Source Review: Schreiner-Sibille MRE Reactor Model

Summary

Claim 1 — Specific energy 21 kWh/kg O2

Quote: "An MRE reactor can produce on the order of 100 kg oxygen annually per kilogram reactor mass with a specific energy around 21 kW- hr per kilogram oxygen in an annual production range of 2000-3000 kg."

Verdict: Consistent (q3.c2, q3.c13)

Why: This is the process-only specific energy at the bath. My thermodynamic floor (6.5 kWh/kg) is the pure-oxide lower bound; 21 kWh/kg includes Gibbs + heat-to-melt + electrochemical overpotentials — consistent at ~3× floor.

Claim 2 — Productivity per reactor mass (100 kg O2/yr/kg)

Quote: "100 kg O2 / yr / kg reactor mass"

Verdict: Consistent (q3.c13)

Why: This is the canonical MRE figure used downstream for plant sizing (BIG Idea Challenge, Helios, Lunar Resources). Direct support for the productivity argument that MRE clears q4's phi threshold over multi-year integration.

Claim 3 — Inert anode is the key advance

Quote: "Inert anode" (no consumable graphite or platinum) is the key 21st-century advance over earlier MRE proposals.

Verdict: Novel supporting (q3.c6)

Why: Distinguishes Sadoway's MRE from FFC Cambridge (which uses CaCl2 + sacrificial anode) and explains why MRE has the Earth-import advantage. Strengthens the q3.c6 framing that MRE is preferred for lunar economics over FFC.

Claim 4 — Co-products

Quote: "Cathode products: iron alloy + silicon, with calcium and aluminum recoverable depending on cell design."

Verdict: Consistent (q3.c9)

Why: Supports the materials-feasibility rollup that MRE produces Fe + Si as default co-products (and Al + Ca with more sophisticated cell design). This is the structural-metals route for lunar manufacturing.

Claim 5 — Plant mass-power-trade

Quote: "400 kg, 14 kW MRE-based ISRU system can produce 1,000 kg O2/yr from lunar Highlands regolith"; "1,593 kg, 56.5 kW system can produce 10,000 kg O2/yr."

Verdict: Novel supporting

Why: Two specific operating points constrain the wall-plug specific energy: small system 140 kWh/kg O2, larger system 50 kWh/kg O2. The larger system is more efficient (economies of scale in heat management). Adds engineering credibility to the 40-150 kWh/kg O2 wall-plug range in my calc.

Schreiner-Sibille MRE Reactor Model — Key Numerical Results

(Direct PDF fetch returned 403; this extract is the summary returned via the NASA NTRS index + research literature aggregation. Cross-referenced against the same authors' parametric sizing paper.)

specific-energy

"An MRE reactor can produce on the order of 100 kg oxygen annually per kilogram reactor mass with a specific energy around 21 kW-hr per kilogram oxygen in an annual production range of 2000-3000 kg."

So Schreiner's MRE specific energy = ~21 kWh/kg O2.

productivity-per-reactor-mass

100 kg O2 / yr / kg reactor mass — i.e., a 30 kg MRE reactor produces ~3 tonnes O2/yr.

mass-power-trade

Optimized parametric models cited in subsequent BIG Idea Challenge literature predict a "400 kg, 14 kW MRE-based ISRU system can produce 1,000 kg O2/yr from lunar Highlands regolith"; a "1,593 kg, 56.5 kW system can produce 10,000 kg O2/yr."

These two operating points imply specific energy ~140 kWh/kg O2 and 50 kWh/kg O2 respectively for electrical input including reactor heating losses (vs Schreiner's 21 kWh/kg which appears to be process-only).

For the calc pass, the conservative wall-plug energy figure is 50-150 kWh/kg O2 depending on integration; the thermodynamic minimum is ~3 kWh/kg O2 (from Gibbs free energy of metal-oxide dissociation at 1600°C).

process-mechanism

"Direct electrolysis of molten lunar regolith at 1600°C, with oxygen gas generated at the anode and iron and silicon at the cathode."

"Inert anode" (no consumable graphite or platinum) is the key 21st-century advance over earlier MRE proposals.

metals-coproducts

Cathode products: iron alloy + silicon, with calcium and aluminum recoverable depending on cell design.

"Molten oxide electrolysis (MOE) using an inert anode is a leading candidate technology for in-situ resource utilization on the moon because it can use un-beneficiated lunar regolith as feedstock to produce oxygen and useful metals, such as iron and silicon."

trl

Sadoway laboratory demonstrations have achieved TRL 3-4 (laboratory proof-of-concept on simulant). NASA BIG Idea Challenge teams targeting TRL 4/5 by 2023-2024; lunar-surface demonstration via CLPS targeted 2028 (per Helios / Lunar Resources roadmaps).