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The need for environmental protection is pushing to a massive introduction of energy production from renewables. Although wind and solar energy present the most mature technologies for energy generation, wave energy has a huge annual energy potential not exploited yet. Indeed, no leading device for wave energy conversion has already been developed. Hence, the future exploitation of wave energy will be strictly related to a specific infrastructure for power distribution and transmission that has to satisfy high requirements to guarantee grid safety and stability, because of the stochastic nature of this source. To this end, an electrical architecture model, based on a common DC bus topology and including a Hybrid Energy Storage System (HESS) composed by Li-ion battery and flywheel coupled to a wave energy converter, is here presented. In detail, this research work wants to investigate the beneficial effects in terms of voltage and current waveforms frequency and transient behavior at the Point of Common Coupling (PCC) introduced by HESS under specific stressful production conditions. Specifically, in the defined simulation scenarios it is demonstrated that the peak value of the voltage wave frequency at the PCC is reduced by 64% to 80% with a faster stabilization in the case of HESS with respect to storage absence, reaching the set value (50 Hz) in a shorter time (by −10% to −42%). Therefore, HESS integration in wave energy converters can strongly reduce safety and stability issues of the main grid relating to intermittent and fluctuating wave production, significantly increasing the tolerance to the expected increasing share of electricity from renewable energy sources. [ABSTRACT FROM AUTHOR]

Beyond solar and wind energy, wave energy is gaining great interest due to its very high theoretical potential, although its stochastic nature causes intermittent and fluctuating power production. Energy storage system (ESS) integration to wave energy converter (WEC) plants represents a promising solution to mitigate this issue. To overcome the technological limits of the single storage devices, the hybridization of complementary ESSs represents an effective solution, extending the operating range over different timeframes. This paper analyzes the benefits of Li-ion battery–supercapacitor hybrid ESS integration into a grid-connected WEC, aiming at smoothing the produced power oscillations. The hybridization concept involves coupling a power-intensive technology, such as a supercapacitor devoted to managing fluctuations at higher frequency, with a battery technology exploited to manage power variations over longer timeframes to mitigate degradation issues. In this study, a multi-objective data-driven power management strategy, based on the simultaneous perturbation stochastic approximation (SPSA) algorithm, is implemented to minimize power fluctuations in terms of power ramp (representing the power variation between two consecutive values with a 1 s time step), both at the Point of Common Coupling (PCC) and the Li-ion battery terminals, thanks to the supercapacitor peak-shaving function. The SPSA management strategy, together with a suitable sizing procedure, allows a reduction of more than 70% in the power oscillations at the PCC with respect to those at the WEC terminals, while decreasing battery stress by more than 25% if compared to a non-hybrid ESS consisting of a Li-ion battery. This shows how supercapacitor features can extend battery lifespan when integrated in a hybrid ESS. [ABSTRACT FROM AUTHOR]

A huge increase in fast−charging stations will be necessary for the transition to EVs. Nevertheless, charging a battery pack at a higher C−rate impacts its state of health, accelerating its degradation. The present paper proposes a different and innovative approach that considers the daily routine of an EV Li−ion battery based on a standard driving cycle, including charging phases when the depth of discharge is 90%. Through dynamic modeling of the EV battery system, the state of charge evolution is determined for different charging C−rates, considering both real discharging and charging current profiles. Finally, by applying a suitable post−processing procedure, aging test features are defined, each being related to a specific EV battery working mode, including charging at a particular C−rate, considering the global battery operation during its lifespan. It is demonstrated that, according to the implemented procedure, fast−charging cycles at 50 kW reduce battery lifespan by about 17% with respect to charge in a 22 kW three−phase AC column, in parity with the discharge rate. Thus, this work can provide a deep insight into the expected massive penetration of electric vehicles, providing an estimate of battery useful life based on charging conditions. [ABSTRACT FROM AUTHOR]

The ongoing spread of electric sustainable mobility is transforming the local ways of transport in metropolitan areas. This is meant to be extended outside of big cities in the near future thanks to new technological developments. Little towns should adapt to these changes, as they are located geographically far from the big cities and are generally characterized by low economic and demographic indicators. Hence, little towns must keep pace with these changes in mobility to avoid being isolated from the main cities in a country. People living in the countryside usually move toward big cities for various reasons, either related to work or living necessities. Therefore, it must be possible to conduct usual displacements through the use of electric vehicles (EVs), i.e., reaching the destinations and supplying the batteries through charging infrastructures. This paper studies the full implementation of electric mobility applied in the case of Cuenca, a city located in middle Spain. A brief geographical context is provided, together with the routes and destinations of interest considered. Then, different EVs are considered and an analytical vehicle model is provided. The model was exploited to simulate the electrical energy demand to reach the destinations chosen; the results allow comparing the performances offered by different types of EVs. This aspect is then considered as the basis to propose further upgrades in the charging infrastructures where needed, to comply with the widespread use of electric mobility. [ABSTRACT FROM AUTHOR]

The development of decarbonised systems is being fostered by the increasing demand for technological solutions for the energy transition. Solid Oxide Cells are high-efficiency energy conversion systems that are foreseen for commercial development. They exhibit potential power generation and power-to-gas applications, including a reversible operation mode. Long-lasting high performance is essential for guaranteeing the success of the technology; therefore, it is fundamental to provide diagnosis tools at this early stage of development. In this context, operando analysis techniques help detect and identify incipient degradation phenomena to either counteract damage at its origin or correct operando protocols. Frequent switches from the fuel cell to the electrolyser mode add more challenges with respect to durable performance, and deep knowledge of reverse-operation-induced damage is lacking in the scientific and technical literature. Following on from preliminary experience with button cells, in this paper, the authors aim to transfer the methodology to commercial-sized Solid Oxide Cells. On the basis of the experimental evidence collected on planar square cells under dry and wet reactant feed gases, the main contributions to impedance are identified as being charge transfer (f = 103–104 Hz), oxygen surface exchanged and diffusion in bulk LSCF (f = 102–103 Hz), and gas diffusion in the fuel electrode (two peaks, f = 1–100 Hz). The results are validated using the ECM methodology, implementing an LRel(RctQ)GWFLW circuit. [ABSTRACT FROM AUTHOR]

