Engineering Evaluation of Metal Combinations for Seawater-Driven Galvanic Power Generation for Marine Sensors

Natural seawater is an abundant electrolyte for powering marine sensors, but systematic performance data for simple galvanic cells using commercially available metals in untreated seawater remain limited under quiescent, passively aerated conditions.This study screened twenty-one unique electrode combinations generated from seven commercially available metals.Based on the screening results, six representative electrode combinations covering high-, intermediate-, and negligible-performance behavior were selected for detailed discussion and graphical presentation.(Zn-Pb, Zn-Mn, Fe-Zn, Mn-Cu, SS-SS, and Pb-Pb) for seawater-driven power generation using natural Red Sea seawater.Open-circuit voltage, loaded voltage under 200 Ω, and current were measured.Electrolyte evolution was evaluated using pH, conductivity, total dissolved solids, and inductively coupled plasma mass spectrometry (ICP-MS) analysis.An eight-cell Zn-SS304 series array was subsequently evaluated as a proof-of-concept demonstration by continuously powering a 30-LED parallel load for three days.Zn-Pb produced the highest output (0.367 mW, 1.36 mA, ~198 Ω), followed by Zn-Mn and Fe-Zn.Mn-Cu, SS-SS, and Pb-Pb showed negligible activity.Electrolyte pH decreased from 8.1 to 6.5-7.2 for the more electrochemically active electrode pairs.The Zn-SS304 array maintained a stable operating output (~2.55 V, ~1.5 mA) over 72 h.This work establishes a systematic engineering performance baseline for commercially available metal electrode combinations operating in untreated natural seawater under passive conditions, identifying Zn-Mn as a promising non-toxic candidate and Zn-Pb as a high-performance reference.