The production of hydrogen from water electrolysis is a consolidated technology field, but in the last few years the interest is growing due to the discussions on the so called hydrogen economy. The increasing interest for higher efficiency and low volume hydrogen storage, and the supposed growth of renewable energy power system for residential and mobility application, have recently motivated new efforts in this domain.
Small energy systems integrating renewable sources (especially PV) and electrolyzers are discussed. In this framework, very early technical developments are focusing on hydrogen production directly at high pressure: in a certain range of pressure, this solution shows favorable influence on the total conversion process (from electric power to already compressed hydrogen), and even a positive effect on the cost reduction in terms of system components, due to the elimination of the whole compressor or of some compression stages. In the paper the design and the construction of an α-prototype laboratory scale electrolyzer, developed at the Dipartimento di Energetica of the Politecnico di Torino in the framework of an agreement with Giner Electrochemical Systems (US), are described. The system has an expected production of 0.1 Nm3/h of H2 at 70 bar.
The main aim of the paper is the description and analysis of the operating results of the first experimental tests. Furthermore, the feasibility of direct high pressure hydrogen production is discussed, and the influence of the pressure in the efficiency of the reaction and in the energy balance of the production+compression process is evaluated.