1,720,992 research outputs found
Comparison of different plant layouts and fuel storage solutions for fuel cells utilization on a small ferry
Full text linkIn the path towards the decarbonization of the maritime sector, Low Temperature Polymer Electrolyte Membrane Fuel Cells (LT-PEMFC) fed by hydrogen are gaining attention as they could guarantee zero local emissions propulsion. In this study, a process simulation model is implemented to analyze the influence of peak shaving in a hybrid LT-PEMFC/lithium-ion battery power plant for the propulsion of a small size RoRo car and passenger ferry in different operative conditions. Results show that battery peak shaving could allow a reduction of FC installed power of up to 72%. As for compressed H2 storage, the results show that for sailing time in the range of 5–10 min, Type I cylinders at 250 bar are a viable option. For longer routes, Type III cylinders at 350 bar or Type IV cylinders at 700 bar should be considered in order to avoid excessive reduction in the pay-load
Multi-objective optimization of hybrid PEMFC/Li-ion battery propulsion systems for small and medium size ferries
Full text linkHybrid Polymer Electrolyte Membrane Fuel Cells/Lithium-ion battery powertrains are a promising solution for zero-local-emissions marine propulsion. The present study aims to optimize the design and operation of such hybrid powertrain for small-size passenger ferries, taking into account the performance degradation of both fuel cells and batteries. A Mixed-Integer Linear-Programming approach and a hierarchical method are adopted to concurrently minimize the fuel cells degradation, the capital expenditure and the operating expenditure, while constraints are included in the model to limit the battery degradation. The results show that the proposed multi-objective optimization can lead to a reduction of fuel cells degradation by up to 65% compared to a cost-minimization only. However, this can imply an increase in the battery capacity by up to 136%. The proposed method has general validity, and it is a useful tool for both preliminary design and choice of the optimal energy management strategy for ships energy systems
Utility-based exergetic cost algorithms for managing cogeneration powered systems
No full textCosting of products based on exergy rather than energy is adjudged rational because it is a commodity of value and provides for accurate prices of products. In this paper, using an absorption chiller system as an example, a set of algorithms is presented that determines specific unit costs of internal flows and products at each component. The absorption chiller has different components that are broadly classified as productive and dissipative types. The methodology of second law of thermodynamics is used to define the productive components as well as for measuring their performance and the formulation of objective function for the determination of unit cost of the desired products. A utility-based exergetic evaluation technique is preferred because it offers the possibility of identifying and quantifying irreversibility as well as assigning available useful exergy among the productive components. Results from the study indicate that total purchase costs of productive components are as follows: €209.1/kW; €4.617/kW; €0.1619/kW; and €3.542/kW for generator, solution heat exchanger, pump and evaporator assembly, respectively. With these parameters, the various unit costs were calculated. It is hoped that information obtained here would be helpful in managing Independent Power Production plants through effective product pricing
A review of emissions reduction technologies for low and medium speed marine Diesel engines and their potential for waste heat recovery
Full text linkReducing emissions from internal combustion engines is becoming one of the most important tasks for engine manufactures and transport regulatory organizations. In particular, the marine transportation sector is one of the most polluting, due to the intense maritime activity and the use of low-quality fuels, burned in Heavy Duty Diesel Engines, for ship propulsion and auxiliary power generation. In order to reduce the global shipping environmental impact, the IMO (International Maritime Organization) is restricting NOx and SOx ships’ emissions through the introduction of the IMO Tier III legislation, which requires to consider a wide spectrum of emissions reduction technologies and strategies, which are going to have an impact on the engine performance and fuel consumption. In this work, the main solutions being currently developed or adopted for low and medium speed Diesel engines have been reviewed from a qualitative, and sometimes quantitative, point of view, but, in comparison to previous literature, focusing more on their potential with respect to possible waste heat recovery systems utilization, such as, in particular, steam Rankine cycles and Organic Rankine Cycles (ORC). Indeed, even though many of the considered emissions mitigation technologies lead to a certain amount of penalty in fuel economy, the use of waste heat recovery systems to recover wasted engines energy could become interesting in order to develop more efficient but, at the same time, cleaner engines
