05 December 2012

Which is Better? Mining Oceans for Platinum, or Mining Asteroids?

Platinum from space
The Earth's oceans contain a massive amount of platinum, worth many $trillions. So why do people keep talking about mining the asteroids for platinum?
Lets do some basic calculations to explore this:

The approximate concentration of Platinum in seawater is about 2.34E-10 grams per liter. That’s a 2 with 9 zeros before it, a very small number:

0.000000000234 grams per liter

On the other hand, lets consider how many liters of water there are in the ocean: 1.3E21 liters

That’s a 1 with 21 zeros after it, a very big number!

1,300,000,000,000,000,000,000 liters

Multiply this together, and we end up with approximately 300,000 tonnes of Platinum in the seawater. At today’s price for Platinum (about US$1600 per ounce), this is $16 Trillion, or a $16 million million. That is a kingly sum.

Sounds attractive, right? But now we need to process all the water in all the oceans, and it’s a big task. We’re going to need to pump a lot of water, so lets get a big pump.

How about something Niagra Falls-sized?

Flow rate of Niagra falls: 5.7E6 liters per second.

It would only take 7 million years to work through all the [sea]water on Earth (if we had a pump and processing plant that big). This will certainly introduce some other problems. So, lets be a little more reasonable and say we could process 1 millionth of the ocean (1.3E15 liters) in 7 years, with a processing plant with the flow rate of Niagra Falls (still quite a challenge).

We’d then have about 300 kg of Platinum, with a market value of around $16 Million.

Thankfully, in asteroids similar to LL chondrites and iron meteorites that have been studied here on Earth, the concentration of precious metals like Platinum is a BILLION times higher than the ocean.

Conclusion: While asteroid mining is a big task, its much more tractable than processing enormous amounts of seawater! _Planetary Resources
The ocean is certainly a lot closer and more accessible than the asteroids. But taking that approach is a little bit like the drunk who lost his keys in a dark alley, but decided to look for them a block away under the street light -- because the light was better. Convenience can be the crutch that prevents things from getting done.

If we had to get the platinum from seawater we could, given enough time and resources. But getting platinum and other valuable materials from the asteroids will begin to make a lot more sense, once humans have done the difficult preliminary work, and once they have established a permanent private industrial presence in space.

This is not a job for governments. The job of governments is to get out of the way, so that larger possibilities for the future of humanity can be developed. Governments would have their hands full just guaranteeing basic protections and equitable justice for their own citizens -- if they could only restrict themselves to the few justifiable rationales for governments in the first place.

More at the Planetary Resources website

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6 Comments:

Blogger Matt M said...

The question is all about taxing authority and ownership.

Are you really going to tax someone who can drop big rocks on your head from space?

Wednesday, 05 December, 2012  
Blogger Matt M said...

BTW, dropping rocks from space will replace nuclear weapons in this century.

Wednesday, 05 December, 2012  
Blogger sykes.1 said...

No, the question is all about energy costs of orbital transfers. The same energy cost problem bedevils extracting any precious metal or deuterium from the ocean. The Gibb's free energy demand for concentrating platinum or gold is truly enormous and much greater than the value of the metal. There will never be any orbital mining nor will there be any precious metal extraction or deuterium extraction from the sea. It's simple economics.

Thursday, 06 December, 2012  
Blogger Matt M said...

The reality is we don't know what quality of metal ores exist in the asteroid belt. Some from the interior of some ancient planet may be incredibly rich in heavy metals.

The simple economics for extracting metals from sea water favor growing GM brown kelp to extract heavy metals.

Thursday, 06 December, 2012  
Blogger al fin said...

Sykes: When energy demands are truly enormous, look for an enormously cheap source of energy. If you are using a dense form of energy such as nuclear fission or fusion, look for fuels that are present in situ, and reactor designs which can be constructed on site from available materials.

Think like a creative and ingenious explorer who has been cut off from re-supply. Make such plans well ahead of time.

And keep in mind, once you are already outside the gravity well, a lot of previously impossible activities suddenly become potentially much more doable.

MattM: Why use a sledgehammer when a lancet will work as well?

Using biology to extract and refine metals from seawater, soils, and ores is an idea that is developing apace. Space-viable microbes have not been developed, although inactive spore forms have been known to survive. But if you want to use microbes to refine space ores in a vacuum, they should be able to be active in a space environment. A much more difficult challenge to be sure.

Thursday, 06 December, 2012  
Blogger neil craig said...

Does anybody know how much the cost of extracting resources would drop if instead of seawater the water had already been extracted? There are a number of hot places in the world below sea level where seawater could flow in (producing electricity) and evaporated off. My favourite is the quatara depression in Egypt since it is both hot and currently uninhabited.

Saturday, 08 December, 2012  

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