My favorite part of the presentations are the questions! One that comes up a lot, is the possibility of obtaining precious metals from seawater being easier than asteroid mining.
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!
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 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!
In a followup, we’ll talk about how the water on carbonaceous asteroids paves the way for a robust space economy!
President & Chief Asteroid Miner