Article

# Renewable Energy Will Not Solve Bitcoin's Sustainability Problem

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## Abstract

In this paper we find that the Bitcoin network, with an electrical energy footprint of 491.4 to 765.4 kWh per transaction on average, is relatively much more energy-hungry than the traditional financial system. Even though it has been argued that renewable energy may help mitigating the environmental impact of this, we find that there exist fundamental challenges in uniting variable renewable energy production with the consistent demand of Bitcoin mining machines. Moreover, we find that the environmental impact of Bitcoin mining reaches beyond its energy use. Continuous increasing energy (cost) efficiency of newer iterations of mining devices ensures that older ones will inevitably be disposed on a regular basis. The resulting electronic waste generation could equal that of a small country like Luxembourg, with a staggering average footprint of four light bulbs worth of electronic waste per processed Bitcoin transaction. Bitcoin will therefore have to address its sustainability problem in another way. This may consist of replacing its mining mechanism with a greener alternative like Proof-of-Stake.

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... Consequently, blockchain is identified as a strategic technological innovation that has remarkably revolutionized monetary transactions and digital commodity exchanges (Aggarwal et al., 2019;Silvestre et al., 2020). However, a severe problem in the form of accumulation of electronic waste owing to the Bitcoin mining process with advanced hardware and machinery is observed of late (De Vries, 2019). Electronic waste generation can be extremely hazardous with severe implications. ...
... So, the miners prefer to opt for high-end sophisticated hardware and machinery (Kristoufek, 2020). The introduction of new machines and growing hash rates force the less effective systems and hardware to phase out at an increasing pace (De Vries, 2019;Li et al., 2019) and result in a tremendous surge in the piling up of electronic waste. Overall, several countries' electronic waste generation in a year is comparable with the electronic waste of the Bitcoin network in the same period. ...
... and www.digiconomist.net have been chosen for extracting the variables. Both data sources have been acknowledged to serve reliable information in the scientific literature (De Vries, 2019) and collate real-time daily data. The said data repositories help to conduct mainstream research for drawing actionable insights (Das and Dutta, 2020). ...
Article
Electronic waste is generating in the Bitcoin network at an alarming rate. This study identifies the determinants of electronic waste generation in the Bitcoin network using machine learning algorithms. We model the evolutionary patterns of electronic waste and carry out a predictive analytics exercise to achieve this objective. The Maximal Information Coefficient (MIC) and Generalized Mean Information Coefficient (GMIC) help to study the association structure. A series of six state-of-the-art machine learning algorithms - Gradient Boosting (GB), Regularized Random Forest (RRF), Bagging-Multiple Adaptive Regression Splines (BM), Hybrid Neuro Fuzzy Inference Systems (HYFIS), Self-Organizing Map (SOM), and Quantile Regression Neural Network (QRNN) are used separately for predictive modeling. We compare the predictive performance of all the algorithms. Statistically, the GB is a superior model followed by RRF. The performance of SOM is the least accurate. Our findings reveal that the blockchain's size, energy consumption, and the historical number of Bitcoin are the most determinants of electronic waste generation in the Bitcoin network. The overall findings bring out exciting insights into practical relevance for effectively curbing electronic waste accumulation.
... As of April 21, 2022, Ethereum is using 105.63 TWh of electrical energy annually (comparable to the power consumption of Kazakhstan), and the carbon footprint is 58.91 Mt CO2 annually (comparable to the carbon footprint of Libya) [41]. The ASIC mining devices of Bitcoin have a service life of only about 1.5 years [58], and after that, they serve no practical purpose anymore because they can only calculate SHA256d hashes. Bitcoin mining generates 30.7 metric kilotons of e-waste annually, per May 2021 [11]. ...
... De Vries [58] concludes that renewable energy is not the answer to Bitcoin's sustainability problem. Also, the lifetime of ASIC mining devices is considerably short, producing lots of e-waste even if the mining itself is using sustainable energy. ...
Article
According to recent estimates, one bitcoin transaction consumes as much energy as 1.5 million Visa transactions. Why is bitcoin using so much energy? Most of the energy is used during the bitcoin mining process, which serves at least two significant purposes: a) distributing new cryptocurrency coins to the cryptoeconomy and b) securing the Bitcoin blockchain ledger. In reality, the comparison of bitcoin transactions to Visa transactions is not that simple. The amount of transactions in the Bitcoin network is not directly connected to the amount of bitcoin mining power nor the energy consumption of those mining devices; for example, it is possible to multiply the number of bitcoin transactions per second without increasing the mining power and the energy consumption. Bitcoin is not only “digital money for hackers”. It has very promising future potential as a global reserve currency and a method to make the World Wide Web (WWW) immune to cyberattacks such as the Distributed Denial-of-Service attacks. This survey approached cryptocurrencies’ various technological and environmental issues from many different perspectives. To make various cryptocurrencies, including bitcoin (BTC) and ether (ETH), greener and more justified, what technological solutions do we have? We found that cryptocurrency mining might be cleaner than is generally expected. There is also a plan to make a vast renewable energy source available by combining Ocean Thermal Energy Conversion and Bitcoin mining. There are plans to use unconventional computing methods (quantum computing, reversible computing, ternary computing, optical computing, analog computing) to solve some of the issues regarding the vast energy consumption of conventional computing (including cryptocurrency mining). We think using spare computing cycles for grid computing efforts is justified. For example, there are billions of smartphones in the world. Many smartphones are being recharged every day. If this daily recharging period of twenty to sixty minutes would be used for grid computing, for example, finding new cures to cancer, it would probably be a significant breakthrough for medical research simulations. We call cryptocurrency communities to research and develop grid computing and unconventional computing methods for the most significant cryptocurrencies: bitcoin (BTC) and ether (ETH).
... We recognize that incentivizing green energy for use in Bitcoin mining does not solve all of Bitcoin's sustainability issues [13] or other efficiency issues that affect Bitcoin and blockchains in general [28]. Discarded ASIC hardware and powerful competing incentives to use carbon-emitting power for some mining will continue to be a factor in Bitcoin's environmental impact. ...
... Apart from Bitcoin and Ethereum, at the time of this writing, the next top ten blockchain projects using PoW have a combined market cap of over fifty-two billion US-dollars, and are consistently growing. 13 Many of these projects, for either technical or philosophical reasons have no plans to transition from PoW consensus. Coins using PoW account for 59% of the total crypto currency market cap [10]-excluding the value of NFTs and other tokens anchored to these chains. ...
