... there must be a system that requires no burning of petrol, cause it's bad for the environment. But here's the killer, if I want to redeem my coin for petrol, I spent almost as much petrol making the coin as it's worth. So I get 1 litre of petrol instead of 2. Brilliant.
Well, conch shells it has to be then. I'm off to register conchcoin.bit
I'm going to invest in a saltwater aquarium right now. In fact, I'm going to set up a whole *farm* of saltwater aquariums.
This is going to be even better than carrots.
Use the aquariums for this instead.