DON27TZ02-NV008 TITLE: Membranes for Separation, Purification, Compression, and Storage of Carbon Resources from Alkaline Water

OUSW (R&E) CRITICAL TECHNOLOGY AREA(S): Contested Logistics Technologies (LOG)

COMPONENT TECHNOLOGY PRIORITY AREA(S): Biotechnology;Renewable Energy Generation and Storage;Sustainment

PROJECTED CMMC LEVEL REQUIREMENT: Level 2 (Self)

OBJECTIVE: Develop a low-cost, robust, energy-efficient, and scalable membrane process to continuously separate, purify, compress, and store carbon dioxide from electrochemically processed alkaline water sources to support the local synthesis of fuels, nutrients, materials, and pharmaceuticals in austere, forward-deployed environments.

DESCRIPTION: This STTR topic seeks to develop a low-cost, low-energy, low-temperature (not to exceed 50°C), high-throughput nonmetallic membrane process to purify and store carbon dioxide (CO₂) (from acidic seawater solutions). Carbon resources harvested from seawater represent a critical renewable feedstock for the localized synthesis of tactical fuels, materials, nutrients, and pharmaceuticals. Developing the capability to generate these resources in-theater or at the tactical edge enhances multi-domain operational sustainment. Current technologies used to recover the dissolved CO₂ produced from electrochemically processed seawater often result in dilution of the CO₂ with air and water vapor that can lead to detrimental sintering and oxidation of catalysts used in thermochemical and biological synthetic approaches. In addition, there are volumetric and compression penalties associated with the dilution of the targeted gas. The proposed membrane process will reduce the complexity, size, and costs associated with supplying pure carbon dioxide resources from alkaline water sources.

The integrated membrane, purification, and compression process will provide equipment, process, design criteria, energy and material balance; and establish operational performance parameters.

PHASE I: Define a concept for a specific membrane process for the separation and purification of CO₂ from acidified seawater solutions. Define, develop, and perform initial laboratory assessment of the proposed membrane process to validate the technical feasibility of the approach for the capture, purification, and storage of CO₂ from seawater over a pH range of 2 to 5. Perform analysis of the CO₂ to determine yield and purity. Perform analysis on the membrane to determine the membranes’ ability to maintain performance, structural and chemical integrity.

PHASE II: Develop a prototype process based on the work achieved in Phase I. Design the prototype as a continuous process to capture, purify, and store 90 to 100% of CO₂ from a 25,000 gal/day acidified seawater source; and to purify the captured CO₂ to 98% with the resulting purified CO₂ stream free of oxygen (O₂) and water (H₂O), compressed to at least 300psi, and stored for utilization in various synthetic processes. Establish performance parameters and proof of concept for development of full-scale process. Prepare a Phase III commercialization/transition plan.

PHASE III DUAL USE APPLICATIONS: Using data on the resulting integrated membrane, purification, and compression process, provide the design criteria for transitioning the technology to larger capacities. Develop and test a 250,000 gal/day process. Provide a cost-benefit analysis to show process outperforms current cryogenic distillation and pressure swing adoption processes.

Dual use applications include: (1) breweries and distilleries to recover and reuse CO₂, (2) desalination plants for post treatment of CO₂ capture and mineral scaling prevention, (3) offshore oil, gas, and maritime industries for commercial fuel synthesis, (4) commercial aquaculture, (5) fire suppression, and (6) dry ice for preservation.

REFERENCES:

1. Marquez, R. A.; Nielander, A. C.; Resasco, J.; Jaramillo, T. F. and Mullins, C. B. "Electrochemical Ocean-Based Carbon Capture: Roadblocks to Scale-Up." ACS Energy Letters, American Chemical Society, February 13, 2026, pp 1241-1259. https://carbondioxide-removal.eu/2026/02/07/marquez-et-al-2026-electrochemical-ocean-based-carbon-capture-roadblocks-to-scale-up/
2. Digdaya, I. A.; Sullivan, I.; Lin, M.; Han, L.; Cheng, W. H.; Atwater, H. A. and Xiang, C. "A Direct Coupled Electrochemical System for Capture and Conversion of CO₂ from Oceanwater." Nat Commun 2020, 11 (1). https://www.nature.com/articles/s41467-020-18232-y
3. Captura "Innovation & cost reductions in Direct Ocean Capture, 08/13/2024." Captura CORP, 2024. https://capturacorp.com/wp-content/uploads/2024/08/DOC-innovations-and-cost-reductions.pdf

KEYWORDS: Synthesis, carbon, membrane, separation, purification, seawater, alkaline water

TPOC 1: Heather Willauer
heather.d.willauer.civ@us.navy.mil

TPOC 2: Cameron Holder
Cameron.f.holder.civ@us.navy.mil