A Comparative Study of Consensus Algorithms for Blockchain

Blockchain (BC) technology has recently gained significant popularity due to its ability to provide a secure and decentralized platform for data storage and transactions. There are tens of thousands of BC-based cryptocurrencies and apps. However, the proof of work consensus mechanism used by most BC networks requires significant energy consumption, leading to concerns about its environmental impact. According to the Cambridge Bitcoin Electricity Consumption Index, the estimated annual electricity consumption of Bitcoin mining in 2022 was approximately 107.65 TWh. This paper provides a recent comparative study of BC consensus mechanisms (CMs). We overview BC technology, consensus mechanisms, and mining algorithms. We investigate the energy and time consumption of the PoW consensus mechanism by executing the SHA-256 mining algorithm at different difficulty levels. Finally, we present new mining approaches to reduce or recycle energy consumption.