NOVELTY - A power cell comprises a membrane having a three-dimensional geometric structure encompassing a volume (1507); a cover (1520) coupled to the membrane to separate a first flow path from a second flow path at the membrane; two catalysts (1530, 1535) in gaseous communication with respective first and second flow paths (1510, 1515); and a first electrode electrically coupled to the first catalyst on the first side of the membrane and a second electrode electrically coupled to the second catalyst on the second side of the membrane.    USE - The power cell is used for generating energy (claimed) for devices, e.g. laptop computers, personal digital assistants and cellular telephones. It is also useful as power source for automobiles and buses.    ADVANTAGE - The power cell can construct fuel cell assemblies (power chips) with higher reactive surface area per unit of substrate area. This creates a large advantage in power density and manufacturing cost.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a method of generating energy using a power cell comprising flowing fuel or oxidant through a volume encompassed by an ion exchange membrane of the power cell;    (2) a power chip comprising an array of power cells, plenum(s), and two terminals;    (3) a power disk comprising an array of power cells, plenum(s), two terminals, and two power buses;    (4) a power stack comprising a power stack structure defining stack manifold(s), power disks, and power stack terminals;    (5) a method of operating power cells, comprising dynamically controlling generation of power by a subset of power cells in a presence of fuel and oxidant through electrical control of electrical element(s) coupled to a subset of the power cells;    (6) an apparatus for generating power, comprising power cells to generate power in a presence of fuel and oxidant; electrical element(s); and a controller; and    (7) an apparatus for reacting reaction components, comprising ion exchange membrane, catalyst(s), and a cover.    DESCRIPTION OF DRAWING(S) - The figure is a simplified schematic cross-sectional view of the fuel cell.    Volume (1507)    Flow paths (1510, 1515)    Cover (1520)    Catalysts (1530, 1535)