Pico-Hydropower and Cross-Flow Technology: Bibliometric Mapping of Scientific Research and Review

This study aims to map the evolution of pico-hydropower and Michell–Banki (cross-flow) turbine research from 2000 to 2025 through a combined bibliometric analysis and qualitative mini-review. In total, 1036 Scopus-indexed records were initially identified and refined to 922 relevant publications for analysis. Bibliometric mapping with CiteSpace, VOSviewer, and Bibliometrix identified publication trends and seven major thematic clusters (dominated by topics such as cross-flow turbine design, renewable energy integration, and asynchronous generators), while a qualitative mini-review of key studies provided contextual depth. The analysis detected 25 keywords with strong citation bursts, indicating a shift in focus over the last decade from traditional electrical regulation toward digitalization and additive manufacturing. The mini-review distilled three dominant lines of inquiry geometric design optimization, hydraulic performance characterization, and socio-economic evaluation and highlighted critical knowledge gaps, including the absence of standardized flow–head–efficiency (Q–H–η) performance data, sparse reporting of economic metrics like levelized cost of energy (LCOE), and limited high-altitude (above 3000 m) validation of pico-hydro systems. This study’s integrative approach is unique compared to prior bibliometric or technical reviews, providing a comprehensive overview of the pico-hydropower landscape and outlining a future research agenda to standardize experimental protocols, integrate economic analysis, and extend cross-flow turbine deployments to high-Andean regions.