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June 2002 - present
Publications
Publications (253)
Increasing municipal solid waste (MSW) generation has become not only a major sustainability challenge and a considerable financial burden for municipalities across the globe, but also an opportunity to promote a circular economy, provided adequate information is made available. Data and information on MSW generation, characterization, and manageme...
Long-term planning of a robust power system requires the understanding of changing demand patterns. Electricity demand is highly weather sensitive. Thus, the supply side variation from introducing intermittent renewable sources, juxtaposed with variable demand, will introduce additional challenges in the grid planning process. By understanding the...
Hydropower will play an essential role in meeting the growing energy needs in Africa but will be affected by climate change. We assess future annual usable capacity and variability of supply for 87 existing hydropower plants in Africa on the basis of a multimodel ensemble of 21 global climate models and two emissions scenarios (representative conce...
Uncrewed aerial vehicles (UAVs) for last-mile deliveries will affect the energy productivity of delivery and require new methods to understand energy consumption and greenhouse gas (GHG) emissions. We combine empirical testing of 188 quadcopter flights across a range of speeds with a first-principles analysis to develop a usable energy model and a...
The deployment of low-carbon vehicles, such as cargo bicycles, will play a key role in reducing road transport emissions and contributing to city logistics’ sustainability. However, it is crucial to assess their ability to replace urban delivery operations and perform a fair carbon footprint comparison with diesel vans. This study aims at providing...
As automated transportation technology advances, public transit agencies could consider how integrating autonomous vehicles and shuttles into existing transit systems affects equity. Capital and operating costs for automated mobility modes managed by public transit agencies are uncertain since few deployments have occurred to date. Automated vehicl...
The ethical implications for the engineering profession of the development and deployment of automated vehicles (AVs) can be explored by analyzing the implications of AVs across three major socio-technical systems-technology, transportation systems, and policy. Mapping the ethical canons of professional engineering societies to these domains provid...
Independent methods for estimating local greenhouse gas emissions have been developed utilizing different instrumentation, sampling, and estimation techniques. Comparing independent estimates theoretically improves understanding of emission sources. However, each method estimates emissions with varying fidelity, complicating comparisons across meth...
The adoption of Uncrewed Aerial Vehicles (UAVs) for last-mile deliveries will affect the energy productivity of package delivery and require new methods to understand the associated energy consumption and greenhouse gas (GHG) emissions. Here we combine empirical testing of 187 quadcopter flights with first principles analysis to develop a usable en...
Commercial cargo bicycles have the potential to reduce greenhouse gas emissions, air pollution, traffic congestion, and delivery times. However, urban physical barriers and small cargo capacities could limit their uptake in city logistics. This analysis explores the effects of payload, air density, wind, and topography on commercial cargo bicycle e...
Life cycle impact assessment (LCIA) transforms inventories of environmental flows to environmental impacts in life cycle assessment (LCA) studies. Many impact assessment methods have been developed for impact categories such as global warming, acidification, and ecotoxicity. These impact assessment methods provide different characterization factor...
We autonomously directed a small quadcopter package delivery Uncrewed Aerial Vehicle (UAV) or “drone” to take off, fly a specified route, and land for a total of 209 flights while varying a set of operational parameters. The vehicle was equipped with onboard sensors, including GPS, IMU, voltage and current sensors, and an ultrasonic anemometer, to...
Transportation network companies (TNC) provide mobility services that are influencing travel behavior in unknown ways due to limited TNC trip-level data. How they interact with other modes of transportation can have direct societal impacts, prompting appropriate policy intervention. This paper outlines a method to inform such policies through a dat...
Hydropower may be a low-carbon option to increase power generation in developing countries, but these countries are some of the most vulnerable to climate change. Climate change can affect hydropower generation through changes in the timing and magnitude of precipitation, rising temperatures, and glacier mass changes. Evaluating climate impacts on...
We autonomously direct a small quadcopter package delivery Uncrewed Aerial Vehicle (UAV) or "drone" to take off, fly a specified route, and land for a total of 209 flights while varying a set of operational parameters. The vehicle was equipped with onboard sensors, including GPS, IMU, voltage and current sensors, and an ultrasonic anemometer, to co...
