Green hydrogen (GH₂) is emerging as a key driver of global energy transition, offering a sustainable pathway to decarbonize energy systems and achieve climate objectives. This review critically examines the state of GH₂ research production technologies and their integration into renewable energy systems, supported by a bibliometric analysis of the recent literature. Produced via electrolysis powered by renewable energy, GH₂ shows significant potential to decarbonize industries, enhance grid stability, and support the Power-to-X paradigm, which interlinks electricity, heating, transportation, and industrial applications. However, widespread adoption faces challenges, including high production costs, infrastructure constraints, and the need for robust regulatory frameworks. Addressing these barriers requires advancements in electrolyzer efficiency, scalable fuel cell technologies, and efficient storage solutions. Sector-coupled smart grids incorporating hydrogen demonstrate the potential to integrate GH₂ into energy systems, enhancing renewable energy utilization and ensuring system reliability. Economic analyses predict that GH₂ can achieve cost parity with fossil fuels by 2030 and will play a foundational role in low-carbon energy systems by 2050. Its ability to convert surplus renewable electricity into clean energy carriers positions it as a cornerstone for decarbonizing energy-intensive sectors, such as industry, transportation, and heating. This review underscores the transformative potential of GH₂ in creating a sustainable energy future. By addressing technical, economic, and policy challenges and through coordinated efforts in innovation and infrastructure development, GH₂ can accelerate the transition to carbon-neutral energy systems and contribute to achieving global climate goals.

Front-face fluorescence method has been used to obtain fluorescence excitation emission matrix (EEM) characteristic of various Italian monocultivar extra virgin olive oil (EVOO), Mixed EVOO, and lower grade virgin olive oil. Specific region of EEM has been explored using principle component analysis. It was found that EEM region of excitation 250-400 and emission 280-620 nm could be used to discriminate each sample type of different cultivar, mixed sample, and virgin olive oil sample. The important fluorescence peaks for the discrimination belong to unique combination of tocopherols, tocotrienols, phenolic compounds, oxidation products, and vitamin E. These results show that frontface fluorescence EEM spectroscopy has a potential to be used for monocultivar EVOO discrimination.

The production of minimally processed vegetables generates large amounts of by-products whose concentrations in bioactive compounds is comparable to those of the edible part. The aim of this work was the optimization of sustainable processes for the extraction of phenolic compounds from chicory and fennel by-products using water as solvent. The results were compared with those obtained through a conventional extraction performed with a 70% ethanol aqueous solution as extraction solvent. The ultrasound-assisted extraction (UAE) and microwave-assisted extractions (MAE) were established by developing two Box–Behnken designs, respectively, a four-factor, three-level design and a three-factor, three-level design. A quadratic polynomial model was useful in optimizing both the ultrasonic (R² 0.8473 for chicory and R² 0.9208 for fennel) and microwave (R² 0.9145 for chicory and R² 0.7836 for fennel) extraction of bioactive compounds as well as the antioxidant activity of extract (R² 0.8638 for chicory and R² 0.9238 for fennel treated with ultrasounds; R² 0.9796 for chicory and R² 0.7486 for fennel submitted to MAE). The UAE conditions able to maximize the total phenolic concentrations were: 10 g/100 mL, 55 °C, t: 60 min, 72 W for chicory (9.07 mg gallic acid/g dm) and 15 g/100 mL, 45 °C, t: 40 min, 120 W for fennel (6.64 mg gallic acid/g dm). Concerning MAE, the highest phenolic concentrations were obtained applying 7.5 g/100 mL; 2 min; 350 W for chicory (8.23 mg gallic acid/g dm); 7.5 g/100 mL; 3 min; 160 W for fennel (6.73 mg gallic acid/g dm). Compared to conventional solvent extraction, UAE and MAE allowed the obtainment of (a) chicory extracts richer in phenolic compounds (+48% and +34%, respectively), in less time (4-fold and 90-fold reduction, respectively) and (b) fennel, extracts with slightly lower amount of phenolics (−11.7% and −10.5%, respectively) but halving the extraction time (UAE) or reducing it to 60-fold (MAE).