Sustainability Model in Blockchain Networks

Abstract

This paper presents a quantitative model to estimate the sustainability of blockchain networks. Blockchains with three different consensus protocols such as Proof of Work (PoW), Proof of Stake (PoS) and Proof of Hybrid consensus protocols across PoW and PoS(PoH) [12], are considered in this research. Sustainability issues in blockchain network systems due to their energy-depleting mining processes and transactions are hindering the technology from further advancement. The sustainability of concern in blockchain networks is assumed, in this paper, to be an inverse of their energy consumption without loss of generality and intuitiveness. The novelty of the proposed model is that the sustainability is estimated quantitatively in a specific context of blockchain network architectures and stochastic behaviors of the transactions. An extensive variety of variables are employed to build a model that is blockchain (e.g., $\mathrm{PoW}, \mathrm{PoS}$ and PoH)-specific, as three representative benchmark architectures with respect to consensus protocols, and each of those will be quantitatively expressed via the baseline chain model [7], the PoS chain model [9] and the PoH chain model [12], respectively. Extensive numerical simulations will be conducted to demonstrate various design considerations to be taken in specific regard of sustainability versus a few primary design variables as employed in the sustainability model. The proposed sustainability model is expected to establish a sound and quantitative foundation for the design of sustainable blockchain networks.