<p>The electrochemical reduction of carbon dioxide (CO₂) can produce value-added chemicals and fuels with reduced greenhouse gas emissions by leveraging renewable electricity. However, the economic viability of this technology is limited by high full-cell voltages due to the combination of various materials and processes between the anode and the cathode. Here we analyse voltage distributions within systems that are candidates for achieving energy-efficient CO₂ electroreduction: CO₂ reduction (CO₂R) in acidic media, cascade CO₂R-CO electroreduction and CO₂ reactive capture. By measuring and resolving the individual contributions to the overall cell voltage, we show that the cascade approach is, at present, the most energy-efficient candidate for achieving economic and scalable CO₂R. The membrane and cathode overpotentials dominate in direct CO₂R approaches (acidic CO₂R and CO₂R with forward-biased bipolar membranes). By contrast, the reactive capture approach benefits from a low membrane overpotential (&lt;0.2 V) as a result of the high proton conductivity of the cation exchange membrane, with remaining overpotentials at the cathode, anode and intrinsic Nernstian pH gradient. Applying these insights, we optimize the CO electroreduction system to reach a full-cell voltage of 1.95 V at 200 mA cm⁻². Our findings offer a framework for steering the advance of more energy-efficient and scalable CO₂R electrolysers.</p>