Why No Consensus on Consensus? A Deep Dive Into Blockchain Consensus Protocols

Abstract

ABSTRACT Blockchain technology has emerged as a foundational infrastructure for decentralized applications, where consensus protocols play a critical role in ensuring security, consistency and trust among distributed participants. This paper presents a comprehensive comparative analysis of nine widely adopted consensus protocols across public (proof of work [PoW], proof of stake [PoS], delegated proof of stake [DPoS]) and private (practical Byzantine fault tolerance [PBFT, Raft, Kafka, proof of elapsed time [PoET], yet another consensus [YAC], Paxos) blockchain systems. Unlike prior surveys, this work integrates workflow‐level operational modelling, quantitative performance comparison and application‐driven decision support within a unified analytical framework. Our analysis shows that PoW achieves strong decentralization at 3–15 transactions per second (TPS) with 10–60 min finality, whereas PoS improves throughput to tens to thousands of TPS with seconds‐to‐minutes finality while reducing energy consumption by approximately 99%. Private blockchain protocols such as PBFT and Kafka achieve sub‐second latency and throughput exceeding 10,000 TPS by trading off decentralization for performance and control. Furthermore, we develop a decision‐support framework that maps consensus mechanisms to application requirements and provides a critical synthesis of security risks, scalability limitations, and emerging solutions. The findings highlight that no single protocol satisfies all design goals, reinforcing the necessity of context‐aware consensus selection.