Contents lists available at ScienceDirect Energy Research & Social Science journal homepage: www.elsevier.com/locate/erss Perspective Bitcoin mining: A global review of energy and power demand Sinan Küfeoğlu a, ⁎ , Mahmut Özkuran b a Energy Policy Research Group, University of Cambridge, Cambridge CB2 1TN, UK b School of Arts and Social Sciences, Istanbul Technical University, 34467 İstanbul, Turkey ARTICLEINFO Keywords: Bitcoin Mining Blockchain Energy Consumption ABSTRACT After its introduction in 2008, increasing Bitcoin prices and a booming number of other cryptocurrencies lead to a growing discussion of how much energy is consumed during the production of these currencies. Being the most expensive and the most popular cryptocurrency, both the business world and the research community have started to question the energy intensity of Bitcoin mining. This paper only focuses on computational power demand during the proof-of-work process rather than estimating the whole energy intensity of mining. We make use of 160GB of Bitcoin blockchain data to estimate the energy consumption and power demand of Bitcoin mining. We considered the performance of 269 diferent hardware models (CPU, GPU, FPGA, and ASIC). For estimations, we defned two metrics, namely; minimum consumption and maximum consumption. The targeted time span for the analysis was from 3 January 2009 to 5 June 2018. We show that the historical peak of power consumption of Bitcoin mining took place during the bi-weekly period commencing on 18 December 2017 with a demand of between 1.3 and 14.8 GW. This maximum demand fgure was between the installed capacities of Finland (∼16 GW) and Denmark (∼14 GW). We also show that, during June 2018, energy consumption of Bitcoin mining from difculty recalculation was between 15.47 and 50.24 TWh per year. 1. Introduction Cryptocurrencies and their energy consumption have become a popular subject of discussion over the last couple of years. Bitcoin, the most well-known and most expensive cryptocurrency, was frst in- troduced by Satoshi Nakamoto, a pseudonym of an author or group of authors, in 2008. There is growing concern about the power and energy demand of Bitcoin mining. This is indeed an energy intensive phe- nomenon. Some views might address this energy consumption as one of the contributing factors to the climate change. There are signifcant diferences in Bitcoin's energy consumption estimations since there are too many unknowns in the process, such as which type of hardware is used in the mining and for how long. This ambiguity necessitates an extensive analysis that will cover all Bitcoin transactions from 2009 until today. This paper aims to present a detailed analysis and estima- tion of the energy consumption of Bitcoin mining by focusing on the use of computational power during the proof-of-work process, and hence the mining process only. In our study, we analyzed 160GB of block- chain Bitcoin data. We deliberately excluded the estimation for energy intensity of Bitcoin mining more generally since it will cover all pro- cesses including the use of external cooling systems and their energy consumption. Even though CO 2 and Green House Gas emissions due to Bitcoin mining is another crucial topic, we omitted this to focus solely on the power and energy demand of the mining process. Bitcoin mining is a decentralized computational process, where transactions are verifed and added to the public ledger, known as the blockchain. Nakamoto explains the working principles of Bitcoin mining in detail in his paper [1]. Bitcoin networking started in 2009 with its unique currency Bitcoin or BTC. The Bitcoin network is a peer- to-peer, distributed network. In this network, all nodes are treated as equal peers. The process of making Bitcoins is called mining, and the participants are called miners. All transactions are carried out and stored in a distributed ledger: the blockchain. The historic transaction data are contained in the blockchain. A signature between the new block and the previous block is needed for adding a new block to the blockchain. This is done via fnding a nonce value that will satisfy the cryptographic hash function, Secure Hash Algorithm 256-bit (SHA- 256). The nonce starts with 0 and is incremented by 1 by the miner until the hash of the block is less than or equal to the target value. Once a node fnds a hash that satisfes the required number of zero bits, it transmits the block it was working on to the rest of the network. The other nodes in the network then express their acceptance by starting to create the next block for the blockchain using the hash of the accepted block. The fnder of the block is rewarded for their eforts with a special https://doi.org/10.1016/j.erss.2019.101273 Received 11 June 2019; Received in revised form 17 July 2019; Accepted 22 August 2019 ⁎ Corresponding author. E-mail address: s.kufeoglu@jbs.cam.ac.uk (S. Küfeoğlu). Energy Research & Social Science 58 (2019) 101273 2214-6296/ © 2019 Elsevier Ltd. All rights reserved. T