Examining the trends of technological development in hydrogen energy using patent co-word map analysis

Hydrogen fuel is a zero CO2 emission fuel which uses in electrochemical cells, or internal combustion engines, to power vehicles and electric devices. It is also can potentially be mass-produced for various applications and be used in propulsion of spacecraft with safely high pressure storage. Therefore, it is an interesting subject to identify the technological trends of hydrogen energy. This study suggests a patent co-word map analysis (PCMA) to examine the trends of technological development in the area of hydrogen energy. The PCMA provides a systematic procedure to demonstrate the overall relationship among patents and produces the important technological insights regarding hydrogen energy. The results of analysis firstly indicate that the technological trends of worldwide hydrogen energy focus on the converting and application of hydrogen. Furthermore, critical technologies obtained from three patent sub-maps can be identified as the production, storage and conversion for hydrogen energy. Finally, hydrogen application is taken for the key factor in sustainable energy research works to improve the use for hydrogen.