Hemeng Miao, Erling Li, Yunlong Xing, Qingqing Deng, Mengjia He, Chenglin Qin
Green technological innovation serves as the core driver for achieving economic green transformation and the strategic goals of the "dual carbon" initiative. Although its importance is widely recognized, previous research has predominantly focused on national- or macro-level analyses. There remains a lack of systematic and detailed characterization of the long-term spatial evolution of green technological innovation, including differences among subsectors and the heterogeneous effects of diverse driving factors. Therefore, this study aims to examine the long-term evolutionary characteristics of geographical agglomeration patterns of green technology innovation in China and to identify the key factors and mechanisms influencing their development, thereby providing empirical evidence for formulating differentiated and targeted regional innovation policies. Based on the World Intellectual Property Organization (WIPO) International Patent Classification (IPC) Green Inventory, this study identifies and utilizes China's green invention patent authorization data from 2002 to 2021. Employing methods such as the locational Gini coefficient and spatial autocorrelation analysis, this study systematically depicts the spatiotemporal evolution of innovation activities in green technology as a whole and across its subsectors. Building on this foundation, a two-way fixed-effects model is used to empirically test the impact of factors across the four dimensions—resource input, market demand, policy support, and openness to the outside world—on the innovation levels of green technology overall and its subsectors. The study reveals several interesting results. 1) From a temporal perspective, China's green technology innovation exhibits a three-stage pattern of "steady growth–gradual enhancement–rapid development," with overall scale expanding rapidly. Spatially, a pronounced gradient emerges: eastern > central > western > northeastern regions, with the East maintaining absolute leadership in both total volume and growth rate. Based on development pace, the green technological subsectors have differentiated into a "three-tier" structure. Among these, alternative energy production, energy conservation, emission reduction, waste management, administrative regulation and design technology collectively, forming the "four pillars," which hold the largest share and exert the strongest pull on the industry. Among these, energy conservation and emission reduction technologies exhibit the fastest growth, becoming the focal point in recent years. 2) Spatially, green technology innovation exhibits a high degree of geographic concentration, increasingly clustering in the eastern coastal regions, particularly the Yangtze River Delta, and forming a distinct "southeast–northwest" spatial differentiation. Innovation activity is significantly higher south of the Hu Huanyong Line than north of it. High-high clusters are visibly contracting toward the Yangtze River Delta, whereas low-low clusters are spreading contiguously across western regions. However, overall regional disparities show a converging trend. 3) From the perspective of driving mechanisms, green technology innovation is influenced by a combination of resource inputs, market demand, policy support, and openness to the outside world. Among these factors, innovation funding support and human resource investment are universally recognized as key drivers. Nevertheless, other factors exhibit significant heterogeneity and unevenness in their impact across different technological domains. Policies should be tailored to leverage the synergistic effects of diverse policy tools based on the specific technological attributes and developmental characteristics of each field. The contributions of this study are as follows: First, by utilizing long-term green patent data, it dynamically reveals the complex spatial evolution of green technological innovation, from widespread clustering to high-value polarization and low-value contiguous clusters, thereby deepening theoretical understanding in innovation geography. Second, it overcomes the research limitation of treating green technology as a homogeneous entity, empirically revealing the heterogeneity of driving factors across different subfields and providing new evidence for understanding the logic of diversified green innovation development. Third, based on these findings, it explicitly proposes a policy shift toward tiered approaches and precision governance, emphasizing the need for differentiated policies tailored to regional resource endowments and technological field attributes. This provides critical decision-making references for building a coordinated and efficient green innovation governance system.