Article
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We present an approach to evaluating the carbon-emitting energy provenance of Bitcoin transactions and transaction outputs. Our approach incorporates published global energy production data and existing state-of-the-art estimates of Bitcoin energy consumption into a scoring algorithm for individual mined blocks. We then present two proposals for deriving scores for transactions based on the coinbase origins of the Bitcoin currency values of the trans-actions' inputs. The first proposal is comparatively simple, and weights coinbase origin contributions to a transaction based on recency in transaction hops from its origin block. The second proposal adjusts the weights of coinbase contributions at each intermediary transaction based on the input and output values of those transactions. Using these methods we are able to associate individual transactions and unspent transaction outputs with specific quantities of atmospheric carbon. Finally, we offer an outline of an incentivization strategy in the form of a blockchain-based carbon-offsetting oracle that would track the creation and exchange of offsets based on the metrics proposed. CCS CONCEPTS • Applied computing → Digital cash; • Hardware → Enterprise level and data centers power issues; Impact on the environment ; Energy metering; • Security and privacy → Economics of security and privacy.
... The system's observed computational output is then modeled as a function of input factors, including hardware and energy. A major challenge of this research design is to mimic the composition of state-of-the-art and obsolescent (but still economically viable) technology, known to be operated in the market (Bevand, 2017;de Vries, 2019;Krause & Tolaymat, 2018). The proposed model leverages a simple economic narrative first introduced by Derks et al. (2018) to deduce such a distribution from the behavior of agents: A rational miner will (i) choose the mining device with the best price-performance tradeoff on the market when investing in a new technology; (ii) cease investment but continue to operate existing machines if expected returns fall below total cost; and (iii) withdraw incumbent equipment if expected returns are insufficient to cover variable costs. ...
... The marginal transition, however, is insufficient to estimate absolute technology stocks. Previous papers involving miners' technology distribution (arbitrarily) select a technology setting to overcome this problem and accept associated inaccuracies (Cocco & Marchesi, 2016;Derks et al., 2018;de Vries, 2019;Garratt & van Oordt, 2020;Krause & Tolaymat, 2018;Küfeoglu &Özkuran, 2019;Song & Aste, 2020). In contrast, I propose an iterative model that exploits innovation-driven convergence in the network to derive the missing distribution provided (i) miners are rational, and (ii) the system is subject to technological progress. ...
Article
Full-text available
The stability of proof-of-work consensus underlying decentralized networks such as Bitcoin relies on an incentive-compatible mining design. While theoretically well studied, the empirical composition of the mining process remains largely opaque due to the unknown distribution of miners and technology. This paper proposes a model that leverages innovation-driven convergence in the Bitcoin ecosystem to reconstruct market conditions and study miners’ behavior. The implications of the model are supported by numerical simulations using 10,000 samples. The results quantify considerable variation in miners’ profits and costs and proof consistent with the proposed theory. The estimates suggest that the cost of a capacity majority, and thus the ability to successfully attack the network, can be astonishingly low (e.g., $2.55 million in May 2020) when adverse events coincide. This pronounces the relevance of cyclical patterns when assessing the immutability of proof-of-work consensus. ... All miners, running equipment to the same specifications, have the same constant energy demand and usually run their machines 24/7. Therefore, miners cannot exclusively rely on intermittent renewable energy sources to meet their energy requirements [42]. ... ... The Accord also assumes that producers of renewable energy would always prioritise non-mining activities before selling to bitcoin miners. Research shows the opposite [42]. For example, in Virunga National Park in the Democratic Republic of Congo, an EU funded hydroelectric plant has been constructed to help ex-combatants build sustainable livelihoods beyond poaching. ... Preprint The rate of adoption of some cryptocurrencies is triggering alarm from energy researchers and social scientists concerned about the industry's growing environmental and social impacts. In this paper we argue that the unsustainable trajectory of some cryptocurrencies disproportionately impacts poor and vulnerable communities where cryptocurrency producers and other actors take advantage of economic instabilities, weak regulations, and access to cheap energy and other resources. Globally, over 100 million people hold cryptocurrency, mostly as a speculative asset. The digital infrastructure behind the most popular cryptocurrency, bitcoin, currently requires as much energy as the whole of Thailand, with a carbon footprint exceeding the gold mining industry. Should bitcoin's mass adoption continue, an escalating climate crisis is inevitable, disproportionately exacerbating social and environmental challenges for communities already experiencing multiple dimensions of deprivation. In mitigating these impacts, the paper considers 4 potential regulatory pathways, including: 1) promoting voluntary private-sector commitments to using only renewable energy, 2) encouraging a system of voluntary carbon offsetting, 3) using existing financial regulations and tax frameworks, and 4) imposing national and/or international bans on cryptocurrency 'mining'. The paper argues that effective environmental regulation of cryptocurrencies is urgently required, both to reduce the threat of catastrophic climate change, and to help the world's poorest towards sustainable development. However, regulating cryptocurrency mining in any context is likely to require a combination of efforts and is unlikely to result in win-win outcomes for all. ... All miners, running equipment to the same specifications, have the same constant energy demand and usually run their machines 24/7. Therefore, miners cannot exclusively rely on intermittent renewable energy sources to meet their energy requirements [42]. ... ... The Accord also assumes that producers of renewable energy would always prioritise non-mining activities before selling to bitcoin miners. Research shows the opposite [42]. For example, in Virunga National Park in the Democratic Republic of Congo, an EU funded hydroelectric plant has been constructed to help ex-combatants build sustainable livelihoods beyond poaching. ... Article The rate of adoption of some cryptocurrencies is triggering alarm from energy researchers and social scientists concerned about the industry’s growing environmental and social impacts. In this paper we argue that the unsustainable trajectory of some cryptocurrencies disproportionately impacts poor and vulnerable communities where cryptocurrency producers and other actors take advantage of economic instabilities, weak regulations, and access to cheap energy and other resources. Globally, over 100 million people hold cryptocurrency, mostly as a speculative asset. The digital infrastructure behind the most popular cryptocurrency, bitcoin, currently requires as much energy as the whole of Thailand, with a carbon footprint exceeding the gold mining industry. Should bitcoin’s mass adoption continue, an escalating climate crisis is inevitable, disproportionately exacerbating social and environmental challenges for communities already experiencing multiple dimensions of deprivation. In mitigating these impacts, the paper considers 4 potential regulatory pathways, including: 1) promoting voluntary private-sector commitments to using only renewable