L2-WTR-ELEC CRITICAL RESOURCES Level 2 · hardware

Electrolysis System

water_electrolysis_system

PEM and alkaline electrolysis units that split purified water into hydrogen and oxygen gases for energy storage, propellant, life support, and manufacturing processes.

Purpose

Convert electrical energy into storable chemical energy (H2/O2) and provide oxygen for breathing and hydrogen for industrial processes.

Context

Key energy-matter conversion node linking the water system to power storage (fuel cells), life support (O2), and manufacturing (H2 reduction, process atmosphere).

Principles

▸Water electrolysis: 2H2O -> 2H2 + O2 at ~1.23V theoretical, ~1.8V practical
▸PEM electrolysis offers high current density and rapid response
▸Alkaline electrolysis provides longer cell lifetime with lower-cost materials
▸Gas purity critical: >99.99% for fuel cell feed, >99.5% for breathing O2
▸Efficiency typically 70-85% electrical-to-chemical energy conversion

Typical implementations

▸PEM electrolyzer stacks with Nafion membranes and IrO2/Pt catalysts
▸Alkaline electrolyzer stacks with KOH electrolyte and nickel electrodes
▸Pressure regulation for direct high-pressure gas output (up to 30 bar)
▸Water deionization pre-treatment to protect PEM membranes
▸Gas-liquid separators and dryers for product gas purification

Lunar considerations

▸1/6 g affects gas-liquid separation requiring forced circulation
▸Dual-technology approach (PEM + alkaline) provides redundancy
▸Platinum group catalysts are limited; long-life low-loading designs essential
▸Produced O2 supplements life support and smelting processes
▸H2 storage at cryogenic or high-pressure for energy density

Specifications

Functional

primary function	Electrochemically split purified water into hydrogen and oxygen gases
inputs	deionized_water, electrical_power
outputs	hydrogen_gas, oxygen_gas
electrical efficiency	>80%
hydrogen purity	>99.99%
oxygen purity	>99.5%
output pressure	up to 30 bar direct from stack

Physical

materials	PEM_nafion_membranes, IrO2_anode_catalyst, Pt_cathode_catalyst, nickel_electrodes, KOH_electrolyte, titanium_bipolar_plates
operating temperature	50-80 C for PEM, 60-90 C for alkaline
location	pressurized module with H2 safety ventilation
safety	H2 leak detection and emergency purge required

Operational

thermal range c	-173, 127
lifetime years	100

Interfaces

Provides

→L0-ARKhydrogen_gascritical
H2 for fuel cells, propellant, and industrial processes
→L0-ARKoxygen_gascritical
O2 for breathing, propellant, and metal smelting

Requires

←Water Purificationdeionized_watercritical
High-purity water to protect membranes and electrodes
←L0-ARKelectrical_powercritical
DC power for electrolysis, scaled to production rate