# AI-Driven Optimization of Blockchain Scalability, Security, and Privacy Protection
## 2 Introduction to Related Technologies
### Blockchain
#### 2.1.2 Consensus Algorithm
According to the Cambridge Bitcoin Electricity Consumption Index (2024), the Bitcoin network consumes approximately 120 TWh of electricity annually, with each transaction consuming around 707 kWh, categorizing PoW as a high-energy consensus mechanism. Additionally, the limited block production speed results in low transaction throughput, making it challenging to support large-scale applications. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Consensus Algorithm** & **Core Description** & **Application Examples** & **Reward Mechanism** & **Advantages** & **Disadvantages** \\ \hline PoW & Consensus is achieved through competitive cryptographic puzzles & Bitcoin & Rewards miners with block rewards and transaction fees, but computationally expensive & High security, resistant to Sybil attacks & High energy consumption, low throughput \\ \hline PoS & Nodes gain block validation rights based on the amount and duration of cryptocurrency held & Ethereum 2.0 & Holders receive block rewards, malicious actors may be penalized & Low energy consumption, efficient & May lead to wealth centralization \\ \hline DPoS & Representatives are elected to validate and confirm transactions & EOS, TRON & Delegates receive rewards, malicious representatives can be voted out & High efficiency, low energy consumption & Potential centralization, risk of delegate collusion \\ \hline PBFT & Consensus is reached through multiple rounds of voting, suitable for a small number of nodes & Hyperledger Fabric, financial blockchain modes & No economic incentives, relies on node trust & Low latency, high throughput & No cryptocurrency incentives, malicious nodes may impact consensus \\ \hline Kafka & Consensus is achieved based on a reliable message queue, commonly used in enterprise architectures & Hyperledger Fabric (ordering service) & No economic incentives, relies on access control & High throughput, suitable for private chains & Relies on centralized nodes, single point of failure risk \\ \hline Raft & Leader-based replication for log consistency, suitable for small-scale distributed systems & Enterprise private blockchains & No economic incentives & Simple implementation, easy deployment & Limited application scope, performance affected by leader \\ \hline Paxos & Achieves consensus in distributed systems through message passing & Google Chubby, AWS DynamoDB & No economic incentives & Suitable for strong consistency databases & High algorithmic complexity, significant communication overhead \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison of consensus algorithms. PoS determines block validation rights based on the amount and duration of cryptocurrency holdings, avoiding the energy-intensive computations of PoW. Ethereum 2.0 adopts this mechanism. The main advantages of PoS include low energy consumption and high efficiency, which enhance transaction processing speed and reduce environmental impact. After Ethereum's transition from PoW to PoS in 2022 (\"The Merge\"), its energy consumption decreased by over 99.95%, dropping to approximately 0.0026 TWh per year, with each transaction consuming only about 0.03 kWh, making PoS a low-energy consensus mechanism. However, PoS may lead to wealth centralization, as large token holders gain greater control over the network, potentially undermining decentralization [46]. DPoS  
DPoS relies on community voting to elect delegate nodes that execute consensus, significantly improving transaction processing efficiency. It is widely adopted by blockchains such as EOS and TRON. The key advantages of DPoS include high efficiency and low energy consumption, enabling rapid processing of large-scale transactions and enhancing system throughput. Energy studies estimate the EOS blockchain consumes only about 0.001 TWh annually, significantly lower than PoW-based systems, confirming that DPoS is a low-energy consensus approach.