energy, 2) encouraging a system of voluntary carbon offsetting, 3) using existing financial regulations and tax frameworks, and 4) imposing national and/or international bans on cryptocurrency ‘mining’. The paper argues that effective environmental regulation of cryptocurrencies is urgently required, both to reduce the threat of catastrophic climate change, and to help the world’s poorest towards sustainable development. However, regulating cryptocurrency mining in any context is likely to require a combination of efforts and is unlikely to result in win-win outcomes for all. ... Moreover, Loviscach proposed two fundamental aspects that must be taken into account in assessing the impact of Bitcoin on the environment: (a) computer power consumption (expressed in kWh) for computing, networking and cooling; (b) disposal of electronic waste produced [68]. Starting from the fact that the mining equipment used to obtain Bitcoin becomes obsolete in about 1.5 years, leaving only those that prove to be economically viable remaining viable, we should also consider how they turn into electronic waste [69], the amount of which is comparable to the total electronic waste generated by a country such as Luxembourg (12 kt) [70]. ... ... De Vries has an international vision of the energy consumption of the Bitcoin network and its ecological implications and concludes that these problems will not be solved only by applying renewable energy and that the only way forward is to change the PoW algorithm with "Proof of Stake" [70]. ... Article Full-text available The controversies surrounding Bitcoin, one of the most frequently used and advertised cryptocurrency, are focused on identifying its qualities, the advantages and disadvantages of using it and, last but not least, its ability to survive over time and become a viable alternative to the traditional currency, taking into account the effects on the environment of the technology used to extract and trade it. Based on such considerations, this article aims to provide an overview of this cryptocurrency, from the perspective of conducting a systematic review of the literature dedicated to the economic and environmental impact of Bitcoin. Using peer-reviewed articles collected from academic databases, we aimed at synthesizing and critically evaluating the points of view in the scientific literature regarding the doctrinal source of the emergence of Bitcoin, the identity of this cryptocurrency from an economic point of view, following its implications on the economic and social environment. Subsequently, this research offers the opportunity of evaluating the level of knowledge considering the impact of Bitcoin mining process on the environment from the perspective of the energy consumption and CO2 emissions, in order to finally analyze Bitcoin regulation and identify possible solutions to reduce the negative impact on the environment and beyond. The findings suggest that, despite high energy consumption and adverse environmental impact, Bitcoin continues to be an instrument used in the economic environment for a variety of purposes. Moreover, the trend of regulating it in various countries shows that the use of Bitcoin is beginning to gain some legitimacy, despite criticism against this cryptocurrency. ... Tokenising physical or digital art via NFTs has enabled ownership to be both indisputably verified using blockchain technology and provided a simplified means of buying and selling such art. Artist Damien Hurst has offered tradeable NFTs that verify the ownership of digital art, 16 while some digital assets, such as YouTube clips and social media posts, have themselves been tokenised, thereby creating a tradeable asset and a store of value. 17 Such content may not have been traditionally thought of as art, but rather part of the digital commons. ... ... This prevents both extreme energy use as well as the incentive to develop specialised (singular purpose) hardware and showcases that blockchain technology does not necessarily have a significant environmental impact." [16] 16 There is scope through a combination of legal, fiscal, and policy tools to encourage a shift in use towards more energy-efficient blockchain, which would also encourage more efficient design of future blockchain platforms. ... Article Full-text available The art industry has commercialised and popularised non-fungible tokens (NFTs), with the volume and value of NFT transactions rapidly growing to US$ 10.7 billion in Q3 2021. The increase in NFT transactions has drawn the attention of the art market to the consequent carbon emissions resulting from verifying transactions in proof-of-work blockchains supporting NFT transactions. With CO2-related deaths attributable to NFT transactions, social pressure from the art market has helped to progress the switch away from the deliberately polluting proof-of-work blockchains to more sustainable consensus protocols. Nonetheless, many popular types of blockchain have resisted the pressure to decrease their environmental impact, including Bitcoin, whose attributed 2021 annual emissions will produce emissions responsible for around 19,000 future deaths. In response, recent global policy interventions have employed legal and fiscal tools to reduce the carbon impact of some or all types of blockchains. Linking the damage caused by proof-of-work blockchains to climate change and human mortality, this study examines the recent policy interventions designed to motivate a shift in blockchain consensus protocols and promote miners' energy efficiency to mitigate environmental damage. This article further explores available policy intervention options that are currently not utilised.
... 3 The ultimate carbon footprint of one Bitcoin transaction compares to New Zealand's annual 37 million tons of CO 2 emission. In comparison, a VISA transaction consumes 0.4 grams of CO 2 , and a Google search equals 0.8 grams (Vries, 2019). Corbet et al. (2019) added to this unfavorable ✩ Acknowledgment: Muhammad Abubakr Naeem gratefully acknowledges the support of Science Foundation Ireland under grant number 16/SPP/3347. ...
Article
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The high power consumption of Bitcoin transactions has raised environmental and sustainable concerns of green investors and regulatory bodies. We utilize the time-varying optimal copula (TVOC) approach to showcase the dependence structure between bitcoin and green financial assets. We find multiple tail-dependence regimes characterize the extreme dependence between bitcoin and green financial assets, and the dependence structure is mainly asymmetric and time-varying. Finally, the hedging effectiveness of green financial assets for bitcoin revealed that all green assets, especially clean energy, are effective hedges for bitcoin.
... According to digiconomist.net [6], as of October 2020, Bitcoin has consumed electrical energy 74.38 TWh per year, which is comparable to the power consumption of Venezuela. The carbon footprint of Bitcoin has reached 35.33 Mt CO 2 per year, comparable to the carbon footprint of New Zealand. ...
Article
Full-text available
Consensus mechanism plays an important role in blockchain. At present, mainstream consensus mechanisms include proof of work (PoW), proof of stake (PoS), and delegated proof of stake (DPoS). PoW, as is widely used in virtual currency, results in significant energy consumption; PoS and DPoS are proposed to reduce energy waste caused by PoW, but their disadvantage is that they tend to create Matthew Effect (ME): “the rich get richer.” In order to balance the discourse power of new nodes and elder ones, this paper proposes a flexible consensus mechanism called proof of engagement (PoE), based on the activity and contribution of network nodes. We analyze the incentive compatibility of PoE from the perspective of mechanism design. In our simulation experiments, we tested the profit changes under PoW, PoS, and PoE. The results illustrate it is easier for new nodes to accumulate their profits under PoE than under PoW or PoS, so as to reduce the negative impacts of ME.
