NOVELTY - An electrochemical cell system (46) comprises a fuel cell (10) comprising a fuel cell housing (12) having a first external surface and a first internal surface defining a first internal volume, and a cathode, an anode, and an electrolyte disposed within the first internal volume. A fuel cartridge (38) is connected to the fuel cell; and comprises a cartridge housing (44) having a second external surface and a second internal surface defining a second internal volume that includes a fuel. A fuel consuming agent (28) is disposed on at least one of the first and second external surfaces.    USE - As electrochemical cell system.    ADVANTAGE - The fuel consuming agent can control fuel leak by consuming the leaking fuel. A fuel cell, cartridge, or container including the fuel consuming agent is safer than it would be without the fuel consuming agent, and requires little to no human intervention in the event of fuel leak. A fuel consuming coating including the fuel consuming agent can convert a potentially harmful, flammable fuel (e.g., hydrogen gas) into harmless, nonflammable byproducts (e.g., water) at ambient temperatures and without generating significant heat or causing an increase in temperature. The fuel consuming agent can be made economically and efficiently, with inexpensive and readily available materials, can be durable, and can form a coating that is resistant to peeling, flaking, or crumbling.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) hydrogen gas cartridge comprising a housing including hydrogen gas, and a hydrogen consuming agent disposed on the housing external surface, where the hydrogen consuming agent is dispersed in a gas-permeable matrix;    (2) coating a fuel cell (e.g., hydrogen fuel cell) or fuel cartridge comprising coating a portion of an external surface of fuel cell or fuel cartridge with a fuel consuming agent; and    (3) controlling a fuel leak comprising contacting fuel leaking from an electrochemical cell system including a fuel cell with a fuel consuming agent external to the fuel cell, where the electrochemical cell further comprises a fuel sensor.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional side view of a container.    Fuel cell (10)    Fuel cell housing (12)    Fuel consuming agent (28)    Fuel cartridge (38)    Cartridge housing (44)    Electrochemical cell system (46)