NOVELTY - Electrochemical energy conversion and storage system (10) (I), comprises: an electrochemical energy conversion device (12), in fluid communication with a source of an organic liquid carrier of hydrogen (14) and an oxidant, for receiving, catalyzing and electrochemically oxidizing at least a portion of the hydrogen (16) to generate electricity (18), a hydrogen depleted liquid, and water; and a vessel for receiving the hydrogen depleted liquid, where the organic liquid carrier of hydrogen comprises at least two secondary hydroxy groups.    USE - (I) is useful for generating electricity and storing electricity (all claimed). (I) is useful in passenger vehicles and fuel cell vehicles.    ADVANTAGE - (I) provides a high-capacity energy storage solution, as the organic liquid carriers of hydrogen provided exceeds 6 wt.% gravimetric hydrogen storage capacity, which is more important for mobile applications, substantial (e.g. 54 g/l) volumetric capacity. The energy storage solution is based on an organic liquid carrier, hence the existing refueling and transportation infrastructure can be utilized without substantial modification. (I) produces electricity without the production of a hydrogen gas, making the dealing of utilization and storage concerns, safety and size much easier. The hydrogen-depleted organic liquid can be re-hydrogenated via on-board electrolysis (when used in a plug-in mode) or off-board (when used in a fuel cell vehicle mode), thus (I) is both an attractive hydrogen storage solution and a high-capacity energy storage solution. (I) provides a single hydrogen/energy storage solution for a combined plug-in electric and pure hydrogen fuel cell vehicles. As a plug-in solution, (I) can be recharged at night, thus regenerating fuel cost effectively and easing the distribution of at least part of the overall energy for transportation via existing electrical grids instead of through fuel transportation and distribution networks.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) an electrochemical energy conversion system-1, comprising: a storage tank for a source of organic liquid carrier of hydrogen; a proton exchange membrane (PEM) fuel cell comprising a solid electrolyte, in fluid communication with the storage tank and an oxidant, for receiving, catalyzing and electrochemically oxidizing at least a portion of the hydrogen to generate electricity, a hydrogen depleted liquid, and water; a vessel for receiving the hydrogen depleted liquid; a recharging component for connecting the electrochemical conversion system to a source of electricity for rehydrogenating the hydrogen depleted liquid across the electrochemical energy conversion; and a source of water, where the organic liquid carrier of hydrogen comprises at least two secondary hydroxy groups;    (2) a method of generating electricity, comprising: directing an organic liquid carrier of hydrogen comprising at least two secondary hydroxy groups to an electrochemical conversion device; and electrochemically dehydrogenating the organic liquid carrier of hydrogen in the presence of a catalyst and oxygen to produce electricity, water and a hydrogen depleted liquid; and    (3) a method of storing electricity, comprising: directing a hydrogen depleted liquid to an electrochemical energy conversion device; supplying water to the electrochemical energy conversion device; and electrifying the electrochemical conversion device to hydrogenate the hydrogen depleted liquid to provide an organic liquid carrier of hydrogen comprising at least two secondary hydroxy groups.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic illustration of electrochemical energy conversion and storage system.    Electrochemical energy conversion and storage system (10)    Electrochemical energy conversion device (12)    Organic liquid carrier of hydrogen (14)    Hydrogen (16)    Electricity (18)