Value chain · CLM-1052
In plain terms
In 1980 the programme's own numbers had a receiving site of about 200 square kilometres per satellite once a safety margin was included, roughly the same land per unit of energy as ground solar of the day and far more than a coal or nuclear plant, but with no mines or waste sites behind it; and the authors said not to add the columns up.
The claim as recorded
The programme's land-use comparison, at a boundary of "primary uses" only (construction, plant, fuel cycle, waste disposal, transmission; "secondary uses such as land for the factories that manufacture plant components" excluded), gives the 1980 reference SPS site as 1480 m2 per MW-yr - a 13 x 17 km ellipse of 2 x 10^8 m2 including a 2 km buffer around a 10 x 13 km rectenna, at 5 GW, 90 per cent and 30 years, the "rectenna proper" being "about 50% of total" - against terrestrial photovoltaics at 600-3800 m2/MW-yr (ERDA cell-area figures at 0.3 capacity factor to Caputo's plant-area figure), solar thermal 2260-6650, coal plant 7.2-150 plus fuel land 1800-4520, LWR plant 57-174 plus fuel 31 plus 4 m2/MW-yr of waste-disposal land "for a million years"; it finds "the solar technologies require much more land area for their central plants (for the rectennas in the case of an SPS) than do the coal or nuclear technologies" while "the coal and nuclear options require substantial amounts of land for fuel mining, fuel processing, and waste disposal", and warns that "it would be misleading to use the sum of each row for comparison as a 'total' land requirement". ER-0055 gives the same site as 79 km2 of rectenna at the equator, up to 35 km2 more at latitude, and "Total land requirement expected to average 200 km2"; its Transmission row reads "Comparable to coal and nuclear."
Evidence behind this: T3-the programme's preliminary land-use matrix, compiled from 1977-78 source studies and normalised by the authors' assumed lifetimes and capacity factors.
Scope and limits
A 1980 PRELIMINARY with the data called "not directly comparable" by its authors; the ERDA photovoltaic figures are near cell-area figures with no ground-cover ratio; launch-site land 20-850 km2 is unallocated; SPS transmission land is a gap ("Transmission - for SPS" listed as a deficiency). Conversions to W/m2 are arithmetic on the stated figures: 22.5 W/m2 buffered, 45 W/m2 rectenna proper, 8.8 W/m2 Caputo PV, 25.6-55.6 W/m2 ERDA PV. The 13 x 17 km buffered ellipse is the "9 x 13-km ellipse" of the source's Refs. 1 and 2 plus the 2 km buffer, both named in the same paragraph (PDF 20, printed 15) as the "about 10 x 13 km" rectenna; 10 x 13 plus 2 km would give 14 x 17, and the 50 per cent and 1480 figures hold on either.
What it assumes
The authors' normalising assumptions (30 years; 0.9 SPS, 0.3 solar, 0.7 coal and nuclear) where sources gave none.
Where it comes from
PDF p.12 normalised: the boundary sentence. PDF p.20 normalised: "A 2-km buffer zone surrounding the rectenna proper would expand the ellipse to 13 x 17 km. Each site would require about 2 x 108 m2 (1480 m2/M.W-yr, assuming a 30-yr lifetime and capacity factor of 0.9)"; raw: "Each site is sized for 5 GW of power output". PDF p.22 raw: "rectenna proper occupies about 50% of total"; "600-3800 m2/MW-yr". PDF p.18 normalised: the four ERDA figures and "3800 m2/MW-yr". PDF p.23 normalised: the two conclusion sentences and the "misleading" sentence. ER-0055 PDF p.97, Table C.7 read at the render: Rectenna row "79 km2 for rectenna at equator"; "Total land requirement expected to average 200 km2"; Transmission row "Comparable to coal and nuclear." Arithmetic: 2 x 10^8 / (5000 x 0.9 x 30) = 1481, reproduces.
Basis: 1977-78 source studies, 30-year lifetimes, capacity factors assumed by the authors
Related records
- Answers question
- QST-007 not published in this release
Cite this
energyaperture.com/c/clm-1052
CLM-1052, Energy Aperture, as of 1980-04.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-527
- CLM-1054The programme reckoned a receiving site would give off about as much heat per square metre as a suburb, a tenth of what the sun puts into...CLM-1055The programme's 1980 look at nuisance and property effects gave space solar its worst marks on six counts, mostly because nobody knew...