A Comparative Life Cycle Assessment of Compressed Natural Gas and Diesel Powered Refuse Collection Vehicles

A comparative life cycle assessment of diesel and compressed natural gas powered refuse collection vehicles in a Canadian city

Accurate and verifiable emission reductions are a function of the degree of transparency and stringency of the protocols employed in documenting project- or program-associated emissions reductions. The purpose of this guide is to provide a background for law and policy makers, urban planners, and project developers working with the many Greenhouse Gas (GHG) emission reduction programs throughout the world to quantify and/or evaluate the GHG impacts of Natural Gas Vehicle (NGVs). In order to evaluate the GHG benefits and/or penalties of NGV projects, it is necessary to first gain a fundamental understanding of the technology employed and the operating characteristics of these vehicles, especially with regard to the manner in which they compare to similar conventional gasoline or diesel vehicles. Therefore, the first two sections of this paper explain the basic technology and functionality of NGVs, but focus on evaluating the models that are currently on the market with their similar conventional counterparts, including characteristics such as cost, performance, efficiency, environmental attributes, and range. Since the increased use of NGVs, along with Alternative Fuel Vehicle (AFVs) in general, represents a public good with many social benefits at the local, national, and global levels, NGVs often receive significant attention in themore » form of legislative and programmatic support. Some states mandate the use of NGVs, while others provide financial incentives to promote their procurement and use. Furthermore, Federal legislation in the form of tax incentives or procurement requirements can have a significant impact on the NGV market. In order to implement effective legislation or programs, it is vital to have an understanding of the different programs and activities that already exist so that a new project focusing on GHG emission reduction can successfully interact with and build on the experience and lessons learned of those that preceded it. Finally, most programs that deal with passenger vehicles--and with transportation in general--do not address the climate change component explicitly, and thus there are few GHG reduction goals that are included in these programs. Furthermore, there are relatively few protocols that exist for accounting for the GHG emissions reductions that arise from transportation and, specifically, passenger vehicle projects and programs. These accounting procedures and principles gain increased importance when a project developer wishes to document in a credible manner, the GHG reductions that are achieved by a given project or program. Section four of this paper outlined the GHG emissions associated with NGVs, both upstream and downstream, and section five illustrated the methodology, via hypothetical case studies, for measuring these reductions using different types of baselines. Unlike stationary energy combustion, GHG emissions from transportation activities, including NGV projects, come from dispersed sources creating a need for different methodologies for assessing GHG impacts. This resource guide has outlined the necessary context and background for those parties wishing to evaluate projects and develop programs, policies, projects, and legislation aimed at the promotion of NGVs for GHG emission reduction.« less

Biomethane CNG hybrid: A reduction by more than 80% of the greenhouse gases emissions compared to gasoline

<div class="section abstract"><div class="htmlview paragraph">Vehicles consume energy and release harmful emissions throughout their life period from the manufacturing stage of raw materials to the vehicle scrapyard. The current Green-House Gas (GHG) emissions from diesel and petrol vehicles are reported to be 164 g CO<sub>2</sub>/km and 156 g CO<sub>2</sub>/km respectively. Thus, enormous research studies are been carried out for low-carbon alternative fuel-powered vehicles to reduce the overall GHG emissions. Numerous research on hydrogen as a transportation fuel has demonstrated the potential of reduced vehicular emissions compared to conventional fuels. Life cycle assessment (LCA) is a comprehensive methodology used for estimating the overall environmental impact of vehicles. In this present work, a comparative LCA is conducted between Compressed Natural gas (CNG) powered vehicles and H-CNG powered vehicles. The effect of the two alternative vehicles is assessed from various points in their lifetime using the GREET model software. The analysis is done in two stages namely, well to pump and pump to the wheel. The obtained results of the analysis reveal that the H-CNG fuel exhibits a favorable reduction in CO emissions by 3% and CO<sub>2</sub> emissions by 5%. It is also found that there is no significant reduction in NO<sub>X</sub> emissions. The H-CNG refueling sites are equipped with on-board small scale reformers for producing hydrogen, which is blended with CNG and then pressurized on-site for vehicle fueling. The proposed H-CNG production process is cheaper than the conventional physical blending process and thus paving way for the potential usage of H-CNG fuel.</div></div>

