Impacts of productive efficiency improvement in the global metal industry on CO2 emissions

Measuring performance of supply chains based on data envelopment analysis and multi-regional input-output analysis: An application to 18 manufacturing sectors in 43 countries

This study developed a novel framework that combined data envelopment analysis and multi-regional input-output database to investigate the economic and environmental productivity change in the global supply chains associated with 18 manufacturing sectors in 43 countries from 2000 to 2014. Two models are developed; manufacturer model is used to evaluate performance of direct production activity of a sector in countries and supplier model is used to evaluate performance of indirect production activity of upstream suppliers of the sector. The proposed framework enables us to separately analyze the performance of supply chains into direct production activity and indirect production activity of suppliers. The empirical results show that the environmental productivity of direct production activity of 18 manufacturing sectors was improved by 12.9 percent, while the environmental productivity of the upstream suppliers was improved by only 4.7 percent during 2000-2014 on average. Different patterns of economic and environmental productivity growth were observed between the direct production activity and upstream suppliers in all sectors. The finding suggests that the performance of an entire supply chain should be separately analyzed to consider industry-specific policies. The proposed framework is used to identify countries that succeed/fail to improve economic and environmental performance. Based on the results, this study discusses policies regarding production and supply chain management toward CO2 mitigation.

Production efficiency and cost reduction potential of biodiesel fuel plants using waste cooking oil in Japan

Biodiesel fuel (BDF) is a potentially carbon-neutral fuel that could play a potentially important role in preventing global warming. However, its high production cost poses a challenge for many BDF producers. To establish an efficient method for BDF production and increase its cost competitiveness, the production efficiencies of 35 BDF plants in Japan, which produce BDF from waste cooking oil, were evaluated. Moreover, the cost reduction potential associated with improved efficiency was estimated. The empirical analysis revealed that (1) approximately 92% of the BDF plants have inefficient production; (2) they exhibit two predominant types of inefficiencies, technical and scale inefficiencies, and (3) improvement of production inefficiency can lead to an average production cost reduction of 3.52 yen per liter of BDF. To increase the production efficiency, it is important to improve the quality of the waste cooking oil used and increase the production scale. It is recommended that operators of inefficient BDF plants learn the production activities of the most efficient plants identified in this study. Furthermore, government policies focused on efficient BDF plants are essential to increase BDF production with limited resources.

Systematic control technologies for gaseous pollutants from non-ferrous metallurgy

Air pollutant emissions represent a critical challenge in the green development of the non-ferrous metallurgy industry. This work studied the emission characteristics, formation mechanisms, phase transformation and separation of typical air pollutants, such as heavy metal particles, mercury, sulfur oxides and fluoride, during non-ferrous smelting. A series of purification technologies, including optimization of the furnace throat and high-temperature discharge, were developed to collaboratively control and recover fine particles from the flue gas of heavy metal smelting processes, including copper, lead and zinc. Significant improvements have been realized in wet scrubbing technology for removing mercury, fluoride and SO₂ from flue gas. Gas-liquid sulfidation technology by applying H₂S was invented to recycle the acid scrubbing wastewater more efficiently and in an eco-friendly manner. Based on digital technology, a source reduction method was designed for sulfur and fluoride control during the whole aluminum electrolysis process. New desulfurization technologies were developed for catalytic reduction of the sulfur content in petroleum coke at low temperature and catalytic reduction of SO₂ to elemental sulfur. This work has established the technology for coupling multi-pollutant control and resource recovery from the flue gas from non-ferrous metallurgy, which provides the scientific theoretical basis and application technology for the treatment of air pollutants in the non-ferrous metallurgy industry.

Study on the Influencing Factors of CO2 from the Perspective of CO2 Mitigation Potentials

As the world pays more attention to carbon reduction, it is of great significance to identify the factors of CO2 to achieve carbon peaking and carbon neutrality goals for China. Therefore, this paper explores the factors of CO2 from the perspective of CO2 mitigation potentials (CESP) and analyzes the heterogeneity of each factor. We first employ the DEA-IDA model framework to analyze the CESP and influencing factors of each region, and then use geographically and temporally weighted regress to analyze the spatiotemporal heterogeneity of influencing factors, the efficiency, coal proportion, energy intensity, per capita GDP, urbanization rate, electrification rate, trade, economic structure, and climate conditions. The research results show that: (1) for 1 unit increase in per capita CO2, the per capita CESP increases by 0.56 units. The CESP of the central and western regions is greater than that of the eastern regions, and the improvement of resource utilization efficiency can achieve the peak in advance. (2) Per capita GDP and energy intensity are the main positive factor and negative factor, respectively, and the impact of efficiency changes on CESP is mostly positive. (3) Efficiency is the most influential factor affecting the CESP; among them, a 1% increase in efficiency in Hebei can reduce the CESP of 62.47 Mt. In regions dominated by clean power, the impact of electrification rates is negative. The rest of the factors also showed spatiotemporal heterogeneity. Our findings have important policy implications, especially in how to effectively reduce carbon emissions to formulate more appropriate policy.

CO2 Reduction Potential from Efficiency Improvements in China’s Coal-Fired Thermal Power Generation: A Combined Approach of Metafrontier DEA and LMDI

Among the G20 countries, China is the only country to experience an increase in electricity generation from coal-fired thermal power plants from 2019 to 2020. This study aims to develop an analytical framework combining metafrontier data envelopment analysis with the logarithmic mean Divisia index for a detailed decomposition analysis of ‘mass-based’ energy-related CO2 reduction potential through efficiency improvements in coal-fired thermal power plants in China. The results show that inefficiency in power generation can be largely attributed to differences in the location of power plants and the production scale. Moreover, the impact of regional heterogeneity on the changes in power generation efficiency is more notable for the small–medium power plants in the northeast region than the large power plants in the western region in China. However, when focusing on the mass-based CO2 reduction potential associated with the regional heterogeneity, its positive effects in the western region for the large power plants are 6.2 times larger than that in the northeast region for the small–medium power plants. These results imply that an analysis that focuses only on the efficiency score would ignore the production scale of coal-fired thermal power plants and thus would fail to properly evaluate the environmental impacts associated with efficiency changes.

Determinants of technical inefficiency in China's coal-fired power plants and policy recommendations for CO2 mitigation

This study applies data envelopment analysis (DEA) to estimate the technical efficiency (TE) and CO₂ emission reduction potential of 1270 coal-fired power plants in 28 Chinese provinces and municipalities. The large dataset used in the study includes 727 combined heat and power (CHP) plants and 543 thermal power plants. Results show an average TE score of 0.57 for the CHP power plants and 0.58 for the thermal power plants, suggesting a significant potential to reduce coal consumption in both types of coal-fired plants. Total CO₂ emission reduction potential was estimated to be 953 Mt-CO₂, or 19% of the total CO₂ emissions of China's electricity and heat producing sectors, indicating that China's coal-fired power plants have a significant potential to mitigate CO₂ emissions through technological improvement. In the second stage of the study, a Tobit regression analysis was conducted to identify the determinants of TE. Factors such as the plant's annual operation rate and capacity utilization rate were found to be significant influences. Based on our results, we propose that the Chinese government create a power distribution structure that generates electricity using technologically efficient equipment in areas rich in coal resources and distributes the generated electricity to other areas of the country.