Alternative fuel vehicle | EPFL Graph Search

An alternative fuel vehicle is a motor vehicle that runs on alternative fuel rather than traditional petroleum fuels (petrol or petrodiesel). The term also refers to any technology (e.g. electric cars, hybrid electric vehicles, solar-powered vehicles) powering an engine that does not solely involve petroleum. Because of a combination of factors, such as environmental concerns, high oil-prices and the potential for peak oil, development of cleaner alternative fuels and advanced power systems for vehicles has become a high priority for many governments and vehicle manufacturers around the world. Vehicle engines powered by gasoline/petrol first emerged in the 1860s and 1870s; they took until the 1930s to completely dominate the original "alternative" engines driven by steam (18th century), by gases (early 19th century), or by electricity ( 1830s). Hybrid electric vehicles such as the Toyota Prius are not actually alternative fuel vehicles, but through advanced technologies in the electric battery and motor/generator, they make a more efficient use of petroleum fuel. Other research-and-development efforts in alternative forms of power focus on developing all-electric and fuel cell vehicles, and even on the stored energy of compressed air. An environmental analysis of the impacts of various vehicle-fuels extends beyond just operating efficiency and emissions, especially if a technology comes into wide use. A life-cycle assessment of a vehicle involves production and post-use considerations. A cradle-to-cradle design is more important than a focus on a single factor such as the type of fuel. there were more than 1.4 billion motor vehicles on the world's roads, compared with just more than 116 million alternative fuel and advanced technology vehicles that had been sold or converted worldwide at the end of 2016 and consisting of: About 55 million flex fuel automobiles, motorcycles and light duty trucks manufactured and sold worldwide by mid 2015, led by Brazil with 29.5 million by mid 2015, followed by the United States with 17.

Emission reduction by targeted transient operations in three-way catalysts for heavy-duty natural gas applications

Moyu Wang

To curb the severe effects of climate change, our society needs to radically reduce its CO2 footprint. For the heavy-duty sector, where electrification is difficult, alternative fuels can be the solution. Methane-fueled engines have lower energy-specific CO2 emissions than conventional Diesel-fueled engines. Furthermore, they have the potential of becoming carbon-neutral, when combined with bio-methane/synthetic methane. However, oxidation of unburnt methane in the exhaust gas poses a challenge for aftertreatment systems. The aim of this thesis is to investigate the mechanism of methane abatement and to reveal methods to reduce methane and other hazardous gas emissions. The majority of the experiments were conducted directly on an engine test bench, which is rarely seen in studies focusing on catalytic reaction pathways. Initial investigations focused on methane abatement under steady state and Î»-step transitions. Under steady state, the presence of oxygen was identified as a prerequisite for methane conversion. Reacting with oxygen is the only methane conversion pathway. However, after step transition from oxygen excess conditions (slightly lean) to oxygen-poor conditions (slightly rich), high methane conversion was observed under rich conditions with no oxygen available. This high conversion was attributed to steam reforming (SR), which was activated by the step transition. The SR reaction rate decreased over time when staying at rich conditions, until full deactivation. Investigations in the lab-scale model gas reactor confirmed this analysis. In addition, the reason for SR deactivation was identified by DRIFTS measurements as the accumulation of carbonates on the catalytic surface, blocking the active sites. Based on the identified importance of the SR reaction, targeted Î» oscillations across stoichiometry were introduced, in order to repeatably activate SR and achieve sustainable high methane conversion. During the rich parts of the oscillations, methane was converted via SR, while, during lean parts, the carbonates were periodically removed from the catalyst surface. With these oscillations, methane conversion has been significantly improved, in comparison to steady state. In parallel, a numerical model has been developed in order to simulate the catalyst behavior under oscillating conditions. The model provided insights on the reaction pathways and their distribution along the catalyst axis. The catalytic activity of the different Platinum-group metals has been investigated for the identified reactions. Various catalysts of different compositions were tested under cold start, Î» oscillations and quasi-steady state conditions. Both Pt and Pd activated SR reactions, however SR attenuation was faster in Pt catalysts. In lean conditions, Pt exhibited higher methane oxidation. Rh was identified as important for enhancing NOx reduction and lowering NH3 emissions. The combination of all three metals has improved the overall catalyst performances. In the final part of the thesis, a special aftertreatment system was investigated. It combines a Pd/Rh catalyst subject to stoichiometric conditions with a Pt oxidation catalyst subject to lean conditions. In the Pd/Rh catalyst, methane was removed via Î» oscillations. In the Pt catalyst, the remaining CO, H2 and NH3 were oxidized. The setup provided a novel perspective in reducing the overall environmental impacts.

EPFL2022

Driving and Filling Personal Vehicles – The Questions of Energy - and Power - Density ( A Fast Filling Station for the Compressed Air Car )

Alfred Rufer, Mahbod Heidari, Arnaud Leuba

In the context of the development of zero emissions personal vehicles, compressed air cars have been proposed, as alternative solutions to electric solutions, with a small energy content leading to a limited range, but with interesting properties regarding aging phenomena, costs, and possibility to be recharged rapidly. This paper discusses the questions of energy – and power-density of alternative vehicles like electric and compressed air solutions. It proposes and describes a concept of a fast filling station recently developed. The system uses a local reservoir that is precharged by an isothermal compression machine. The fast transfer itself uses a low dissipation nozzle limiting the transfer flow rate. Then, in order to recover the heat produced during the fast pressure rise in the vehicle’s reservoir, a dedicated recirculation system is activated in order to reach finally the higher air mass-density in it, corresponding to the best energy content on board. Simulation results are presented, and an experimental setup is described.

2011

Emission reduction by targeted transient operations in three-way catalysts for heavy-duty natural gas applications

Moyu Wang

EPFL2022