**5. Conclusions**

This study investigates the impact of information and communication technology in several ways using multiple productive performance indicators and data on three types of information and communication technology capital. The main results are summarized as follows.

Total information and communication technology capital do not significantly a ffect capital productivity and material productivity. Meanwhile, information technology and software capital contribute to increasing material productivity and capital productivity in the energy sector, respectively. On the other hand, communication technology capital negatively a ffects these two indicators. These results imply that the e ffects of specific types of information and communication technology capital are canceled out.

Another important finding is that the interaction term of renewable energy share with the information technology and communication technology capital shares significantly contributes to improving capital productivity. Meanwhile, information technology capital and communication technology capital negatively a ffect capital productivity when renewable energy di ffusion is not considered. This result indicates the importance of a research framework that assumes that the impacts of information and communication technology capital on productive performance di ffer according to the degree to which there are renewable energy systems.

The limitation of this research is the detailed data (e.g., cost and investment) on specific information and communication technology capital. Further analysis with more detailed data regarding each technology is expected to compare the cost-e ffectiveness of di fferent technologies in increasing the productivity of the energy sector.

**Author Contributions:** Conceptualization, H.F. and A.S.; methodology, H.F.; investigation, H.F.; writing—original draft preparation, H.F.; writing—review and editing, H.F., A.S., S.K., and S.M.

**Funding:** This research was funded by a Grant-in-Aid for Young Scientists (B) [JP17K12858] from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

**Conflicts of Interest:** The authors declare no conflict of interest.
