larsschellhas OP t1_je0hg54 wrote on March 28, 2023 at 3:09 PM

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

Well, starship is aiming to bring launch costs down to as low as 10 $/kg.

At that price SBSP would still be slightly more expensive than solar and wind, but much cheaper than storage, backup & peak load technologies which we will be needing in a purely renewable system anyway.

SBSP has the big advantage that it can deliver power to many markets, simply by switching to another base station. Thanks to this, it can capture much higher wholesale prices for electricity than wind and solar.

Essentially, it could capture 24/7 peak power prices, putting it at a better position than ground-based wind and solar even though it has higher levelised cost of energy.

EnigoMontoya t1_je0mila wrote on March 28, 2023 at 3:42 PM

Bunch of questions here, but starting with a couple...

What's your assumption on the cost of the distributed ground based plants accepting SBSP on a $/MW basis?

What's the breakdown of percent loss from SBSP for the transmission down to ground and conversion into usable AC?

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

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.

Brain_Hawk t1_je16al7 wrote on March 28, 2023 at 5:47 PM

That $10 per kilogram is an extremely optimistic estimate cited by a person who was well known to exaggerate in order to drive interest and investment.

Personally I suspect it's going to be quite a bit more than that, not that I'm an expert on launch cost. But I think we need to be a bit more skeptical of the claims being made at this time.

To the bigger question, I think any technology may be feasible in the future, but as far as I can see there's still a lot of challenges with orbital-based power. In particular the cost of sending it up and maintaining it, and the amount of power we can get generated back down on earth, and distributing that to a wide area.

But, if we don't come up with a better solution, it's definitely something I can see being in place in the next 50 or 100 years.