Power: solar, nuclear and beamed

Key results

• Paul451's list of issues every rotating station faces (8 likes) puts power second after stability Paul451, 2019-05-14.
• Orientation drives array design. See also sun-pointing.
• Sun on the spin axis (sun-pointing): arrays fixed in the rotation plane and radiators out the back in shadow; only comms counter-rotate Paul451, 2022-10-27; Paul451, 2015-08-30.
• Axis not at the sun: arrays must counter-rotate at station rpm, ~2.1 million revolutions a year at 4 rpm Paul451, 2022-10-27.
• Edge-on torus: cells on the outer rim work at 1/π efficiency (~32–40%) Paul451, 2022-10-27. Edge-on panels are ~1/3 lit LarryCanuck, 2023-02-20. A sun-perpendicular station needs 3× the cell mass lamontagne, 2022-11-29.
• Conformal side panels (+~50% area) Twark_Main, 2022-11-30. Non-rotating solar bearings on hubless designs lamontagne, 2022-11-29.
• Arrays and stability.
• Hang power arrays in the rotation plane at 90° to the habs, so the station is frisbee-stable and the panels self-stabilize Paul451, 2015-11-13; Paul451, 2019-01-07.
• Arrays on the sides increase the second-axis inertia (like Vast) Paul451, 2022-12-06. Arrays pivoting north–south adjust axial inertia and balance docked vehicles Paul451, 2023-11-01.
• Zig-zag and roll-out panels are not designed for sideways spin-g loads mikelepage, 2024-09-24. "Sticky-outy bits" swamp stability Twark_Main, 2022-10-31.
• Extra panels on cables between arms Coastal Ron, 2019-03-31. Solar arrays as counter-rotating flywheels A_M_Swallow, 2015-09-07; A_M_Swallow, 2019-01-08.
• Nose-to-nose spin of BFS would tear its solar arrays off lamontagne, 2018-08-01.
• Array data.
• iROSA: 6 × 18.2 m, ~600 kg, 30+ kW new, ~20 kW after 15 years. ROSA: 6 × 13.7 m, 20 kW mikelepage, 2024-09-20.
• Rigid panels at ~70 W/kg in Twark_Main's Vast estimate Twark_Main, 2024-09-20.
• mikelepage's hotel uses "IROSA MAX" 9.5 × 40 m arrays at ~240 kW mikelepage, 2023-05-16.
• PV degrades, so constant maintenance is needed lamontagne, 2023-02-21.
• Demand.
• lamontagne: lights and fans ≈ 48 MW for 10,000 people (6 air changes/h). CO₂ processing via Sabatier needs ≥10–12 MW lamontagne, 2022-10-07.
• Food dominates: ≥50–60 kW per person for food and a mild ecosystem; "energy for people trivial vs food" lamontagne, 2023-02-20.
• ISS arrays are mostly for electrolysis, so it may be better to ship O₂ and food than make them lamontagne, 2023-01-26.
• Beamed power.
• Kalpana One (2007): rim cells were insufficient, so primary power was beamed by microwave from a companion solar station Shevek23, 2019-10-25. BIS Avalon also uses beamed power and rectennas lamontagne, 2023-09-28.
• lamontagne: a rectenna at ~250 W/m² is no smaller than a 19%-efficient array, so beaming is pointless for power density Paul451, 2022-11-29. Formation-flying power stations with rectennas at 85–90% tankat0208, 2023-01-26.
• US Navy demonstrated 1.6 kW over 1 km lamontagne, 2022-10-06.
• A station's own PV is needed for survival if the beam fails lamontagne, 2023-02-20.
• Nuclear.
• Recurring suggestions: LFTR cycler Roy_H, 2014-02-16, reactors in the quadrants of JohnFornaro's ring JohnFornaro, 2022-10-04, a reactor as counterweight (NASA TransHab study) Lampyridae, 2016-01-13, and a reactor on one arm with a shielded arc of habs opposite rakaydos, 2019-03-25.
• Nuclear appears mostly in large or far designs, not near-term ones.

Open questions

• Sun-pointing (fixed arrays, propellant for precession) vs edge-on (rotating or low-efficiency arrays): which wins at each scale?
• Is beamed power ever competitive for stations in LEO?

