larsschellhas OP t1_je0yd9s wrote on March 28, 2023 at 4:57 PM

Reply to comment by EnigoMontoya in Is Space-Based Solar Power An Option to Solve Humanity's Energy Hunger After All? by larsschellhas

It's around 50% at the moment, but has no physical limit really. The advantage of microwaves (like Radar) is that they are much less impacted by clouds and weather than visible light.

The receiver stations are also simple antennas which can be manufactured much cheaper than solar PV, therefore making up only a small share of the total CAPEX. I don't have the number off the top of my head, but they can be found in the Roland Berger and Frazer Nash studies.

EnigoMontoya t1_je11jm3 wrote on March 28, 2023 at 5:17 PM

Right so the conversion is 50% but the transmission over distance is a distinct loss correct? Yes, microwaves can penetrate the atmosphere, but there is still a cost.

https://ars.els-cdn.com/content/image/1-s2.0-S2352484720317273-gr9.jpg

This diagram from a 2021 study touting a 45% conversion efficiency but notes a huge drop from the transmission... 400 KW -> 10 KW over just 10 KM.

When you consider geosynchronous orbit is all the way out at 35,000 KM. This seems like a major issue. What am I missing?

larsschellhas OP t1_je11s3v wrote on March 28, 2023 at 5:19 PM

That there are only around 10-50 km of atmosphere is the way and that accuracy is the primary driver of losses. :)

larsschellhas OP t1_je1rz1o wrote on March 28, 2023 at 8:01 PM

Or rather, according to EMROD, the main loss driver is the conversion to microwaves. Reconversion and transmission appear to be relatively efficient.