The widespread adoption of smartphones followed by an emergence of transportation network companies (TNC) have influenced the way individuals travel. The authors use the 2017 National Household Travel Survey to explore socioeconomic, frequency of use, and spatial characteristics associated with TNC users. The results indicate that TNC riders tend t...
Emissions inspection and maintenance (I/M) programs for light-duty motor vehicles manage ambient air quality by enforcing emissions standards and requiring non-compliant vehicles to be repaired or retired. I/M programs in the United States typically identify over-emitters through on-board diagnostics (OBD) systems and vehicles' proprietary firmware...
Past studies have shown that public support for battery electric (BEV) vans is justified by their emission external cost savings compared to their diesel equivalent. This study builds on this previous work and focuses on temperature effects on costs and energy use of large BEV and diesel vans. The authors find that temperature effect has relatively...
National Renewable Energy Laboratory's Materials Flows through Industry tool was developed to analyze energy consumption across the supply chains of U.S. manufacturing industries. Due to the limitation of the data sources, the Tool may have incomplete data in some industries’ supply chains. To overcome this issue, this study provides a method to id...
Life cycle assessment (LCA) analysts are increasingly being asked to conduct life cycle‐based systems level analysis at the earliest stages of technology development. While early assessments provide the greatest opportunity to influence design and ultimately environmental performance, it is the stage with the least available data, greatest uncertai...
Despite a long-term focus on passenger vehicle safety, there are still 38,000 vehicle-related fatalities annually. Some are the result of failure to maintain safety components of vehicles, such as brakes, tires, or headlights. Following NHTSA guidelines, 18 states have implemented periodic safety inspection programs in which certified inspectors as...
In recent years, cities across the United States have devoted considerable attention and resources to developing greenhouse gas (GHG) inventories and climate action plans (CAPs). Using integrated metropolitan-level GHG estimates from publicly available national datasets, we explore the implications of inventory scope and boundary choices for 41 met...
Uncertainty assessment is crucial to the reliability of decisions made based on results of life cycle assessment (LCA) models. However, the most popular uncertainty analysis method in LCA models defines uncertainty as quantified empirical judgment of the sources of the inventory data, which lacks the deviations due to the measurements of the data....
Blockchain and distributed ledger technologies (DLTs) have the capacity to improve how many companies and organizations conduct transactions or store information securely, among many other potential benefits. However, their development and implementation does not occur in a contextual vacuum and instead must adapt to the needs and requirements of t...
United States federal regulations require increasing renewable fuel blending in the transportation sector, a majority of which is corn ethanol. Nationally, ethanol is blended with gasoline up to 10% (E10) for use in conventional vehicles, and up to 85% (E85) for use in flexible fuel vehicles (FFVs). Meeting the blending requirements could mean incr...
Poor air quality in urban areas and environmental concerns attributable to road transportation are growing and significant problems for governments. Many different options have been proposed to lower emissions, and a critical one is the use of battery electric vehicles (BEVs).
Since city-logistics accounts for about 25% of urban mobility emissions,...
The Intergovernmental Panel on Climate Change quantified a cumulative remaining carbon budget beyond which there is a high likelihood global average temperatures will increase more than 2 °C above preindustrial temperature. While there is global participation in mitigation efforts, there is little global collaboration to cooperatively mitigate emis...
This study reviewed 147 life cycle studies, with 28 found suitable for harmonizing food waste management methods’ climate and energy impacts. 80 scientific soil productivity studies were assessed to rank management method soil benefits. Harmonized climate impacts per kilogram (kg) food waste range from -0.20 kg of carbon dioxide equivalents (CO2e)...
Cities have become key players in climate change mitigation policy. To develop their climate policies, cities need good assessments of their current and future emissions. We use publically available national datasets to develop an integrated approach for estimating GHG emissions at the metropolitan level over time, between multiple locations, and a...
Living in different areas is associated with different impacts; the movement of people to and from those areas will affect energy use and emissions over the US. The emissions implications of state-to-state migration on household energy and GHG emissions are explored. 3 million households move across state lines annually, and generally move from the...
Tertiary treatment is needed to render secondary-treated municipal wastewater usable in power plant cooling systems. Various tertiary treatment options exist to provide different levels of water quality. This paper integrates life cycle inventory emissions from a life cycle assessment approach with direct costs to determine the optimal treatment al...
