TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Method: In the method, the alcohol (RCH2OH) is oxidized to form aldehyde in the anodic reaction; the aldehyde (RCHO) is oxidized to form an acid in the anodic reaction; or the acid (RCOOH) is oxidized to form carbon dioxide and alcohol or water, respectively. In the method, the catalyst for the anodic reaction in the oxidation of alcohol to aldehyde is used a catalyst containing (%): silver (Ag) (60-94), tellurium (Te) and/or ruthenium (Ru) (5-30), and platinum alone or in combination with gold (Au) and/or titanium oxide (TiO2) (at the ratio of 90:9:1) (1-10); the catalyst for the anodic reaction in the oxidation of aldehyde to acid is used silicon oxide (SiO2) and TiO2 in combination with Ag; and the catalyst for the anodic reaction in the oxidation of acid to carbon dioxide and alcohol or water, respectively, is used Ag alone or in combination with TiO2 and/or Te. In the method, the oxidant is oxygen such as oxygen in air or hydrogen peroxide. The hydrogen peroxide is used in combination with a catalyst of carbon powder, anthraquinone and Ag for the cathodic reaction. The reaction steps are conducted in cells that are connected flow-wise in series in a fuel cell unit. The supply of oxidant to the different steps is controlled such that the reactions on the anodic and the cathodic sides are in stoichiometric balance with each other in every separate step. Preferred Device: In the fuel cell unit, all cells are designed to use a liquid oxidant; and all cells on the cathodic side has a catalyst of carbon powder, anthraquinone and Ag for using hydrogen peroxide as liquid oxidant for the cathodic reaction. The membrane constitutes a carrier for the catalysts on the anodic side and/or the cathodic side. In the fuel cell unit, the anode, the cathode and the membrane are constituted by thin plates with a thickness of less than 1 mm and a planar side, attached to each other, that both sides of the membrane are planar, and that the anode and the cathode each have one planar side and on its respective opposite side facing the membrane is provided with a surface structure that will give an optimized liquid flow over essentially the entire side of the plate. The surface structure is constituted by channels having a waved cross-section. The thin anodic and cathodic plates consist of sheet metal with a thickness in the magnitude of 0.1-0.6 (preferably 0.3) mm, and the channels have a width in the magnitude of 2-3 mm and a depth in the magnitude of 0.05-0.5 mm. The membrane consists of glass. The glass is doped to allow for passage of protons/hydroxonium ions. The fuel cell unit, for the use of liquid ethanol as fuel, comprises six cells that are connected flow-wise in series, of which a first cell has a catalyst that is optimized to conduct the anodic reaction where ethanol is oxidized to form acetaldehyde; a second flow-wise cell has a catalyst that is optimized to conduct the anodic reaction where the acetaldehyde is oxidized to form an acetic acid; and a third cell has a catalyst that is optimized to conduct the anodic reaction where the acetic acid is oxidized to form carbon dioxide and methanol; a fourth cell has a catalyst that is optimized to conduct the anodic reaction where the methanol is oxidized to form formaldehyde; a fifth cell has a catalyst that is optimized to conduct the anodic reaction where the formaldehyde is oxidized to form a formic acid and a sixth cell has a catalyst that is optimized to conduct the anodic reaction where the formic acid oxidized to form carbon dioxide and water.