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Wind farm control has been a topic of research for more than two decades. It has been identified as a core component of grand challenges in wind energy science to support accelerated wind energy deployment and to transition to a clean and sustainable energy system for the 21st century. The prospect of collective control of wind turbines in an array, to increase energy extraction, reduce structural loads, improve the balance of systems, reduce operation and maintenance costs, etc. has inspired many researchers over the years to propose innovative ideas and solutions. However, practical demonstration and commercialization of some of the more advanced concepts has been limited by a wide range of challenges, which include the complex physics of turbulent flows in wind farms and the atmosphere, uncertainties related to predicting structural load and failure statistics, and the highly multi-disciplinary nature of the overall design optimization problem, among others. In the current work, we aim at providing a comprehensive overview of the state of the art and outstanding challenges, thus identifying the key research areas that could further enable commercial uptake and success of wind farm control solutions. To this end, we have structured the discussion on challenges and opportunities into four main areas: (1) insight in control flow physics, (2) algorithms and AI, (3) validation and industry implementation, and (4) integrating control with system design (co-design).

Photocatalytic degradation of waste materials in aqueous solutions, as well as photocatalytic hydrogen generation, were investigated for remediation of environment and renewable energy production. alpha-Fe(2)O(3 )and CdS are attractive visible-light-driven semiconductor photocatalysts because of their inexpensive cost, simple production methods, and stability. Whereas, its implementations were limited by the photocorrosion, narrow optical band gap for solar-light operations and poor separation of photogenerated electron hole pair. To increase the performance of alpha-Fe2O3, CdS, alpha-Fe2O3/CdS, and g-C3N4; a ternary nanocomposite (alpha-Fe2O3/CdS/g-C3N4) was designed. To obtain binary structure, CdS nanoparticles were overgrown on alpha-Fe(2)O(3 )nanorods-cubes using a simple wet-chemical process, and as-prepared g-C(3)N(4 )was decorated with binary composite. XRD, SEM, XPS, BET, UV-Visible spectrometry, FT-IR, PL and EIS were employed to investigate the crystal structures, surface morphology, optical properties, functional groups and electrochemical characteristics. Considering the optical absorption properties, the photocatalytic studies were performed for hydrogen production and MB dye degradation under solar light irradiation. Among the synthesized semiconductors, the ternary material had the highest photocatalytic hydrogen evolution, 165 mu mol g(-1)2 h(-1 ) from water. Within 120 min, the photocatalytic performance resulted in 99.4% degradation of the MB. The higher activities were attributed to Z-scheme mechanism, optical band levels and strict heterojunctions of the photocatalysts that induces an influential electron-hole separation, subsequently rapid diffusion of photogenerated charge between components and also the optical bandgap value of the ternary structure that more convenient for solar lights applications. This work paves a way for improvement of photocatalysts working in practical conditions of pollution and energy issues. (C) 2022 Elsevier B.V. All rights reserved.

High oxygen:carbon dioxide ratios may have a negative effect on growth and productivity of microalgae. To investigate the effect of O2 and CO2 concentrations and the ratio between these on the metabolism of Chlamydomonas reinhardtii we performed turbidostat experiments at different O2:CO2 ratios. These experiments showed that elevated O2 concentrations and the corresponding increase in the ratio of O2:CO2 common in photobioreactors led to a reduction of growth and biomass yield on light with 20–30%. This is most probably related to the oxygenase activity of Rubisco and the resulting process of photorespiration. Using metabolic flux modeling with measured rates for each experiment we were able to quantify the ratio of the oxygenase reaction to the carboxylase reaction of Rubisco and could demonstrate that photorespiration indeed can cause the reduction in biomass yield on light. The calculated ratio of the oxygenase reaction to the carboxylase reaction was 16.6% and 20.5% for air with 2% CO2 and 1% CO2, respectively. Thus photorespiration has a significant impact on the biomass yield on light already at conditions common in photobioreactors (air with 2% CO2).

Municipalities of small islands have limited capacities for waste disposal. In the case of Green Island, Taiwan, continuing with business as usual would only allow the disposal of waste on the island for another 8 years. Three alternatives for solid waste management (SWM) are compared. The cost-effective solution is the one, which is the most expensive in the short run: continuing business as usual and introducing an incineration plant in the year 2010. The results indicate furthermore that deviations from optimal timing of investment only slightly change average annual costs. In the long run, the municipality can hardly avoid transporting waste to the mainland. By investing in an incineration plant, they can buy additional time to investigate alternative SWM strategies.