Abstract: A passive fuel cell assembly, in which there is neither air pump, nor fuel pump, is comprised of a plurality of bi-cell units. Each bi-cell unit includes a first cell and a second cell, and each cell includes an electrode of a first polarity and an electrode of a second polarity, with an ion permeable membrane disposed therebetween. The bi-cell unit further includes a fuel container which comprises a housing defining a fuel chamber having a first and second open surface. The first and second cells are disposed on opposite sides so that electrodes of each cell having the first polarity are disposed in fluid contact with the fuel chamber. The assembly further includes an oxidizer supply member disposed between adjacent pairs of bi-cell units. The oxidizer supply member includes an oxidizer chamber having four sides to take in air, and having first and second open surfaces.