Efficiency assessment of coal energy and non-coal energy under bound dynamic DDF DEA

The demand for energy has continued to increase because of global economic development, which has led to rising fuel prices and continued pollution problems. China is currently the largest coal consumer and is also the largest emitter of coal-fired CO₂ emissions. However, past efficiency studies have been mostly limited to static analyses and have not considered undesirable outputs. Therefore, this study developed a bound dynamic directional distance function (DDF) data envelopment analysis (DEA) model to explore the energy and environmental efficiencies in 30 Chinese provinces from 2011 to 2015, from which it was found that (1) the overall efficiency was the best in the eastern region, but relatively low in the western region; (2) Beijing, Guangdong, Jiangsu, Shandong, Shanghai, Tianjin, Jiangxi, Jilin, and some other regions had efficiencies of 1; (3) the revenue and non-coal indicator efficiencies were reasonably good, but the expenditure and emissions efficiencies were generally poor; and (4) the key direction for primary improvements was found to be the emissions index.