• Energy Research

The paper deals with a fuzzy logic based strategy managing the power flows in an hybrid generation plant. Such a plant works in island mode and is composed of: a wind turbine, a photovoltaic generator and a fuel cell/electrolyzer energy storage system. The performances of the proposed strategy are evaluated by simulation in different operating conditions. To this purpose some performance indexes are considered, such as: the frequency deviation, the stability of the DC bus voltage and the AC voltage total harmonic distortion. Simulation results confirm the effectiveness of the proposed power management strategy, providing the ground for the practical realization of a fuzzy logic based control system. Moreover the efficiency of the developed fuzzy logic controller is compared to that of a more conventional controller taking into the fuel cell H 2 consumption, the amount of H 2 generated from the Electrolyzer and the final battery state of charge (SOC).

Fuel cells based on polymer electrolyte membrane are considered as the most hopeful clean power technology. The operating principles of polymer electrolyte membrane fuel cells (PEMFC) system involve electrochemistry, thermodynamics and hydrodynamics theory for which it is difficult to establish a mathematical model. In this paper a nonlinear data driven model of a PEMFC stack is developed using Neural Networks (NNs). The model presented is a black-box model, based on a set of measurable exogenous inputs and is able to predict the output voltage and cathode temperature of a high power module working at the CNR- ITAE. A 5 kW PEM fuel cell stack is employed to experimentally investigate the dynamic behaviour and to reveal the most influential factors.

Abstract Hydrogen and regional energy infrastructure are significant for the European Green Deal and was the focus of the SuperP2G research Project (Synergies Utilising renewable Power Regionally by means of Power to Gas). Five national projects (Denmark, Netherlands, Germany, Austria, and Italy) cooperated to investigate power-to-gas feasibility. The energy crisis due to the war in Ukraine peaked during the project. The demand for green hydrogen increased as natural gas was reduced. In 2022, the cost of blue hydrogen was 9.5–12.6 €/kg. Higher electricity prices impacted the cost of green hydrogen less. Considering the 2021–22 level of electricity and gas prices, and the potential flexibility of electrolysers, electrolytic hydrogen was on a par with blue hydrogen. On the long term, green hydrogen is assumed to be competitive around 2030. A fast ramping up and favourable electricity cost development could halve the hydrogen production cost until 2040 with investment being the major contributor to a cost reduction. Meanwhile, the smart operation of a wind/electrolyser system might achieve 24% reduction of its operation cost. The following measures are recommended to introduce green hydrogen on a large scale: 1) certification of green and low carbon hydrogen and a uniform CO2 price; 2) ensuring a level playing field across markets; 3) enabling policies to enhance European security of supply by increasing domestic production and diversifying imports; 4) fast ramping of renewable electricity generation; and 5) coordinated planning of hydrogen, methane, and electricity infrastructures.

Abstract Nowadays, resilient grids meet growing interest for their capability of supplying critical load even in case of power fault coming from grid disturbance and natural disasters. To do this, such grids involve redundant apparatus and predictive control schemes. For high value services, unexpected system unavailability is source of economic losses to the providers. Hence, beside the internal energy storage devices, such plants had better to have redundancy of energy sources (e.g. electrical grid and natural gas network) and tailored power flows control strategies still valid even in the case of energy shortage. On the other hand, distributed storage resources is attracting growing interest to support the power networks in terms of both resiliency and flexibility facing the impact of generation from the Renewable Energy Sources. In this work, a power supply system controller based on Artificial Intelligence was developed and simulated to wisely operate the storage resources to serve the ICT equipment as Uninterruptible Power Supply (above all in case of emergency) as fundamental mission. Secondly, the investigation assessed the capability, to offer ancillary services to the power network increasing its resiliency measured system response in terms of survival time during grid faults and restoration transient time to recover initial service level.

Bifacial photovoltaic (BPV) panels represent one of the main solar technologies that will be used in the near future for renewable energy production, with a foreseen market share in 2030 of 70% among all the photovoltaic (PV) technologies. Compared to monofacial panels, bifaciality can ensure a gain in energy production per unit panel area together with a competitive cost. However, it is of paramount importance to identify whether there is also an environmental benefit when adopting bifacial technologies as opposed to traditional monofacial ones. To obtain a proper insight into the environmental impact, this paper reviews the Life Cycle Assessment (LCA) studies of bifacial solar panels, identifying the most crucial processes and materials that raise environmental burdens. The analysis also contributes to determining whether the major aspects that influence energy production in real operation scenarios and, most of all, that can ensure the gain associated with bifaciality, are considered and how these can further affect the overall environmental impacts. In this sense, it was found that the installation parameters like the mounting structure, or the choice of ground material to raise the albedo as well as the diffuse irradiation that hits the rear surface of thepanel, are commonly not considered during LCA analysis. However, none of the analyzed studies address the issue in a comprehensive way, hampering an effective comparison between both the different works and traditional monofacial PV panels. Recommendations for future LCAs are finally proposed.

Abstract According to recent literature and technical analyses, used batteries from electric vehicles can still be used, before the final treatment at the end-of-life, in stationary applications that are usually less stressing than the automotive ones. In this framework, a circular economy inspired pathway is emerging between the building and the transportation sector, generally called “second life” of batteries. Used batteries from electric vehicles can be re-used in residential buildings together with renewable electricity generation technologies to improve the matching between the highly variable electricity generation from renewables and the electricity demand in buildings. This study aims to contribute to the assessment of the environmental sustainability of using battery storage systems for stationary applications made of used batteries in substitution of new batteries in a life cycle perspective. The analysis is performed considering an expanded circular system that includes both the functions provided in buildings (provide the electricity required in a residential building for a specific time frame) and in the transportation sector (provide electricity needed for driving until the battery capacity reached about 80% of the rated capacity). The study shows that reusing used batteries as stationary storage systems in residential buildings can enhance the overall environmental sustainability of the two systems considered. In particular, the environmental impacts decrease of a percentage ranging from around -4% (in cumulative energy demand) to -17% (in abiotic depletion potential). The examined strategy can contribute to initiate the transition towards a circular and low-carbon economy.

The integration of distributed storage systems (DSSs) at users and prosumers level can significantly contribute to energy efficiency and increase profits from renewable energy exploitation, thanks to suitable scheduling of charging and discharging periods. On the other hand, to preserve network stability and secure operation, Distribution Systems Operators (DSOs) are interested in DSSs control and cooperation with the grid. In this framework this work proposes a simple monitoring and management system for DSSs scheduling and its integration in a distributed measurement and control system architecture for smart grids. In the paper the proposed algorithm is tested on a simple case study at home level; the obtained results show its feasibility in addressing both users/prosumers economic interests and DSOs needs for grid secure operation.

The H-BUS is a joint project of National Research Council of Italy and two supplier companies to develop a range extender Fuel Cell/Battery Hybrid Electric city bus. Within the project, CNR ITAE Institute is involved in determining the optimal level of hybridization assessing all boundary conditions (mission, performances, hydrogen consuption, range, etc...). The paper reports the characterization results of the hybrid system which allowed the identification of the power and energy consumption. These data were the starting points to define the size of Batteries and Fuel Cell (FC) system and to optimize the batteries State of Charge (SoC). PEM (Polymer Electrolyte Membrane) and ZEBRA® (Zero Emission Battery Research Activities) technologies have been selected for the fuel cell system and batteries, respectively.