*5.3. The BTH Coordinated Development Strategy and Industrial Energy Pollution Intensities*

The effects of the BTH coordinated development strategy on different sources of energy-related pollutions may vary. For example, Beijing started replacing coal with electricity for heating in 2013, followed by Tianjin and some cities of Hebei province after implementation of the coordinated development strategy, which greatly reduced industrial sulfur dioxide and dust emissions in the BTH region [43]. In this part, this paper will examine the impacts of the BTH coordinated development strategy on different sources of industrial energy-related pollution including the three wastes, which are industrial wastewater, sulfur dioxide, and dust emissions, based on the DID method.

First, in Table 4, the variable *BTH*·*POST* is significantly negative at the 10 percent level in Model 2, significantly negative at the 5 percent level in Model 3, and positive but insignificant in Model 4. The results indicate that the BTH coordinated development strategy tends to decrease industrial wastewater and sulfur dioxide emission intensities but may have no significant impact on dust emission intensity though the coefficient is positive. The main reason may be that, while environmental regulation and industrial upgrades have reduced the three waste emissions, some transportation infrastructure construction and operation, such as high-speed rails and highways for regional transportation development, have caused much dust pollution. Specifically, at the city level, Zhangjiakou, Baoding, Chengde, Tangshan, and other cities which are constructing expressways and high-speed railways on a large scale to build the one-hour economic circle in the BTH region may encounter more serious dust pollution issues.


**Table 4.** Regression results of Models 2–4.

Source: Authors' estimation. Notes: *p*-values are in brackets \* *p* < 0.1, \*\* *p* < 0.05, and \*\*\* *p* < 0.01.

As to the countermeasures for the industrial three wastes, the most direct way to mitigate these industrial pollutions is to use clean technologies or facilities. There are some available methods for the BTH region to mitigate industrial pollutions. For example, end-of-pipe treatment technologies for the water- and energy-intensive coal-fired power industry with high emissions in the BTH region could reduce SO2, NOx, and dust emissions by 89%, 90%, and 88%, respectively, while consuming an average of 2% less energy and 8% more water as tradeoffs [44]. As the most polluted region in China caused by the coal-based heating system, the integration of large-scale heat pumps can potentially result in at least 9.5% energy savings and 9.28% reduced CO2 emissions compared to the baseline of 2015 for the whole BTH region by 2030 while ensuring economic feasibility [45]. Besides, based on a slacked-based data envelopment analysis (DEA) model by cluster benchmarking of 861 wastewater treatment plants (WWTPs) in China, the technology gap ratio confirmed that large WWTPs operated more efficiently than small ones [46].

It is worth mentioning that this paper does not make an empirical analysis of the industrial solid waste pollution, which is also a crucial environmental issue in China, because some city data are not available. From the latest available data, the solid waste utilization rates of Beijing, Tianjin, and Hebei in 2019 were 80%, 98%, and 75%, respectively, which are all higher than the average of 65% in China. However, there is still potential for further improvement, particularly in Beijing and Hebei. In the process of coordinated development, corresponding environmental regulations on industrial solid waste should be strengthened to improve the utilization rate.

For the control variables, the impact of FDI stock over GDP on industrial wastewater emission intensity is significantly negative but the impacts on sulfur dioxide and dust emission intensities are insignificant. In the BTH region, foreign enterprises invest very little in energy-intensive industries but more in labor-intensive light industries which may produce mainly wastewater. As a result, the technology spillover effect can be generated in these industries and relevant enterprises will reduce industrial wastewater discharge. The impact of R&D expenditure over GDP on industrial sulfur dioxide intensity is significantly negative but the impacts on industrial wastewater discharge and dust emission intensities are insignificant. The results suggest that research spending should be focused more on reducing industrial wastewater and dust emissions for further regional sustainable development. The regression results of other control variables are consistent with the theories and expectations.
