Modelling of full electric and hybrid electric fuel cells buses

Future road transports will increasingly move towards zero emissions. Although electric bus technology is available today, low energy density of lithium-ion (li-ion) batteries is a major drawback, leading to higher vehicle mass and range limitations. Hybrid buses, with more energy dense storage, appear as an easier transition from fossil fuels towards zero local emissions. Main objective of the research is drive systems' modelling and calculating energy consumption for public buses. Simulations were conducted in MATLAB/Simulink by modelling fuel cells and li-ion batteries where power consumption is driven by the instantaneous power demand of a bus on a given route. The simulation output includes the output power, energy consumption, efficiency, energy storage system requirements and refuelling times. The model can iterate energy storage options, to determine effects on system efficiency. Simulation results show that hybrid fuel cells buses offer up to 75% mass reduction, up to 43% volume reduction, with faster refuelling time, over battery only systems. This study provides a tool that allows comparison of multiple bus configuration for any route, on the path of viable, efficient and environmentally friendly transport system

The State of the Art in Fuel Cell Condition Monitoring and Maintenance

Fuel cell vehicles are considered to be a viable solution to problems such as carbon emissions and fuel shortages for road transport. Proton Exchange Membrane (PEM) Fuel Cells are mainly used in this purpose because they can run at low temperatures and have a simple structure. Yet to make this technology commercially viable, there are still many hurdles to overcome. Apart from the high cost of fuel cell systems, high maintenance costs and short lifecycle are two main issues need to be addressed. The main purpose of this paper is to review the issues affecting the reliability and lifespan of fuel cells and present the state of the art in fuel cell condition monitoring and maintenance. The Structure of PEM fuel cell is introduced and examples of its application in a variety of applications are presented. The fault modes including membrane flooding/drying, fuel/gas starvation, physical defects of membrane, and catalyst poisoning are listed and assessed for their impact. Then the relationship between causes, faults, symptoms and long term implications of fault conditions are summarized. Finally the state of the art in PEM fuel cell condition monitoring and maintenance is reviewed and conclusions are drawn regarding suggested maintenance strategies and the optimal structure for an integrated, cost effective condition monitoring and maintenance management system

A H2 PEM fuel cell and high energy dense battery hybrid energy source for an urban electric vehicle

Electric vehicles are set to play a prominent role in addressing the energy and environmental impact of an increasing road transport population by offering a more energy efficient and less polluting drive-train alternative to conventional internal combustion engine (ICE) vehicles. Given the energy (and hence range) and performance limitations of electro-chemical battery storage systems, hybrid systems combining energy and power dense storage technologies have been proposed for vehicle applications. The paper discusses the application of a hydrogen fuel cell as a range extender for an urban electric vehicle for which the primary energy source is provided by a high energy dense battery. A review of fuel cell systems and automotive drive-train application issues are discussed, together with an overview of the battery technology. The prototype fuel cell and battery component simulation models are presented and their performance as a combined energy/power source assessed for typical urban and sub-urban driving scenario

Battery, Hybrid and Fuel-Cell Propulsion Systems

The main purpose of the Research is theoretical and experimental evaluation of electric propulsion systems: pure electric ones, fed exclusively by electrochemical energy storage, hybrid electric, in which the power for propulsion comes from different sources, and fuel cell-based vehicles. These studies were carried on through an extended modelling and experimental activity, related to: • Modelling and experimental activities on electrochemical storage systems and super-capacitors, to evaluate their performance and to better individuate the optimal sizing for usage on-board electric and hybrid vehicles. • Design and realisation of a Fuel-Cell based vehicle, starting from the design of the propulsion system, for which dedicated models in Matlab-Simulink® environment were specifically realised, coming to an extended laboratory test activity for all the components, specially for the Fuel-Cell System. • Design of a complete line of electric and hybrid buses, based on the modelling of the propulsion system in collaboration with the manufacturer, through the usage of new object-oriented modelling techniques realised in Dymola-Modelica® environment. After evaluating different energy management strategies, an exhaustive comparison with conventional and electric pure versions has been carried on. The PhD Thesis, after an introduction about innovative propulsion systems, describes in detail all the activities presented, trying to summarise general techniques of design and management for hybrid vehicles

Powering Future Transport in Scotland: A Review for the Scottish Association for Public Transport

