Value chain · CLM-0838
In plain terms
The authors of a 2022 life-cycle study of the UK Space Energy Initiative's planned space solar power programme said that, if the whole programme's emissions were spread evenly across its 58-year life, the electricity generated would pay back that carbon debt in under six years against the average carbon intensity of the UK energy fuel mix in the government's 2020 figures, which they called a hypothesis in the body of the paper but stated as a result in its summary, and the paper gave no equivalent energy payback time.
The claim as recorded
SRC-016 states that "when evenly distributing the total CO2e emitted by the SEI technology roadmap over its 58-year lifespan as a constant, it can be hypothesised that the carbon payback period will be less than 6 years based on the average UK figure" of 233 gCO2e/kWh for the UK energy fuel mix, while its abstract states the same result without that hedge, and states no energy payback time anywhere in its abstract, goal and scope, comparative analysis or conclusions sections.
Evidence behind this: The payback arithmetic is SRC-016's own, but it applies BEIS 2020's UK average carbon intensity of 233 gCO2e/kWh as an external benchmark, not independently checked here.
Scope and limits
In the body text the modal is "it can be hypothesised", and that hedge may not be dropped, even though the abstract states the figure as a result and s2 says the payback period was calculated: only the body passage gives the method (an even spread over 58 years), so in our judgement it governs. The averaging period is the 58-year whole-programme span, NOT the 30-year per-satellite lifetime used for the headline 23.6 gCO2e/kWh figure, and the two periods must not be interchanged. The benchmark is the UK energy fuel mix alone, so this is not a generic or global payback figure. It is a CARBON payback time, not an energy payback time, and no energy payback figure exists in this source. The 233 gCO2e/kWh benchmark is reference [32], the UK government's greenhouse gas reporting conversion factors for 2020 (p.18), so the result is tied to that published factor; on the even-spread method the payback varies inversely with the benchmark, so a lower UK figure would lengthen it. Our arithmetic from the paper's totals (3.22E+14 g CO2e, and 1.37E+13 kWh spread over 58 years and valued at 233 g/kWh) gives about 5.9 years, consistent with "less than 6 years".
What it assumes
No assumptions are recorded against this claim.
Where it comes from
p.14: "When evenly distributing the total CO2e emitted by the SEI technology roadmap over its 58-year lifespan as a constant, it can be hypothesised that the carbon payback period will be less than 6 years based on the average UK figure." Same page, the benchmark: "This compares to an average carbon intensity of 233 gCO2e/kWh for the UK energy fuel mix [32]." Abstract, p.1: "produces a carbon payback period of less than 6 years based on the current carbon intensity of the UK energy fuel mix." s2, p.3: "The results were then used to calculate the CO2e payback period". No occurrence of "energy payback", EPBT or an EROI-style metric was found on searching the Abstract p.1, s2 Goal and Scope p.2-3, s5.2 Comparative Analysis p.14 and s6 Conclusions p.16.
Related records
- Answers question
- QST-008 not published in this release
Cite this
energyaperture.com/c/clm-0838
CLM-0838, 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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