A method for generating hydrocarbons using a solid oxide electrolysis cell (SOEC) and a Fischer-Tropsch unit in a single microtubular reactor is described. This method can directly synthesize hydrocarbons from carbon dioxide and water. The method integrates high temperature co-electrolysis of H2O and CO2 and low temperature Fischer-Tropsch (F-T) process in a single microtubular reactor by designation of a temperature gradient along the axial length of the microtubular reactor. In practice, methods disclosed herein can provide direct conversion of CO2 to hydrocarbons for use as feedstock or energy storage.