The electromagnetic generator requires sophisticated power take‐off systems to effectively capture low‐frequency mechanical motion such as ocean waves and human gait. Conversely, electrostatic generators are variable capacitors, which harness charge separation processes that can directly capture low‐frequency mechanical energy. The fundamentals of mechanical‐to‐electrical energy conversion with an electrostatic generator that exploits the high energy density of electric double layer (EDL) capacitors and varies capacitance by physical manipulation of the electrode–electrolyte interfacial area are elucidated. A model system is designed where all experimental parameters are easy to access in order to gain a detailed understanding of the energy flow in this conversion process. The system, termed a variable EDL generator, is based on titanium electrodes in NaCl aqueous electrolyte and operated as a charge pump. The net positive electrical energy generation of the system in the voltage–charge work‐conjugate plane is analyzed, and it shows that the variable EDL generator can be scaled‐up to spin an electric motor and increase the output power of the generator through the use of waste heat. The detailed analysis of this energy conversion principle suggests multiple avenues to enhance the performance of the variable EDL generator.