Energy storage becomes a necessity when a high penetration of renewable energy sources is desirable. Variability in the energy production from these types of energy sources can make the utility grid unstable, if the percentage of production is important. In order to minimize this problem, the HiDRENER project was designed to study the effect of combining different renewable energy sources with energy storage on grid stability. The system has a wind generator, a gasifying biomass power plant with syngas storage, a solar photovoltaic plant, and a hydrogen energy buffer. Controlling the entire system is very complex. This paper shows the results of the grid-connected hydrogen energy buffer characterization, considering hydrogen production in this first stage. The objective is to know the complete behavior of the system, which could help us to define the energy buffer control. This control is oriented toward consuming excess energy produced by the other sources in real time. This means that the hydrogen buffer control has to negotiate how much energy can be stored, and act on the production system. Thus, actuation variables and dynamic behavior have to be discovered. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.