... 11 The success of Bitcoin revealed the drawbacks of PoW. The arms race between the miners led to an enormous energy consumption, [13][14][15][16] and the throughput limited to seven transactions per second limits its scalability. 17 Ethereum is a blockchain popular for its generalized technology on which all transaction-based state machine concepts can be built. ...
Article
Full-text available
Today, the integrity and authenticity of digital documents and data are often hard to verify. Existing public key infrastructures (PKIs) are capable of certifying digital identities but do not provide solutions to store signatures immutably, and the process of certification is often not transparent. We propose Veritaa, a distributed public key infrastructure with an integrated signature store (DPKISS). The central part of Veritaa is the Graph of Trust that manages identity claims and singed declarations between identity claims and document identifiers. An application-specific distributed ledger is used to store the transactions that form the Graph of Trust immutably. For the distributed certification of identity claims, a reputation system based on signed trust declarations and domain vetting is used. In this work, we have designed and implemented the proposed architecture of Veritaa, created a testbed, and performed several experiments. The experiments show the benefits and the high performance of Veritaa.
... The entire network generates as much electronic waste as a country like Luxembourg does annually, which results in an electronic waste footprint of almost 135 g of equipment (equivalent to the weight of an iPhone 12 mini) per transaction processed on the Bitcoin network. 6 This equipment is primarily made of aluminum, copper, iron, and rare earths. Low waste collection and recycling rates in countries with high mining activity create the risk of toxic chemicals and heavy metals leaching into soils and causing air and water pollution. ...
Article
The digital currency Bitcoin is known for its energy hunger and associated carbon footprint. Investors, how-ever, must not neglect further environmental, social, and governance issues related to digital currencies. Therefore, we urge the adoption of a more comprehensive view in assessing the externalities of investments in Bitcoin and other cryptocurrencies.
... Over the course of 2019, the network processed 120 million transactions (Blockchain, 2020), while traditional payment service providers processed about 539 billion transactions (Capgemini, 2019). Dividing emissions estimates by the number of transactions yields a carbon footprint in the range between 233.4 and 363.5 kg of CO 2 per Bitcoin transaction (de Vries, 2019). It is noteworthy that such annual estimates as depicted in Fig. 1 are typically based on results at a certain day assuming those daily conditions persisted for a year to facilitate comparisons with other emitting activities or national emissions on country level. ...
Article
Bitcoin’s increasing energy consumption has triggered a passionate debate about the sustainability of the digital currency. And yet, most studies have thus far ignored that Bitcoin miners cycle through a growing amount of short-lived hardware that could exacerbate the growth in global electronic waste. E-waste represents a growing threat to our environment, from toxic chemicals and heavy metals leaching into soils, to air and water pollutions caused by improper recycling. Here we present a methodology to estimate Bitcoin’s e-waste and find that it adds up to 30.7 metric kilotons per annum, per May 2021. This number is comparable to the amount of small IT and telecommunication equipment waste produced by a country like the Netherlands. At peak Bitcoin price levels seen early in 2021, the annual amount of e-waste may grow beyond 64.4 metric kilotons in the midterm, which highlights the dynamic trend if the Bitcoin price rises further. Moreover, the demand for mining hardware already today disrupts the global semiconductor supply chain. The strategies we present may help to mitigate Bitcoin’s growing e-waste problem.
... de Vries et al. [40] found that bitcoin mining generates lots of hardware waste or e-waste: 30.7 metric kilotons annually as of May 2021. de Vries [39] estimated mining equipment to become obsolete in roughly 1.5 years. ...
Conference Paper
We analyzed the Bitcoin difficulty data and noticed that the difficulty has been around the level of $$10^{13}$$ for three years (H2 2018 - H1 2021). Our calculation showed about $$10^{28}$$ hashes have been generated during bitcoin mining around the world for securing the addition of 703,364 blocks to the Bitcoin blockchain. We introduced a concept of Recycling Hashes in the hope to (a) jump-start bespoke silicon (customized silicon) for reversible computing, (b) open up the possibility of Bitcoin's Proof-of-Work to be less energy-consuming in the future, (c) provide scientific value or new services, in the form of entropy pool or random numbers, to Internet users while still achieving the security level of Bitcoin of today, (d) decrease the old mining hardware e-waste by using them to recycle hashes to the entropy pool, and (e) solve the problem of low mining rewards. We found that the bit rates of the current irreversible bitcoin miners are millions of times as high as the existing Internet connections, so it would be difficult to send all the hashes generated in real-time via the Internet. Even if only 0.000000355$$\%$$ of the hashes can be recycled, it would still mean that $$355\cdot 10^{18}$$ hashes (355 EH) would have been recycled since the beginning of Bitcoin. Storing all the hashes, so far, would need storage of $$2.560\cdot 10^{30}$$ bits, and it is not currently possible to keep all of them. Our simulation of 10,000 bitcoin hashes showed that the occurrences of zeros and ones in bitcoin hashes are almost 50$$\%$$ and 50$$\%$$, so it is an encouraging finding for seeding the Pseudorandom Number Generators. We also proposed a second coin for the Bitcoin blockchain, an inflationary coin with a different currency unit (BTCi), to motivate the entropy providers to keep the old mining hardware online. The proposed second coin might keep Bitcoin's security model safe in the future when the deflationary bitcoin (BTC or BTCd) block reward is becoming too low.
... As for the future energy demand, a first possible source of future increases is the proliferation of blockchain technology applications and cryptocurrencies, notably the bitcoin, e.g., [36]. However, [37] argues that the problem just affects bitcoin, since blockchain technology can be implemented much more efficiently than has been up to now. A second possible source is an increase in telecommunications services and applications [38,39]. ...