Natural gas vehicles (NGVs) have seen increased attention as a way to reduce reliance on petroleum (diesel/gasoline) for transportation, but adoption rates lag behind conventional vehicles. There are multiple challenges connected to a globally large scale expansion of natural gas as an alternative transportation fuel including refueling infrastructure, safety, vehicle range, natural gas supply chain emissions, engine performance, engine durability, vehicle cost, public acceptability and policy options. Therefore to maximize the benefits of natural gas as an alternative transportation fuel, these factors must be considered. The aforementioned challenges are the focus of this thesis. The overall aim of the thesis is to identify and analyze the technological, strategic and environmental aspects of compressed natural gas (CNG) as a viable alternative transportation fuel option in the international as well as in Pakistani context. The thesis links twelve journal papers to present a cohesive body of research with the aid of 6 brief contextual chapters. The findings from the papers address three core themes in natural gas as an alternative transportation fuel. The first theme supported with five papers introduces and discusses the technical aspects of CNG technology with the particular focus on the environmental competitiveness of natural gas vehicles (NGVs), safety issues with NGVs, performance of natural gas fueled engines, durability of NGV’s engine parts and current research progress in using natural gas as an alternative transportation fuel. The second theme supported with five papers discusses the strategic framework and transitions to NGVs in four particular respects: addressing the barriers towards natural gas vehicles, policy options for the development of natural gas vehicles, strategies ranking for NGVs’ market and analysis of a specific CNG market by using Pakistan as a case study. The final theme supported with two paper presents a comparative life cycle (Well-to-Wheel) assessment of energy use and greenhouse gas (GHG) emission of natural gas vehicles. The research associated with the first theme identifies comparative drawbacks and advantages of NGV technology. Some of the identified drawbacks include 15–20% loss in brake horsepower, dependence of NGVs safety on the materials, operating conditions and maintenance of CNG system, the build-up of high combustion deposit between engine’s valve face and seat and lack of empirical work which examines the comparative maintenance cost-effectiveness of NGVs over total vehicle lifespan. On the other hand, the identified advantages include relatively lower tailpipe emission of CO2 (20-25%), CO (50-68%), PM (10-75%) and NMHC (50-70%). The research findings associated with the second theme suggest that the principle driving force in the successful removal of barriers to the growth of NGVs program is the user economics. Therefore setting CNG retail prices of 30–50% below the price of gasoline and diesel prices can play a key role in wide adoption of NGVs. In addition the findings suggest that there is no universal policy for the implementation of natural gas as a transportation fuel and it is identified that a combination of the various policy measures is required to remove the existing barriers to NGVs. The findings also suggest that, although due to the Government’s consumer friendly policy and the price differential between CNG and gasoline/ diesel, the NGVs sector in Pakistan has shown significant growth but due to lack of sustainable natural gas supply plans, Pakistan's gas supplies cannot support the high demand of the CNG sector. The findings of the third theme suggest that on Well-to-Wheel (WtW) basis 80 - 89% energy consumption and 73 - 86% greenhouse gas (GHG) emissions for all fuel pathways comes from the Tank-to-Wheel (TtW) phase. Moreover on WtW basis, the GHG emissions for dedicated NGVs may be reduced by 20% and 12% against gasoline and diesel fuel.

Environmental concerns relating to gaseous emissions from transport have led to growth in the use of compressed natural gas (CNG) as transportation fuel worldwide with over 19 million natural gas vehicles (NGVs) currently in operation. This paper reviews the environmental advantages of natural gas fuel, presenting laboratory and real world comparative emission performance of NGVs with diesel and gasoline fueled vehicles. The aim is to clarify the worldwide experience of NGVs in terms of various emission factors i.e. CO\(_{2}\), CO, NO\(_\mathrm{x}\), NMHC and PM. The paper provides a critical analysis of information collected and draws general conclusions on the world-wide NGVs experience. The results reveal that CNG in public transportation can contribute to the improvement of urban air, reduce adverse health effects and social costs of air pollution. It was observed that on a well-to-wheels basis, CNG produce less greenhouse gases as compared to conventional gasoline and diesel vehicles. The results showed that there is large variation in the resulted NMHC emission data of CNG fuel. Some studies reveal that CNG can significantly reduce NMHC emission while other concluded that CNG increase the NHMC emission.

Passenger cars, trucks, commercial airplanes, and railways all contribute to greenhouse gas emissions as part of the transportation sector. The usage of fossil fuels such as gasoline and diesel emits exhaust gases commonly referred to as greenhouse gases (GHGs) into the atmosphere. The buildup of these greenhouse gases in the atmosphere is responsible for global warming, a phenomenon that is becoming increasingly pronounced in today’s climate. In response to the GHG problem, cities have started setting targets to reduce their emission values. Adana is one of the cities that has set reduction targets. In all of the studies forming the basis of this research, the potential for transitioning buses and minibuses used in public transportation in Adana to alternative vehicles is investigated, with a focus on reducing greenhouse gas emissions. This study includes a comparison between electric, compressed natural gas (CNG), hydrogen and conventional vehicles, considering various parameters such as fuel economy estimates, vehicle size, and emission calculations. The research delves into greenhouse gas emission calculations specific to the Adana province, along with potential alternative applications in public transportation. Within the province, the transportation sector accounts for 27% of the total city inventory’s emissions. This study shows that converting the existing urban public transport fleet to alternative buses can lead an impressive reduction in greenhouse gas emissions as 81.93% with electric car, while hydrogen vehicles achieve a commendable 57.37% decrease. This underscores the substantial potential of electric and hydrogen-powered vehicles to lead to a significant reduction in transportation-related carbon emissions in the city. Consequently, the research places significant emphasis on addressing the transportation sector, which stands out as a primary contributor to emissions.

