Processes of the concentration of energy at the formation of rogue waves have been studied in computer experiments based on the exact hydrodynamic equations for an ideal fluid. The distribution of anomalies of waves both in height and in energy has been found in the computer experiment. Correlation between the energy concentration and height of anomalously large surface waves has been revealed. The results can be used to estimate the danger of anomalously large surface waves. © 2014, Maik Nauka-Interperiodica Publishing. All rights reserved.