Value chain · CLM-1218
In plain terms
SPS-ALPHA's design catches sunlight with a few thousand units of large, thin plastic-film mirrors. The mirrors are grouped into several hundred assemblies, and each assembly points on its own, like the mirrors around a solar tower plant, but the frame they sit on stays still, so the design needs no big moving joint.
The claim as recorded
SPS-ALPHA gathers sunlight with large, thin-film reflectors grouped into Solar Reflector Assemblies (SRAs), each SRA pointed on its own like a heliostat, several hundred of them mounted on a structure that does not move; the transmitter array faces Earth, and there is no single gimballed joint. The preliminary mass statement for the 2 GW baseline case (DRM_5 / Case_1) lists 4,305 Thin-Film Reflectors & Pod (TFRP) modules; in the baseline hexagonal configuration each pod deploys "some six" triangular thin-film reflectors. Table 3-1 gives an approximate count of 4,000 to 5,000 Reflectors & Deployment Modules for a 1,000 to 1,200 m array.
Evidence behind this: The concept author's own NIAC Phase 1 report; a preliminary design and mass statement, not a built system.
Scope and limits
PRELIMINARY, NOT BUILT. The 4,305 is DRM_5 / Case_1 (the baseline), not DRM_5 / Case_4B, whose 2,000 MW and costs are CLM-0188 (low confidence). "Some six" reflectors per pod is the report's approximate figure, so the total reflector count is not stated. The frame's shape is open: PDF 30 lists half-ellipsoid and sigmoid options, so "trumpet-shaped" is a reading of Figure 3-3, not the report's word. PDF 29 says detailed analysis is needed to show the robotic arms can point the reflectors.
What it assumes
That the TFRP module of Table 7-7 is the reflector unit called the RDM in Table 3-1; the report uses both names and does not equate them on these pages.
Where it comes from
PDF 18, raw: "(1) a large primary array that is nadir pointing (toward Earth). (2) a very large sunlight-intercepting reflector system (involving a large number of reflectors that act as individually pointing "heliostats", mounted on a non-moving structure". PDF 19, Table 3-1, raw (one en dash written as a hyphen): "The "Reflectors and Deployment Module" (RDM) are large, thin-film reflectors (e.g., aluminum on Kapton) that redirect incoming sunlight to the SPG, along with a central deployment plate. 4,000- 5,000"; footnote, raw: "Number of elements based on approximately 1,000 meter-1,200 meter diameter power generation/transmitter array". PDF 19-20, raw: "capable of providing constant solar energy to the transmitter modules (described below), but there is no single-point-of-failure gimbaled system, as there are in many other SPS concepts." PDF 20, raw: "SPS-ALPHA uses large, thin-film reflectors to redirect and concentrate sunlight." and "SPS-ALPHA uses such structures as pointed mirrors - analogous to ground-based solar thermal power systems" (dash written as a hyphen; the page's example plant is not quoted). PDF 24, raw: "each TFRP would have six sides and would deploy some six triangular thin-film reflectors." PDF 30, raw: "The Primary Structure Assembly (PSA) is the unmoving scaffold on which the individually pointed SRA heliostats are mounted." PDF 29, raw: "The SRA is assembled from five of the modular elements: HexBuses, Interconnects, HexFrames, TFRP modules, and MPPR Arms." and "Figure 3-17 illustrates how several hundreds of SRAs are joined together in the PSA." PDF 73, Table 7-7 "Summary of Preliminary Mass Statement of SPS-ALPHA DRM_5 / Case_1", raw: "TFRP Module 4,305 79 340,095" (number of modules, average unit mass kg, total mass kg); same page, raw: "DRM_5's baseline case (D5/C1) as the starting point - i.e., the fully commercial, recurring SPS-ALPHA case @ 2 GW power delivered".
Basis: count of reflector modules; reflector type; structure motion
Cite this
energyaperture.com/c/clm-1218
CLM-1218, Energy Aperture, as of 2012-09.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-027
- CLM-0188 (low confidence)A 2012 NASA-funded concept study shows its own cost estimate falling from about $3.26 per kWh for a small near-term system down to about 9...CLM-1219 (low confidence)SPS-ALPHA's mirrors concentrate sunlight about three times on the array. The report estimates that five times would save almost 15,000...CLM-1220The receiving site sends a guide signal up to the satellite, and the satellite's many small transmitters use it to line up their beams on...CLM-1321The 2012 design study for SPS-ALPHA put the weight of its 2 gigawatt satellite at about 35,000 tonnes, about half of it in the transmitter.