This short communication introduces the first marine-current power generation model to be integrated into power flow studies of smart grids. The stochastic aspect of marine-current velocity affecting the real power output of marine-current generators is provided by a closed formula. Also, a new closed formula for power coefficient of marine-current generators versus marine-current velocities is set up. The introduced marine-current power generation model is validated on real measurements obtained in the sub-sea areas of Alderney Race (Channel Islands) in UK and Gun-barrel passage in Fiji. (C) 2013 Elsevier B.V. All rights reserved.