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The paper aims to demonstrate the improvement of power dispatchability that can be achieved with a suitable integration of Concentrating Solar Power (CSP) and Concentrating Photovoltaic (CPV) plants to mitigate the effects of the variability and intermittency of solar energy. In particular, the CSP–CPV plant analyzed here refers to the design data of the Ottana Solar Facility, which is currently under construction in the industrial district of Ottana (Sardinia, Italy). Since it is very difficult to know the power curves that are going to be required during the operation phases of the hybrid CSP–CPV plant, the present study has been carried out by assuming a reference daily power output curve, which is simply represented by a constant power output. Moreover, two different energy management strategies, fully integrated (F-INT) and partially integrated (P-INT), are analyzed and compared. The results of this study show the advantages of using an integrated management strategy to satisfy a constant power output curve. Optimization of the CSP and CPV power share leads to an effective use of the dispatch capabilities of the CSP plant owing to the TES section, while the CPV plant is fully exploited, especially during the hours of high solar radiation. Comparison of the results achieved with the F-INT and P-INT control strategies demonstrates that the F-INT one leads to better performance both in terms of annual energy production and hours of potential time duration. [ABSTRACT FROM AUTHOR]

• A novel multi-objective optimization model is proposed for a biogas-solar-wind IES. • A multitasking multi-objective optimization algorithm, MO-MFEA-II, is proposed. • Digester heating is applied to improve the efficiency of biogas production. • Online parameter estimation technology is used to boost the efficacy of MO-MFEA-II. The optimal operation of integrated energy systems (IESs) is of great significance to facilitate the penetration of distributed generators and improve its overall efficiency. A grid-connected IES is proposed in this paper for the synergetic interactions of electricity, thermal and gas energy flows, in which the biogas-solar-wind complementarities are fully considered and the digester heating is applied to provide an appropriate temperature for biogas production from anaerobic digestion. Its multi-objective optimization (MOO) model is constructed to optimize the operational cost, carbon dioxide emission and energy loss while considering digesting thermodynamic effects for anaerobic digester and uncertainty of wind and solar power, which is then compared to that of a natural gas-solar-wind IES. Thereafter, we develop an improved realization of multitasking paradigm within the domain of MOO to simultaneously solve the multi-objective operation optimization of the two IESs. In the associated multitasking algorithm, the underlying similarities of distinct optimization tasks are learned online to mitigate the harmful inter-task interactions and thereby facilitate improved convergence characteristics. The efficacy of the proposed multitasking algorithm has been comprehensively assessed on a novel biogas-solar-wind IES and a natural gas-solar-wind IES. Simulation results validated that the proposed IES can be operated in a more cost-efficient and environmentally friendly manner by comparing to the natural gas-solar-wind IES; the developed multitasking MOO algorithm can provide a better performance than other state-of-art multitask and single-task optimization algorithms. [ABSTRACT FROM AUTHOR]

• Mechanical energy storage systems are very efficient in overcoming the intermittent aspect of renewable sources. • Flywheel, pumped hydro and compressed air are investigated as mechanical energy storage. • Parameters that affect the coupling of mechanical storage systems with solar and wind energies are studied. Mechanical energy storage systems are among the most efficient and sustainable energy storage systems. There are three main types of mechanical energy storage systems; flywheel, pumped hydro and compressed air. This paper discusses the recent advances of mechanical energy storage systems coupled with wind and solar energies in terms of their utilization. It also discusses the advances and evolution in each type and compares them in terms of performance, capacity, response and utilizations. The reviewed studies exhibit all parameters that affect the performance of each storage type in which the configuration of the system has the major effective role. Choosing the suitable mechanical storage type depends on the requirements of each application such as using the flywheel for short duration applications. If long duration is needed, then it is preferred to use either pumped hydro or compressed air storage systems, knowing that the former has higher efficiency while the latter provides a faster start up. For the sake of the environment, it is recommended to use the adiabatic or isothermal compressed air storage. In all cases that combine MESSs with solar or wind energy, the series connection is preferred in order to provide stability and better control strategy. [ABSTRACT FROM AUTHOR]