I'm reading Kim Stanley Robinson's Ministry for the Future[1], where one of the major plot elements is the introduction of a "carbon coin" -- a complementary currency issued for reducing carbon, backed by central banks. It's essentially a targeted form of quantitative easing.

This idea is inspired by the Global Carbon Reward here in the submitted link. Given the numerous threads discussing whether blockchain and cryptocurrency technologies are or can be overall socially beneficial, thought the HN crowd might be interested, and a link to the original idea seemed the most relevant link.

[1] https://en.wikipedia.org/wiki/The_Ministry_for_the_Future