What Huck said. And back on track.
What has to be asked, and what I said last time this appeared as a thread:
A: How long will development and certification take?
B: How many years of cost saving will it take to recoup (A)?
C: How long will the oil last?
If A + B > C it's a dead duck.
If it helps let's remember that even BP (surely the definition of fossil fuel optimists) are saying just over 40 years