The issue is in the methodology text on Page 3: They state, “The research articles are included only from the areas of business, management and accounting, social science, economics, econometrics, and finance.“
This is a massive, fatal selection bias for a study on Green Energy Innovation. They have systematically excluded the core fields where these innovations are actually invented and reported: Engineering, Energy, Environmental Science, Chemistry, and Material Science.
But if you look at Fig. 1, it just shows a neutral process: “Scopus search” -> “Refined using Scopus filters” -> “Document type: Journal articles” -> “Language: English”. The diagram presents a clean, systematic process, but it completely hides the most biased and limiting filter of all—the exclusion of essential scientific disciplines.
This is misleading because:
– The figure suggests a comprehensive search, but the methodology reveals a narrow, skewed one.
– The “current state of knowledge” they describe is not the state of technical innovation, but only the state of economic and business discussions about innovation.
– Their “future research directions” are likely uninformed by the actual technical challenges and breakthroughs published in the engineering literature.