ECO coins can be earned through sustainable action. These are usually specific to the context. Think eating a meat free lunch, biking to work or recycling your plastic cup at a music festival. In the end the community will decide what is most valuable to them. Over time sustainable actions will become the new normal and more ambitious sustainable actions will be added to the economy.
ECO coins can then be spent spent on sustainable products, services and experiences. For instance, in a city you may be able to rent a bike for an hour for a few ECOs, while in a rural community you could get discounts at the farmers market on locally grown fruit and vegetable. It could also be new songs, films and access to the latest and most desirable events and talks and workshops.