Patent ID: 7235321

Claim:
A fuel cell system comprising: (a) an outer tubular solid oxide fuel cell comprising an inner electrode layer configured to receive a first reactant fluid, an outer electrode layer configured to receive a second reactant fluid, and an electrolyte layer sandwiched between the electrode layers; (b) a solid phase porous matrix located inside the outer fuel cell and attached to its inner electrode layer; and (c) at least one inner tubular solid oxide fuel cell embedded in the matrix substantially inside the outer fuel cell, the inner fuel cell having an outer electrode layer configured to receive the first reactant fluid, an inner electrode layer configured to receive the second reactant fluid, and an electrolyte layer sandwiched between the inner and outer electrode layers; the matrix having sufficient mechanical strength to support the inner fuel cell within the outer fuel cell and sufficient porosity to enable the first reactant fluid to flow through the matrix to the inner electrode layer of the outer fuel cell and to the outer electrode layer of the inner fuel cell.