This report discusses energy costs and emissions associated with transport in Scotland and reviews options for future power sources for different modes of public transport. Transport provides a major contribution to greenhouse gas and other harmful emissions worldwide and efforts to reduce these are important for all forms of public transport, as well as for private cars and for the movement of freight. The effects of transport policy decisions are recognised, increasingly, as being very important for the electricity supply industry at national and local levels, largely because of the growth in the numbers of electric and hybrid road vehicles. Moving from oil to low carbon energy for transport raises important issues for electrical power generation and distribution systems in addition to challenges already being faced by the electrical power industry as the proportion of generating capacity involving renewables increases. The report starts by considering current energy costs and emissions for different forms of passenger transport and then outlines some current developments in areas such as internal combustion engine technology, battery storage systems and hydrogen fuel cells. Systems involving short-term energy storage and recovery of energy that would otherwise be dissipated as heat during braking are also discussed. Such systems generally involve the use of super-capacitors, flywheels or hydraulic devices. References are provided to the sources of data used in the analysis carried out for this review and, also, to sources of information about relevant developments in science and engineering. For all the new developments mentioned, there is a brief review of some transport applications in the United Kingdom and elsewhere. The possible impact of autonomous vehicles on future car ownership is still not known and the effects of this technology on public transport remain uncertain. As well as discussing autonomous road vehicles, the report makes brief mention of the potential of autonomous systems and increased automation for rail transport and for tramway operations. The benefits of further conventional railway electrification are reviewed in terms of energy usage, costs and emissions and the advantages of a more integrated approach to the provision of public transport in Scotland are emphasised. The value of using mathematical modelling and simulation methods to explore options in transport systems developments and planning is discussed, and the importance of testing simulation models in ways that are appropriate for the intended application is emphasised. This review presents the first results from a continuing study which was started in 2018 and is intended to provide information that should be relevant for those involved in decision-making in Scotland at the time of publication. The quantitative information contained within it clearly needs to be updated on a regular basis. The review concludes with recommendations for the Scottish Association for Public Transport about possible priorities for its efforts to increase public awareness about transport issues and is intended to be the first of a series of publications on transport and energy issues in the Scottish context. The references form an important part of the report and provide a potentially important bibliography which must be augmented and updated regularly

Urban and extra-urban hybrid vehicles: a technological review

Pollution derived from transportation systems is a worldwide, timelier issue than ever. The abatement actions of harmful substances in the air are on the agenda and they are necessary today to safeguard our welfare and that of the planet. Environmental pollution in large cities is approximately 20% due to the transportation system. In addition, private traffic contributes greatly to city pollution. Further, “vehicle operating life” is most often exceeded and vehicle emissions do not comply with European antipollution standards. It becomes mandatory to find a solution that respects the environment and, realize an appropriate transportation service to the customers. New technologies related to hybrid –electric engines are making great strides in reducing emissions, and the funds allocated by public authorities should be addressed. In addition, the use (implementation) of new technologies is also convenient from an economic point of view. In fact, by implementing the use of hybrid vehicles, fuel consumption can be reduced. The different hybrid configurations presented refer to such a series architecture, developed by the researchers and Research and Development groups. Regarding energy flows, different strategy logic or vehicle management units have been illustrated. Various configurations and vehicles were studied by simulating different driving cycles, both European approval and homologation and customer ones (typically municipal and university). The simulations have provided guidance on the optimal proposed configuration and information on the component to be used

Electric vehicles and smart grids: impacts, challenges and opportunities

Electric vehicles and smart grids: impacts,challenges, opportunitie

Uncertainty in electric bus mass and its influence in energy consumption

Throughout recent years, a public awareness of climate change and a social trend for preserving the environment have emerged. Transport sector is the principal contributor to greenhouse gas emissions, consequently electric buses are a great opportunity to reduce these emissions and fossil fuel dependence. To increase the competitiveness of electric buses, batteries with an accurate size are needed in order to optimize the charging infrastructure and reduce the total costs. Therefore, it is necessary to analyse the influence of certain parameters on electrical consumption. This thesis evaluates the impact of passenger loads on the electrical consumption of an electric city bus and provides a reliable energy consumption forecast. An electrical consumption sensitivity analysis was created with the number of passengers in the bus as uncertainty. This uncertainty is stochastically modelled for each stop in the bus route based on actual data and it is evaluated with the Monte Carlo method. In addition, the uncertainty in the number of stops is also considered. An algorithm for passenger load calculation was created in Matlab, based on driving cycles generated randomly (with a random number of stops and different speed profiles). Passenger data for each bus stop were represented by a normal probability distribution and they were related to each other using a multivariate normal distribution. These are the uncertain inputs of the model, as well as the number of stops which was modelled previously by another normal distribution. A validated electric bus model created in Simulink was simulated by means of the Monte Carlo sampling method, varying in each iteration the driving cycle and passenger flow introduced. The results obtained for a particular bus route, described as a probability distribution, define an electrical consumption with an average of 0.549 kWh/km. It is also possible to assure with an 80% of probability that the electrical consumption in this route will be between 0.485 kWh/km and 0.613 kWh/km. These results represent an electrical consumption forecast for the route, including all the possible outcomes taking into account the uncertainties of the model. Moreover, the analysis of the results indicates that the passenger load has a clear influence on the bus electrical consumption that increases with the number of passengers. In addition, the results show a clear influence of driving cycle average speed and number of stops on the consumption. Electrical consumption increases as the number of stops increases and as the average speed decreases. The results also confirm that Monte Carlo method provides an efficient tool for estimating the consumption of an electric city bus since it enables to obtain results for the different possible scenarios and cover all the variations

Transport and energy in India. Energy used by Indian transport systems and consequent emissions: the need for quantitative analyses (Well-to-Wheel, Lifecycle)

The purpose of this work is, at first, a general overview on the state-of-art of the transportation system in India outlining the related energy consumption, for the different transport modes, with consequent estimated emissions. These elements are essential for the preparation of a high-level strategic transport planning on the whole energy issue, to help India in the choices of most suitable transportation systems, according to the well-to-wheel analysis (WTW). Pursuing a WTW global index for India that takes into account both the energy and environmental aspects on a uniform basis is an important aim: it allows the best choices to be made as well as enabling the comparison between some of the most important powertrain and fuel options on the Indian market, the results are discussed from three different points of view: energy, environmental and economic impac