The invention consists of a system for generating regulated and controllable AC electricity from renewable sources of energy that are intermittent in their power output. The whole configuration comprises a renewable energy source and an appropriate conversion mechanism, an electrolyzer to produce hydrogen from water, a hydrogen storage tank, fuel cells to generate DC electricity using hydrogen as the fuel, and an electromechanical energy conversion system, comprising a DC motor in series with an AC generator to convert the DC electricity output of the fuel cells to controllable, regulated, harmonics-free AC output, directly connected to the power system grid. Other features of the system include the capability to modify the system, so as to generate electricity from natural gas, propane and hydrogen that was produced by off-peak electricity.