. A fuel cell comprising: (a) a fuel cell assembly comprising at least one fuel cell unit, the fuel cell unit having an intermediate electrolyte layer, an outer cathode layer and an innermost fuel-contacting anode layer; characterized in that (b) a first centrifugal blower system provides a flow of gaseous oxidizer to the cathode layer of the fuel cell unit and a second centrifugal blower system provides a flow of gaseous fuel to the anode layer of the fuel cell unit, each centrifugal blower system comprising: (i) a series of blower units (11,12), each blower unit in the series comprising a casing (14,19) having an axial inlet (15,22) and a radial outlet (16, 23), an impeller (17,20) disposed within the casing for drawing a gaseous medium at a first pressure into the inlet and expelling gaseous medium at a second higher pressure through the outlet and a motor (18,21) for driving the impeller; and, (ii) a duct connecting the outlet of at least one blower unit in the series with the inlet of at least one other blower unit in the series, the interior walls of the duct configured to be substantially parallel to the trajectory of the gaseous medium expelled from the outlet of a blower unit to which the duct is connected, and a gas stream housing for receiving the gas stream from the outlet of a successive blower unit in the series, the walls of the gas stream housing being configured to be substantially parallel to the trajectory of the gaseous medium expelled from the outlet. (a) a fuel cell assembly comprising at least one fuel cell unit, the fuel cell unit having an intermediate electrolyte layer, an outer cathode layer and an innermost fuel-contacting anode layer; characterized in that (b) a first centrifugal blower system provides a flow of gaseous oxidizer to the cathode layer of the fuel cell unit and a second centrifugal blower system provides a flow of gaseous fuel to the anode layer of the fuel cell unit, each centrifugal blower system comprising: (i) a series of blower units (11,12), each blower unit in the series comprising a casing (14,19) having an axial inlet (15,22) and a radial outlet (16, 23), an impeller (17,20) disposed within the casing for drawing a gaseous medium at a first pressure into the inlet and expelling gaseous medium at a second higher pressure through the outlet and a motor (18,21) for driving the impeller; and, (ii) a duct connecting the outlet of at least one blower unit in the series with the inlet of at least one other blower unit in the series, the interior walls of the duct configured to be substantially parallel to the trajectory of the gaseous medium expelled from the outlet of a blower unit to which the duct is connected, and a gas stream housing for receiving the gas stream from the outlet of a successive blower unit in the series, the walls of the gas stream housing being configured to be substantially parallel to the trajectory of the gaseous medium expelled from the outlet. (i) a series of blower units (11,12), each blower unit in the series comprising a casing (14,19) having an axial inlet (15,22) and a radial outlet (16, 23), an impeller (17,20) disposed within the casing for drawing a gaseous medium at a first pressure into the inlet and expelling gaseous medium at a second higher pressure through the outlet and a motor (18,21) for driving the impeller; and, (ii) a duct connecting the outlet of at least one blower unit in the series with the inlet of at least one other blower unit in the series, the interior walls of the duct configured to be substantially parallel to the trajectory of the gaseous medium expelled from the outlet of a blower unit to which the duct is connected, and a gas stream housing for receiving the gas stream from the outlet of a successive blower unit in the series, the walls of the gas stream housing being configured to be substantially parallel to the trajectory of the gaseous medium expelled from the outlet.