Uncertainty analysis of the optimal health-conscious operation of a hybrid PEMFC coastal ferry
Full text linkHydrogen fueled Polymer Electrolyte Membrane Fuel Cells/Lithium-Ion Battery powertrains could be a promising solution for zero-local-emission shipping. The power allocation between PEMFC and LIB and their respective performance degradation play a crucial role in reducing the powertrain operating and maintenance costs. While several research works proposed energy management strategies to face these issues, a long-term operation optimization including the uncertainty in the input parameters of the model has not been extensively addressed. To this purpose, this study couples an operation optimization model of a PEMFC/LIB ferry propulsion system with a Monte-Carlo analysis to investigate the influence of PEMFC, LIB and hydrogen costs on the optimal operation of a hydrogen-powered ferry in the long-term. Hydrogen cost results to be the most influent parameter, in particular toward the end of the plant lifetime, when hydrogen consumption increases by up to 30%. Nevertheless, the variability of optimal ferry operation gradually decreases with the progressive PEMFC/LIB degradation
Fuel cells for airborne usage: Energy storage comparison
No full textThe global drone market is growing every year. The number of applications is increasing: from search and rescue, security, surveillance to science and research and unmanned cargo systems.
A limiting factor for drone exploitation is that for the energy storage, normally, a battery is used and this solution affects flight time. A possible solution could be the utilization of fuel cells. This paper focuses on the utilization of fuel cells power as an alternative solution for drone propulsion.
The aim of the study is to determine when it is more appropriate, in terms of mass, to use a battery or a hybrid (fuel cell þ battery) system to power drones. To compare the different systems, a numerical simulation model has been developed in order to choose the best power system once the drone operation profile has been defined.
The model allows comparing different type of fuels and battery systems. The data to tune the model have been taken from commercial products, today already available. The simulation model considers a light-weight open-air cathode PEM (Polymer Exchange Membrane) fuel cell. The stack power output is chosen according to the mission profile and rages from 200 W to 1000 W.
The presented results show that, for the considered drone segment, multi-rotor drones with weight of 7 kg at take-off, lithium batteries are still the best choice for time flight shorter than about 1 h. A hybrid system, appears to be interesting for longer flights. For example, it has been calculated that a hybrid quadcopter drone with a mass of 7 kg, considering a flight profile that requires 1089 Wh can be powered with a 4.4 kg hybrid system composed by a 500 W and 1.4 kg PEM fuel cell system, 1.9 kg hydrogen composite pressure vessel and a 0.8 kg lithium battery. The same amount of energy can be stored in a lithium battery with a weight of about 6.6 kg. These means a weight saving of more than 30%. The hybrid system, in term of weight, is even more convenient for flight profiles that require more energy
A multi-objective planning tool for the optimal supply of green hydrogen for an industrial port area decarbonization
Full text linkThis study addresses the challenge of decarbonizing highly energy-intensive Industrial Port Areas (IPA), focusing on emissions from various sources like ship traffic, warehouses, buildings, cargo handling equipment and hard-to-abate industry, typically hosted in port areas. The analysis and proposal of technological solutions and their optimal integration in the context of IPA is a topic of growing scientific interest with considerable social and economic implications. Representing the main novelties of the work, this study introduces (i) the development of a novel IPA energy and green hydrogen hub located in a tropical region (Singapore); (ii) a multi-objective optimization approach to analyse, synthesize and optimize the design and operation of the hydrogen and energy hub, with the aim of supporting decision-making for decarbonization investments. A sensitivity analysis identifies key parameters affecting optimization results, indicating that for large hydrogen demands, imported ammonia economically outperforms other green hydrogen carriers. Conversely, local hydrogen production via electrolysis becomes economically viable when the capital cost of alkaline electrolyser drops by at least 30 %. Carbon tax influences the choice of green hydrogen, but its price variation mainly impacts system operation rather than design. Fuel cells and batteries are not considered economically feasible solutions in any scenario
