• Energy Research

Abstract Taking the four-stage SBM-DEA as the theoretical tool, this paper evaluates the total factor waste gas treatment efficiency (TFWGTE) of 65 Chinese iron and steel enterprises (CISEs) from 2005 to 2014. Then, after the influences of external environmental factors and statistical noise are eliminated, TFWGTE is decomposed into total factor waste gas managerial efficiency (TFWGME) and total factor waste gas environmental efficiency (TFWGEE), and the differences between TEWGTE, TEWGME and TEWGEE are systematically analysed from regional and enterprise perspectives. The results reveal that: (1) TFWGTE and TFWGEE showed an upward trend from 2005 to 2014, whereas TFWGME showed a downward trend from 2005 to 2014. The elimination of external environmental factors had provincial specific effects on TFWGTE; (2) By comparing the dynamic trends of TFWGTE in eastern, central and western regions, it is found that there are differences among different regions, which indicates that the external environmental factors in the region have an impact on TFWGTE; (3) In 4 provinces, TFWGME increased compared with TFWGTE, while in 23 provinces, TEWGME decreased compared with TFWGTE; (4) The Tobit regression results show that the command-and-control environmental regulation, environmental awareness and manufacturing process have significant effects on the input slacks of waste gas treatment, indicating that the strengthening of command-and-control environmental regulation, the improvement of environmental awareness, and the decline of the proportion of the short process can effectively reduce the input slacks of waste gas treatment.

Abstract This investigation extends the HAR model to include the role of after-hours information and leverage effects to forecast daily volatility of the Chinese non-ferrous metals futures market. Furthermore, volatility clustering in the residuals of the volatility model is investigated. In addition to the usual leverage effects, the findings indicated new insights into additional leverage effects, which are captured by negative overnight returns and negative lunch-break returns. Moreover, after-hours information has a highly in-sample explanatory and there is no risk–return trade-off in the Chinese non-ferrous metals futures market. One-step ahead forecasts are investigated and the results indicated that the introduction of after-hours information and leverage effects in the HAR model exhibit better predictive power. Finally, the results are robust for various sampling frequencies. Our findings have important significance for investors and policy makers and will elucidate further research directions.

Abstract Using the nonparametric causality-in-quantiles approach, we investigate the causal effects of oil price uncertainty on the returns and volatility of clean energy metal stocks under different market conditions in China. The results suggest that there is a causal relationship between oil price uncertainty and the returns and volatility of Chinese clean energy metal stocks. The effect differs slightly between returns and volatility. Specifically, the causal effect of oil price uncertainty on returns is mainly observed for lower quantiles, whereas the effect on volatility exists for all quantiles. In addition, the effects of change of market environment in China on the causal relationship are tested. The results show that change in market environment has significantly weakened the causal relationship between oil price uncertainty and clean energy metal stocks, suggesting that the structure of the Chinese clean energy metal stock market has undergone major changes.

AbstractIn recent years, increasing attention has been given to the potential supply risks of critical battery materials, such as cobalt, for electric mobility transitions. While battery technology and recycling advancement are two widely acknowledged strategies for addressing such supply risks, the extent to which they will relieve global and regional cobalt demand–supply imbalance remains poorly understood. Here, we address this gap by simulating historical (1998-2019) and future (2020-2050) global cobalt cycles covering both traditional and emerging end uses with regional resolution (China, the U.S., Japan, the EU, and the rest of the world). We show that cobalt-free batteries and recycling progress can indeed significantly alleviate long-term cobalt supply risks. However, the cobalt supply shortage appears inevitable in the short- to medium-term (during 2028-2033), even under the most technologically optimistic scenario. Our results reveal varying cobalt supply security levels by region and indicate the urgency of boosting primary cobalt supply to ensure global e-mobility ambitions.

Abstract Increasing financial attributes of non-ferrous metals after financialization and higher uncertainty lead to a more complicated stock market of non-ferrous metal industry, while no study has explored the relations among the three under a unified framework. This paper attempted to investigate the effects of non-ferrous metal prices and uncertainty on stock indices of non-ferrous metal industries in China under different market conditions. Results show that: (1) non-ferrous metal prices have positive impacts, indicating that the hedging effects of non-ferrous metals are weaker after financialization; (2) the impacts of uncertainty are negative at the mean level or bearish market, but positive under the bullish markets; (3) the impact strength of non-ferrous metal prices and uncertainty are stronger under lower and upper quantiles than intermediate quantile; (4) effects of non-ferrous metal prices and uncertainty are more significant and stronger after the global financial crisis in 2008. These findings imply the importance of non-ferrous metal prices and uncertainty for coping with fluctuations of non-ferrous metal stock markets, making investment portfolios, formulating targeted strategies, and maintaining financial security under different market conditions.

Based on a structural vector autoregression (SVAR) model, we investigate the impacts of different types of oil price shocks on industrial producer price index (PPI) in China for the period from 199...