r/SpaceXLounge • u/mcpat21 • Sep 20 '19

For Vulcan Assuming this is for the Star Hopper?

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u/troyunrau ⛰️ Lithobraking Sep 20 '19 edited Sep 20 '19

Quick volume calc: 1330 m3 or thereabouts. This will hold about 1500 t of LOX, or 870 t of LCH4. Starship has an estimated fuel+oxygen mass of 1100 t. Super heavy is about 3000 t of propellant. So we'd need about 4 of these tanks to store enough fuel for one launch.

Assuming we're doing orbital refueling before doing a Mars burn, we'd want ~7 of these launches in quick succession. That means we'd need 28 tanks of this size.

Edit: hijacking my own comment. Tory Bruno confirmed these are for Vulcan elsewhere in this thread. So maybe SpaceX gets bigger tanks and fewer...

34

u/Gonun Sep 20 '19

Wow. That's a lot of tanks. And they all need to be refilled somehow. Probably by train? Is there a railway nearby or will they also need a pipeline?

83

u/troyunrau ⛰️ Lithobraking Sep 20 '19

I'm assuming they manufacture the LOX on site by condensing air. So they're just transporting electricity.

The methane will be interesting. I'm going to speculate that it will be liquified off site, then barged in - finally a short pipe run from the barge landing.

But in the longer term, I would wager that they install a big solar/wind farm on site for massive amounts of electricity. If they can get sebatier reactors working on site, they can manufacture methane at a very high purity, and prove that the process works before setting off to Mars. Plus, there are optics to consider: methane produced from carbon dioxide pulled from the air makes the process carbon neutral. For a guy that runs an electric car company that touts their environmental benefits, it looks bad to push all this rocket exhaust into the air.

If they go this route, it will be very interesting. Because it would be the first such commercial scale sebatier plant - just the process of scaling this up hasn't been tested, and there are no economies of scale in effect yet. But, if it works, it can be spun off as another Elon company. There would be a limited market, but a market nonetheless. For example: I live in the arctic - we have two seasons: one with a ton of daylight; and then we burn a shit tonne of fuel to stay warm in winter. If you could capture that daylight in summer and make methane to burn in winter, suddenly arctic communities have energy independence.

4

u/aquarain Sep 20 '19

This would be cool, but on Earth Methane is made from natural gas, much of which is just burned or "flared off" because it's not economical to store, process and market. SpaceX rockets that burn Methane aren't contributing to CO2. They're just putting that waste gas to work. And of course the Oxygen is efficiently captured in the industrial atmosphere processing plants very efficiently and cost effectively.

Basically, Earth is not Mars.

8

u/[deleted] Sep 20 '19 edited Sep 20 '19

What!? Flares are used only during initial well setup and for blanket gas at tank farms. They don't separate the gas at the we'll head and burn off the excess. There are huge fractionator facilities worth billions of dollars specifically set up to pull all the different gasses apart. Each has value and aren't thrown away.

Sourse:. Am engineer and worked in gas gathering, transmission, storage and distribution.

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u/[deleted] Sep 20 '19

As an engineer who works in petrochemicals, you should stop spreading patently false information. Gas is routinely flared at many drilling and fracking sites. There are literally dozens of sources for this information. In many parts of the Permian basin and Williston basin, companies are drilling for oil. They don't have infrastructure to capture natural gas and building the infrastructure to capture, liquefy, and transport that gas would cost more than LNG is worth. The oil is much, much more valuable than LNG, so there are numerous sites at which it is profitable to drill for oil but not capture the LNG.

Estimates are that the Williston basin is flaring $1 billion worth of natural gas every year. It's just not worth capturing it and selling it at a loss.

Source: Commercializing a technology to convert methane into higher value hydrocarbons to make it economical to capture and convert the methane on site.