We examine the life cycles of gasoline, diesel, compressed natural gas (CNG), and ethanol (C2H5OH)-fueled internal combustion engine (ICE) automobiles. Port and direct injection and spark and compression ignition engines are examined. We investigate diesel fuel from both petroleum and biosources as well as C2H5OH from corn, herbaceous bio-mass, and woody biomass. The baseline vehicle is a gasoline-fueled 1998 Ford Taurus. We optimize the other fuel/powertrain combinations for each specific fuel as a part of making the vehicles comparable to the baseline in terms of range, emissions level, and vehicle lifetime. Life-cycle calculations are done using the economic input-output life-cycle analysis (EIO-LCA) software; fuel cycles and vehicle end-of-life stages are based on published model results. We find that recent advances in gasoline vehicles, the low petroleum price, and the extensive gasoline infrastructure make it difficult for any alternative fuel to become commercially viable. The most attractive alternative fuel is compressed natural gas because it is less expensive than gasoline, has lower regulated pollutant and toxics emissions, produces less greenhouse gas (GHG) emissions, and is available in North America in large quantities. However, the bulk and weight of gas storage cylinders required for the vehicle to attain a range comparable to that of gasoline vehicles necessitates a redesign of the engine and chassis. Additional natural gas transportation and distribution infrastructure is required for large-scale use of natural gas for transportation. Diesel engines are extremely attractive in terms of energy efficiency, but expert judgment is divided on whether these engines will be able to meet strict emissions standards, even with reformulated fuel. The attractiveness of direct injection engines depends on their being able to meet strict emissions standards without losing their greater efficiency. Biofuels offer lower GHG emissions, are sustainable, and reduce the demand for imported fuels. Fuels from food sources, such as biodiesel from soybeans and C2H5OH from corn, can be attractive only if the co-products are in high demand and if the fuel production does not diminish the food supply. C2H5OH from herbaceous or woody biomass could replace the gasoline burned in the light-duty fleet while supplying electricity as a co-product. While it costs more than gasoline, bioethanol would be attractive if the price of gasoline doubled, if significant reductions in GHG emissions were required, or if fuel economy regulations for gasoline vehicles were tightened.

Urban pollution is of increasing concern due to human health implications. Therefore, emissions pollutant from commercial vehicles which move daily at fixed itineraries, such as buses and refuse collection vehicles must be monitored. In this study we have aimed to show the results of the test made on refuse collection vehicles, in real conditions, with regard to their energy consumption and emissions pollutant. A comparative study is carried out with regard to CO, HC, NOx, PM and greenhouse gas emissions, with two types of engines and with three different fuels. The fuels analyzed are diesel, biodiesel (B50 and B100) and compressed natural gas (CNG).

Mitigating Curtailment and Carbon Emissions through Load Migration between Data Centers

