TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Stack: In the stack, the porous core of the separator plate has channels formed in a direction parallel to the metal layers. At least a portion of the channels of the porous core are parallel to the flow field channels formed in the outer surfaces of the first and second metal layers. The contours of the channels of the porous core correspond to contours of the flow field channels formed in the outer surfaces of the metal layers. The porous core is ceramic. The porous core is polymer. The porous core is carbon. The porous core is formed from a material that is not electrically conductive. The separator plate is a bi-polar separator plate with the first metal layer nearest to a first electrode in a first fuel cell having a polarity opposite that of a second electrode in a second fuel cell nearest to the second metal layer. The separator plate is a mono-polar separator plate with the first and second metal layers being nearest to electrodes of the same polarity in the two fuel cells. The fuel cell is a low temperature fuel cell. The fuel cell is a proton exchange membrane fuel cell. Alternatively, the fuel cell stack comprises: a first twin mono-polar fuel cell; a second twin mono-polar fuel cell; and an electrically insulating plate positioned between the first twin cell unit and the second twin cell unit. Preferred Plate: In the separator plate, the porous material is not electrically conducting. The porous material has a channel formed in a direction parallel to the metal layers. At least one edge of the first metal layer and at least one edge of the second metal layer are physically joined. Preferred Cell: In the twin mono-polar fuel cell, the electrode of the first type is an anode, and where the first and second outer current collector plates have through holes formed. The electrode of the first type is a cathode. The center separator/current collector plate is a composite plate including a non-metallic porous core, a first metal layer on a first side of the porous core and a second metal layer on a second side of the porous core opposite the first side, and where at least one of the first metal layer and the second metal layer has through holes formed. Each face of the center separator/current collector plate forms flow field channels.