The basic formulae for calculating the moving long wave energy were derived and presented. The problems related to the energy counting in the course of numerical modeling of tsunami wave generation and propagation. Through a number of computational experiments, the wave energy radiation directivity of tsunami generated by an ellipsoidal source with a various axis length ratio was studied. The wave energy radiation directivity of the dipole tsunami source consisting of two ellipsoidal sources with opposite sign of the water surface displacement is considered.