Bitcoin remains the leading cryptocurrency in the world of crypto mining, but concerns have been raised about the sustainability of its Proof-of-Work (PoW) consensus algorithm. Critics argue that the energy consumption and environmental impact associated with PoW mining are unsustainable, and that the concentration of mining power could compromise the decentralized nature of the network. While Ethereum has transitioned to Proof-of-Stake (PoS), Bitcoin is unlikely to follow suit due to its commitment to decentralization and security. However, layer-2 solutions such as the Lightning Network can be employed for scalability. Efforts are being made to address Bitcoin's environmental impact, and the upcoming halving event in 2024 could incentivize miners to seek cost-effective and sustainable solutions.