# Evolution of the conceptualization of hydrogen through knowledge maps, energy return on investment (EROI) and national policy strategies

> Research article (Clean Technologies and Environmental Policy, 2022) · cited 13× · AI/ML

**Wikidata**: [openalex:W4296270246](https://www.wikidata.org/wiki/openalex:W4296270246)  
**Source**: https://4ort.xyz/entity/evolution-of-the-conceptualization-of-hydrogen-through-knowledge-maps-energy-return-on-investment-eroi-and-national-poli