Revolutionizing Underwater Exploration: Seawater Electrolyte Fuel Cells & Maximizing UUV Endurance

The burgeoning field of seawater electrolyte fuel cells holds transformative potential for Uncrewed Underwater Vehicles (UUVs) and as well as broader maritime operations. This technology offers a sustainable and efficient method to generate power on demand. The integration of such systems across various maritime agencies--including the U.S. Navy, the U.S. Coast Guard, NOAA (National Oceanic and Atmospheric Administration), and the U.S. Army Corps of Engineers—could revolutionize their operational capabilities. Here, we delve into the science of these fuel cells, as well as specific in-water Operational Test and Evaluation (OT&E) protocols as applied by the U.S. Navy that could accelerate the applicability of the technology, broadly improving maritime operations globally.

Fuel cells convert chemical energy into electrical power through an electrochemical reaction between a fuel and an oxidant. Seawater, abundant in ions, presents a virtually unlimited medium for this process. If seawater is directly supplied as the electrolyte, it will facilitate electron flow between electrodes and enable the continuous generation of electricity. At the anode, the oxidation reaction takes place, where water molecules are split into hydrogen ions (protons), electrons, and oxygen gas. The reaction can be represented as follows:

At the cathode, a reduction reaction occurs, where hydrogen ions combine with electrons (from the external circuit) to form hydrogen gas, a clean fuel. The reaction is:

The overall reaction in the fuel cell can be simplified as:

This process converts the chemical energy of the saltwater into electrical energy, which can be harnessed to power electric motors and electronic devices onboard surface ships and UUVs. This process, however, demands electrodes resistant to seawater’s corrosive nature and innovations in materials science to ensure durability and efficiency.

Incorporating seawater-based fuel cells into UUVs transforms these vessels into nearly unlimited autonomous entities capable of prolonged missions. The immediate benefit from the direct intake of seawater is that will sustain power systems eliminating the need for resurfacing for energy replenishment. This capability is indispensable for deep-sea exploration and operations in remote areas, where logistical support is scarce such as exploration under the polar ice.

The integration of seawater-based fuel cells into UUV designs represents a significant leap in operational endurance and autonomy. This technology allows UUVs to directly utilize the surrounding seawater to generate the electrical power needed for propulsion and onboard systems, drastically reducing the need for frequent recharging or refueling missions. Such enhancement is pivotal for extended surveillance, research, and data collection missions in remote or deep-water areas. For example, UUVs could be strategically placed around the globe to monitor protected species and marine sanctuaries, provide critical information on ocean acidification, and hypoxia, and even monitor heat content in the upper ocean to better forecast hurricane intensification. As an example of the art of the possible, AQST’s Trinity Power Nexus system, embodies the practical application of on-demand hydrogen power generation using seawater. The system electrolyzes seawater to produce hydrogen, which powers the fuel cells, significantly reducing the weight and complexity associated with hydrogen storage. Early testing suggests that rather than hours of power for a UUV executing a typical hydrographic mapping mission, weeks, and even months of power for the platform are produced by the technology. The potential of this and other similar innovations to enhance safety and ensure an efficient, clean energy source for marine applications without necessitating the storage of the produced hydrogen may very well support an unprecedented acceleration of ocean exploration.

Achieving wide-scale adoption of seawater electrolyte fuel cells by 2026 demands a concerted effort in research and development, manufacturing, and policy formulation. Collaborations between public agencies, private sector partners, and academic institutions will be crucial for overcoming technical challenges, scaling up production, and establishing any necessary regulatory frameworks. The development of standardized testing and evaluation protocols, alongside pilot programs and phased rollouts, will pave the way for rapidly integrating this technology into the maritime domain.

The journey to scaling seawater electrolyte fuel cells for increasing the pace of ocean exploration will involve intensive R&D to refine the technology. This phase will need to focus on improving electrolysis efficiency, reducing system weight, and enhancing the durability of materials exposed to harsh marine environments. Collaboration with academic institutions and private sector partners will be crucial to leverage cutting-edge materials science and electrochemical research from a multitudes of disciplines.

Transitioning from prototype to production requires establishing manufacturing processes capable of producing these systems at scale. Key considerations include sourcing materials resistant to marine environments, scaling up electrolysis and fuel cell production, and ensuring quality control. The lead time for scaling production is contingent upon the complexity of the manufacturing process, with a targeted goal of readiness for the global ocean exploration community by 2026. This ambitious timeline necessitates early and sustained investment in manufacturing capabilities and partnerships with industrial leaders in marine technology.

Adopting this technology within Non-Profit, Federal, and Academic organizations/agencies will necessitate rigorous Test and Evaluation (OT&E) protocols to ensure reliability, safety, and performance under real-world conditions. Specific protocols that the community of proactive could adopt might include:
a) Endurance and range testing: Assessing how fuel cells enhance the operational range and duration of UUVs under various conditions, comparing performance against traditional power systems.
b) Depth and pressure tolerance: Verifying the structural integrity and functional reliability of fuel cells at the maximum operational depths expected for UUV missions.
c) Corrosion resistance and biofouling: Evaluating the long-term effects of seawater exposure on fuel cell materials, including potential corrosion or biofouling impacts on performance and maintenance requirements.
d) Safety protocols for hydrogen use: If hydrogen is used as a fuel, testing safety measures for hydrogen storage and handling, including emergency protocols for leak detection and containment.
e) Integration with existing systems: Ensuring that fuel cell systems can be integrated with existing UUV platforms without disrupting their performance or requiring extensive modifications.
f) These protocols are crucial for validating the reliability and efficacy of seawater electrolyte fuel cells in real-world maritime operations, laying the groundwork for their adoption across various naval and civilian maritime applications.

The adoption of seawater electrolyte fuel cells is not limited to UUVs or even the U.S. Navy: it has potential applications across a wide range of maritime operations:
i. Commercial shipping: For the world’s surface fleet, these fuel cells could provide auxiliary power for onboard systems or propel Unmanned Surface Vehicles (USVs) transporting bulk or liquid cargos, enhancing operational efficiency, and reducing logistic footprints.
ii. Coast guard: Enhanced endurance for USVs and UUVs could significantly bolster the Coast Guard’s capabilities in search and rescue operations, maritime law enforcement, and environmental protection.
iii. NOAA: Longer mission durations enabled by hyperefficient power systems could revolutionize oceanographic research, allowing for more extensive data collection on climate change and severe weather, marine ecosystems, and underwater topography.
iv. U.S. Army Corps of Engineers: Improved UUV and USV endurance would aid the Corps of Engineers in infrastructure inspection, maintenance, and environmental restoration projects, especially in challenging or remote aquatic environments.

Seawater electrolyte fuel cells represent a paradigm shift in maritime power generation, offering the potential to extend the capabilities of UUVs and other maritime assets significantly. By adhering to rigorous T&E protocols and fostering cross-sector collaboration, the broad adoption of this technology could redefine maritime operations across not only the U.S. Navy, U.S. Coast Guard, NOAA, and the U.S. Army Corps of Engineers, but Commercial shipping and the ocean exploration community, ensuring a more sustainable, efficient, and secure future for maritime exploration and protection.