The main goal of this work is to study the role of energy storage in the context of the Portuguese power system by the year 2030. Portugal is one of the countries in the world with more installed energy storage capacity, namely pumped hydro storage (PHS). The simulations are performed with energyplan tool and allow us to predict the energy mix in Portugal by the year 2030; to forecast the utilization of the storage capacity, namely projections for the energy produced by PHS; to estimate CO 2 emissions and percentage of renewable energy sources (RES) utilization; to assess the necessary storage capacity to avoid renewable curtailment; and to evaluate the future needs of installing further storage capacity, either with more PHS capacity or with the introduction of batteries. PHS revealed that it is important to avoid the curtailment of renewable energy, especially in a scenario of higher RES shares. It is shown that the increase in RES contribution would decrease the overall costs of the system, leading to thinking that further efforts should be made to increase the RES installed capacity and go beyond the official RES predictions for 2030. It is also concluded that the predicted storage capacity for 2030 can accommodate the expected increase in variable renewable generation without any further need for investments in PHS or battery solutions.

The green energy production through water splitting under visible light irradiation has become an emerging challenge in the 21st century. Photocatalysis, being a cost-competitive and efficient technique, has grabbed much more attention for environmental applications, especially for hydrogen evolution. In this article, the hybrid Cu 3 V 2 O 8 -WO 3 nanostructures were prepared through the hydrothermal method by using copper acetate, ammonium metavanadate, and Na 2 WO 4 · 2H 2 O as precursors. The varying contents of Cu 3 V 2 O 8 in WO 3 were 0.2%, 0.5%, 1.0%, 2.0%, and 3.0%. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), UV-Vis, and photoluminescence (PL) emission spectroscopy were used to investigate the structural, morphological, surface area, and optical properties of prepared samples. The average crystalline size of the pure WO 3 ranges from 10 to 15 nm and 70 to 195 nm for an optimal composite sample. The structural phase of the hybrid WO 3 -Cu 3 V 2 O 8 nanoparticles was found to transfer from monoclinic to hexagonal by incorporating the Cu 3 V 2 O 8 contents. The enhanced photocatalytic performance for hydrogen evolution was observed for 2% Cu 3 V 2 O 8 -WO 3 composite sample. The key to this enhancement lies at the heterojunction interface, where charge separation occurs. In addition, the excellent photocatalytic activity was attributed to a higher surface area, efficient charge separation, and extended visible light absorption. This work provides an in-depth understanding of efficient separation of charge carriers and transfer processes and steer charge flow for efficient solar-to-chemical energy applications.