The browser could throttle the cc mining based on your battery level/power state. In theory, your device could even mine while charging and then distribute the mined tokens later.
Or you could distribute tokens mined from a computer that's plugged in somewhere, or even purchased with normal currency. But I'm not sure I'd want to navigate a web where I'm constantly making purchase decisions with every hyperlink.
so why bother with additional steps (and cryptocurrency) instead of just pay with real money from the beginning? you are suggesting to introduce just additional unnecessary steps.
so I could not get access to content if my battery is low and I cannot mine cc ? or would I get access with "credit" so I would need to return "load" later?