Environment

Refining Urban Typologies: Causal Insights into Urban Form, Car Commuting, and Related CO2 Emissions

Wagner, Felix
Nachtigall, Florian
Milojevic-Dupont, Nikola
Franken, Lukas
Koch, Nicolas
Runge, Jakob
Pereira, Rafael
Marta Gonzalez
Creutzig, Felix
2026

Urban transport is a major source of greenhouse gas emissions, making effective urban planning crucial for climate mitigation. Global typologies of cities can help to scale planning strategies, yet they hardly capture how interventions translate into local contexts. Big urban data, combined with artificial intelligence, holds great potential to facilitate scalable yet location-specific planning to reduce urban travel and related emissions. However, current research falls short in recognizing underlying variable dependencies, understanding neighborhood-specific differences, and comparing...

Extreme Heat Disproportionately Increases Severe Road Traffic Crashes in High Conflict Settings and Among Vulnerable Road Users in California

Hsu, Cheng-Kai
Quistberg, D. Alex
Pérez-Ferrer, Carolina
Daniel Rodriguez
2026

Emerging evidence suggests that extreme heat elevates road-traffic injuries, undermining international road safety efforts like Vision Zero as global warming intensifies. However, the mechanisms underlying heat-related crashes remain poorly understood, with limited research linking heat exposure to specific crash types that may be driven by heat-induced unsafe road behaviors. Here, we analyzed temperature data and police-reported crash records—including detailed crash scene information—from 177 California cities (2012–2023) using a time-stratified case-crossover design, examining...

Exploring Bidirectional Charging Strategies for an Electric Vehicle Population

Soomin Woo
Leo Strobel
Yuhao Yuan
Marco Pruckner
Tim Lipman
2025

Vehicle-grid integration (VGI) technologies control the energy exchange of electric vehicles (EVs) with power grids for economic and environmental benefits. Despite early investigations, it is still unclear how VGI operations should be designed to balance the goals of mobility needs and electrical grid operational costs. In this paper, our objectives are to examine VGI strategies including bidirectional or vehicle-to-grid (V2G) concepts reflecting realistic operation scenarios, evaluate the performance of the proposed strategies using actual EV charging data and future concepts for hourly...

Plug-In Electric Vehicles in California: Review of Current Policies, Related Emissions Reductions for 2020, and Policy Outlook

Maggie Witt
Matthew Bomberg
Tim Lipman
Brett Williams
2012

California's emissions reduction goals for criteria air pollutants (CAPs) and greenhouse gases (GHGs) have encouraged policies that support plug-in electric vehicles (PEVs). This paper explores current and planned policies that promote PEVs, potential emissions benefits from PEV adoption in California by 2020, and future policy directions. The reviewed policies include the zero-emission vehicle regulations, the low-carbon fuel standard, and the clean car standards, which all require GHG reductions. Policies prompted by the California Public Utilities Commission Alternative-Fueled Vehicle...

Plug-in-Hybrid Vehicle Use, Energy Consumption, and Greenhouse Emissions: An Analysis of Household Vehicle Placements in Northern California

Brett Williams
Elliot Martin
Tim Lipman
Daniel Kammen
2011
We report on the real-world use over the course of one year of a nickel-metal-hydride plug-in hybrid—the Toyota Plug-In HV—by a set of 12 northern California households able to charge at home and work. From vehicle use data, energy and greenhouse-emissions implications are also explored. A total of 1557 trips—most using under 0.5 gallons of gasoline—ranged up to 2.4 hours and 133 miles and averaged 14 minutes and 7 miles. 399 charging events averaged 2.6 hours. The maximum lasted 4.6 hours. Most recharges added less than 1.4 kWh, with a mean charge of 0.92 kWh. The average power drawn was...

Fuel Cell Systems: Total Cost of Ownership

Max Wei
Ahmad Mayyas
Tim Lipman
Hanna Breunig
Roberto Scataglini
Shuk Han Chan
Joshua Chien
David Gosselin
Nadir Saggiorato
Adam Weber
2019

Fuel cells are an electrochemical technology that are reaching the market in transportation and are a growing market in stationary power systems for backup power, primary power, combined heat and power, and materials handling equipment. The first part of this entry describes the manufacturing cost reductions from PEM and SOFC technologies that are estimated from higher-volume fuel cell manufacturing from economies of scale and improvements in overall yield. Fuel cells combined heat and power systems have the capability to displace grid electricity and on-site fuel combustion. In general...

Fuel Cells and Hydrogen Production: Introduction

Adam Weber
Tim Lipman
2019

Hydrogen is a widely produced and used commodity, now being used as an energy carrier for stationary power and transportation markets. Tens of millions of tons of hydrogen are produced each year globally, mostly for large-scale industrial uses. As awareness grows for the need to reduce greenhouse gases and enable new energy paradigms, hydrogen is being seen as playing a critical role as shown in Fig. 1 [1]. Hydrogen provides chemical storage of electrical energy and can be efficiently converted to electricity on demand for distributed applications, thus enabling the global electrification...

Dynamics in Behavioral Response to Fuel-Cell Vehicle Fleet and Hydrogen Fueling Infrastructure: An Exploratory Study

Susan Shaheen
Elliot Martin
Tim Lipman
2008

Transportation is a major contributor of carbon dioxide and other greenhouse gas emissions from human activity. It accounts for approximately 14% of total anthropogenic emissions globally and about 27% in the United States. Growing concern regarding the impacts of climate change and greenhouse gas emissions, along with petroleum dependence and energy security, has led to innovations in automotive and fuel technology. However, the behavioral response to the newest transportation technologies, such as hydrogen fuel-cell vehicles (FCVs) and fueling infrastructure, is not well understood. The...

Reducing Greenhouse Emissions and Fuel Consumption: Sustainable Approaches for Surface Transportation

Susan Shaheen
Tim Lipman
2007

Climate change is rapidly becoming known as a tangible issue that must be addressed to avoid major environmental consequences in the future. Recent change in public opinion has been caused by the physical signs of climate change–melting glaciers, rising sea levels, more severe storm and drought events, and hotter average global temperatures annually. Transportation is a major contributor of carbon dioxide (CO2) and other greenhouse gas emissions from human activity, accounting for approximately 14 percent of total anthropogenic emissions globally and about 27 percent in the U.S....

A Total Cost of Ownership Model for Solid Oxide Fuel Cells in Combined Heat and Power and Power-Only Applications

Roberto Scataglini
Ahmad Mayyas
Max Wei
Shuk Han Chan
Tim Lipman
David Gosselin
Anna D’ Alessio
Hanna Breunig
Whitney Colella
2015

A total cost of ownership model (TCO) is described for emerging applications in stationary fuel cell systems. Solid oxide fuel cell systems (SOFC) for use in combined heat and power (CHP) and poweronly applications from 1 to 250 kilowatts-electric (kWe1) are considered. The total cost of ownership framework expands the direct manufacturing cost modeling framework of other studies to include operational costs and life-cycle impact assessment of possible ancillary financial benefits during operation and at end-of-life. These include credits for reduced emissions of global warming gases such...