Using social network analysis to examine the technological evolution of fermentative hydrogen production from biomass

In recent years, hydrogen energy has become important to sustainable energy supply as a source that can help mitigate the impact of climate change. This study examines the evolution of biomass fermentation, an important part of hydrogen production, by using patent searches and citations, and surveying the momentum of the technology. The social networking created by the relationships among patent citations for patent technologies are first analyzed, and the evolution of patent technology is discussed by describing its momentum. Following this, the core patents emerging from the evolution of patent technology are identified, and the cycle time for the patent technology is estimated from the cited patents. The study analyzed approximately 1970 patents by United States Patent and Trademark Office to describe the evolution of fermentative hydrogen production through biomass technology. The results revealed that the developmental stage of fermentative hydrogen production from biomass is growing, and its technological cycle of approximately 12.59 years indicated a gradually changing trend in fermentative hydrogen production from biomass. The study findings should provide governments with a reference point in the formulation of future energy policy. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.