Fuel cell vehicle | EPFL Graph Search

A fuel cell vehicle (FCV) or fuel cell electric vehicle (FCEV) is an electric vehicle that uses a fuel cell, sometimes in combination with a small battery or supercapacitor, to power its onboard electric motor. Fuel cells in vehicles generate electricity generally using oxygen from the air and compressed hydrogen. Most fuel cell vehicles are classified as zero-emissions vehicles that emit only water and heat. As compared with internal combustion vehicles, hydrogen vehicles centralize pollutants at the site of the hydrogen production, where hydrogen is typically derived from reformed natural gas. Transporting and storing hydrogen may also create pollutants. Fuel cells have been used in various kinds of vehicles including forklifts, especially in indoor applications where their clean emissions are important to air quality, and in space applications. Fuel cells are being developed and tested in trucks, buses, boats, ships, motorcycles and bicycles, among other kinds of vehicles. The first road vehicle powered by a fuel cell was the Chevrolet Electrovan, introduced by General Motors in 1966. The Toyota FCHV and Honda FCX, which began leasing on December 2, 2002, became the world's first government-certified commercial fuel cell vehicles, and the Honda FCX Clarity, which began leasing in 2008, was the world's first fuel cell vehicle designed for mass production rather than adapting an existing model. In 2013, Hyundai Motors began production of the Hyundai ix35 FCEV, claimed to be the world's first mass-produced fuel cell electric vehicle, which was subsequently introduced to the market as a lease-only vehicle. In 2014, Toyota began selling the Toyota Mirai, the world's first dedicated fuel cell vehicle. 31,225 passenger FCEVs powered with hydrogen had been sold worldwide. , there were only two models of fuel cell cars publicly available in select markets: the Toyota Mirai (2014-present) and the Hyundai Nexo (2018–present). The Honda Clarity was produced from 2016 to 2021, when it was discontinued.

The Application of Fuel-Cell and Battery Technologies in Unmanned Aerial Vehicles (UAVs): A Dynamic Study

Jan Van Herle, Hossein Pourrahmani, Claire Marie Isabelle Bernier

The harmful impacts of fossil-fuel-based engines on the environment have resulted in the development of other alternatives for different types of vehicles. Currently, batteries and fuel cells are being used in the automotive industry, while promising progress in the maritime and aerospace sectors is foreseen. As a case study in the aerospace sector, an unmanned aerial vehicle (UAV) was considered. The goal and the novelty of this study are in its analysis of the possibility of providing 960 W of power for a UAV with a weight of 14 kg using a hybrid system of a lithium-ion (Li-ion) battery and proton-exchange membrane fuel cell (PEMFC). The dynamic performance of the system was analyzed considering three different load profiles over time in an optimized condition. PEMFC was the main supplier of power, while the battery intervened when the power load was high for the PEMFC and the system demanded an immediate response to the changes in power load. Additionally, the impacts of the operating temperature and the C-rate of the battery were characterized by the state of the charge of the battery to better indicate the overall performance of the system.

MDPI2022

Decreasing the Stability of Borohydride with Ionic Liquids for Hydrogen Storage and Carbon Dioxide Conversion

