Renewable Energy Sources (RES) have drawn significant attention in the past years to make the transition towards low carbon emissions. On the one hand, the intermittent nature of RES, resulting in variable power generation, hinders their high-level penetration in the power system. On the other hand, RES can aid not only to supply much more eco-friendly energy but also it allows the power system to enhance its stability by ancillary service provision. This article reviews the challenges related to the most intermittent RES utilised in Belgium, that is, wind energy and solar energy. Additionally, wind speed and solar irradiance variations, which are the cause of wind and solar intermittency, are studied. Then, recent techniques to forecast their changes, and approaches to accommodate or mitigate their impacts on the power system, are discussed. Finally, the latest statistics and future situation of RES in the Belgian power system are evaluated.

Offshore production of hydrogen using seawater reverse osmosis (SWRO) and proton exchange membrane (PEM) technologies offers a promising pathway for green hydrogen generation from renewable energy sources (RESs). Realising this potential requires the integration of the SWRO unit and PEM electrolyser into a single system, with precise modelling to address the variability of RESs. Nevertheless, there are limited studies in the literature that examine a coupled SWRO-PEM electrolyser model. Therefore, in this article, an integrated SWRO-PEM electrolyser model is developed, detailing the modelling steps for each component. The models are subsequently validated against experimental data and upscaled to reflect a realistic scenario. Finally, a straightforward control method for the SWRO unit based on the electrolyser operation is suggested. The PEM electrolyser model showed an average relative error of 0.66% in static operation and 3.93% in dynamic operation. Meanwhile, the SWRO unit demonstrated an average relative error of 3.64% for water quantity and 1.48% for water quality compared to experimental results at low total dissolved solids (TDS) values, and 2.74% and 0.13% for water quantity and quality, respectively, at seawater TDS levels. Also, the control method estimated the water demand of the electrolyser with an average error of 1.20%.