Marcellus Shale development is occurring rapidly and relatively unconstrained across Pennsylvania (PA). Through 2013, over 7400 unconventional wells had been drilled in the Commonwealth. Well pads, access roads, and gathering lines fragment forestland resulting in irreversible alterations to the forest ecosystem. Changes in forest quantity, composi...
This study analyzes how incremental U.S. liquefied natural gas (LNG) exports affect global greenhouse gas (GHG) emissions. Emissions of LNG exported from U.S. ports to Asian and European markets account for only 3.5-5.5% of pre-combustion life cycle emissions, hence shipping distance is not a major driver of GHGs. This study finds exported U.S. LNG...
The narrow scope of the U.S. renewable fuel standard (RFS2) is a missed opportunity to spur a wider range of biomass use. This is especially relevant as RFS2 targets are being missed due to demand-side limitations for ethanol consumption. This paper examines the greenhouse gas (GHG) implications of a more flexible policy based on RFS2, which includ...
The paper examines the potential effects of failure of heavily used, outdated locks and dams on the Monongahela River in southwestern Pennsylvania. Catastrophic failure would result in lengthy outage of barge traffic. The displaced volume of coal shipments from mines to power plants is estimated using Energy Information Administration survey data....
The electric power industry plays a critical role in the economy and the environment, and it is important to examine the economic, environmental, and policy implications of current and future power generation scenarios. However, the tools that exist to perform the life cycle assessments are either too complex or too aggregated to be useful for thes...
Recent sustainability research has focused on urban systems given their high share of environmental impacts and potential for centralized impact mitigation. Recent research emphasizes descriptive statistics from place-based case studies to argue for policy action. This limits the potential for general insights and decision support. Here, we impleme...
A widely cited 1991 study predicted that nearly 150 million personal computers (PCs) would be sent to landfills by 2005. Taking into consideration newer end-of-life disposition options now available, the general premise of the original study is reconsidered.
Renewed emphasis on the cost and environmental impacts of electricity are leading to a greater awareness for the need to measure and manage loads in buildings of all types. In this paper we focus on the residential buildings sector by looking at best available technologies for the com- mercial sector and discuss how they can be best applied to resi...
Natural gas (NG)-related fugitive methane (CH4) emissions estimates from life cycle assessments (LCA) and local field measurements are highly uncertain. Globally distributed long-term atmospheric measurements and top-down modeling can help understand whether LCA and field studies are representative of the global industry average. Attributing source...
The amount of methane emissions released by the natural gas (NG) industry is a critical and uncertain value for various industry and policy decisions, such as for determining the climate implications of using NG over coal. Previous studies have estimated fugitive emissions rates (FER) - the fraction of produced NG (mainly methane and ethane) escape...
The practice of modeling biomass yields on the basis of deterministic point values aggregated over space and time obscures important risks associated with large-scale biofuel use, particularly risks related to drought-induced yield reductions that may become increasingly frequent under a changing climate. Using switchgrass as a case study, this wor...
The transportation sector is the second largest source of greenhouse gas (GHG) emissions in the United States. This study examines the cost effectiveness of Leadership in Energy and Environmental Design (LEED)-certified residential brownfield developments as vehicle miles traveled (VMT) and GHG-emission-reduction strategy. Costs incurred by develop...
Fossil fuels comprise 93% of Malaysia's electricity generation and account for 36% of the country's 2010 Greenhouse Gas (GHG) emissions. The government has targeted the installation of 330 MW of biomass electricity generation capacity by 2015 to avoid 1.3 Mt of CO2 emissions annually and offset some emissions due to increased coal use. One biomass...
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Until recently, the main environmental concerns associated with information and communication technologies (ICTs) have been their use-phase electricity consumption and the chemicals associated with their manufacture, and the environmental effects of these technologies on other parts of the economy have largely been ignored. With the advent of mobil...
Residential electricity users need more detail than monthly bills to reduce consumption. With the emergence of technologies that provide detailed usage estimates for energy consumption, two questions arise. First, how many different energy-consuming appliances contribute to household electricity load, and secondly which appliances? Using national a...
With urban space at a premium, roofs are being targeted as an opportunity to deploy sustainable energy technologies for buildings. This research evaluates the combination of green roofs and solar photovoltaics specifically through their temperature and electricity production relationship. Measurements over a one year study period from July 1, 2011...
