Value chain · CLM-0853
In plain terms
The wide range of published carbon figures for space solar power is not simply disagreement: most of it separates into two causes, which calculation method was used and which satellite design was assessed, and the method effect does not even point the same way in every case. The lowest published figure also counts carbon dioxide alone, while the others count all greenhouse gases, so part of the spread is a difference in what was counted.
The claim as recorded
The published SBSP lifecycle carbon range of roughly 20 gCO2/kWh (carbon dioxide only) to 123 gCO2e/kWh is not one undifferentiated spread but decomposes along two axes: holding the DESIGN constant at the 1978 DOE/NASA Reference System and changing the METHOD, and with it the gas basis, moves the result from about 20 gCO2/kWh by input-output to 112.27 and 122.63 gCO2e/kWh by process-based analysis; while holding the METHOD AND TOOL constant and changing the DESIGN, and with it fleet scale and period, from that 1978 system to the CASSIOPeiA-based UK roadmap, moves it from 112.3 and 122.6 down to 23.6 gCO2e/kWh; and a third comparison, holding design constant on NASA's 2050 concepts and changing method again, moves it the OPPOSITE way, from 26.58 and 40.38 by input-output down to 21.89 and 35.74 gCO2e/kWh by process-based analysis.
Evidence behind this: A synthesis over claims resting on SRC-212 (T5), SRC-009 (T5) and SRC-016 (T2). Weakest link is T5. The reasoning is the register's own; every input figure is a published one.
Scope and limits
This is a structural reading of four published comparisons, NOT a reconciliation and NOT a derivation of any single correct figure. It may not be used to assert a best estimate for SBSP's lifecycle carbon intensity. Each leg carries its own source's limits, including that SRC-016's design leg rests on the authors' own attribution rather than a published decomposition, and that no leg has been independently replicated outside the one research group that produced three of the four studies. The 2050-concept leg is a modelled comparison of two models, neither validated against measurement. The 1978-design method leg does not isolate method: its input-output figure of 20 is grams of carbon dioxide only per kWh (SRC-216 printed p.8, Table 6, "units: g CO2 /kWh"), while the process-based figures are CO2 equivalent (see CLM-0858). The design leg does not hold scale or period constant: the 1978 system is modelled as 60 units and 300 GW over 2040 to 2100 at a 98.09% capacity factor (SRC-212 p3-4), the UK roadmap as twenty-five 2 GW systems plus ten prototypes over 2022 to 2080 (SRC-016 p3).
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Method axis on one design, from CLM-0813: SRC-212 p12 states its result is "over 5.62 times higher" than the input-output estimate of the same reference system. Design axis on one method, from CLM-0835: SRC-016 p16 states 23.6 gCO2e/kWh "compares to the 112.3 gCO2e/kWh carbon footprint of the silicon option of the NASA/DOE Reference System and 122.6 gCO2e/kWh for the gallium arsenide option based on the same methodology and calculation tool", and attributes the gap to "the modernisation of the design". Reversed method axis, from CLM-0826: SRC-009 printed p.9 states its reanalysis "suggests that the reported EEIO results are 21.40% and 12.97% overstated for these concepts".
Related records
- Answers question
- QST-008 not published in this release
Cite this
energyaperture.com/c/clm-0853
CLM-0853, Energy Aperture, as of 2024.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-009
- CLM-0182When two different research teams assessed the exact same 1978 space solar power design, the older accounting method (which spreads...CLM-0825The authors argue that the cost-based way of estimating carbon is too coarse for a custom-built industry like spacecraft, and they conclude...CLM-0826When the authors redid NASA's own 2024 figures for two satellite designs using their materials-based method instead of NASA's cost-based...CLM-0827The authors say NASA's 2024 carbon figures for two satellite designs came out of a model built on NASA's own cost estimates, and that NASA...CLM-0828The authors say ESA's own space life-cycle guidance advises against the cost-based method because it tends to overstate environmental...CLM-0829The authors leave alumina, black carbon and water vapour from rocket exhaust out of their own carbon study because the atmospheric effects...CLM-0830The authors say an environmental claim about a space technology counts for nothing unless a proper standardised life-cycle study backs it...CLM-0831This is a conference paper from October 2024 that does not claim to have been independently peer reviewed, states that it calculated no...More on the source page.
- Also from SRC-016
- CLM-0184This study's headline carbon-per-kWh figure for a UK space solar power programme leaves out the possible climate effect of soot and...CLM-0185In a 2022 life-cycle study commissioned by the UK Space Energy Initiative, the lightweight CASSIOPeiA design it used as an example for the...CLM-0832A UK-commissioned study modelled the whole planned 2022-2080 fleet of space solar power satellites and found that, spread across all the...CLM-0833This 2022 life-cycle study spells out exactly what it counted: the UK Space Energy Initiative's whole 2022-2080 roadmap, from early...CLM-0834The authors say their model does not count the soot and aluminium oxide that rockets release into the upper atmosphere, because the science...CLM-0835In a 2022 study, the research team compared its estimated carbon footprint per unit of electricity for a planned UK Space Energy Initiative...CLM-0836A 2022 life-cycle study set its estimate of 23.6 grams of carbon dioxide equivalent per kilowatt-hour for the UK Space Energy Initiative's...CLM-0837Although the study's headline number is about carbon, its own results show ozone damage is the far bigger relative problem, at about 32 per...More on the source page.
- Also from SRC-212
- CLM-0316In 2009 three researchers guessed that, once the energy to deliver and use it is counted, an oil-based fuel must return at least about 3...CLM-0810A 2020 modelling study estimated that, across its whole operating life from 2040 to 2100, the 1978 NASA/DOE space solar power design would...CLM-0811In a 2020 modelling study of the 1978 NASA/DOE space solar power design, the carbon per kilowatt-hour fell the longer the satellites were...CLM-0812A 2020 modelling study of the 1978 NASA/DOE design estimated that its ozone-depleting emissions, almost all from burning rocket fuel at...CLM-0813The paper's detailed component-by-component calculation gives a carbon figure five to six times higher than an older top-down calculation...CLM-0814A 2020 conference paper's own cost model put the whole 60-satellite programme of the 1978 US reference design at about 3.86 trillion US...CLM-0815The 2020 study of the 1978 NASA/DOE design did not count any warming from the microwave beams themselves, saying that is too hard to...CLM-0816In their 2020 study of the 1978 NASA/DOE design, the authors list their own weak points: only whole-system detail rather than part-by-part...More on the source page.