Hydrogen production system from photovoltaic panels: experimental characterization and size optimization

In this paper an approach for the determination of the optimal size and management of a plant for hydrogen production from renewable source (photovoltaic panels) is presented. Hydrogen is produced by a pressurized alkaline electrolyser (42 kW) installed at the University Campus of Savona (Italy) in 2014 and fed by electrical energy produced by photovoltaic panels. Experimental tests have been carried out in order to analyze the performance curve of the electrolyser in different operative conditions, investigating the influence of the different parameters on the efficiency. The results have been implemented in a software tool in order to describe the behavior of the systems in off-design conditions. Since the electrical energy produced by photovoltaic panels and used to feed the electrolyser is strongly variable because of the random nature of the solar irradiance, a time-dependent hierarchical thermoeconomic analysis is carried out to evaluate both the optimal size and the management approach related to the system, considering a fixed size of 1 MW for the photovoltaic panels. The thermo-economic analysis is performed with the software tool W-ECoMP, developed by the authors\u2019 research group: the Italian energy scenario is considered, investigating the impact of electricity cost on the results as well

Environmental economic analysis of speed reduction measure onboard container ships

: The International Maritime Organization (IMO) has concerned significant care to the reduction of ship emissions and improvement of energy efficiency through operational measures. One of those measures is ship speed reduction, which is classified as a short-term measure; in which the speed is reduced below its designed value. The present paper aims at evaluating the potential energy efficiency, and environmental and economic benefits because of applying speed reduction measures. The research methodology depends on establishing a simple mathematical model for technical, environmental, and economical aspects because of this concept. As a case study, container ships from different categories in a range of 2500-15,000 twenty-foot equivalent units (TEU) are investigated. The results show that a 2500 TEU ship can comply with the energy efficiency existing ship index (EEXI) by reducing the service speed to 19 knots. While for the bigger ships, the service speed must be 21.5 knots or below. Furthermore, the operational carbon intensity indicator (CII) has been evaluated for the case studies and found that the CII rating will keep its score between A and C levels if the service speed is equal to or below 19.5 knots. Moreover, the annual profit margin of the ship will be calculated based on applying speed reduction measures. Based on the economical results, the annual profit margin value, and its corresponding optimum speed change with the size of the vessel and the applicable status of carbon taxes

Thermodynamic analysis for SOFC/ICE integration in hybrid systems for maritime application

As the International Maritime Organization has set 2030 and 2050 targets to reduce the environmental impact of the maritime sector, it is mandatory to investigate innovative solutions aimed at fuel saving and reduction of ship emissions. In this paper, the integration of Solid Oxide Fuel Cells (SOFC) and Internal Combustion Engine (ICE) is investigated for maritime application, targeting a short-sea ferry as a case study operated by a marine gas engine (MGE) rated 750 kW. The paper aims to model via an in-house tool (WTEMP) the proposed hybrid system and study thermodynamic interaction among the two main energy systems, SOFC and ICE, considering blending anode-off gas from the SOFC with natural gas in the ICE. The results showed relevant efficiency enhancement and fuel/CO2 emission savings if compared with traditional MGE while the main source of exergy loss of the hybrid system is ICE

Ammonia as hydrogen carrier for transport application

As the interest in hydrogen to help the decarbonization of the transport sector is growing fast, the interest in new methods for its storage is a key point to improve its diffusion in many contexts, investigating innovative methods. Ammonia is a promising solution, as its hydrogen content per volume unit is higher than hydrogen stored in liquid form; furthermore, ammonia does not require cryogenic temperature nor high amounts of energy for liquefaction. In this study, two different plant layouts have been investigated, considering as a case study an ammonia-to-hydrogen conversion plant to feed a bus station composed of ten hydrogen buses (106 kg H2/day). In the end, a techno-economic analysis is performed to investigate the Levelized Cost of Hydrogen production from ammonia for the two cases and evaluate the most feasible solution. For both the plant layouts, the following results are obtained: (i) the optimal size of the main components; (ii) the global energy efficiency; (iii) the purity of H2 obtained; (iv) the H2 production cost. Finally, the size effect is investigated to evaluate the economic feasibility of the best plant solution for large-scale hydrogen refuelling stations (2000 kg H2/day), which are a more representative case for future implementations

Techno-economic analysis of innovative solutions for island grids with high renewable solar share

This paper presents a techno-economic analysis of a hybrid dispatch strategy on an island through conventional internal combustion engine (ICE) and innovative gas turbine (GT) with pressure gain combustion (PGC) in the presence of renewable solar-PV. Plant configurations with conventional technologies were defined based on established industrial data, and specifications of novel PGC-GT technology were estimated using the industrial data of conventional GT and on-design results available in the literature. Optimization of the operational strategy was conducted in WECoMP, a modular and flexible software tool developed by Thermochemical Power Group (TPG) at the University of Genova. The performance of different hybrid plants was analyzed in terms of annual production, fuel consumption, curtailment, CO2 emissions, cost, and sensitivity to fuel price. This is complemented by a parallel paper investigating the mechanical rotating inertia features of such prime movers, further supporting their suitability in enabling the integration of non-dispatchable renewables. Results showed that the 2-stroke ICE technology provided the best performance in terms of emissions and cost. Moreover, for all dispatchable prime movers, minimum LCOE occurred at an optimum value of PV capacity that facilitated annual CO2 reduction by 58.6 kton and LCOE reduction by 8.9 €/MWh. Finally, the optimum PV capacity was found to increase with fuel price, signifying the environmental benefits of high fuel prices

