Biomass (e.g., plant biomass, animal biomass, and municipal waste biomass) is processed to produce useful products, such as fuels. For example, systems can use feedstock materials, such as cellulosic and/or lignocellulosic materials and/or starchy materials, to produce ethanol and/or butanol, e.g., by fermentation.

A method for producing bipolar plates includes removing scrap material from an electrically conductive plate. The scrap material is created when the plate is cut through to produce a fluid flow opening therein and in which an inlet manifold opening and an outlet manifold opening are located at the ends of the fluid flow opening and in communication therewith.

A direct isopropanol fuel cell adapted for use in ambient conditions and utilizing as fuel isopropanol and water preferably with isopropanol at relatively high concentrations representing 30% to 90% isopropanol.

Disclosed herein are membraneless direct liquid fuel cells comprising an anode comprising an anode catalyst; a cathode comprising a cathode catalyst; an aqueous solution comprising a fuel, an electrolyte, and water; an oxygen source in electrochemical contact with the cathode catalyst; wherein the anode catalyst and the cathode catalyst are in electrochemical contact with the aqueous solution; wherein the anode catalyst is catalytically active for the oxidation of the fuel; wherein the cathode catalyst is catalytically active for the reduction of oxygen and is substantially catalytically inactive for the oxidation of the fuel. Also disclosed herein are catalysts that are catalytically active for the oxygen reduction reaction and/or the oxygen evolution reaction and substantially catalytically inactive for the oxidation reaction of a fuel.

A method of operating a fuel cell system includes vaporizing a liquid fuel in a vaporizer located in a hot box using heat generated by the fuel cell system to form a fuel vapor, and providing the fuel vapor to a stack of fuel cells located in the hot box to generate power.

A method of operating a fuel cell system includes vaporizing a liquid fuel in a vaporizer located in a hot box using heat generated by the fuel cell system to form a fuel vapor, and providing the fuel vapor to a stack of fuel cells located in the hot box to generate power.

A method of operating a fuel cell system includes vaporizing a liquid fuel in a vaporizer located in a hot box using heat generated by the fuel cell system to form a fuel vapor, and providing the fuel vapor to a stack of fuel cells located in the hot box to generate power.