Medis "24/7" Power Pack: A Disposable Fuel Cell


Back in 2005, we posted on the Medis disposable fuel cell prototype, which was being tested for commercial applications. Medis now reports, on their website, that "1.5 million Medis "24/7" Power Packs per month will be in production in the second quarter of 2007." At the retail level, they state that consumers will find the device at "Best Buy and Circuit City, as well as Office Max and Office Depot," under the Kensington brand name. The 24/7 will offer 'mobile phones up to 30 hours talk time, and 60-80 hours use time for certain iPods.' Retail price will be in the $19.99 - $24.99 range. Medis states that although this is a direct liquid fuel cell (DLFC) that the fuel used is 'not methanol'. Several earlier media reports mentioned sodium boro-hydride as the liquid "fuel" (structural diagram of that molecule pictured above). Note, that in reviewing the Medis website, we were unable to determine exactly what the "fuel" or hydrogen source was: an odd situation given that they are going to have to report the hydrogen carrier via Material Safety Data Sheet if the device is to be sold in the US.The JT Baker on-line MSDS for sodium borohydride, offers this Emergency Overview DANGER! CORROSIVE. CAUSES BURNS TO ANY AREA OF CONTACT. HARMFUL IF SWALLOWED, INHALED OR ABSORBED THROUGH SKIN. FLAMMABLE SOLID. DANGEROUS WHEN WET.

We notice also on the MSDS that the dry powder form of sodium borohydride reacts with water to evolve hydrogen and sodium hydroxide. Wetting a dry powder then could be one way for the pack to be 'activated'. Apparently the stability of an aqueous solution, and hence of the inorganic material's tendency to hold on to the loosely bound hydrogens, is increased at low pH. So there's another hint at how a "liquid" version could be activated: mix with mild acid. Other methods also are possible of course. The point is, we can't see widespread retail acceptance until the basics of risk management can be thoughtfully considered. For example, how will the transportation security inspector react when told by the gadget loaded passenger: "I don't really know what's in it Sir."

==== UPDATE =====
Recycling of the spent "fuel" is hypothetically possible, based on the link provided by the first comment (below).

Tags: Electronics


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