Sea Technology

NOV 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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www.sea-technology.com November 2017 / st 27 To provide oxygen for the fuel cell, it was desired to find a solid, stable material that also reacted with water to provide pure oxygen. Fortunately, such fuels have been developed previously for use as an oxygen source in space and other uses. GA starts with a common, robust material and forms it into pellets for storage, transportation and use. Similar to the aluminum-water reaction, it will react with any quality of liquid containing water and provide pure oxygen. The by- product is a liquid of the same volume as the reactant, but it is a base that needs dilution before disposal. This system provides an amount of pure oxygen equal to that of liquid oxygen without the need for cryogenics. A significant advantage to both the hydrogen and oxy- gen generation systems is that the gasses are only generated upon demand by adding water. Thus, in storage or transport, there is no gaseous hydrogen or oxygen present, only be- nign solid fuels. If water is accidentally introduced to these fuels in storage, the result is the oxidation reaction at safe rates—there are no explosions. Overpressure conditions can be protected against with standard engineering techniques. After a successful Phase I program with the Office of Na- val Research to develop a UUV energy system based on this technology, GA is currently assembling a test system that will undergo a relatively long-term autonomous test in a water tank, simulating sea operations. If that test, expected to be complete in the first quarter of 2018, is successful, GA hopes to proceed to an at-sea trial. Assessing Performance It is important to maintain a broad system-level perspec- tive when considering these high-energy-density technolo- gies. In some applications, safety can be traded off for per- formance (remote unmanned applications); in others, the larger total energy storage in an existing, fixed volume may enable new missions or significantly improve operations (one application that required recharge after 6 hours, and, hence, daily site presence, can now go two to three days without site presence), and all must be traded off against cost. These new technologies typically cost more than older technologies, so it is imperative to fully understand the costs and benefits. Additional savings are often found in reduced maintenance, extended time between total replacement, and possibly environmental and insurance costs. The Big Picture New and improved forms of energy storage and con- version are extending the reach and operations of multiple platforms under and on the sea. With higher energy density, however, comes an obligation to understand system limits and implement appropriate safety precautions. These new technologies can be deployed safely and successfully, but only with sufficient understanding and appreciation. Build- ing safe architectures for more powerful lithium-ion batter- ies, and using safer, more efficient fuels for fuel cell systems, as well as continuous research and development, places General Atomics at the forefront of this wave of new capa- bility. ST Dr. Jerome Gormley earned his dolphins as an officer on board U.S. Navy sub- marines and has held various technical management positions in government, start-ups and large government contractors. Currently, he is the director for undersea business development at General Atomics Electromagnetic Systems Group.

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