Surveillance and communication are the lifeline of the armed forces. These days they are utilizing small UAVs for naval missions. If the armed forces are using electric UAVs, they have the additional advantage. Electric UAVs can’t be detected from the ground. The Ion Tiger has just demonstrated the likelihood of a long endurance missions with an electric UAV. Naval forces can get a larger cruise range. Naval forces can reduce the number of daily launches and landings too. This increases the capability and yet naval crew can save on the time and effort fronts.
via Fuel Cell Powered UAV Completes 23-hour Flight.
Comment on youtube:
Korean UAVs don't need the dangerous hydrogen tanks any more; one has flown 10 hours continuously on NaBH4 fuelcells.
From wikipedia:
Sodium borohydride, also known as sodium tetrahydroborate, has the chemical formula NaBH4. This white solid, usually encountered as a powder, is a specialty reducing agent used in the manufacture of pharmaceuticals and other organic and inorganic compounds. It is soluble in methanol and water, but reacts with both in the absence of base.[2] The compound was discovered in the 1940s by H. I. Schlessinger, who led a team that developed metal borohydrides for wartime applications.[3] Sodium borohydride is also used in experimental fuel cell systems. As a fuel it is less flammable and less volatile than gasoline but more corrosive. It is relatively environmentally friendly because of the low toxicity of borates. The hydrogen is generated for a fuel cell by catalytic decomposition of the aqueous borohydride solution:
- NaBH4 + 2H2O → NaBO2 + 4H2 + heat
SPACE, PROPULSION & ENERGY SCIENCES INTERNATIONAL FORUM: SPESIF-2009. AIP Conference Proceedings, Volume 1103, pp. 157-163 (2009).
Fuel cells have played an important role in NASA's space program starting with the Gemini space program. However, improved fuel cell performance will be needed to enable demanding future missions. An advanced fuel cell (FC) using liquid fuel and oxidizer is being developed by U of IL/NPL team to provide air independence and to achieve higher power densities than normal H2/O2 fuel cells (Lou et al., 2008; Miley, 2007). Hydrogen peroxide (H2O2) is used in this FC directly at the cathode (Lou and Miley, 2004). Either of two types of reactant, namely a gas-phase hydrogen or an aqueous NaBH4 solution, is utilized as fuel at the anode. Experiments with both 10-W single cells and 500-W stacks demonstrate that the direct utilization of H2O2 and NaBH4 at the electrodes result in >30% higher voltage output compared to the ordinary H2/O2 FC (Miley, 2007). Further, the use of this combination of all liquid fuels provides-from an operational point of view-significant advantages (ease of storage, reduced pumping requirements, simplified heat removal). This design is inherently compact compared to other fuel cells that use gas phase reactants. This results in a high overall system (including fuel tanks, pumps and piping, waste heat radiator) power density. Further, work is in progress on a regenerative version which uses an electrical input, e.g. from power lines or a solar panel to regenerate reactants. - harvard.edu
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