, reducing carbon footprint and hydrogen leakage.
• Implementing advanced stack designs and recycling strategies are crucial for minimizing the environmental impact of hydrogen production.
• Further research should focus on optimizing balance of plant materials and operation cycles for variable renewable energy integration to mitigate hydrogen leakage.