Value chain · CLM-0823
In plain terms
A 2002 Japanese study's carbon dioxide figures for space solar power come from Japan's 1990 economic input-output tables, with 405 industry sectors; they cover only building and launching the satellites, not running or maintaining them or delivering the power, and assume the satellites run for thirty years at full output around the clock.
The claim as recorded
The estimate uses a 1990 Japanese environmentally-extended input-output table of 405 sectors, covers only production and construction of the 1978 DOE/NASA Reference System hardware while excluding in-orbit operational combustion, satellite and rectenna maintenance, and electricity-distribution losses for SPS specifically, and assumes a 30-year satellite lifetime with continuous 24-hour 365-day full-output operation in order to convert total lifecycle tonnes into a per-kWh figure.
Scope and limits
The evidence date is 2002 but the data vintage is 1990; these are different facts and must not be merged. The 30-year lifetime is the authors' assumption and matches the Reference System's own guideline of a 30-year system life (SRC-085 PDF p.22); continuous full output is the authors' own, since the Reference System report expects eclipse shutdowns of up to about 75 minutes a night for about six weeks in spring and autumn (SRC-085 PDF p.109). The method attributes emissions through monetary flows across 405 economic sectors using input-output unit prices, which is indirect price-based attribution, NOT direct process measurement of the hardware. The space transportation figures rest on an explicit "Raw Material Ratio" of 2.5 applied to a raw-material-only estimate, worked for the HLLV and used for the other three vehicles, because the tables' aerospace vehicle sector also covers aircraft and is not specific to them (printed p.14); that is a modelled proxy the authors describe, and the space transportation share at CLM-0822 rests on it. The paper describes its estimate as covering "constructing and operating the SPS system" (printed p.2 and p.4); its Table 6 gives SPS operations as 0, so the exclusion of operation here is that zero, not a term left out. Where the claim says electricity-distribution losses, the paper's words are "the CO2 released in distributing the electricity generated" (printed p.8).
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Section 3, printed p.2 to 3 (PDF p.5 to 6): "estimated using 1990 Environmental Input-Output Tables", published by the KEO research group of reference [11], with an "input coefficients matrix with 405 sectors"; the abstract (unnumbered title page, PDF p.3) says the tables are "broken down into 405 sectors". Table 1 p.2: 5 GW per satellite, 60 units, 24 hours/day, 365 days/year, 2,628,000 GWh/year. Section 6, printed p.6 (PDF p.9): "If we assume a lifetime of 30 years for the SPS-Baseline scenario". Section 4, printed p.4 (PDF p.7): "The CO2 released by maintenance is not included, however, since data is not available:if the maintenance ratio of the satellite and rectenna is 1 % per year, the overall CO2 emission would increase by some 30 %."
Related records
- Answers question
- QST-008 not published in this release
Cite this
energyaperture.com/c/clm-0823
CLM-0823, Energy Aperture, as of 2002.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-216
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