Article
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The primary purpose of this research is to assess the long-range energy demand assumption made in relevant Roadmaps for the transformation to a low-carbon energy system. A novel interdisciplinary approach is then implemented: a new model is estimated for the aggregated world primary energy demand with long historical time series for world energy, income, and population for the years 1900–2017. The model is used to forecast energy demand in 2050 and assess the uncertainty-derived risk based on the variances of the series and parameters analysed. The results show that large efficiency savings—up to 50% in some cases and never observed before—are assumed in the main Roadmaps. This discrepancy becomes significantly higher when even moderate uncertainty assumptions are taken into account. A discussion on possible future sources of breaks in current patterns of energy supply and demand is also presented, leading to a new conclusion requiring an active political stance to accelerate efficiency savings and lifestyle changes that reduce energy demand, even if energy consumption may be reduced significantly. This will likely include replacing the income-growth paradigm with other criteria based on prosperity or related measures.
... 12 Moreover, specialized Bitcoin mining devices cannot be repurposed, potentially resulting in a substantial amount of electronic waste once they become obsolete in several years' time. 8 On top of the environmental impact of cryptocurrency mining, the effects of the sector's energy-hunger may also spill over to other parts of the economy. Prior to the latest surge in Bitcoin price, it was already reported that there was a global shortage of chips for an array of electronic devices. ...
Article
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As the price of Bitcoin rises, the negatively externalities associated with Bitcoin mining increase in kind. This article shows how a simple economic model may be used to estimate the potential environmental impact of Bitcoin mining for a given Bitcoin price. These estimates reveal that the record-breaking surge in Bitcoin price at the start of 2021 may result in the network consuming as much energy as all data centers globally, with an associated carbon footprint matching London’s footprint size.
... To model this, every week the least efficient 1% of the hashrate is replaced with the most efficient hardware. This means that all ASICs are replaced every 2 years, which is close to an often cited hardware lifetime of 1.5 years [78]. ...
Thesis
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Much confusion and uncertainty exists about Bitcoin's-and by extension all cryptocurrencies'-carbon footprint. Although it is impossible to calculate the exact carbon footprint of cryptocurrencies, due to their decentralized nature, it is possible to make some fair predictions. This work proposes a method to estimate both the electricity consumption of and the e-waste generated by the cryptomarket industry, and convert them to emissions. Furthermore, an approach to estimating future consumption in function of the price is developed. We estimate that the cryptocurrency market consumes on average 80 TWh/year, with an average lower and upper bound of respectively 35.7 and 150.6 TWh/year. Between June 2019 and June 2020, we estimate that 27.1 kilotons of e-waste were produced by mining ASICs, and during the same period, 2.92 million new ASICs were produced. By using geographic mining data and an extensive study of the used electricity mixes, we calculate that per kWh of electricity consumed for mining, 473.64 g CO 2-eq is emitted. This results in an average carbon intensity of 38 million tonnes CO 2-eq per year for the used electricity. Finally , an extra 1.27 million tonnes is added by the creation of ASICs.
... Bitcoin mining involves solving computationally complex cryptographic puzzles linked to blockchain transaction verification, which requires high-end and energy-intensive computational systems for extended durations (Bitcoin Energy Consumption Index, 2021). The empirical evidence suggests that energy consumption is not the only weakness of the Bitcoin mining process (de Vries, 2019). Due to excessive returns, the growing attractiveness of Bitcoin mining has been engaging many participants in mining competition. ...
Article
The Bitcoin mining hosted in the blockchain network consumes enormous amounts of energy and generates electronic waste at an alarming rate. The paper aims to model and predict the future values of these two hazardous variables linked to conventional Bitcoin mining. We develop two predictive models using Facebook's Prophet algorithm and deep neural networks to identify and explain energy consumption and electronic waste generation patterns. The models rely on several explanatory features linked to the blockchain microstructure and the Bitcoin marketplace. We assess the predictive performance of the two models based on daily data of energy consumption and electronic waste generation and eleven key input features. We use local interpretable model-agnostic explanation (LIME) and Shapley additive explanation (SHAP) for explaining how these inputs can predict and control energy consumption and electronic waste generation. The findings assist in accurately estimating the future figures of energy discharge and electronic waste accumulation in the present Bitcoin mining setup. The study also reveals the block size to be the major driver.
... On the other hand, the digiconomist's results prove that the development of cryptocurrency could lead to huge environmental issues. De Vries [55] believes that these environmental dilemmas will not be solved by renewable and sustainable energy and suggested changing the POW algorithm with "Proof of Stake" (POS) as the best solution. The POS protocol was proposed by ETH, the world's second-largest digital coin behind BTC. ...
Article
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Due to the impressive growth in digital coins trading, most cryptocurrencies' market cap has increased drastically. Therefore, more people are engaged in the mining process, causing a significant increase in electrical power consumption. To make cryptocurrency technology sustainable, using renewables such as photovoltaic solar power, wind energy, tidal power, geothermal power, hydroelectric power, fuel cell, and biomass has been implemented. Moreover, to decrease electrical power consumption in the cooling process of mining systems and computers, using phase change material (PCM) has been recommended. Since the cryptocurrency mining process is very competitive, only those miners will survive who employ the most competitive mining systems and benefit from the lowest electrical power costs. While the profitability of renewable electricity-based mining is lower than grid-based mining, the latter method compensates for better sustainability in cryptocurrency and lower environmental costs. This paper reviews the possible ways to make the cryptocurrency mining process clean and environmentally friendly.
... We also restrict our consideration of digital finance to two particular forms. The first is the use of cryptocurrencies based on proof-of-work and blockchain technology, such as bitcoin, because they are currently viewed as the tool with the highest CO2 emissions among forms of digital finance (de Vries, 2019). Of course, bitcoin is less used in SSA countries than in other countries, but the impact of CO2 is by nature a global externality; hence, it is interesting to study these countries' contribution to this externality. ...
Conference Paper
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Sub-Saharan African (SSA) countries are increasingly adopting digital finance, which generally represents a positive driver of development and growth. However, the digital finance sector is known to be a source of large CO2 emissions, thereby contributing to climate change, and SSA countries will likely be the ones that suffer most from climate change. This constitutes a negative channel through which digital finance could impair development. This article aims to disentangle these two channels to assess which effect prevails overall. We analyse the impact of mobile money and bitcoin on the Human Development Index (HDI). We find that mobile money mitigates the negative impact of CO2 emissions. Globally, through its interaction with CO2 emissions, mobile money has a positive impact on development. In contrast, we find weak evidence concerning bitcoin. On its own, bitcoin has a negative impact on HDI. JEL Classification: Q43; Q54; G23; E42; O14; O16; O55
... The purported advantages of Bitcoin are dwarfed by the intentionally resourceintensive design in its transaction verification process which threatens the environment integral to our survival. 7 Environmental science and engineering studies have estimated the detrimental environmental impacts of cryptomining (e.g., Li et al., 2019;de Vries, 2019;Truby, 2018). Again, this is a manifestation of the impossibility triangle: for a large-scale decentralized system, generating consensus could be very costly. ...
