Experimental results of differential heat loss calorimetry measurements during the electrolysis of light water solutions of K2CO3 and Na2CO3 with a nickel cathode are presented. A significant increase in temperature with every watt input, compared with the calibration experiment, is observed during the electrolysis of K2CO2. This effect is not observed when Na2CO3 is electrolyzed. No trivial explanation (in terms of chemical reactions, change in heat transfer properties, etc.) of this effect has been found so far. If the nontriviality of the observed overcoming of the energy breakeven barrier is further confirmed, this phenomenon may find application as an important new energy source.