The way it works is that your electricity provider company buys the amount of electricity you consume from renewable electricity producers. It balances out and

The way it works is that your electricity provider company buys the amount of electricity you consume from renewable electricity producers. It balances out and it's equivalent on average to you using only renewable electricity. Multiple providers are working like this in Europe at least. They partner with many local solar/hydro/wind producers. It's approximate of course they can't predict exactly the amount required in advance but in the grand scheme of things it works by supply/demand mechanics.. You could trace btc to a reward allocated to a miner on a renewable electricity contract. Then you know an equivalent amount of energy used to mine these coins was produced sustainably.