Financial innovation has given great importance to sustainability. The Sustainable Finance Strategy represents one of the central points of the European agenda, and Fintech offers important opportunities in this field. However, some “valuable” Fintech instruments seem to not have been adequately considered. The reference is to Bitcoin and to the “crypto-industry”. The most common public belief about Bitcoin and sustainability is that Bitcoin is polluting the ecosystem. Immediately, the concept is extended to Distributed Ledger Technologies (DLTs), to blockchain and to all related innovations. Notwithstanding this, some research shows that there is still some uncertainty on the precise amount of energy used by Bitcoin-related activities and on how to calculate it. The scope of this paper is to make give some clarity on this uncertainly in order to show, on the one hand that DLT is not “polluting”, but that pollutions come from the way each miner decides to conduct their businesses. On the other hand, a DLT system can be considered sustainable thanks to its capacity to solve a various number of environmental problems “related” to how businesses are conducted.