#### Transcript W6-4: Platinum Depletion

```Rare Earth Mineral
Exhaustion
The Example of Platinum
1. How much is in the Crust?
• Ask the geologists and they claim, from a
few source surveys that the crust has a
total of 67.3 Giga Grams of platinum
• Of that 30 has already been mined leaving
behind a total resource of 37 Gg
2. What is the recovery efficiency
• Data shows that its 89%
• Recoverable Pt is now 37 Gg x .89 = 32.9
3. How much platinum is needed
per fuel Cell
• 0.4 g per KW generated
• Average vehicle power is 75 KW
• 0.4 x 75 = 30 g of Pt needed per vehicle
4. What is the lifetime of a fuel cell
• 10 years
• So need 30g of replacement Pt every 10
years per fuel cell
5. What about recycling of fuel
cells and Pt recovery
• About 50% of Pt can be recovered via a
recycled fuel cell.
• So, dig up Pt and put 30g in a fuel cell 
10 years later get 15g to put back into
another fuel cell to go along with 15g of
newly mined Pt
6. How much Pt resource goes to
fuel cells?
• Other uses of Pt: jewelry, fuel cells for
stationary power, catalytic converters for
clean air (1-5 g) per vehicle, industrial
processes.
• Assume 1/3 of Pt goes to the above
• This leaves us with 2/3 of 32.9 or 22 Giga
grams of Pt for fuel cells
7. Pick a starting point
• In the year 1 we make 50 million fuel cells
for 50 million vehicles
• This uses 1.5 Gg of the available 22 Gg of
the Pt reservoir
• Every year we make 50 million new
vehicles and we continue this until we
have ramped up to 500 million vehicles
• How long can this be sustained?
The Pt Depletion Chart
Year
Gg/year
Remaining
1
2
1.5
1.5
22-1.5 =20.5
19
3
4
1.5
1.5
17.5
16
5
1.5
14.5
6
7
1.5
1.5
13
11.5
8
9
1.5
1.5
10
8.5
10
1.5
7.0
Now we recycle
Year
11
12
13
14
15
16
17
18
19
Gg/per year
(.75) +.75
.75
.75
.75
.75
.75
.75
.75
.75
Pt Left
7-.75 = 6.25
5.5
4.75
4
3.25
2.50
1.75
1.0
.25 and done
```