Blockchain Technology and Energy Efficiency: A Systematic Literature Review of Consensus Mechanisms, Architectural Innovations, and Sustainable Solutions

Blockchain technology offers promise for decentralization and transparency, yet faces increasing scrutiny due to the high energy consumption of consensus mechanisms like Proof-of-Work (PoW). This systematic literature review evaluates the energy efficiency of eight major mechanisms—PoW, Proof-of-Stake (PoS), Delegated PoS (DPoS), Proof-of-Authority (PoA), Proof-of-Space (PoSpace), Directed Acyclic Graphs (DAGs), Byzantine Fault Tolerance (BFT), and Proof-of-History (PoH)—along with architectural innovations such as sharding, rollups, and hybrid models. Drawing from 53 peer-reviewed studies and industry reports (2018–2024), the review synthesizes empirical energy metrics (e.g., kWh/transaction, TWh/year), explores scalability-energy trade-offs, and identifies technical and regulatory barriers. Findings show PoS and DAGs reduce energy use by over 99% compared to PoW, though potential compromises in decentralization and security remain. Architectural enhancements like Layer-2 scaling and modular designs improve energy efficiency but increase system complexity. Regulatory frameworks such as the EU’s MiCA and the Crypto Climate Accord promote renewable integration and call for standardized energy metrics. This study offers practical insights for developers, policymakers, and enterprises, and proposes future research into quantum-resistant protocols and decentralized energy solutions. It concludes that blockchain can support global climate goals through interdisciplinary innovation and sustainable governance.