Energy efficiency and emissions reductions are effective initiatives to address climate change and energy security. China has increased government subsidies and intellectual property protection (IPP) intensity to promote technological innovation in the renewable energy sector. This paper selects samples of geothermal, wind, and solar energy companies and examines whether the two initiatives mentioned above can improve company innovation, and assesses their action pathways. The results reveal that: (i) government subsidies can directly facilitate renewable energy enterprises’ innovative performance, and research and development (R&D) input served as a medium; and (ii) the intensity of IPP moderation needed for geothermal and solar enterprises to utilize the government subsidy to enhance innovation. The government should consider the differences of different sub-sectors of renewable energy when increasing subsidies. Better laws and policies are needed to strengthen the protection of intellectual property rights and stimulate innovation in renewable energy enterprises.

The proposal of the “double carbon” goal of “carbon peak, carbon neutralization” highlights the determination of China’s green and low-carbon development. Carbon capture is one of the essential ways to reduce carbon dioxide (CO₂) emissions and cope with climate change. Then, how to improve the green innovation capability of organizations and promote the transformation and upgrading of enterprises with green development is a practical problem that needs to be dealt with quickly. This paper uses multiple linear regression to investigate the impact of environmental regulation on corporate green innovation and explores the mediating effect of corporate environmental investment and the moderating effect of corporate digital transformation. The analysis results show that government environmental regulation can effectively enhance the green innovation of enterprises and environmental investments play an intermediary role. However, the development of environmental regulation in China is still relatively backward, and its positive incentive role needs to be further played. As a result, the government should strengthen environmental legislation while also accelerating system development, increasing corporate investment in environmental protection, and raising protection awareness among companies using digital network technology.

The Chinese government is actively promoting green and low-carbon transformation for economic and social development, especially in the wastewater treatment industry. This article uses regression analysis to study the impact of company R&D input on patent performance and company operating income for different regulatory environments and regions. Companies in the wastewater treatment industries of the Shanghai and Shenzhen stock exchanges from 2013 to 2020 are selected as research samples. The results show that there is a partial mediating effect of patent performance between company R&D input and company operating income; the stimulative effect of company R&D input is strongest in a high external-high internal environment; this stimulative effect is also more significant in the three strategic regions when compared with other regions. The findings suggest that company R&D input can promote company operating income. Thus, wastewater treatment enterprises should establish complete R&D systems to improve their innovative output capabilities. Enterprises in more developed regions should play a leading role in undertaking technological innovation. Furthermore, the government should formulate policies to improve the capacity of companies to conduct wastewater treatment and continue down the road of green development.

To achieve the harmonious development of economic growth and the environment, nations must pay more attention to wastewater treatment and boost efficiency using green technology. This study applies the Malmquist-DEA model to assess the efficiency of green technology innovation in 19 Chinese wastewater treatment companies between 2017 and 2020. In addition, focus is placed on the core wastewater treatment technology of the companies with excellent performance, indicating how wastewater treatment companies may improve their green technology. The results of the study indicate that, first, the overall effectiveness of green technology innovation in companies follows a rising and then decreasing trend. In 2020, wastewater treatment companies’ green technology innovation efficiency was around 17.4 percent lower than in 2017. Improving technical progress is the key to boosting the total factor productivity of wastewater treatment companies. Second, based on the Tobit regression, the shareholding ratio of companies has a positive influence on the technical efficiency of companies. Therefore, China should increase innovation capacity and productivity, adopt current sewage treatment technology from overseas, and thus gradually achieve clean sewage utilization and ecological environment management.