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The US Navy is moving forward with an unmanned fuel cell sub and has just patented a seawater-to-hydrogen and carbon dioxide system for renewable fuels.

US Navy Is Hearting Renewable Hydrogen + Fuel Cell Submarines

The US Navy is moving forward with an unmanned fuel cell sub and has just patented a seawater-to-hydrogen and carbon dioxide system for renewable fuels.

The US Navy has been hot on the trail of the sustainable warfighter energy supply of the future, and one of its top candidates is renewable hydrogen for use in fuel cells. The “renewable” angle is a key issue, since the primary source of hydrogen today is fossil natural gas. It looks like the Navy has hit upon one solution, with a newly patented one-shot system that extracts hydrogen from seawater, with the added bonus of capturing carbon dioxide, too.

Navy hydrogen carbon capture for fuel cells

Renewable Hydrogen At Sea, From Seawater

CleanTechnica first noticed the Navy’s hydrogen and carbon capture system back in 2012, when the Naval Research Laboratory was working on a way to scavenge jet fuel for its aircraft carriers while at sea.

Aside from the climate benefit of using less petroleum in aircraft, the logistical benefits include reducing the need to conduct risky refueling operations while at sea.

Fast forward to January 2015, and we had this to say about the system’s carbon capture capability:

The real beauty of the device, dubbed the Electrolytic Cation Exchange Module, is that the whole process takes place without requiring additional chemicals or creating toxic byproducts. That’s a huge advantage compared to the conventional processes for recovering CO2 from seawater.

In the latest development, earlier this month the lab announced that it has received a patent for the system, making it the first such system that simultaneously extracts both carbon dioxide and hydrogen from seawater.

With all the ingredients for making synthetic fuel at hand, the Navy anticipates being able to produce practically any kind of fuel it needs from seawater. Aside from JP-5 jet fuel, that includes LNG and CNG, as well as the multi-purpose fuel F-76.

Renewable Energy To Rule The Seas

The logistical and strategic advantages of seagoing energy harvesting are significant. Here is one of the system’s inventors, US Naval Reserve Comdr. Felice DiMascio, on that topic:

A ship’s ability to produce a significant fraction of the battle group’s fuel for operations at sea could reduce the mean time between refueling, and increase the operational flexibility and time on station. Reducing the logistics tail on fuel delivery with the potential to increase the Navy’s energy security and independence, with minimal impact on the environment, were key factors in the development of this program.

So far, the system is still in the proof-of-concept stage, as demonstrated at the lab’s Marine Corrosion Facility at Key West in Florida on a scaled-up version of the initial module.

The earlier versions of the module captured enough carbon dioxide and hydrogen to produce a fraction of a gallon of fuel daily. The next step is to increase the scale and efficiency 40 times over to achieve a one gallon-per-day goal.

That’s a lot of scaling up to do, but by the end of this year the lab expects to have both systems up and running — one for recovering carbon dioxide and hydrogen, and the other for creating hydrocarbon fuels.

For that matter, one gallon per day is pretty small potatoes, but it’s a start.

How About Some Renewable Hydrogen For That Fuel Cell

In case there’s any leftover hydrogen from all that activity, no worries about what to do with that.

The Navy has been collaborating with General Motors on an underwater unmanned vehicle — aka an autonomous mini-submarine — powered by a hydrogen fuel cell that GM developed.

Just last week, the Office of Naval Research and GM announced that the Naval Research Laboratory has evaluated the prototype version of the mini-sub, and it passed with flying colors. The test took place at the Naval Surface Warfare Center in Maryland.

Here’s a photo of the little fellow:

navy GM hydrogen fuel cell submarine

Hmmm…why not a battery? The Navy is looking for onboard energy storage with a 60-day endurance framework and it appears that fuel cells are best suited to foot the bill, at least for now.

According to Frank Herr, ONR’s department head for Ocean Battlespace Sensing, yes, that’s right:

Our in-water experiments with an integrated prototype show that fuel cells can be game changers for autonomous underwater systems. Reliability, high energy, and cost effectiveness — all brought to us via GM’s partnering — are particularly important as Navy looks to use UUVs as force multipliers.

So what is GM’s stake in all this? Despite a plethora of skeptics about fuel cells in passenger cars, GM is among a number of global auto companies that are moving forward with fuel cell EV technology. The financials aren’t exactly working out in the street vehicle sector but with a nice Defense Department contract in hand, the company could continue justifying fuel cell vehicle R&D to its shareholders.

Last fall, GM generated a lot of buzz by renaming its GM Powertrain division to GM Propulsion Systems. The shift in nomenclature was aimed at transitioning out of petroleum dependency and into fuel diversity, as articulated by GM:

The new name is another step on our journey to redefine transportation and mobility. Global Propulsion Systems better conveys what we are developing and offering to our customers: an incredibly broad, diverse lineup – ranging from high-tech 3-cylinder gasoline engines to fuel cells, V8 diesel engines to battery electric systems, and 6-, 7-, 8-, 9- and 10-speed to continuously variable transmissions.

Did you catch that part about fuel cells? Aside from the Navy collaboration, GM is already in tight with the Defense Department on fuel cell EVs through its hydrogen-powered vehicle fleet for the US Army in Hawaii, so stay tuned.

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Images: via US Navy, Office of Naval Research.

 
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Written By

Tina specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

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