The Case for Space Solar PowerJohn C. Mankins
The Case for Space Solar Power
by John C. Mankins · first published 2014
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A year ago I read the book The Case for Space Solar Power, which goes into the engineering in detail. The old SPS designs from the '70s were monolithic beasts that would have been ridiculously expensive. Current designs would use a large number of identical…
on “China wants to put a solar farm in space by 2025” ↗…geosynchronous orbit. If SpaceX delivers on the extremely low launch cost they're promising for the BFR, this looks surprisingly economical with current solar power satellite designs; a good book about this is The Case for Space Solar Power: https://www.amazon.com/Case-Space-Solar-Power-ebook/dp/B00HN...
on “Lockheed Martin has obtained a patent for a compact fusion reactor” ↗…monolithic beasts, but current designs use lots of identical parts (of several varieties) that self-assemble in orbit, so you get economies of scale with factory production. A year ago I read the book The Case for Space Solar Power [2], which broke down the costs in detail. With pre-SpaceX launch costs they got 15 cents/kWh, including manufacturing and ground stations. I plugged in the BFR cost Musk was claiming (I think I used…
on “SpaceX nails triple booster landing after satellite delivery” ↗Solar power satellites without all that tedious beaming of microwaves back to Earth. It might actually work. The book The Case for Space Solar Power runs through detailed engineering costs for modern solar power sats, and came up with a cost of $15/kWh at scale. That was before SpaceX. I plugged in Starship costs and it came to 4 cents/kWh. Of that,…
on “Elon Musk wants clean power. But Tesla's carrying Bitcoin's dirty baggage” ↗…https://space.nss.org/sps-alpha-a-novel-approach-to-space-so... and the study itself: https://www.nasa.gov/directorates/spacetech/niac/2011_Practi... A book-length treatment of modern SPS designs is The Case for Space Solar Power. It has detailed cost figures but was written before SpaceX had accomplished much, estimating a cost at gigawatt scale of 15 cents/kWh. I plugged in Starship launch costs and it came to 4 cents/kWh, which…
on “Electricity from Space: The 1970s DOE/NASA Solar Power Satellite Studies” ↗…mass-produce them. I plugged SpaceX Starship launch costs into the book's estimate and got a total system cost of 5 cents/kWh, which is pretty good for steady clean power that doesn't need storage. [1] The Case for Space Solar Power by John Mankins
on “X-37b space plane’s microwave power beam experiment” ↗…so Musk may not have been aware of it. Modern designs use a phased-array transmitter, and a reference signal from the ground for targeting. Overall energy loss is 40 to 60% according to the book The Case for Space Solar Power. [1] https://www.nasa.gov/pdf/716070main_Mankins_2011_PhI_SPS_Alp...
on “Electricity from Space: The 1970s DOE/NASA Solar Power Satellite Studies” ↗> The Case for Space Solar Power by John Mankins Wired ran a story featuring him last year: https://www.wired.com/story/how-to-get-solar-power-on-a-rain... The main news in it was this: https://www.robins.af.mil/News/Article-Display/Article/19980...
on “X-37b space plane’s microwave power beam experiment” ↗…designs from the 1970s would be absurdly expensive, but modern designs like SPS-Alpha get economies of scale by using lots of small identical parts that self-assemble in orbit. According to the book The Case for Space Solar Power, a 2GW satellite would deliver electricity at 15 cents/kWh at pre-SpaceX launch costs. I plugged BFR's $50/kg into its cost breakdown and got 4 cents/kWh, which is pretty good for zero-carbon baseload.…
on “Starship Prototype Unveiled” ↗…phased array transmitter that uses a reference signal from the ground. If it somehow repoints somewhere without the ground transmitter, the beam would spread out much more than that. (source: the book The Case for Space Solar Power)
on “Space-based solar power is getting serious” ↗…throw away anything and it's designed to be used about a thousand times. At scale it's basically just the cost of fuel and ground services, which drops cost by a couple orders of magnitude. The book The Case for Space Solar Power has detailed cost estimates for NASA's SPS-ALPHA design. It was published about a decade ago so has old launch costs. I plugged in Starship costs and got a total cost of $0.04/kWh, which is pretty great…
on “Space-based solar power is getting serious” ↗The ground stations are basically just antenna wire. For a large plant they would contribute just 0.7 cents/kWh to the total cost, according to the book The Case for Space Solar Power.
on “Caltech to Launch Space Solar Power Technology Demo into Orbit” ↗…the ground, so if the beam went astray it would spread out much more. Despite the low power density the ground station would still be cheap, since it'd mostly be wire antenna. (Source: the book The Case for Space Solar Power)
on “Nuclear technology’s role in the world’s energy supply is shrinking” ↗See the book The Case for Space Solar Power or NASA's SPS-ALPHA project. Basic idea is a phased array microwave trasmitter, a transmitter on the ground that sends a reference signal, and a receiving station that's basically several square miles…
on “Space-based solar power is getting serious” ↗That depends on launch costs and satellite design. The old designs from the 1970s would have been absurdly expensive. Modern designs like NASA's SPS-Alpha are cheap to manufacture at scale. The book The Case for Space Solar Power has a detailed cost breakdown and puts a 2GW geostationary plant at 15 cents/kWh, but was published before SpaceX did much. I plugged in Starship launch costs and it came to 4 cents/kWh, which is pretty…
on “Why fusion will never happen” ↗