The body of life cycle assessment (LCA) literature is vast and has grown over the last decade at a dauntingly rapid rate. Many LCAs have been published on the same or very similar technologies or products, in some cases leading to hundreds of publications. One result is the impression among decision makers that LCAs are inconclusive, owing to perceived and real variability in published estimates of life cycle impacts. Despite the extensive available literature and policy need formore conclusive assessments, only modest attempts have been made to synthesize previous research. A significant challenge to doing so are differences in characteristics of the considered technologies and inconsistencies in methodological choices (e.g., system boundaries, coproduct allocation, and impact assessment methods) among the studies that hamper easy comparisons and related decision support. An emerging trend is meta-analysis of a set of results from LCAs, which has the potential to clarify the impacts of a particular technology, process, product, or material and produce more robust and policy-relevant results. Meta-analysis in this context is defined here as an analysis of a set of published LCA results to estimate a single or multiple impacts for a single technology or a technology category, either in a statisticalmore » sense (e.g., following the practice in the biomedical sciences) or by quantitative adjustment of the underlying studies to make them more methodologically consistent. One example of the latter approach was published in Science by Farrell and colleagues (2006) clarifying the net energy and greenhouse gas (GHG) emissions of ethanol, in which adjustments included the addition of coproduct credit, the addition and subtraction of processes within the system boundary, and a reconciliation of differences in the definition of net energy metrics. Such adjustments therefore provide an even playing field on which all studies can be considered and at the same time specify the conditions of the playing field itself. Understanding the conditions under which a meta-analysis was conducted is important for proper interpretation of both the magnitude and variability in results. This special supplemental issue of the Journal of Industrial Ecology includes 12 high-quality metaanalyses and critical reviews of LCAs that advance understanding of the life cycle environmental impacts of different technologies, processes, products, and materials. Also published are three contributions on methodology and related discussions of the role of meta-analysis in LCA. The goal of this special supplemental issue is to contribute to the state of the science in LCA beyond the core practice of producing independent studies on specific products or technologies by highlighting the ability of meta-analysis of LCAs to advance understanding in areas of extensive existing literature. The inspiration for the issue came from a series of meta-analyses of life cycle GHG emissions from electricity generation technologies based on research from the LCA Harmonization Project of the National Renewable Energy Laboratory (NREL), a laboratory of the U.S. Department of Energy, which also provided financial support for this special supplemental issue. (See the editorial from this special supplemental issue [Lifset 2012], which introduces this supplemental issue and discusses the origins, funding, peer review, and other aspects.) The first article on reporting considerations for meta-analyses/critical reviews for LCA is from Heath and Mann (2012), who describe the methods used and experience gained in NREL's LCA Harmonization Project, which produced six of the studies in this special supplemental issue. Their harmonization approach adapts key features of systematic review to identify and screen published LCAs followed by a meta-analytical procedure to adjust published estimates to ones based on a consistent set of methods and assumptions to allow interstudy comparisons and conclusions to be made. In a second study on methods, Zumsteg and colleagues (2012) propose a checklist for a standardized technique to assist in conducting and reporting systematic reviews of LCAs, including meta-analysis, that is based on a framework used in evidence-based medicine. Widespread use of such a checklist would facilitate planning successful reviews, improve the ability to identify systematic reviews in literature searches, ease the ability to update content in future reviews, and allow more transparency of methods to ease peer review and more appropriately generalize findings. Finally, Zamagni and colleagues (2012) propose an approach, inspired by a meta-analysis, for categorizing main methodological topics, reconciling diverging methodological developments, and identifying future research directions in LCA. Their procedure involves the carrying out of a literature review on articles selected according to predefined criteria.« less

Mitigation of greenhouse gas emissions from beef production in western Canada – Evaluation using farm-based life cycle assessment

Projection of passenger cars’ fuel demand and greenhouse gas emissions in Iran by 2050

Energy-related activities are a major contributor of greenhouse gas (GHG) emissions. A growing body of knowledge clearly depicts the links between human activities and climate change. Over the last century the burning of fossil fuels such as coal and oil and other human activities has released carbon dioxide (CO2) emissions and other heat-trapping GHG emissions into the atmosphere and thus increased the concentration of atmospheric CO2 emissions. The main human activities that emit CO2 emissions are (1) the combustion of fossil fuels to generate electricity, accounting for about 37% of total U.S. CO2 emissions and 31% of total U.S. GHG emissions in 2013, (2) the combustion of fossil fuels such as gasoline and diesel to transport people and goods, accounting for about 31% of total U.S. CO2 emissions and 26% of total U.S. GHG emissions in 2013, and (3) industrial processes such as the production and consumption of minerals and chemicals, accounting for about 15% of total U.S. CO2 emissions and 12% of total ...

The increasing demand for carrageenan flour products in various industries was directly proportional to the potential environmental impact generated. The environmental impact was global warming (GW) caused by greenhouse gas (GHG) emissions. The industry was one of the producers of GHG emissions from materials, energy, and waste produced. Hence, it hoped that it could improve the eco-friendlier production system. This study aimed to analyze GHG emissions generated in the life cycle of carrageenan flour products and give an alternative strategy for environmental improvement. This research was assessed using a life cycle assessment (LCA) approach with a cradle to gate scope. The research used were primary and secondary data. This research was carried out by determining the goal and scope, collecting input and output as inventory data for each process unit, analyzing the impact of GHG emitting sources, and interpreting the results to formulate a recommendation for improvement. The result of the LCA study showed that Global warming caused GHG emission in the carrageenan flour production process with a value of 47.54 kg-CO2eq/kg of carrageenan flour, with the most significant emission source the use of coal as boiler fuel. Recommendations for improvement that can be made to reduce GHG emissions are replacing coal with compressed natural gas (CNG) with an emission reduction value of 47.73 kg-CO2eq/kg of carrageenan flour with an improvement percentage of 44.29%.