Article
The concept of zero waste is an ideal situation that will require different solutions for different categories of waste. Electronic waste (E-waste), the fastest growing category of solid hazardous waste presents various unique challenges. Electronic product repair, reuse and remanufacture (3re) are crucial for effective source reduction of E-waste and the integration of the electronics industry into a circular or zero-waste economy framework. Increasingly, 3re implementation is restricted by regulatory difficulties, particularly the invocation of copyright laws. Here, we use the examples of electronic printer cartridges and restored compact discs (CDs) to identify the challenges and to explore solutions for managing the risks associated with E-waste through circular economy and the opportunities presented by innovative Blockchain solutions. A set of international consensuses on judicial definitions, such as 3re, refurbish fake/counterfeit product and copyright exhaustion, are proposed to accelerate source reduction in E-waste management toward the goal of zero waste.
Article
Cryptocurrencies employ different consensus protocols to verify transactions. While the “proof-of-work” consensus protocol is the most energy-consuming protocol, “proof-of-stake” and the hybrid of these two consensus protocols, which consume considerably less energy, have also been introduced. We employ portfolio analysis to explore whether energy is a fundamental economic factor affecting cryptocurrency prices. Surprisingly, our results suggest that, on average, cryptocurrencies employing proof-of-work consensus protocols do not generate returns that are significantly different from those that incorporate proof-of-stake consensus protocols. Even more surprising is that our results show that cryptocurrencies that incorporate the hybrid version of these consensus protocols generate significantly higher average returns than the other groups. A possible explanation for this phenomenon may be that the cryptocurrency market is still driven by the trust factor rather than the energy factor.
Article
This paper presents an overview of the main developments of cryptocurrencies and discusses their future perspectives. First, it briefly reviews the history of cryptocurrencies since the creation of Bitcoin, presents the main market trends, and discusses the key features of cryptocurrencies in the context of blockchain. Second, it analyses current cryptocurrency projects, like the Libra project, and other applications of the blockchain technology. Third, it presents a systematic economics and financial literature review on cryptocurrencies. Fourth, it examines the challenges, benefits, and future perspectives of cryptocurrencies and blockchain technology, with a focus on the environmental issues and central bank digital currencies.
Article
This article presents an overview of the main developments of cryptocurrencies and discusses their future perspectives. First, it briefly reviews the history of cryptocurrencies since the creation of Bitcoin, presents the main market trends, and discusses the key features of cryptocurrencies in the context of blockchain. Second, it analyses current cryptocurrency projects, like the Libra project, and other applications of the blockchain technology. Third, it presents a systematic economics and financial literature review on cryptocurrencies. Fourth, it examines the challenges, benefits, and future perspectives of cryptocurrencies and blockchain technology, with a focus on the environmental issues and central bank digital currencies.
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Supplementary information for the manuscript 'Machine Learning the Carbon Footprint of Bitcoin Mining'.
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The paper deals with the cryptoeconomy impact on the environment. The term 'cryptoeconomy' is used for designating the emerging industry around cryptocurrencies and blockchain. Cryptocurrency mining consumes a lot of electricity. As of September 2019, the estimated annual miners' electricity consumption was 78.93 TWh. According to the upper boundary estimation, miners' carbon dioxide emissions were about 80.43 million tons of CO2, which corresponds to 0.24% of the world's total carbon dioxide emissions. The aim of this paper is to develop bitcoin mining carbon footprint estimation methodology. The suggested method is based on the miners' geographical distribution obtained by analyzing the traffic of mining pools login pages. The methodology includes 1) assessment of the miners' geographical distribution; 2) estimation of the miners' carbon dioxide emissions by regions. According to the proposed methodology, miners' carbon dioxide emissions are about 44.12 million tons per year (0.13% of the world's total emissions), which is two times lower than the upper boundary estimate.
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This commentary considers the challenges and trade-offs in using blockchain as the facilitating digital infrastructure for degrowth projects. A blockchain is simply a distributed database. The technology is being used for a wide range of applications relevant to economic exchange and environmental sustainability. Many degrowth scholars wholly reject technical fixes for politically induced environmental crises, seeing blockchain projects as wasteful and counter to convivial social relations. Others highlight the technology's potential for facilitating redistributive and regenerative economies, but without much detail. This paper argues that if blockchain is ever to prove useful for the degrowth movement it would need to overcome challenges in three important areas: 1) building democratic and (re)distributive economies, 2) regenerating the environment without commodifying it, and 3) facilitating international alliances without imposing a particular set of values. What is certain is that technology on its own will not transcend the political struggles tackled by degrowth activists. However, under certain conditions, blockchain might make those struggles more effective.
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This research aims to design a model to forecast and simulate aggregated world energy demand at distant horizons in time. This is done by estimating statistically a simplified interrelated model for the three variables considered, total primary Energy, world population and GDP. The approach intends to offer a complementary perspective to current practice, based on simulating energy demand conditional on GDP and population. The model is based on long historical series spanning the years (1900;2017) available from renowned researchers and institutions in their respective fields. The estimated models allow a forecast of future energy demand and a risk/sensitivity analysis. Alternative solutions and simulation methods are carried out to assess the robustness of the results derived. These forecasts are compared to the results of key relevant roadmaps put forward in the literature - in the range (330;408) EJ/yr for final energy consumption -, the general conclusion being that the aforementioned roadmaps assume sizeable efficiency savings, relying mainly on electrification and renewable energies deployment, that depart significantly from historical trends embodied in the model estimated - 900 EJ/yr on average, and 600 EJ/yr under favourable assumptions. These results jeopardise the unbounded GDP-growth paradigm, suggesting a replacement by alternative welfare measures as suggested by the UN human development index, the prosperity approach, and related standards.
