Abstract: Significant progress has been made in laboratory thermonuclear fusion research. The United States has achieved inertial confinement fusion ignition at the National Ignition Facility; China has obtained important experimental results on the maintenance duration of steady-state plasma, plasma ion temperature and the fusion triple product at the Tokamak facility EAST and HL-3. Advances in laboratory thermonuclear fusion research have raised high expectations for the application of nuclear fusion energy. To understand the technical status of research on nuclear fusion energy applications, this paper evaluates various physical quantities related to nuclear fusion energy applications, such as fusion power density. Based on these results, the author argues that it is difficult at the current stage to accurately determine when nuclear fusion energy can be commercially deployed.