Renewable hydrogen production from reverse power flows in the Maltese medium voltage distribution network

The continued growth of nonprogrammable renewable energy sources, such as wind and photovoltaics, which is necessary in the energy transition process, is leading to the emergence of a number of issues for electric grid operators. Among these are reverse power flows, which consist of power going up from the distribution grid to the transmission grid at the time generation exceeds demand. In mitigating this phenomenon, power-to-gas plants can make an important contribution. In this paper, an optimization study is presented for the sizing of a power-to-hydrogen plant consisting of a PEM electrolyzer, a compressed hydrogen storage system, and a fuel cell for local hydrogen-to-power capabilities. The model was applied to the case study of an industrial medium-voltage distribution network in Malta, evaluating a scenario in which the currently installed photovoltaic capacity was doubled from the current 2 MWp to 4 MWp, according to existing expansion plans. The optimal results obtained allow for an 81.52% reduction in reverse power flows, while producing 4 tons of renewable hydrogen per year.