Related pages

• Thermal and radiators · Sun-pointing · Agriculture · Lighting

Sources

Forum posts

• Roy_H, 2014-02-16 (reply #1): LFTR + VASIMR cycler. Post. Attachments: MCT.png.
• Paul451, 2015-08-30 (reply #574): Radiators on back of arrays. Post.
• A_M_Swallow, 2015-09-07 (reply #626): Arrays as counter-rotating items. Post.
• Paul451, 2015-11-13 (reply #760): Arrays at 90°, hang radially. Post. Attachments: Station solar arrays.png.
• Lampyridae, 2016-01-13 (reply #808): Reactor counterweight. Post.
• lamontagne, 2018-08-01 (reply #1093): BFS arrays tear off. Post. Attachments: 9m gravity.jpg.
• Paul451, 2019-01-07 (reply #1261): Arrays in plane of rotation. Post.
• A_M_Swallow, 2019-01-08 (reply #1286): Arrays as flywheels. Post.
• rakaydos, 2019-03-25 (reply #1397): Peace-sign reactor arm. Post.
• Coastal Ron, 2019-03-31 (reply #1458, 1 like): Panels on cables between arms. Post.
• Paul451, 2019-05-14 (reply #1633, 8 likes): Open letter: stability, power, thermal, resupply, health, purpose (8 likes). Post.
• Shevek23, 2019-10-25 (reply #1687): K1 beamed power. Post.
• JohnFornaro, 2022-10-04 (reply #1837): 4 reactors. Post. Attachments: Ring-Station-Plan.jpg.
• lamontagne, 2022-10-06 (reply #1884): 1.6 kW over 1 km. Post.
• lamontagne, 2022-10-07 (reply #1912, 1 like): 48 MW lights+fans; 10–12 MW CO₂. Post. Attachments: radiator.xlsx.
• Paul451, 2022-10-27 (reply #2237): Sun-pointing: fixed arrays in rotation plane. Post.
• Paul451, 2022-10-27 (reply #2240, 1 like): Edge-on rim cells 1/π. Post. Attachments: Spin station not pointing at sun.jpg.
• Twark_Main, 2022-10-31 (reply #2284): Sticky-outy bits. Post.
• Paul451, 2022-11-29 (reply #2491, 2 likes): Rectenna vs PV. Post.
• lamontagne, 2022-11-29 (reply #2512, 3 likes): 3× cell mass sun-perpendicular. Post.
• lamontagne, 2022-11-29 (reply #2517, 1 like): Non-rotating solar bearings. Post. Attachments: Extrusion construction (6).png, Extrusion construction (5).png.
• Twark_Main, 2022-11-30 (reply #2522): Conformal side panels. Post.
• Paul451, 2022-12-06 (reply #2554, 1 like): Side arrays add inertia. Post.
• tankat0208, 2023-01-26 (reply #3115): Power beaming pros/cons. Post.
• lamontagne, 2023-01-26 (reply #3117): ISS power mostly electrolysis. Post.
• lamontagne, 2023-02-20 (reply #3357, 2 likes): 50–60 kW/person for food (2 likes). Post.
• lamontagne, 2023-02-20 (reply #3361, 1 like): Own PV as backup. Post. Attachments: ring2a.jpg.
• LarryCanuck, 2023-02-20 (reply #3366): Edge-on panels ~1/3 lit. Post.
• lamontagne, 2023-02-21 (reply #3385, 2 likes): PV decay. Post. Attachments: ring2c.jpg, ring2d.jpg, ring2e.jpg, quebec-weather-20140108-topix.jpg.
• mikelepage, 2023-05-16 (reply #3717, 2 likes): IROSA MAX ~240 kW. Post. Attachments: Screen Shot 2023-05-16 at 5.54.00 pm.png, Screen Shot 2023-05-16 at 6.31.55 pm.png, Screen Shot 2023-05-16 at 7.23.02 pm.png.
• lamontagne, 2023-09-28 (reply #4033, 3 likes): Avalon beamed power. Post. Attachments: Image122_002.png, Image123_003.png.
• Paul451, 2023-11-01 (reply #4260): Pivoting arrays trim axial inertia. Post.
• mikelepage, 2024-09-20 (reply #4802): iROSA/ROSA specs. Post.
• Twark_Main, 2024-09-20 (reply #4804): Panels 70 W/kg. Post.
• mikelepage, 2024-09-24 (reply #4805, 1 like): Roll-out panels not for spin loads. Post.