Conference Paper
In this paper, a technological assessment of a solar PV collector system for freshwater, cooling and electricity is evaluated. Technological assessment is made via use of energy and exergy analyses and system performance is carried out in terms of exergetic and energetic efficiencies. Desalination of water is carried out by employing freezing defreezing technique run by the evaporator of a vapor compression cycle. The heat from the PV is utilized for defreezing the water. A parametric study is carried out to see the effect of key parameters such as ambient temperature, evaporator temperature, and mass flow rate of freshwater. Analysis shows that system attains an energetic efficiency of 19.2% whilst exergetic efficiency as 7.5%. The system produces a net electric power of 4.7 kW and freshwater of 54 liter per hour.
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The impacts of climate change are increasingly felt globally, leading to an increasing demand of funding needs for climate change mitigation and conservation efforts, more specifically by emerging and low-income economies. While there are numerous mechanisms that have been proposed, their implementation have been slow, warranting the need for additional support mechanisms that are both innovative and can gain the trust of both private and institutional funders. One emerging asset which may offer a new structural perspective on this subject is that of cryptocurrencies, particularly bitcoin, where their increasing popularity is providing a new perspective on their prospects and on the evaluation of digital assets. This chapter thus offers a parallel between cryptocurrencies and questions their potential application in the funding of climate change and conservation efforts.
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The paper considers technical feasibility of the direct monetization of casing-head gas, which is being flared now. The proposed approach is based on the technology of low-temperature steam conversion of hydrocarbons, which makes it possible to enhance the quality of flame gases to comply with the requirements on a fuel for gas-piston and gas-turbine power stations. The synthesis and performance of advanced rhodium catalysts for the low-temperature steam conversion of flame gas are discussed. For such catalysts, mixed cerium-zirconium oxides are most promising as the supports. The indicated catalysts have some advantages over the well-studied nickel catalysts in the low-temperature steam conversion of hydrocarbons.
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The “circular economy” practices within the concept of sustainability offer solutions to the problem of uncontrolled production and irresponsible consumption that the world is trying to overcome. Approaches are being developed within the framework of circular economy in many areas from economy to environment, from education to local government policies, from finance to trade. The book “Circular Economy and Sustainable Living” discusses the circular economy conceptually and questions its necessity. Afterwards, it focuses on the applications of this concept with chapters written by experts in the field. The peculiarity of this book is that it does not focus solely on the definition of the circular economy. Besides economic issues such as capital markets, value chains, labor market, cryptocurrencies, management of enterprises, the book also includes practices in education and environment. We hope that the book will contribute to the solution of the global economic and environmental problems experienced by the world with detections and suggestions.
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Building on an economic model of rational Bitcoin mining, we measured the carbon footprint of Bitcoin mining power consumption using feed-forward neural networks. We found associated carbon footprints of 2.77, 16.08 and 14.99 MtCO2e for 2017, 2018 and 2019 based on a novel bottom-up approach, which (i) conform with recent estimates, (ii) lie within the economic model bounds while (iii) delivering much narrower prediction intervals and yet (iv) raise alarming concerns, given recent evidence (e.g., from climate–weather integrated models). We demonstrate how machine learning methods can contribute to not-for-profit pressing societal issues, such as global warming, where data complexity and availability can be overcome.
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Exergetic and environmental metrics of aircraft engines are topics of paramount importance for studies examining the effects of fuel consumption & combustion on environment. Therefore, it is important to quantify these parameters so as to predict the extent of environmental impact originated from aircraft engines such as turbofans. In this study, effects of turbine inlet temperature (TIT) varying between 1450-1550 K and high pressure compressor pressure ratio (HPC PR) varying between 7.5-8.5 on several thermodynamics metrics of the turbofan engine producing thrust of 110 kN are parametrically analyzed for thirty-six cases. According to the exergetic evaluations, exergy efficiency of the turbofan engine varies between 33.46% and 36.78%, whereas the specific irreversibility production (SIP) of the engine varies between 0.1676 MW/kN and 0.1752 MW/kN due to variation of TIT and HPC PR.
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In view of the continuous debates on the environmental impact of blockchain technologies, in particular, crypto currency mining, accompanied by severe carbon dioxide emissions, a technical solution has been considered assuming direct monetization of associated petroleum gas currently being flared. The proposed approach is based on the technology of low-temperature steam reforming of hydrocarbons, which allows flare gas conditioning towards the requirements for fuel for gas piston and gas turbine power plants. The generation of electricity directly at the oil field and its use for on-site crypto currency mining transforms the process of wasteful flaring of valuable hydrocarbons into an economically attractive integrated processing of natural resources. The process is not carbon neutral and is not intended to compete zero-emission technologies, but its combination with technologies for carbon dioxide capture and re-injection into the oil reservoir can both enhance the oil recovery and reduce carbon dioxide emissions into the atmosphere. The produced gas can be used for local transport needs, while the generated heat and electricity can be utilized for on-site food production and biological carbon dioxide capture in vertical greenhouse farms. The suggested approach allows significant decrease in the carbon dioxide emissions at oil fields and, although it may seem paradoxically, on-site cryptocurrency mining actually may lead to a decrease in the carbon footprint. The amount of captured CO2 could be transformed into CO2 emission quotas, which can be spent for the production of virtually “blue” hydrogen by steam reforming of natural gas in locations where the CO2 capture is technically impossible and/or unprofitable.
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With the increasing use of information technologies (IT) their opportunities to ensure environmental sustainability and the risks of their widespread adoption are growing. And if the possibilities have been studied well enough, then the risks have been paid attention to relatively recently. However, awareness of these risks is becoming increasingly important with the spread of technologies. Currently, there are already hundreds of cryptocurrencies, and the technological basis for many of these currencies is the blockchain—a digital ledger of transactions. This article has assessed the environmental burden of mining and supporting transactions in the cryptocurrency market in Russia using CO2-equivalent. For this, for the first time, the amount of electricity consumed to support cryptocurrency transactions in Russia was calculated, data on the largest cryptocurrency mining centres were collected and systematized, and the main factors for the placement of both large and small private farms were determined. Based on the collected data a map of the spread of mining centres in Russia was created. Our analysis showed that on average, 2.977 million tons of CO2 equivalent are emitted in Bitcoin production in Russia, and the total emissions from cryptocurrency mining in Russia are 4.466 million tons of CO2 equivalent. Based on our data on environmental damage, we believe that when deciding on the use of blockchain technology, not only its capabilities should be taken into account, but also an assessment of the ratio of potential benefits and impact on the environment. A systematic understanding of interrelated direct and indirect impacts is needed to make decisions on the use of blockchain, since the technology shows itself as potentially one of the most energy and resource intensive.
