The author has been engaging in the study on energy systems and energy technology evaluation over 30 years. The study is to develop the methodologies of system analysis on energy technology evaluation and to apply them to technological evaluation of various energy technologies. Engineering economy methods on energy technologies were developed and new technologies of electric power generation were evaluated by the methods. The integrated method based on the multi-utilities function theory was developed in order to evaluate new technologies from viewpoints of intangible items such as energy security, environmental problems, site problems, etc. as well as economic aspects. The economical analysis method developed for electric energy storage technologies was applied to pumped hydro, compressed air energy storage, superconductivity magnetic energy storage, flywheel and batteries. Pioneer study on life cycle assessment was conducted for the environmental analysis of various power generation technologies, which was able to clarify embodies energy consumption as well as carbon dioxide emissions from entire processes of construction, operation and disposal on fuel chains of extraction, tran