Citywide Transportation Greenhouse Gas Emissions Inventories: A Review of Selected Methodologies

Outlines the methodological issues in creating transportation emissions inventories and how they affect the results, reviews currently used methodologies, and explores ways to integrate inventories with climate policies to inform reduction strategies

Biphasic Electrode Suspensions for Li-Ion Semi-solid Flow Cells with High Energy Density, Fast Charge Transport, and Low-Dissipation Flow

Biphasic electrode suspensions composed of well-dispersed electrochemically active particles and weakly attractive electronically conductive particles are created. They exhibit high energy density, fast charge transport, and low viscous dissipation during flow.United States. Department of Energy. Office of Science, Basic Energy SciencesArgonne National Laboratory (Contract No. DE-AC02–06CH11357

Electron bottleneck in the charge/discharge Mechanism of Lithium Titanates for Batteries

The semi-solid flow battery (SSFB) is a promising storage energy technology featured by employing semi-solid fluid electrodes containing conductive additive and active Li-ion battery materials. The state of art anode material for SSFB is LiTiO (LTO). This work shows that LTO improves drastically the performance in fluid electrode via hydrogen annealing manifesting the importance of the electrical conductivity of the active material in SSFBs. On the other hand, the properties of fluid electrodes allow the contributions of ionic and electrical resistance to be separated in operando. The asymmetric overpotential observed in LiTiO and TiO is proposed to originate from the so-called electron bottleneck mechanism based on the transformation from electrically insulator to conductor upon (de-)lithiation, or vice versa, which should be considered when modelling, evaluating or designing advanced materials based on LiTiO, TiO or others with insulating-conducting behavior materials

Modelling of redox flow battery electrode processes at a range of length scales : a review

In this article, the different approaches reported in the literature for modelling electrode processes in redox flow batteries (RFBs) are reviewed. RFB models vary widely in terms of computational complexity, research scalability and accuracy of predictions. Development of RFB models have been quite slow in the past, but in recent years researchers have reported on a range of modelling approaches for RFB system optimisation. Flow and transport processes, and their influence on electron transfer kinetics, play an important role in the performance of RFBs. Macro-scale modelling, typically based on a continuum approach for porous electrode modelling, have been used to investigate current distribution, to optimise cell design and to support techno-economic analyses. Microscale models have also been developed to investigate the transport properties within porous electrode materials. These microscale models exploit experimental tomographic techniques to characterise three-dimensional structures of different electrode materials. New insights into the effect of the electrode structure on transport processes are being provided from these new approaches. Modelling flow, transport, electrical and electrochemical processes within the electrode structure is a developing area of research, and there are significant variations in the model requirements for different redox systems, in particular for multiphase chemistries (gas–liquid, solid–liquid, etc.) and for aqueous and non-aqueous solvents. Further development is essential to better understand the kinetic and mass transport phenomena in the porous electrodes, and multiscale approaches are also needed to enable optimisation across the relevent length scales

Robots as Energy Systems: Advances in Robotics across Scales and Technologies

Robots are operating at unprecedented scales and in uniquely challenging environments, particularly near the human body. These robots are enabled by novel actuation, sensing, energy storage, and conversion technologies. Across different scales and between different technologies, the key metrics of performance are related on energy: how it is stored, delivered, or dissipated

Semi-solid redox flow battery

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (page 53).materials used in Li-ion batteries and the design and functioning of a redox flow cell. The use of Li-ion battery materials offers significant increases in energy and power density (200 Wh/kg compared to 25-35 Wh/kg for current commercial vanadium redox batteries). The implementation of a redox flow system allows for energy to be stored outside the cell and for the power and energy of the battery to be decoupled. A proof of concept is achieved by successful cycling of anode and cathode suspensions under intermittent flow conditions. The importance of materials' stability to cell life, energy and power densities is discussed. The high energy densities may enable the use of the proposed system in a variety of application, ranging from grid-level storage to fully electric charge.by Mihai Duduta.S.B

Direct Ridership Models of Bus Rapid Transit and Metro Systems in Mexico City, Mexico

Direct ridership models (DRM) have been introduced in the United States as an alternative to four-step travel demand modeling. DRMs can be used to obtain quick, order-of-magnitude estimates of transit patronage at a fraction of the cost of a full travel demand model and are more adept at capturing the effects of smart growth on transit ridership. The relatively low cost, flexible data requirements, and rapidity make these models particularly suited to developing world cities. Yet these cities still rely almost exclusively on full travel demand models to advise investments in new transit infrastructure. In doing so, cities often use old data and out-of-date household surveys and do not capture important recent changes in travel patterns. Mexico City, Mexico, is taken as a case study to illustrate the benefits of using DRM models in a developing world context. Ridership models are developed for the city\u27s bus rapid transit and Metro networks to study how land use and service and station attributes affect ridership for each mode and also how connections between bus rapid transit and Metro affect each other\u27s ridership. The two systems are complementary, each getting ridership benefits from connecting to the other. Implications of findings for transport policy in Mexico City are discussed, as well as some short-comings of DRM models, particularly their difficulty in accounting for informal transit

Understanding Platform Overcrowding at Bus Rapid Transit Stations

Platform overcrowding is a very common but relatively poorly understood occurrence at most bus rapid transit (BRT) systems in cities in the developing world. Most literature on BRT capacity focuses on vehicle throughput for different types of lane and station configurations; relatively little is known about how different station layouts handle specific volumes of boarding and alighting passengers. In this paper, this gap in knowledge was addressed by building a microscopic simulation model to test the ability of a typical Latin American BRT station (median, high-platform, one bus bay per direction) to handle various volumes of passengers under different scenarios. With this modeling exercise, areas in a station most likely to experience overcrowding were first identified: the median refuge island at the main entrance and the turnstiles. The station performance at those critical points was then evaluated for different passenger volumes, with mainly pedestrian density (persons/m2) as an indicator. Results indicated a pedestrian capacity range for a typical BRT station and also quantified the effect of friction between pedestrians entering and leaving the station. Finally, a regression based on the simulation results was estimated and used to develop a predictive equation for crowding as a function of passenger volumes and direction. The results can help BRT planners better adapt their station designs to forecast passenger volumes and ensure that they provide an adequate level of servic

Saving Lives with Sustainable Transport

Traffic safety improvements are an often-overlooked benefit of sustainable transport projects and policies. New research from EMBARQ finds that investments in biking and pedestrian infrastructure, improved mass transit systems, and measures to limit motor vehicle usage can all significantly improve traffic safety, reducing traffic crashes and saving lives. The issue brief also contains recommendations for integrating safety into transport planning and policy, with a focus on the context of cities in the developing world. - See more at: http://www.embarq.org/publication/saving-lives-sustainable-transport#sthash.S3WaikY7.dpu