Value chain · CLM-0185
In plain terms
In a 2022 life-cycle study commissioned by the UK Space Energy Initiative, the lightweight CASSIOPeiA design it used as an example for the initiative's planned programme was estimated to be far cleaner per kWh than the old, heavy NASA/DOE design, and in the same broad range as wind and solar on this measure, though above nuclear's 5.1-6.4 range - but the same study found that almost all of a completely different, non-carbon environmental impact (ozone depletion) came from rocket exhaust during launch.
The claim as recorded
The same study's 23.6 gCO2e/kWh UK SEI roadmap figure compares to 112.3 gCO2e/kWh (silicon) and 122.6 gCO2e/kWh (gallium arsenide) for the older NASA/DOE 1979 SPS Reference System (Wilson et al. 2020 process-based re-analysis, i.e. the same figures as CLM-0182), to an average carbon intensity of 233 gCO2e/kWh for the UK energy fuel mix, and to a cited UNECE range for terrestrial technologies of 751-1095 gCO2e/kWh (coal, from IGCC in the USA to pulverised coal in China, falling to 147-469 respectively with carbon capture), 403-513 gCO2e/kWh (gas combined cycle, falling to 49-220 with CCS), 5.1-6.4 gCO2e/kWh (nuclear), 27-122 gCO2e/kWh (concentrated solar), 8-83 gCO2e/kWh (PV), 7.8-16 gCO2e/kWh (onshore wind) and 12-23 gCO2e/kWh (offshore wind); the paper also reports that 99.99% of the roadmap's ozone-depletion impact (a separate impact category from GWP) comes from launch-event exhaust radical compounds (ClOx, HOx, NOx from cryogenic propellant combustion).
Scope and limits
The comparison of the NASA/DOE Reference System with the UK SEI 2022 roadmap is not a like-for-like design comparison (1960s/70s bulky architecture vs a modern lightweight CASSIOPeiA-based roadmap including prototype phases) - the source attributes the gap to design, not method: the two figures are "based on the same methodology and calculation tool" and "The main reason for this difference is the modernisation of the design" (PDF p.15, printed p.16). CLM-0182 uses the same two figures, rounded to 112 and 123, for a different comparison: two methods on the same NASA/DOE Reference System design, where this record compares two designs by one method. The 233 gCO2e/kWh benchmark is the study's reference [32], the UK government's greenhouse gas reporting conversion factors for 2020 (PDF p.17), so the benchmark is that 2020 published factor. SRC-016 gives no year for the Reference System; 1979 is the year its report was published (January 1979, for a report dated October 1978, SRC-085 PDF p.3).
What it assumes
The cited UNECE figures use comparable system boundaries to this study's own cradle-to-grave scope; the paper itself flags that its own boundary is WIDER than the UNECE study's ("the system boundary of this study had a wider scope than the UNECE study, also including aspects such as design activities"), and states in the next sentence that "these additional activities have a completely insignificant effect on the results (<1%)" (PDF p.15, printed p.16).
Where it comes from
"This also 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]." "This compares to an average carbon intensity of 233 gCO2e/kWh for the UK energy fuel mix." Coal: "Coal power shows the highest scores, with a minimum of 751 gCO2e/kWh (IGCC, USA) and a maximum of 1095 gCO2e/kWh (pulverised coal, China). Equipped with a carbon dioxide capture facility, and accounting for the CO2 storage, this score can fall to 147-469 gCO2e/kWh (respectively)." Gas: "A natural gas combined cycle plant can emit 403-513 gCO2e/kWh from a life cycle perspective, and anywhere between 49 and 220 gCO2e/kWh with CCS." Nuclear "5.1-6.4 gCO2e/kWh." CSP "27 to 122." PV "8-83." Wind onshore "7.8 and 16," offshore "12 and 23." "the ozone depletion impact stemmed almost entirely from exhaust emissions producing during the launch events which was responsible for 99.99% of the result." (PDF p.13-15, printed p.14-16; the 112.3 and 122.6 quotation is at PDF p.15, printed p.16).
Basis: gCO2e/kWh, various boundaries per comparator (see limits)
Related records
- Answers question
- QST-008 not published in this release
Cite this
energyaperture.com/c/clm-0185
CLM-0185, Energy Aperture, as of 2022.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-016
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