Value chain · CLM-0297
In plain terms
The low electricity costs in a 2025 Caltech study rest on two assumptions among others. First, it assumes that SpaceX's Starship will in time launch cargo for about 7 million dollars a flight, falling to 3 million, which works out at roughly 128 dollars and then 55 dollars per kilogram. Those are the authors' own projections, built on the way SpaceX said in 2020 that Starship would reach geostationary orbit and on the long-run fall in launch costs, not prices anyone has paid. Second, it assumes that the money to build the system costs 2 percent a year (a 2 percent discount rate), taken from a US government energy memorandum, which the paper itself says reflects one country's funding arrangements at one moment. With the costs and hardware available when it was published in 2025, the same study's own figure is about 778 US cents per kilowatt-hour.
The claim as recorded
The launch and financing assumptions behind the Joule CSSPS LCOE figures are: current tier, Falcon 9 Heavy at a projected USD 97M per launch carrying 13,000 kg, 280 launches, USD 27,160M total launch cost, about USD 7,462/kg; middle and asymptotic tiers, Starship at a projected USD 7M and USD 3M per launch carrying 54,500 kg, 11 launches, USD 82M and USD 33M total launch cost, about USD 128/kg and USD 55/kg; the launch cost model is stated to be "projected off of the format proposed by SpaceX for Starship" citing the 2020 SpaceX Starship User's Guide, with a GEO delivery chain of launch to LEO, refuel, transfer to GTO then to GEO; the discount rate is 2%, taken from a 2024 US Department of Energy memorandum (WAP Memorandum 123), which the paper's own endnote qualifies as reflecting "one particular funding structure in one specific country during one specific macroeconomic climate".
Scope and limits
The USD 128/kg and USD 55/kg figures must never be cited as launch market prices, current or historical. They are the authors' projection, which starts from the Starship transport format in a manufacturer's 2020 planning document and extrapolates a historic fall in launch costs 10 and 20 years forward, and are, on the evidence held, roughly one to two orders of magnitude below any launch price actually transacted. For comparison, SpaceX's price sheet as held in 2026 lists a Falcon 9 launch at USD 74 million and 22,000 kg to low Earth orbit on an expendable vehicle, about USD 3,364/kg if one is divided by the other, a pairing the sheet does not make (CLM-1450 (low confidence)); and a 2026 peer-reviewed study puts the average cost, not price, of reaching low Earth orbit in 2025 at USD 3,868/kg in 2024 dollars (CLM-1389). For contrast, the 2022 ESA/Frazer-Nash study tested EUR 454, 1,877 and 3,301 per kg to GEO (CLM-0281), and this paper's own current-technology tier uses about USD 7,462/kg. Note a small internal inconsistency: 11 launches at a projected USD 7M is USD 77M against the stated USD 82M total; 82 / 11 is about USD 7.45M, so the printed per-launch cost is most likely rounded down, and the table's rows are not exactly self-consistent. A 2% discount rate is far below the 15% and 20% investor hurdle rates used in the ESA and UK commissioned studies; the paper itself says its 2% reflects one funding structure in one country at one time.
What it assumes
This claim IS the assumption set. Per-kg figures are computed here from the paper's own stated per-launch cost and mass-per-launch values, not quoted from the paper. Orbit: GEO, via LEO refuelling and orbit transfer, so per-kg figures are per kg launched, not per kg delivered to GEO after transfer losses. Launch-price basis: the authors' own model, which takes the Starship GEO transport format from a 2020 SpaceX document, prices fuel and Falcon 9 upper-stage hardware, and then reduces the result by a logarithmic fit to historic launch cost data projected 10 and 20 years forward - so the middle and asymptotic tiers reflect no observed launch market of any year. Service life is 10, 15 and 20 years for the three tiers; rate-adjusted energy multipliers N2 of 7, 11 and 13 years are also given. Unit count: a single system, first of a kind, with no Nth-of-a-kind learning curve found.
Where it comes from
Table 2 (PDF p.8, printed p.7), in paraphrase: for the current, middle and asymptotic tiers, the launch vehicle is Falcon 9H, Starship and Starship; projected cost per launch USD 97M, 7M and 3M; mass per launch 13,000, 54,500 and 54,500 kg; launches 280, 11 and 11; total launch cost USD 27,160M, 82M and 33M; service life 10, 15 and 20 years; LCOE 777.8, 9.4 and 3.8 US cents/kWh. Methods, Launch cost model (PDF p.12, printed p.11): "Launch costs were projected off of the format proposed by SpaceX for Starship" (reference 167 follows) "GEO transport: launch to low Earth orbit (LEO), refuel, transfer to geostationarySNR [sic] transfer orbital (GTO), and transfer to GEO." and "Launch cost prices were then reduced by a factor based on a logarithmic fit to historic launch cost data and projecting it forward the relevant number of years: 10 for middle and 20 for asymptotic." Reference 167 (PDF p.20, printed p.19): "SpaceX (2020). Starship User's Guide". Endnote 117 (PDF p.19, printed p.18): "The discount rate, which reflects the cost of capital, is assumed to be 2%, as per a 2024 U.S. Department of Energy memorandum." (reference 115 follows) "However, this number reflects one particular funding structure in one specific country during one specific macroeconomic climate." Reference 115: "United States Government: Department of Energy. (2024). Wap memorandum 123. Discount rate for cost-effectiveness calculations."
Basis: USD, basis year not stated in the paper; treat as approximately USD2024
Related records
- Answers question
- QST-003 not published in this release
Cite this
energyaperture.com/c/clm-0297
CLM-0297, Energy Aperture, as of 2025-05-13.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-006
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