Experimental analysis on the influence of operating profiles on high temperature polymer electrolyte membrane fuel cells
Full text linkThe Energy System lab at the University of Trieste has carried out a study to investigate the reduction in performance of high temperature polymer electrolyte membrane (HTPEM) fuel cell membrane electrode assemblies (MEAs) when subjected to different ageing tests. In this study, start and stop cycles, load cycles, open circuit voltage (OCV) permanence and constant load profile were considered. Polarization curves (PC) together with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) data were recorded during the ageing tests to assess the fuel cell per-formance. In this paper, experimental data are presented to confirm the test methodology previ-ously proposed by the authors and to quantitatively correlate the performance degradation to the operational profiles. It was demonstrated that OCV condition, start and stop and load cycling in-crease degradation of the MEAs with respect to constant load operation. As expected, the OCV is the operational condition that influences performance degradation the most. Finally, the MEAs were analyzed with synchrotron small angle X-ray scattering (SAXS) technique at the Austrian SAXS beamline at Elettra-Sincrotrone Trieste to analyze the nano-morphological catalyst evolution. As for the catalyst morphology evolution, the ex situ SAXS methodology proposed by the authors is confirmed in its ability to assess the catalyst nanoparticles aggregation
High energy density storage of gaseous marine fuels: An innovative concept and its application to a hydrogen powered ferry
Full text linkThe upcoming stricter limitations on both pollutant and greenhouse gases emissions represent a challenge for the shipping sector. The entire ship design process requires an approach to innovation, with a particular focus on both the fuel choice and the power generation system. Among the possible alternatives, natural gas and hydrogen based propulsion systems seem to be promising in the medium and long term. Nonetheless, natural gas and hydrogen storage still represents a problem in terms of cargo volume reduction. This paper focuses on the storage issue, considering compressed gases, and presents an innovative solution, which has been developed in the European project GASVESSEL® that allows to store gaseous fuels with an energy density higher than conventional intermediate pressure containment systems. After a general overview of natural gas and hydrogen as fuels for shipping, a case study of a small Roll-on/Roll-off passenger ferry retrofit is proposed. The study analyses the technical feasibility of the installation of a hybrid power system with batteries and polymer electrolyte membrane fuel cells, fuelled by hydrogen. In particular, a process simulation model has been implemented to assess the quantity of hydrogen that can be stored on board, taking into account boundary conditions such as filling time, on shore storage capacity and cylinder wall temperature. The simulation results show that, if the fuel cells system is run continuously at steady state, to cover the energy need for one day of operation 140 kg of hydrogen are required. Using the innovative pressure cylinder at a storage pressure of 300 bar the volume required by the storage system, assessed on the basis of the containment system outer dimensions, is resulted to be 15.2 m3 with a weight of 2.5 ton. Even if the innovative type of pressure cylinder allows to reach an energy density higher than conventional intermediate pressure cylinders, the volume necessary to store a quantity of energy typical for the shipping sector is many times higher than that required by conventional fuels today used. The analysis points out, as expected, that the filling process is critical to maximize the stored hydrogen mass and that it is critical to measure the temperature of the cylinder walls in order not to exceed the material limits. Nevertheless, for specific application such as the one considered in the paper, the introduction of gaseous hydrogen as fuel, can be considered for implementing zero local emission propulsion system in the medium term
Performance degradation study on polybenzimidazole fuel cells subjected to different ageing tests
No full textThe study presented in this paper aims to evaluate the performance degradation of Polybenzimidazole (PBI) based High Temperature PEM (HTPEM) fuel cells subjected to triangular load cycling ageing test, according to a methodology already used by the authors. A HTPEM Membrane Electrode Assembly (MEA) has been subjected to 125,000 triangular sweep cycle between Open Circuit Voltage (OCV) and 0.5 A/cm2 with 2 seconds of permanence at OCV at each cycle. In order to assess the cell performance, polarization curves, Electro Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV) have been recorded during the ageing tests
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