Carbon Negative.

Carbon Negative wasn’t a pool’s own name. It is what mempool.space calls a miner nobody has identified, after a message in its first blocks: “This block was mined with a carbon negative power source”. Carbon negative means taking more carbon dioxide out of the air than you put in; how this miner did so isn’t known. Its first block, 688,156, was found on 19 June 2021. After October 2021 its blocks carried no message until its last week, and the researcher 0xB10C tracked them by the two addresses they paid. When mempool.space added the name in June 2024, it said this miner had found about 90% of the past year’s blocks that it couldn’t match to any pool.

It found 1,263 blocks, about 0.6% of all blocks while it was active. Each block’s first transaction paid the whole reward to one address. That reward is separate from the transactions confirmed inside the block.

Its last block, 900,657, was found on 10 June 2025, and no announcement of why it stopped has been found. A few days earlier two of its blocks carried new messages. One quoted the novel Robinson Crusoe: “things of this world are no farther good to us than they are for our use”. The other read “Crusoe used >27bcf flare gas to secure BTC, avoiding 3.4MMT CO2e emissions”: more than 27 billion cubic feet of gas that oil wells would otherwise burn off, and 3.4 million tonnes of greenhouse gases avoided. No published source says who found these blocks.