Laura Tribioli

Analysis of energy management strategies in plug-in hybrid electric vehicles: Application to the GM Chevrolet Volt

In this paper, we analyze and compare the performances, in terms of fuel economy, of two energy management strategies developed for the GM Chevrolet Volt vehicle. First, an optimal control strategy based on Pontryagins Minimum Principle (PMP) is developed and implemented on the first plug-in hybrid electric vehicle (PHEV) in the mainstream market. This strategy is used as a benchmark for fuel consumption evaluation to assess the Charge Depleting-Charge Sustaining (CDCS) paradigm used today on-board of the vehicle. Moreover, a comparison of the powertrain modes of operation under the optimal and CDCS scenarios is conducted which shows a significant different use of the powertrain in the two cases. The advantages brought by the blended strategy obtained from PMP set the basis for future research work towards the direction of developing adaptive strategies to achieve performance near the optimal when minimum information, such as the traveled distance, is available to the energy management controller.

SOFC Management in Distributed Energy Systems

Among the distributed generation emerging technologies, solid oxide fuel cells (SOFCs) seem to be the most promising for small and medium power (up to 1 MW) as they feature extremely high efficiency and low pollutant emissions, and the high-grade waste heat can be utilized for space heating, process steam, and/or domestic hot water demands. As their main drawbacks are high cost and relatively short lifetime, much research is devoted to solve technological problems and to develop less expensive materials and mass production processes. However, even if SOFCs are close to commercialization and several demonstration units are already running, only few researches have been performed on their integration in power plants for distributed power generation, which are complex systems made up of different components that have to satisfy energy requirements (heat, electricity, and cooling). In this paper, we investigate the behavior of SOFCs in distributed energy systems and how their operation in terms of load and fuel utilization factor could optimize fuel consumption and/or minimize energy costs. The potential advantages of SOFCs related to their excellent part-load operation and their ability to meet and follow the highly noncoincident electric and thermal loads in either grid-connected or stand-alone configurations are discussed.

Comparative environmental assessment of conventional, electric, hybrid, and fuel cell powertrains based on LCA

PurposeThe purpose of this study is to compare the environmental impact differences of four types of vehicles on a life cycle assessment (LCA) perspective: a conventional gasoline vehicle, a pure electric vehicle, a plug-in hybrid gasoline-electric vehicle, and a plug-in hybrid fuel cell-battery vehicle. The novelty of the approach is to consider the different powertrains—electric and hybrids—as a repowering of the conventional powertrain. This way, the attention can be focused only on the powertrain differences and inefficiencies, with the added value of avoiding further assumptions, which could cause the analysis to be somehow rough.MethodsThus, we compared four powertrain scenarios maintaining the same vehicle chassis, and we compared the impacts from the powertrain production, vehicle use phase, and powertrain end of life only. Hence, special attention was paid to the inventory for powertrain construction and use phase. For the powertrain components, an accurate literature survey has been carried out for the life cycle inventory. For the use phase, several driving cycles, both standardized and real-world type, have been simulated in order to properly evaluate the effect on the fuel/electricity consumption. For the comparison, environmental indicators according to cumulative energy demand (CED) and ReCiPe Midpoint methods have been used. This way, an analysis of the environmental impact, based on a life cycle impact assessment approach, is provided, which allows thoroughly comparing the systems based on the different powertrains. Moreover, a sensitivity analysis on different energy mixes has been included, which represents also a way to take into account changes in electricity production.Results and discussionResults are presented according to life cycle impact assessment, which examines the mass and energy inventory input and output data for a product system to translate these data to better identify their possible environmental relevance and significance. In the case of the climate change (CC), fuel depletion (FD), and CED indicators, the lowest value corresponds to the plug-in hybrid gasoline-electric vehicle, followed by the plug-in hybrid fuel cell-battery vehicle, the pure electric, and finally the conventional gasoline vehicle. Substituting a conventional gasoline powertrain with the corresponding pure electric one offers the lowest reduction, but still of valuable amount. In our analysis, for the considered systems, the reduction of the value of CC is about 15%, the reduction of the value of CED is about 12%, and the reduction of FD value is about 28%. This analysis underlines the weakness of a tank-to-wheel comparison, according to which the pure electric powertrain, having a very high average efficiency, results in being the less consuming, followed by the hybrid gasoline-electric and fuel cell-battery vehicles, respectively, and then by the conventional vehicle. Instead, in terms of CED, the bad influence of the low average efficiency of the Italian electricity production is highlighted. The LCA approach also stresses out the importance of the battery inventory, which can make the environmental performance of the system based on the pure electric vehicle significantly worse than those based on the conventional vehicle. Of a great significance is the presence of a group of indicators—including human toxicity, eutrophication, and acidification—with lower values in the case of conventional gasoline vehicle than in the electric and hybrid ones, which further confirms that the potential of electrified vehicles strictly depends on an efficient production and recycling of the battery.ConclusionsThe analysis underlines an alarming list of environmental impact indicators, usually neglected, which are worsened by the powertrains electrification. Operating on the production processes, used materials and recycling phase can possibly mitigate these worsening effects. Also, the type of electricity is shown to strongly affect the results. Thus, performing specific evaluations for different countries is crucial and a sensitivity analysis, involving drastically different energy mixes, can allow for taking into account possible changes in the future electricity production.

On-board diesel autothermal reforming for PEM fuel cells: Simulation and optimization

Alternative power sources are nowadays the only option to provide a quick response to the current regulations on automotive pollutant emissions. Hydrogen fuel cell is one promising solution, but the nature of the gas is such that the in-vehicle conversion of other fuels into hydrogen is necessary. In this paper, autothermal reforming, for Diesel on-board conversion into a hydrogen-rich gas suitable for PEM fuel cells, has investigated using the simulation tool Aspen Plus. A steady-state model has been developed to analyze the fuel processor and the overall system performance. The components of the fuel processor are: the fuel reforming reactor, two water gas shift reactors, a preferential oxidation reactor and H2 separation unit. The influence of various operating parameters such as oxygen to carbon ratio, steam to carbon ratio, and temperature on the process components has been analyzed in-depth and results are presented.

Virtual Academic Teaching for Next Generation Engineers

Recent advances in web technology have transformed the World-Wide-Web from delivering static text to providing an easily accessible multimedia channel for dynamic, interactive communication. By using such technologies, academic teaching may evolve toward the next-generation way to transfer knowledge. At present time, there are two approaches that can be found: the Massive Open Online Courses (MOOC) approach that delivers video interactive classes to the vast audience with an open-access philosophy and Restrict-Access Courses (RAC) that deliver classes and, more important, standard degrees to limited audience [1]. While the two approaches are comparable when dealing with most academic disciplines, teaching engineering has some peculiarities that let the restricted–access course a more viable solution.First of all, engineering schools must prepare the student for the profession. In most countries, after the degree there is a professional practice period, thus a closer relation between teacher and students allows bringing the professional knowledge embedded in the academy.Being also a scientific discipline, engineering takes advantage from a close contact between teaching and research, especially for cutting-edge technologies. Finally, student projects are one of the most important steps of the educational path of the young engineers. Good student projects need one to one supervision, an adequate environment in particular for lab practice, and campuses that only restricted-access academies may provide.Copyright