[demircancelebi]

As I know there are some standards like https://www.goldstandard.org/ and https://verra.org/ . They audit the projects that claim to remove CO2 from the atmosphere worldwide and issue CO2 credits. These credits then can be sold to companies that want to offset their emissions. Usually OTC deals, sometimes involving brokers as well. There's also https://www.cblmarkets.net/ , which is one of the big marketplaces where such deals are happening.

I've heard deals with prices in the range of $0.5 to $5 per tonne CO2 equivalent. There's also a decentralized protocol that aims to move these credits onchain (https://toucan.earth/), their BCT (Base Carbon Tonne) token price is currently around $3.1.

As stated in the post, last year ~$1B worth of credits are sold. One McKinsey report expects it to be around $50B at 2030.

There are much more details of course, but these are the basics as I know.