A green low-cost redox flow battery using Zn/Znredox couple in HAc/NaAc medium and Fe/Feredox couple in HSOmedium was first proposed and investigated for potential stationary energy storage applications. The presence ...A green low-cost redox flow battery using Zn/Znredox couple in HAc/NaAc medium and Fe/Feredox couple in HSOmedium was first proposed and investigated for potential stationary energy storage applications. The presence of HAc/NaAc in the negative electrolyte can keep the pH between 2.0 and 6.0even when a large amount of Hions move into negative electrolyte from positive electrolyte through ion exchange membrane. In the pH range of 2.0–6.0, the chemical reaction of Zn species with Hspecies is very insignificant; furthermore, the electroreduction of Hion on the negative electrode is significantly suppressed at this pH range. The zinc-ferrum redox flow battery（Zn/Fe RFB） operated within a voltage window of 0.5–2.0 V with a nearly 90% utilization ratio, and its energy efficiency is around 71.1% at room temperature. These results show that Zn/Fe RFB is a promising option as a stationary energy storage equipment.展开更多
The IPCC has drawn attention to an apparent leveling-off of globally-averaged temperatures over the past 15 years or so. Measuring the duration of the hiatus has implications for determining if the underlying trend ha...The IPCC has drawn attention to an apparent leveling-off of globally-averaged temperatures over the past 15 years or so. Measuring the duration of the hiatus has implications for determining if the underlying trend has changed, and for evaluating climate models. Here, I propose a method for estimating the duration of the hiatus that is robust to unknown forms of heteroskedasticity and autocorrelation (HAC) in the temperature series and to cherry-picking of endpoints. For the specific case of global average temperatures I also add the requirement of spatial consistency between hemispheres. The method makes use of the Vogelsang-Franses (2005) HAC-robust trend variance estimator which is valid as long as the underlying series is trend stationary, which is the case for the data used herein. Application of the method shows that there is now a trendless interval of 19 years duration at the end of the HadCRUT4 surface temperature series, and of 16 - 26 years in the lower troposphere. Use of a simple AR1 trend model suggests a shorter hiatus of 14 - 20 years but is likely unreliable.展开更多
基金financially supported by the NSFC(No.21361010,China)
文摘A green low-cost redox flow battery using Zn/Znredox couple in HAc/NaAc medium and Fe/Feredox couple in HSOmedium was first proposed and investigated for potential stationary energy storage applications. The presence of HAc/NaAc in the negative electrolyte can keep the pH between 2.0 and 6.0even when a large amount of Hions move into negative electrolyte from positive electrolyte through ion exchange membrane. In the pH range of 2.0–6.0, the chemical reaction of Zn species with Hspecies is very insignificant; furthermore, the electroreduction of Hion on the negative electrode is significantly suppressed at this pH range. The zinc-ferrum redox flow battery（Zn/Fe RFB） operated within a voltage window of 0.5–2.0 V with a nearly 90% utilization ratio, and its energy efficiency is around 71.1% at room temperature. These results show that Zn/Fe RFB is a promising option as a stationary energy storage equipment.
文摘The IPCC has drawn attention to an apparent leveling-off of globally-averaged temperatures over the past 15 years or so. Measuring the duration of the hiatus has implications for determining if the underlying trend has changed, and for evaluating climate models. Here, I propose a method for estimating the duration of the hiatus that is robust to unknown forms of heteroskedasticity and autocorrelation (HAC) in the temperature series and to cherry-picking of endpoints. For the specific case of global average temperatures I also add the requirement of spatial consistency between hemispheres. The method makes use of the Vogelsang-Franses (2005) HAC-robust trend variance estimator which is valid as long as the underlying series is trend stationary, which is the case for the data used herein. Application of the method shows that there is now a trendless interval of 19 years duration at the end of the HadCRUT4 surface temperature series, and of 16 - 26 years in the lower troposphere. Use of a simple AR1 trend model suggests a shorter hiatus of 14 - 20 years but is likely unreliable.
