My read of the article was that they were hedging their bets a...

My read of the article was that they were hedging their bets a bit, either the reporter doesn't know the answer or the reserve will work differently for different materials.
It talks about the reserve digging up, processing and storing minerals. If they went down this route, then the processing would be eligible for the production tax credit.
But the other option was that the reserve would purchase options, so essentially they would buy the right to have future production, the theory being that you don't need to dig it up, process it and store it, you can just have the right to future production at a specified time for a specified price (presumably they would want the right to queue jump). To make the example specific to RNU, it would mean Albo or Madeleine could jump on the phone and tell DC they want the next 100t that comes out of the mine at any stage, instead of digging it up and storing it. They would pay us for the option, then pay for the production when it was requested.

My guess is for graphite is that the option would be the preferred for graphite, just because of the volume required the warehousing costs would be too high.