Seawater electrolysis

Electrolysis uses electricity to split water into its basic components (H2 and O2). The use of seawater as the electrolyte is still at early stages of development, due to its high fouling/scaling potentials to both the membrane and electrodes. Furthermore, the low conductivity of the seawater also leads to the low process efficiency, since more electricity from the solar panels converts to heat rather than for hydrogen production, in comparison to the conventional electrolyte (30 wt% KOH solution). It can involve a two-stage process of desalinisation followed by electrolysis, with technologies that are already developed but by also increasing CAPEX needs and efficiency losses. The quality of water from seawater reverse osmosis is not sufficient, residual trace ions can poison active Pt- and Ir catalysts. Or it can be done in a one-stage process using water directly in the electrolyser, operating at low power densities and electrolysing only part of the water put in contact with the electrodes, although this technology is still at lab-scale. Seawater electrolysis can be an enabler for electrolysis in geographical regions that present high water-stress.