Purpose Oil shale is an unconventional petroleum source that can be produced domestically in the USA. Oil shale resources are primarily located in Utah, Wyoming, and Colorado, within the Colorado River Basin. In this paper, we analyze the life cycle consumptive water use for oil shale production and its impacts on water resources of the Colorado Ri...
The United States (US) Environmental Protection Agency's (EPA) Greenhouse Gas (GHG) Mandatory Reporting Program (GHGRP) is designed to collect accurate and timely facility-level emissions data that might be used by policy makers to support sound climate policy decisions in the future. After reviewing the US Inventory and the expected improvements u...
This article reports on a literature review and meta-analysis of 82 studies, mostly life cycle assessments (LCAs), which quantified end-of-life (EOL) management options for organic waste. These studies were reviewed to determine the environmental preferability, or lack thereof, for a number of EOL management methods such as aerobic composting (AC),...
Projections of increased domestic natural gas supply and low prices have encouraged increased natural gas utilization in the United States electricity sector. Natural gas can offset coal, likely decreasing overall greenhouse gas (GHG) emissions and other air emissions such as SO2 and NOX. Previous life cycle assessment (LCA) studies using limited s...
The transportation sector is the second largest source of greenhouse gas (GHG) emissions in the United State. Developing underutilized urban industrial sites with certain characteristics (i.e., close proximity to transit, job and services, low remediation cost, and high density) can potentially reduce the transportation sector's impact on the envir...
Coal is an abundant energy resource, consumed in the United States chiefly by the power generation sector. Due to potential energy security benefits, it has also been considered as an alternate source for gasoline and diesel production. Life cycle assessment (LCA) studies have previously estimated the greenhouse gas emissions associated with coal c...
Regulations monitoring SO(2), NO(X), mercury, and other metal emissions in the U.S. will likely result in coal plant retirement in the near-term. Life cycle assessment studies have previously estimated the environmental benefits of displacing coal with natural gas for electricity generation, by comparing systems that consist of individual natural g...
This study estimates fossil-based CO(2) emissions and energy use from 1900-2000 for Allegheny County, PA. Total energy use and emissions increased from 1900 to 1970, reflecting the significant industrial, economic, and population growth that occurred in Allegheny County. From 1970 to 2000, Allegheny County experienced a 30% decrease in total emissi...
â–º We analyze various scenarios to examine supply chain results of reducing freight truck transport. â–º There are no individual sectors with a majority burden of freight transport energy and emissions. â–º Increasing truck efficiency 10% or reducing truck in the top 20% sectors reduces emissions 6%. â–º Policies encouraging higher efficiency in f...
Reducing greenhouse gas emissions (GHG) is an important social goal to mitigate climate change. A common mitigation paradigm is to consider strategy "wedges" that can be applied to different activities to achieve desired GHG reductions. In this policy analysis piece, we consider a wide range of possible strategies to reduce light-duty vehicle GHG e...
This paper presents a nonintrusive electricity load-monitoring approach that provides feedback on the energy consumption and operational schedule of electrical appliances in a residential building. This approach utilizes simple algorithms for detecting and classifying electrical events on the basis of voltage and current measurements obtained at th...
Employing life cycle greenhouse gas (GHG) emissions as a key performance metric in energy and environmental policy may underestimate actual climate change impacts. Emissions released early in the life cycle cause greater cumulative radiative forcing (CRF) over the next decades than later emissions. Some indicate that ignoring emissions timing in tr...
Increasing concerns about greenhouse gas (GHG) emissions in the United States have spurred interest in alternate low carbon fuel sources, such as natural gas. Life cycle assessment (LCA) methods can be used to estimate potential emissions reductions through the use of such fuels. Some recent policies have used the results of LCAs to encourage the u...
Information and communication technologies (ICTs) have become critical components of global infrastructure over the past few
decades, and computers are now fundamental to most business processes. The global adoption of the Internet has only accelerated
the transition from physical to digital infrastructure. More generally, the use of information an...
This study illustrates how alternative and supplemental community-level greenhouse gas (GHG) inventory techniques could improve climate action planning. Eighteen US community GHG inventories are reviewed for current practice. Inventory techniques could be improved by disaggregating the sectors reported, reporting inventory uncertainty and variabili...
