Scope and limits

This is a T0 synthesis in the register, built from two already-registered NASA claims plus one EIA table; it has not been checked by a second party and rests on the basis-year mismatch noted above. It may NOT be quoted as a precise abatement-cost figure; it may be quoted only as an order-of-magnitude illustration that MAC does not rescue SBSP's economics even where its carbon case is favourable. SRC-012's p.viii SUMMARY TRANSPOSES COAL AND NATURAL GAS; its Table 25 does not. NASA OTPS p.viii states "the GHG emissions intensities of coal and natural gas are 486 gCO2eq./kWh and 1001 gCO2eq./kWh, respectively". Its own footnote 11 cites EIA FAQ 74, which gives coal 2.31 lb/kWh and natural gas 0.96 lb/kWh - coal more than DOUBLE gas. Converting at 453.59 g/lb: coal is about 1048 gCO2/kWh and gas about 435. So 1001 is the coal figure and 486 the gas figure, and the report has the two labels the wrong way round. Verified against the EIA source and the arithmetic re-checked 2026-09-05. The transcription here is faithful; the defect is the source's, and the fix is therefore an annotation rather than a rewrite of the quote. SRC-012 Table 25 (printed p.72, PDF 89, "Source data from NREL") gives natural gas 486 and coal 1001 gCO2eq/kWh as life-cycle medians, so the p.viii pair is Table 25's medians with the labels swapped (our reading of the two pages; footnote 11 points to EIA, but the numbers are NREL's). A SECOND BASIS FAULT APPLIES TO THE EIA END ONLY: 486 is a life-cycle figure, like SBSP's 26, but EIA's 0.96 lb/kWh is COMBUSTION CO2, so the about 1,400 end sets combustion CO2 against life-cycle CO2eq for SBSP. CONSEQUENCE FOR THIS RECORD, and it runs AGAINST SBSP: correcting the transposition roughly DOUBLES the implied marginal abatement cost, from about 588 to about 1,250 USD/tCO2. The register as it stood UNDERSTATED the abatement cost and made SBSP look better than the corrected arithmetic supports. Recorded 2026-09-05. The claim's term, terrestrial renewables, follows NASA's own label for its 13 to 43 gCO2eq/kWh range (PDF p.9, printed viii). That set is five renewable technologies plus nuclear fission, which is not renewable. The five renewables alone span 13 to 43 (Figure 2, PDF p.11; Table 25, PDF p.89), because wind ties nuclear at 13, so the near-zero carbon difference holds against the renewables alone and against nuclear.