Dramatic fall in costs of renewable energy in the last 24 months has not only accelerated the replacement of fossil fuels by renewable energy in electricity generation. The low cost renewable electricity is now starti...Dramatic fall in costs of renewable energy in the last 24 months has not only accelerated the replacement of fossil fuels by renewable energy in electricity generation. The low cost renewable electricity is now starting to replace fossil fuels in other sectors. One reason is that renewable electricity is now cheaper per unit energy than oil, about the same price as fossil methan but, still, more expensive than coal. Another reason is that electricity often offer other opportunities, such as cheaper transport, better control, higher energy efficiency in final production of energy services and lower local environmental costs.展开更多
Road transport produces significant amounts of emissions by using crude oil as the primary energy source.A reduction of emissions can be achieved by implementing alternative fuel chains.The objective of this study is ...Road transport produces significant amounts of emissions by using crude oil as the primary energy source.A reduction of emissions can be achieved by implementing alternative fuel chains.The objective of this study is to carry out an economic,environmental and energy(EEE)life cycle study on natural gas-based automotive fuels with conven-tional gasoline in an abundant region of China.A set of indices of four fuels/vehicle systems on the basis of life cycle are assessed in terms of impact of EEE,in which natural gas produces compressed natural gas(CNG),methanol,dimethy-lether(DME)and Fischer Tropsch diesel(FTD).The study included fuel production,vehicle production,vehicle opera-tion,infrastructure and vehicle end of life as a system for each fuel/vehicle system.A generic gasoline fueled car is used as a baseline.Data have been reviewed and modified based on the best knowledge available to Chongqing local sources.Results indicated that when we could not change electric and hydrogen fuel cell vehicles into commercial vehicles on a large scale,direct use of CNG in a dedicated or bi-fuel vehicle is an eco-nomical choice for the region which is most energy efficient and more environmental friendly.The study can be used to support decisions on how natural gas resources can best be utilized as a fuel/energy resource for automobiles,and what issues need to be resolved in Chongqing.The models and approaches for this study can be applied to other regions of China as long as all the assumptions are well defined and modified to find a substitute automotive energy source and establish an energy policy in a specific region.展开更多
The most viable path to alleviate the Global Climate Change is the substitution of fossil fuel power plants for electricity generation with renewable energy units.This substitution requires the development of very lar...The most viable path to alleviate the Global Climate Change is the substitution of fossil fuel power plants for electricity generation with renewable energy units.This substitution requires the development of very large energy storage capacity,with the inherent thermodynamic irreversibility of the storage-recovery process.Currently,the world experiences a significant growth in the numbers of electric vehicles with large batteries.A fleet of electric vehicles is equivalent to an efficient storage capacity system to supplement the energy storage system of the electricity grid.Calculations based on the hourly demand-supply data of ERCOT,a very large electricity grid,show that a fleet of electric vehicles cannot provide all the needed capacity and the remaining capacity must be met by hydrogen.Even though the storage capacity of the batteries is close to 1–2%of the needed storage capacity of the grid,the superior round-trip storage efficiency of batteries reduces the energy dissipation associated with the storage and recovery processes by up to 38%and the total hydrogen storage capacity by up to 50%.The study also shows that anticipated improvements in the round-trip efficiencies of batteries are almost three times more effective than improvements in hydrogen storage systems.展开更多
文摘Dramatic fall in costs of renewable energy in the last 24 months has not only accelerated the replacement of fossil fuels by renewable energy in electricity generation. The low cost renewable electricity is now starting to replace fossil fuels in other sectors. One reason is that renewable electricity is now cheaper per unit energy than oil, about the same price as fossil methan but, still, more expensive than coal. Another reason is that electricity often offer other opportunities, such as cheaper transport, better control, higher energy efficiency in final production of energy services and lower local environmental costs.
基金This work was supported by the Chongqing Municipal Planning and Development Commission,Ford Motor Company as well as Changan Automobile(Group)Corporation.
文摘Road transport produces significant amounts of emissions by using crude oil as the primary energy source.A reduction of emissions can be achieved by implementing alternative fuel chains.The objective of this study is to carry out an economic,environmental and energy(EEE)life cycle study on natural gas-based automotive fuels with conven-tional gasoline in an abundant region of China.A set of indices of four fuels/vehicle systems on the basis of life cycle are assessed in terms of impact of EEE,in which natural gas produces compressed natural gas(CNG),methanol,dimethy-lether(DME)and Fischer Tropsch diesel(FTD).The study included fuel production,vehicle production,vehicle opera-tion,infrastructure and vehicle end of life as a system for each fuel/vehicle system.A generic gasoline fueled car is used as a baseline.Data have been reviewed and modified based on the best knowledge available to Chongqing local sources.Results indicated that when we could not change electric and hydrogen fuel cell vehicles into commercial vehicles on a large scale,direct use of CNG in a dedicated or bi-fuel vehicle is an eco-nomical choice for the region which is most energy efficient and more environmental friendly.The study can be used to support decisions on how natural gas resources can best be utilized as a fuel/energy resource for automobiles,and what issues need to be resolved in Chongqing.The models and approaches for this study can be applied to other regions of China as long as all the assumptions are well defined and modified to find a substitute automotive energy source and establish an energy policy in a specific region.
基金This research was partly supported by the Tex Moncrief Chair of Engineering at TCU.
文摘The most viable path to alleviate the Global Climate Change is the substitution of fossil fuel power plants for electricity generation with renewable energy units.This substitution requires the development of very large energy storage capacity,with the inherent thermodynamic irreversibility of the storage-recovery process.Currently,the world experiences a significant growth in the numbers of electric vehicles with large batteries.A fleet of electric vehicles is equivalent to an efficient storage capacity system to supplement the energy storage system of the electricity grid.Calculations based on the hourly demand-supply data of ERCOT,a very large electricity grid,show that a fleet of electric vehicles cannot provide all the needed capacity and the remaining capacity must be met by hydrogen.Even though the storage capacity of the batteries is close to 1–2%of the needed storage capacity of the grid,the superior round-trip storage efficiency of batteries reduces the energy dissipation associated with the storage and recovery processes by up to 38%and the total hydrogen storage capacity by up to 50%.The study also shows that anticipated improvements in the round-trip efficiencies of batteries are almost three times more effective than improvements in hydrogen storage systems.
