NOVELTY - The cell (10) has a functional layer system comprising an electrolyte layer formed between an air electrode layer (12) and a storage electrode layer (13). The storage electrode layer has an oxidizable and reducible material (131) reversible between a metallic form and an oxidic form. A tubular support structure (11) has a portion (111) made of gastight, oxygen ion-conductive material, which serves as the electrolyte layer of the layer system or a portion made a gas-permeable porous ceramic material, on which an outer side or an inner side the layer system is applied.    USE - Tubular metal air cell e.g. high temperature metal air cell and high temperature combined metal air electrolysis fuel cell, for use in a power system e.g. photovoltaic plant, wind-power plant, biological gas facility, apartment or firm, industrial plant, power plant or vehicle (all claimed), for storing excess current.    ADVANTAGE - The oxidizable and reducible material of the storage electrode layer is reversible between a metallic form and an oxidic form, so that effective electrical power storage in the cell is ensured by avoiding degradation appearances such as cracking and electrode material losses. The storage electrode is designed in the form of a planar layer so that the storage electrode has a large surface, thus increasing the volume change of the material about 30 %, and hence reducing local volume changes and deformation of the storage electrode. The provision of the tubular support structure reduces the mechanical load on the electrode layers, and/or enhances the mechanical stability of the function layer system during the volume change of the reversible oxidizable and reducible material, thus increasing the service life of the cell. The air electrode layer has layer thickness of about 50 micrometer, so that the electrical characteristics and the gas diffusion are optimized, thus reducing the cost and the weight of the cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a method for manufacturing a tubular metal air cell    (2) a power system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic sectional view of a tubular metal air cell.    Tubular metal air cell (10)    Tubular support structure (11)    Air electrode layer (12)    Storage electrode layer (13)    Oxygen ion-conductive material portion (111)    Oxidizable and reducible material (131)