Thermodynamic analysis for SOFC/ICE integration in hybrid systems for maritime application

As the International Maritime Organization has set 2030 and 2050 targets to reduce the environmental impact of the maritime sector, it is mandatory to investigate innovative solutions aimed at fuel saving and reduction of ship emissions. In this paper, the integration of Solid Oxide Fuel Cells (SOFC) and Internal Combustion Engine (ICE) is investigated for maritime application, targeting a short-sea ferry as a case study operated by a marine gas engine (MGE) rated 750 kW. The paper aims to model via an in-house tool (WTEMP) the proposed hybrid system and study thermodynamic interaction among the two main energy systems, SOFC and ICE, considering blending anode-off gas from the SOFC with natural gas in the ICE. The results showed relevant efficiency enhancement and fuel/CO2 emission savings if compared with traditional MGE while the main source of exergy loss of the hybrid system is ICE

Hydrogen Carriers: Scientific Limits and Challenges for the Supply Chain, and Key Factors for Techno-Economic Analysis

Hydrogen carriers are one of the keys to the success of using hydrogen as an energy vector. Indeed, sustainable hydrogen production exploits the excess of renewable energy sources, after which temporary storage is required. The conventional approaches to hydrogen storage and transport are compressed hydrogen (CH2) and liquefied hydrogen (LH2), which require severe operating conditions related to pressure (300-700 bar) and temperature (T < -252 ?C), respectively. To overcome these issues, which have hindered market penetration, several alternatives have been proposed in the last few decades. In this review, the most promising hydrogen carriers (ammonia, methanol, liquid organic hydrogen carriers, and metal hydrides) have been considered, and the main stages of their supply chain (production, storage, transportation, H-2 release, and their recyclability) have been described and critically analyzed, focusing on the latest results available in the literature, the highlighting of which is our current concern. The last section reviews recent techno-economic analyses to drive the selection of hydrogen carrier systems and the main constraints that must be considered. The analyzed results show how the selection of H-2 carriers is a multiparametric function, and it depends on technological factors as well as international policies and regulations

An innovative tool for the evaluation and comparison of different fuels and technologies onboard ships

The paper focuses on the analysis of innovative energy systems onboard ships with the aim to evaluate, in a preliminary stage, which can be the most promising solution depending on the considered application. For this purpose, the dedicated tool HELM developed by the authors’ research group is employed. The tool uses maps reporting the main indicators (weight, volume, costs and emissions) for each component in relation to the installed power and the operational hours required (given by the user as an input), then it compares the results providing the best solution depending on the considered application. The maps have been built from a database developed throughout a wide analysis of the available market solutions in terms of energy generation devices (i.e. fuel cells, internal combustion engines), fuels (hydrogen, natural gas, diesel, methanol) and related storage technologies. The main strong point of HELM resides in its flexibility: it can be used for different typologies and sizes of ships (e.g. ferry boat, cruises, yachts); moreover, the database can be easily updated with more technologies. In this work, the focus is particularly on hydrogen application with PEM Fuel Cells and the use of innovative fuels (methanol, ammonia) in Internal Combustion Engines. Analysing different applications, it will be highlighted how the specific characteristics and priorities of the application affect the results of the best solutions. Furthermore, considering the regulation roadmap for the next years in the maritime context, promising technologies are highlighted also for future scenarios

An algorithm for comparative analysis of power and storage systems for maritime applications

This paper presents an innovative algorithm to compare traditional and innovative energy systems onboard for maritime applications. The solutions are compared adopting a multi-criteria method, considering four parameters (weight, volume, cost, emissions) and their relevance according to the kind of ship and navigation route. The algorithm, which includes a large and updated database of market solutions, leads to the implementation of HELM (Helper for Energy Layouts in Maritime applications) tool. HELM was conceived to support the design of maritime systems: it chooses the best technology comparing traditional marine diesel engines, propulsion systems with alternative fuels (methanol, ammonia, LNG) and innovative low-emission technologies (fuel cell and batteries). Two case studies are investigated: (i) a small passenger ship for short routes (ii) and a large size ro-ro cargo ship. For case (i), fuel cells represent a competitive solution, in particular considering navigation in emission control areas. For case study (ii) Internal Combustion Engines shows are the best solution. The evaluation of alternative fuels is performed, considering a sensitivity analysis on emissions’ importance: methanol, LNG, and ammonia are promising solutions. For case (i), the installation of electrical batteries is also evaluated to analyse potential advantages to reduce the amount of H2 stored onboard

Response Surface Methodology for 30 kW PEMFC stack characterization

Hydrogen is a promising energy carrier to allow the reach of the zero-emission targets established for the next years. Polymeric Electrolyte Membrane FC are studied inside the HI-SEA laboratory of the University of Genoa, to assess the opportunities of this technology on marine applications. Here, 8 PEMFC stacks, sized 30 kW each for a total power installation of 240 kW, have been tested to draw guidelines for the best system design onboard ships and to deepen the know-how on the experimental management of the technology. During the tests, it was possible to observe the reciprocal influence of some parameters, which may influence the system efficiency. In this work, a statistical investigation is developed to quantify the cell voltage variation correlated to the values of temperature and current. This has been possible thanks to Design Expert (DE), a software developed by Stat-EASE, Inc. Through the Design of Experiment approach, it is possible to evaluate the significance of variables in the FC system, called factors. The experiment under consideration is also characterized by non-controllable factors, cause of disturbances that induce further variability in the response. Eventually, it was possible to analyse the significance of the parameters involved, to build a regression model by performing the analysis of variance with which the significant values are identified, and to assess the presence of outliers