Low temperature fuel cells are an attractive technology for transportation and residential applica-tions due to their quick start up and shut down capabilities. This review analyzed the current status of nanocatalysts...Low temperature fuel cells are an attractive technology for transportation and residential applica-tions due to their quick start up and shut down capabilities. This review analyzed the current status of nanocatalysts for proton exchange membrane fuel cells and alkaline membrane fuel cells. The preparation process influences the performance of the nanocatalyst. Several synthesis methods are covered for noble and non-noble metal catalysts on various catalyst supports including carbon nanotubes, carbon nanofibers, nanowires, and graphenes. Ex situ and in situ characterization methods like scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and fuel cell testing of the nanocatalysts on various supports for both proton exchange and alkaline membrane fuel cells are discussed. The accelerated durability estimate of the nanocat-alysts, predicted by measuring changes in the electrochemically active surface area using a voltage cycling method, is considered one of the most reliable and valuable method for establishing durabil-ity.展开更多
Remanufacturing is a key enabler for sustainable production due to its effectiveness in closing the loop on material flows, extending product life cycle and reducing production waste and emission. In this paper, a hol...Remanufacturing is a key enabler for sustainable production due to its effectiveness in closing the loop on material flows, extending product life cycle and reducing production waste and emission. In this paper, a holistic decision support tool to facilitate the product end-of-life （EOL） strategy planning, specifically using remanufactur- ing as a key strategy is presented. The proposed model incorporates checklist methods to evaluate the viability of conducting remanufactufing for a product and its compo- nents. An optimization model for determining the Pareto set of optimal EOL strategies that correspond to maximum economic profit and minimum environmental impact is presented. Since determination of this Pareto set via enu- meration of all EOL strategies is prohibitively time-con- suming, even for a product with a small number of components, genetic algorithm （GA）, specifically NSGA-II has been utilized to achieve rapid calculation of the set of optimum EOL strategies. This NSGA-II method permits extensive sensitivity analysis to understand thoroughly the impact of situational variables, such as reverse logistic cost, technology and replacement part availability, etc., on the EOL decision making, i.e., Pareto front, and thus leading to improved strategy planning and better product design. The case study involving EOL treatment of two types of desktop phones is described to illustrate the utility of the proposed methodology.展开更多
The Climate Change Conference of Parties(COP)21 in December 2015 established Nationally Determined Contributions toward reduction of greenhouse gas emissions.In the years since COP21,it has become increasingly evident...The Climate Change Conference of Parties(COP)21 in December 2015 established Nationally Determined Contributions toward reduction of greenhouse gas emissions.In the years since COP21,it has become increasingly evident that carbon dioxide removal(CDR)technologies must be deployed immediately to stabilize concentration of atmospheric greenhouse gases and avoid major climate change impacts.Biochar is a carbon-rich material formed by high-temperature conversion of biomass under reduced oxygen conditions,and its production is one of few established CDR methods that can be deployed at a scale large enough to counteract effects of climate change within the next decade.Here we provide a generalized framework for quantifying the potential contribution biochar can make toward achieving national carbon emissions reduction goals,assuming use of only sustainably supplied biomass,i.e.,residues from existing agricultural,livestock,forestry and wastewater treatment operations.Our results illustrate the significant role biochar can play in world-wide CDR strategies,with carbon dioxide removal potential of 6.23±0.24%of total GHG emissions in the 155 countries covered based on 2020 data over a 100-year timeframe,and more than 10%of national emissions in 28 countries.Concentrated regions of high biochar carbon dioxide removal potential relative to national emissions were identified in South America,northwestern Africa and eastern Europe.展开更多
基金financial support from the Arizona State University
文摘Low temperature fuel cells are an attractive technology for transportation and residential applica-tions due to their quick start up and shut down capabilities. This review analyzed the current status of nanocatalysts for proton exchange membrane fuel cells and alkaline membrane fuel cells. The preparation process influences the performance of the nanocatalyst. Several synthesis methods are covered for noble and non-noble metal catalysts on various catalyst supports including carbon nanotubes, carbon nanofibers, nanowires, and graphenes. Ex situ and in situ characterization methods like scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and fuel cell testing of the nanocatalysts on various supports for both proton exchange and alkaline membrane fuel cells are discussed. The accelerated durability estimate of the nanocat-alysts, predicted by measuring changes in the electrochemically active surface area using a voltage cycling method, is considered one of the most reliable and valuable method for establishing durabil-ity.
文摘Remanufacturing is a key enabler for sustainable production due to its effectiveness in closing the loop on material flows, extending product life cycle and reducing production waste and emission. In this paper, a holistic decision support tool to facilitate the product end-of-life （EOL） strategy planning, specifically using remanufactur- ing as a key strategy is presented. The proposed model incorporates checklist methods to evaluate the viability of conducting remanufactufing for a product and its compo- nents. An optimization model for determining the Pareto set of optimal EOL strategies that correspond to maximum economic profit and minimum environmental impact is presented. Since determination of this Pareto set via enu- meration of all EOL strategies is prohibitively time-con- suming, even for a product with a small number of components, genetic algorithm （GA）, specifically NSGA-II has been utilized to achieve rapid calculation of the set of optimum EOL strategies. This NSGA-II method permits extensive sensitivity analysis to understand thoroughly the impact of situational variables, such as reverse logistic cost, technology and replacement part availability, etc., on the EOL decision making, i.e., Pareto front, and thus leading to improved strategy planning and better product design. The case study involving EOL treatment of two types of desktop phones is described to illustrate the utility of the proposed methodology.
文摘The Climate Change Conference of Parties(COP)21 in December 2015 established Nationally Determined Contributions toward reduction of greenhouse gas emissions.In the years since COP21,it has become increasingly evident that carbon dioxide removal(CDR)technologies must be deployed immediately to stabilize concentration of atmospheric greenhouse gases and avoid major climate change impacts.Biochar is a carbon-rich material formed by high-temperature conversion of biomass under reduced oxygen conditions,and its production is one of few established CDR methods that can be deployed at a scale large enough to counteract effects of climate change within the next decade.Here we provide a generalized framework for quantifying the potential contribution biochar can make toward achieving national carbon emissions reduction goals,assuming use of only sustainably supplied biomass,i.e.,residues from existing agricultural,livestock,forestry and wastewater treatment operations.Our results illustrate the significant role biochar can play in world-wide CDR strategies,with carbon dioxide removal potential of 6.23±0.24%of total GHG emissions in the 155 countries covered based on 2020 data over a 100-year timeframe,and more than 10%of national emissions in 28 countries.Concentrated regions of high biochar carbon dioxide removal potential relative to national emissions were identified in South America,northwestern Africa and eastern Europe.
