Energy storage and renewables in district Heating: Trends, economics and outlook

• Conducted a bibliometric analysis of 726 papers on district heating (2000–2024). • Found 14.49% annual growth showing rising global interest in decarbonized heating. • Identified key research themes: thermal storage, heat pumps, and smart control systems. • Emerging trends include hydrogen integration, digitalization, and model predictive control. • Provides insights for policy, technology, and investment in sustainable heating systems. This study presents a systematic bibliometric analysis of research on energy storage and renewable energy integration in district heating (DH) networks from 2000 to 2024. A total of 726 articles authored by 2088 authors (with 4.13 co-authors per article on average) were obtained from the Scopus database for the analysis, which demonstrates strong interdisciplinarity, with 23.97 % of the research featuring international co-authorship. The results show increased annual publication growth of 14.49 %, reflecting global policy and scientific interest in smart urban energy systems and decarbonization. The study is evidence of contemporary relevance, with a mean document age of 5.22 years and 22.87 citations per article. Germany contributed 448, then China (430), and Italy (289), with the most frequent collaboration between China and Denmark (14 times). The thematic analysis also highlights dominant research interests in such core domains as thermal storage, heat pumps, system flexibility, and data-driven optimization, while also pointing toward new trends in borehole thermal storage, hydrogen integration, and model predictive control. The outcomes reflect the increasing sophistication of DH research toward low-carbon, digitalized, and resilient energy infrastructures. Prospects lie in digitalization, integration with smart grid, and well-coordinated policy and technology innovations to conquer the financial and operational hurdles in the development of sustainable and adaptive DH systems.