Loris Giovanni Lombardo

The world needs to move from a fossil fuel to a renewable energy based society. With the increasing electricity production from wind and PV, short and long term energy storage are becoming one of challenge of the 21st century. While batteries are the preferred method for short term storage, another technology is required for seasonal storage. Hydrogen is a valuable energy carrier owning its high energy density (122 kJ/g). However, compact and safe storage of H2 is challenging. The current solution is to compress hydrogen up to 700 bar for mobile application (fuel cell cars), and metal hydrides for stationary application. Material-based H2 storage avoids using high-pressure cylinder. Complex hydrides are especially attractive for solid-state H2 storage due to their high gravimetric and volumetric hydrogen density. Sodium borohydride (NaBH4) contains 10.6 mass% of H2, but high temperatures are needed to release H2 (505 Â°C) and the reaction is not reversible under moderate conditions. To apply complex hydrides in real applications, they must be modified to improve the kinetics and thermodynamics of H2 desorption. Several possibilities exist such as confinement into scaffolds, catalyst addition, or combination of several hydrides to modify the dehydrogenation pathway. The stability of complex hydrides is determined by the localization of the charge on the central atom of the complex. Therefore, in this thesis the interaction of highly polar or ionic compounds with complex hydrides were investigated. We combine NaBH4 with a special class of organic salts: ionic liquids (IL). Considering their chemical and thermal stability, IL are attractive additive. Using organic additives instead of expensive metal catalysts is another advantage. Two different techniques were employed to combine the IL and NaBH4. The first one consists of mechanochemically milling them to create an interaction between BH4- and IL. The second one is to directly synthesized IL borohydrides ([IL][BH4]) by metathesis reaction. Different ILs, such as vinylbenzyltrimethylammonium chloride ([VBTMA][Cl]), 1-butyl-3-methylimidazolium chloride ([bmim][Cl]), and 1-ethyl-1-methylpyrrolidinium bromide ([EMPY][Br]) were tested. [bmim][BH4] was able to release H2 below 100 Â°C. The hydrogen content ranges between 2.4 mass% and 2.9 mass%. The second challenge of this century is the CO2 problematic. Atmospheric CO2 concentration linearly increases, leading to greenhouse effect. Carbon capture and sequestration (CCS) and utilization (CCU) are primordial research topic to stabilize the CO2 emission. Hydrides are primary reducing agents, thus reduction of CO2 can be accomplished with them. Direct CO2 reduction at ambient conditions is challenging for classical borohydrides. With our [IL][BH4], gaseous CO2 can be captured and reduced under ambient conditions (1 bar, RT). Three CO2 bounds with boron to give triformatoborohydride ([HB(OCHO)3]â. Dilute CO2 (6 vol%) can be used as well. The reaction was followed in real time with a magnetic suspended balance (MSB). Further, CO2 reduction happened when air is used as a carbon dioxide source. Formic acid can be obtained by adding HCl. Thus, ionic liquid borohydrides have great potential as a CO2 absorber and reducer to alternative fuels. In short, we applied ionic liquid to destabilized borohydrides. The resulting materials exhibited potential for solid-state hydrogen storage, as well as CO2 capture and transformation.

EPFL2021

The influence of trip length distribution on urban traffic in network-level models

Mikhail Murashkin

Modeling urban traffic on the level of network is a wide research area oriented to the development of ITS. In this thesis properties of models based on MFD (Macroscopic Fundamental Diagram) are studied. The idea behind MFD is to say that the state of the traffic inside an urban zone is fully determined by its accumulation (the number of traveling vehicles) and that the dynamics of accumulation is caused by the inflow of vehicles (flow of vehicles that enter the zone or start their trips from inside). Nowadays, two different philosophies of modeling dynamics of accumulation exist in the literature. The first one (outflow-MFD) postulates that the outflow of vehicles depends on accumulation. The second one (speed-MFD) postulates that the space-mean speed of vehicles depends on accumulation. The second philosophy already has strong empirical support based on observations of traffic inside many big (kilometer-scale) urban areas around the world. Thus, different speed-MFD models are of great scientific interest. The thesis is mainly devoted to the comparison of so-called PL model (which assumes the existence of both speed-MFD and outflow-MFD) and TB model (which assumes the equality of speeds of vehicles and explicitly assumes the existence of trip length distribution). It was shown that PL model cannot accurately describe the dynamics of accumulation after the jump of inflow. In this case TB model is more preferable. Moreover, it was proven that PL model is a specific case of TB model for the exponential trip length distribution. This makes TB model more attractive than PL model for the practical usage. TB model can be formulated mathematically either as integral equation or nonlocal PDE. Thus, the main drawback of TB model that can be an obstacle in practice is its computational complexity. In this thesis it was proposed to approximate TB model with a simpler model which does not require precise information about the trip length distribution. This so-called M model operates with only the mean and the standard deviation of distribution and has a form of ODE. The analytical comparison between PL, TB and M models proved that M model is much closer to TB model than PL model in the case of constant speed-MFD. The more realistic case of decreasing speed-MFD was studied through the numerical tests and also showed the same effect. Thus, the main conclusion of the study is that M model has practical potential as an elegant and computationally cheap approximation of TB model. Also, given that in the case of constant speed TB model is a type of LTI system, it can be expected that M model might be useful for a wide range of problems that are not related to transportation. However, in this thesis the conclusion about the small difference between M and TB models was made for the inflows that are typical for the transportation field. More precisely, only peak hour shaped (smooth and with small jumps) functions were studied. Despite the simple form of M model it was found that there exists even more simple ODE approximation of TB model. This so-called

\alpha

model works quite well for both smooth and jumping inflows except the case of a short period of time following the jump of inflow. Thus, it might be another good alternative to TB model. The main advantage of

\alpha

model in the case of realistic speed-MFD function is its convex formulation which allows

\alpha

model to be efficiently used inside optimization frameworks.

EPFL2021

The influence of trip length distribution on urban traffic in network-level models

Mikhail Murashkin

\alpha

\alpha

model in the case of realistic speed-MFD function is its convex formulation which allows

\alpha

model to be efficiently used inside optimization frameworks.

EPFL2021