• Performance analysis of power production using biomass producer gases in fuel cells. • Long-term investigation of SOFC operation. • Biomass downdraft gasification producer gas with hot gas cleaning as fuel for SOFC. • Selection of technically relevant operating parameters. • Online-monitoring of the long-term SOFC operation. Coupling biomass gasification with high temperature Solid Oxide Fuel Cells (SOFCs) is a promising solution to increase the share of renewables and reduce emissions. The quality of the producer gas used can, however, significantly impact the SOFC durability and reliability. The great challenge is to ensure undisturbed operation of such system and to find a trade-off between optimal SOFC operating temperature and system thermal integration, which may limit the overall efficiency. Thus, this study focuses on experimental investigation of commercial SOFC single cells of industrial size fueled with different representative producer gas compositions of industrial relevance at two relevant operating temperatures. The extensive experimental and numerical analyses performed showed that feeding SOFC with a producer gas from a downdraft gasifier, with hot gas cleaning, at an operating temperature of 750 °C represents the most favorable setting, considering system integration and the highest fuel utilization. Additionally, a 120 h long-term test was carried out, showing that a long-term operation is possible under stated operating conditions. Local degradation took place, which can be detected at an early stage using appropriate online-monitoring tools. [ABSTRACT FROM AUTHOR]

Char is the solid by-product of biomass gasification. It usually represents a cost for plant owners, who have to dispose of it at a cost. However, its high carbon content and surface area could make it suitable for further applications, such as adsorption. In this work, we studied its potential for the adsorptive removal of hydrogen sulphide (H 2 S), a common pollutant present in the producer gas of gasification, as well as in biogas from anaerobic digestion. Different samples of char collected from commercial gasification plants in South Tyrol (Italy) were tested. The adsorption was reproduced in a lab-scale tubular fixed-bed reactor. The results highlight that all samples could capture hydrogen sulphide, showing different adsorption performances. The materials' specific surface area and metal and oxygen content seem to affect the removal capacity. After these tests, we selected the best-performing char, and tested its adsorption performance in different operative conditions, i.e. at different inlet concentrations of H 2 S and temperatures. Image 1 • The use of the residual char from biomass gasification to adsorb H 2 S was studied. • Samples of char from commercial plants collected, characterised and employed. • All the samples were able to adsorb H 2 S with different efficiency. • Different behaviours due to the specific surface area, oxygen and metal content. • The effect of the H 2 S inlet volume fraction and temperature was also assessed. [ABSTRACT FROM AUTHOR]

MicroGrids (MGs) are one of the most useful and efficient ways to integrate renewable energy technologies in rural areas. In these areas, the biogas produced by transformation of organic waste can be electrically valorized in a MG using a Hybrid Power System (HPS) based on a Solid Oxide Fuel Cell (SOFC) and a Gas microTurbine (GT), in order to obtain a high electrical efficiency. In this study, in order to keep the best efficiency while ensuring a safe operation, the HPS is controlled using a single Three-Level Neutral Point Clamped (3LNPC) inverter. After sizing the hybrid system, digital robust R-S-T type controllers are designed to regulate the SOFC power in the DC side of the inverter and the voltage and frequency in the AC side, in an islanded MG. Then, the feasibility and the performance of the 3LNPC inverter together with the associated controllers are evaluated in simulation and experimentally using a SOFC/GT emulator. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel geothermal-driven multi-generation system is proposed. • The subsystems are ORC, PEM electrolyzer, and Li/Br absorption refrigeration. • The proposed system is applied to Sabalan geothermal wells. • The optimum exergy efficiency and cost rate are 37.85 % and 15.09 USD/h, respectively. • The evaporators have the highest exergy destruction. Concerning limited sources of fossil fuels, humankind should ensue new avenues to meet its energy demands. Towards this, geothermal energy is acknowledged as a promising, reliable, safe, and clean means for this aim. In the present study, a multi-generation system driven by geothermal energy, which produces electrical power, hydrogen, oxygen, and cooling, is proposed, appraised from thermodynamic and economic standpoints. Due to today's importance of hydrogen production, pure hydrogen production is one of the primary purposes of the system here described and analyzed. The subsystems include an organic Rankine cycle (ORC), a polymer electrolyte membrane (PEM) electrolyzer, and a lithium/bromide absorption refrigeration cycle. The model is implemented in the Engineering Equation Solver software and a multi-objective optimization is performed with NSGA-II. The results indicate that the parameters mostly affecting system performance include geothermal fluid mass flow rate, geothermal fluid temperature, ORC turbines inlet temperature, and evaporator pinch-point. The highest exergy destruction is pertinent to evaporators and the PEM electrolyzer, respectively. Moreover, the results reveal that the higher the geothermal well temperature, the higher the output parameters of the system. Also, a case study was carried out to implement the proposed system in Sabalan geothermal wells; the results indicate that the system can support the energy need of 160 families during one year by producing 4,696 MWh of electrical power. Lastly, the multi-objective optimization lead to a optimal scenario with 37.85 % exergy efficiency and 15.09 USD/h system cost rate. [ABSTRACT FROM AUTHOR]