Steve Jackson Games Forums - GURPS O'Neill Cylinder Design

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- - GURPS O'Neill Cylinder Design (https://forums.sjgames.com/showthread.php?t=171618)

Anthony

01-02-2021 12:27 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by Johnny1A.2 (Post 2361007)

Solar power sats probably don't make sense on their own terms.

Solar power sats make sense if you can get launch costs below a certain threshold (which we are nowhere close to).

ericthered

01-02-2021 12:32 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by Anthony (Post 2361011)

Solar power sats make sense if you can get launch costs below a certain threshold (which we are nowhere close to).

Usually the mechanism given is the by-product from rare-metal asteroid mining or production on the moon, both of which are evading the launch cost of earth's gravity well by never going down it at all.

Or occasionally some mega-structure like an space elevator or orbital ring.

cptbutton

01-02-2021 12:45 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by Johnny1A.2 (Post 2361007)

One problem with the whole concept for fictional/gaming purposes is 'why'. That is, why would whoever is putting up the money build this immense flying parkland, when high-density urban is more cost efficient? It's possible to think of reasons, but they're likely to involve a vastly wealthier and more advanced society than most of the O'Neil enthusiasts envision.

The classic O'Neil concept of the habitats building power satellites to pay for themselves is of course nonsensical. Solar power sats probably don't make sense on their own terms, and if you're going to build them, you don't need O'Neil habs, you need the space equivalent of a line shack or an oil rig. For comparison, you don't build a chain of mansions on site if you're starting a mine in a remote region, you build efficient living modules or something along those lines, if the workers are lucky, something less if they're not. It's cheaper.

I think the argument was that if you don't get out into the open air in the big outdoors sometimes it cause Bad Things to happen to your mental health. And that at scale, this would be cheaper than having to fly your workers down to Earth for a month twice a year or whatever.

AlexanderHowl

01-02-2021 04:33 PM

Re: GURPS O'Neill Cylinder Design

SPS is easily achievable at a cost of ~$300,000/ton launch cost and the development of lunar mines. As long as ~99% of the materials are taken from the Moon, the economics are actually fairly good, as it ends up resulting in a wholesale electricity cost of ~$10/MW-h. It is actually much better than contemporary renewable sources when you subtract the tax credits and other subsidies, especially since you do not have to bother with the environmental consequences of mining rare earths.

martinl

01-02-2021 06:54 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by Anthony (Post 2361011)

Solar power sats make sense if you can get launch costs below a certain threshold (which we are nowhere close to).

How do you get the power down to Earth without making a weapon?

Anaraxes

01-02-2021 07:36 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by martinl (Post 2361090)

How do you get the power down to Earth without making a weapon?

Low density over a larger area. Typical plans I've read about suggest about half the energy density of sunlight. It's not a focused gigawatt blast from space.

Anthony

01-02-2021 07:38 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by martinl (Post 2361090)

How do you get the power down to Earth without making a weapon?

By designing your microwave transmitter without the ability to focus to dangerous levels. A typical geostationary orbit transmitter is something like a 1 kilometer transmitter and a ten kilometer rectenna, which won't be useful as a weapon unless your power is in the tens to hundreds of gigawatts (and the physics simply doesn't permit a transmitter of that side to focus to smaller than that area).

ericthered

01-03-2021 06:53 AM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by Anthony (Post 2361095)

I mean, you probably can still use it as an economic weapon to disrupt your opponent's weather patterns, but that's a slow process that takes time to bear fruit.

martinl

01-03-2021 12:09 PM

Re: GURPS O'Neill Cylinder Design

Quote:

Originally Posted by Anaraxes (Post 2361094)

Low density over a larger area. Typical plans I've read about suggest about half the energy density of sunlight.

Quote:

Originally Posted by Anthony (Post 2361095)

By designing your microwave transmitter without the ability to focus to dangerous levels.

After digging around a little to figure out the trade offs between diffuse space microwaves and land-based Solar, I'm still pretty skeptical about this approach, but it's fine for gaming.

Orbiting gigawatt blasts are better for gaming mind you.

AlexanderHowl

01-03-2021 01:53 PM

Re: GURPS O'Neill Cylinder Design

The primary economic advantage of SPS is you need a 1/5th as much solar gathering capacity, plus you do not need the storage capacity for 4x the hourly production as on the surface. In essence, 50% of the time is night and, for the day, you average 50% production, as solar intensities waxes and wanes throughout the day, plus you have cloud cover and storage inefficiencies, meaning that a nation like the USA would need 140,000 square kilometers of solar panels and 80 million metric tons of lithium ion batteries. Since the materials for lithium ion batteries cost $7,500 per metric ton, the material costs alone for the batteries would be over $600 billion, and that it before prices increase due to increased demand.

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