Several proposals on the power production application of neutronless fusion reactions and the ${\rm D}+{\rm D}\to ^3{\rm He}+{\rm n}+3.27$~MeV reaction are reviewed. Compressing low tritium fuel by thermal radiation from one or more D--T microexplosions possibly combined with one or more drivers is considered as the optimum ignition strategy for microexplosions with physically important D--D fusion reactions. Results are presented which show the incorrectness of three assumptions that argue that the ignition of the ${\rm p}+^{11}{\rm B}\to {3\alpha} +8.9$~MeV reaction can be facilitated by chain reactions. The delivery of lunar $^3{\rm He}$ as a thermonuclear fuel component for large-scale power production on the Earth is discussed from the viewpoint of the expedience problem.