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In this paper, we critique ICT's current and projected climate impacts. Peer-reviewed studies estimate ICT's current share of global greenhouse gas (GHG) emissions at 1.8%–2.8% of global GHG emissions; adjusting for truncation of supply chain pathways, we find that this share could actually be between 2.1% and 3.9%. For ICT's future emissions, we explore assumptions underlying analysts' projections to understand the reasons for their variability. All analysts agree that ICT emissions will not reduce without major concerted efforts involving broad political and industrial action. We provide three reasons to believe ICT emissions are going to increase barring intervention and find that not all carbon pledges in the ICT sector are ambitious enough to meet climate targets. We explore the underdevelopment of policy mechanisms for enforcing sector-wide compliance, and contend that, without a global carbon constraint, a new regulatory framework is required to keep the ICT sector's footprint aligned with the Paris Agreement.
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This paper investigates the relationship between the bitcoin price and the hashrate by disentangling the effects of the energy efficiency of the bitcoin mining equipment, bitcoin halving, and of structural breaks on the price dynamics. For this purpose, we propose a methodology based on exponential smoothing to model the dynamics of the Bitcoin network energy efficiency. We consider either directly the hashrate or the bitcoin cost-of-production model (CPM) as a proxy for the hashrate, to take any nonlinearity into account. In the first examined subsample (01/08/2016–04/12/2017), the hashrate and the CPMs were never significant, while a significant cointegration relationship was found in the second subsample (11/12/2017–24/02/2020). The empirical evidence shows that it is better to consider the hashrate directly rather than its proxy represented by the CPM when modeling its relationship with the bitcoin price. Moreover, the causality is always unidirectional going from the bitcoin price to the hashrate (or its proxies), with lags ranging from one week up to six weeks later. These findings are consistent with a large literature in energy economics, which showed that oil and gas returns affect the purchase of the drilling rigs with a delay of up to three months, whereas the impact of changes in the rig count on oil and gas returns is limited or not significant.
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The electricity that is expended in the process of mining Bitcoin has become a topic of heavy debate over the past few years. It is a process that makes Bitcoin extremely energy-hungry by design, as the currency requires a huge amount of hash calculations for its ultimate goal of processing financial transactions without intermediaries (peer-to-peer). The primary fuel for each of these calculations is electricity. The Bitcoin network can be estimated to consume at least 2.55 gigawatts of electricity currently, and potentially 7.67 gigawatts in the future, making it comparable with countries such as Ireland (3.1 gigawatts) and Austria (8.2 gigawatts). Economic models tell us that Bitcoin’s electricity consumption will gravitate toward the latter number. A look at Bitcoin miner production estimates suggests that this number could already be reached in 2018.
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The electrical efficiency of computation has doubled roughly every year and a half for more than six decades, a pace of change comparable to that for computer performance and electrical efficiency in the microprocessor era. These efficiency improvements enabled the creation of laptops, smart phones, wireless sensors, and other mobile computing devices, with many more such innovations yet to come. The Web Extra appendix outlines the data and methods used in this study.
Article
Existing studies on the evaluation of CO2 emissions due to electricity consumption in China are inaccurate and incomplete. This study uses a network approach to calculate CO2 emissions of purchased electricity in Chinese provinces. The CO2 emission factors of purchased electricity range from 265 g/kWh in Sichuan to 947 g/kWh in Inner Mongolia. We find that emission factors of purchased electricity in many provinces are quite different from the emission factors of electricity generation. This indicates the importance of the network approach in accurately reflecting embodied emissions. We also observe substantial variations of emissions factors of purchased electricity within sub-national grids: the provincial emission factors deviate from the corresponding sub-national-grid averages from -58% to 44%. This implies that using sub-national-grid averages as required by Chinese government agencies can be quite inaccurate for reporting indirect CO2 emissions of enterprises' purchased electricity. The network approach can improve the accuracy of the quantification of embodied emissions in purchased electricity and emission flows embodied in electricity transmission.
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A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power. As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. The network itself requires minimal structure. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.
An order-ofmagnitude estimate of the relative sustainability of the Bitcoin Network
• H Mccook
McCook, H. (2014). An order-ofmagnitude estimate of the relative sustainability of the Bitcoin Network. https://bitcoin.fr/public/ divers/docs/Estimation_de_la_ durabilite_et_du_cout_du_reseau_ Bitcoin.pdf.
How Chainalysis helps solve crimes: Jonathan Levin tells all -Ep
Forbes. (2018). How Chainalysis helps solve crimes: Jonathan Levin tells all -Ep.62. http://unchained.forbes.libsynpro.com/ how-chainalysis-helps-solve-crimesjonathan-levin-tells-all-ep62.
The Global E-waste Monitor -2017
• C P Baldé
• V Forti
• V Gray
• R Kuehr
• P Stegmann
Baldé, C.P., Forti, V., Gray, V., Kuehr, R., and Stegmann, P.. The Global E-waste Monitor -2017. http://collections.unu.edu/ eserv/UNU:6341/Global-E-waste_ Monitor_2017__electronic_single_ pages_.pdf.
Inside Visa's Data Center
• T Kontzer
Kontzer, T. (2013). Inside Visa's Data Center. Netw Comput.. https:// www.networkcomputing.com/ networking/inside-visas-datacenter 15. VISA (2018). Annual Report 2018. https://s1. q4cdn.com/050606653/files/doc_financials/ annual/2018/Visa-2018-Annual-Report-FINAL. pdf.
The Netherlands *Correspondence: alex.de.vries@pwc
Experience Center of PwC, Amsterdam, The Netherlands *Correspondence: alex.de.vries@pwc.com https://doi.org/10.1016/j.joule.2019.02.007
• Bnp Capgemini
• Paribas
Capgemini, BNP Paribas (2018). World Payments Report 2018. https:// worldpaymentsreport.com/wp-content/ uploads/sites/5/2018/10/World-Payments-Report-2018.pdf.
• C Bendiksen
• S Gibbons
• E Lim
Bendiksen, C., Gibbons, S., and Lim, E.; The Bitcoin Mining Network (2018). Coinshares. https://coinshares.co.uk/wp-content/ uploads/2018/11/Mining-Whitepaper-Final. pdf.