“With Chia, Cohen aims to replace the energy-greedy part of Bitcoin’s code, which rewards miners for generating trillions of numbers a second, with an energy-efficient system, which rewards miners (or “farmers” in Chia’s parlance) based on the amount of unused hard-drive space they have on their computers and how long they’ve had it. If you opt in, the Chia Network will essentially populate that unused space with bingo cards. If Chia calls the numbers on your card, you’ll be awarded newly minted chia.”