The digital currency industry’s electricity consumption is equivalent to that of an average European country
Andrey Rudakov / Bloomberg via Getty Images
Mining cryptocurrencies, especially Bitcoin, the oldest and most successful digital currency, requires vast amounts of energy and contributes significantly to greenhouse gas emissions. Energy expenditure in the sector increased approximately 34-fold between 2015 and 2023, reaching 121 terawatt-hours (TWh), equivalent to the consumption of an average European country, such as Poland. Demand is expected to increase by a further 40% by 2026, predicts the International Energy Agency (IEA).
“Executing a single Bitcoin transaction equates approximately to the greenhouse gas emissions of a moderate-sized electric or gasoline engine sedan vehicle traveling between 1,600 and 2,600 km,” state the authors of the article “Carbon footprint of global bitcoin mining: Emissions beyond borders,” published in the journal Sustainability Science in January.
The energy consumption is so high due to competition between miners, who are part of the cryptocurrency industry. To validate a block of cryptocurrency transactions, miners try to solve a mathematical problem as quickly as possible, a process called proof-of-work (PoW). The miner who solves the equation first receives bitcoins as payment. Performed by thousands of computers around the world, these calculations ensure the reliability of digital currency purchase and sale operations, but they consume a lot of energy.
“The problem is the consensus method used by Bitcoin: PoW. Although it is distributed [run by multiple computers in different locations] and reliable, it uses too much energy. Miners will always try to use the cheapest possible energy source, which may not always be clean and renewable,” says computer scientist Arlindo Flavio da Conceição of the Institute of Science and Technology at the Federal University of São Paulo (UNIFESP), São Jose dos Campos campus.
A few years ago, the cryptocurrency Ethereum migrated from proof-of-work to another consensus mechanism known as proof-of-stake (PoS), reducing energy consumption by 99%. “The problem is that to modify the core algorithm of a cryptocurrency, the community needs to agree—and the people operating with Bitcoin cannot agree because they are worried that any mistake that might occur in the migration process would affect the currency’s price,” says Conceição, coauthor of the book Blockchain: Conceitos básicos (Blockchain: Basic concepts; independently published, 2020).
In PoS, participants called validators are randomly chosen to verify and add blocks to the blockchain (a type of digital ledger), dispensing with the need for competition between them, as occurs in PoW. “With minimal energy consumption, PoS has a much smaller carbon footprint, making it better aligned with sustainability goals,” concludes the Sustainability Science article, written by researchers from Qatar, the USA, and Canada.
The story above was published with the title “Cryptocurrencies take a toll” in issue in issue 349 of march/2025.
Scientific articles
ONAT, N. C. et al. Carbon footprint of global bitcoin mining: Emissions beyond borders. Sustainability Science. Vol. 20, pp. 173–89. Jan. 2025.
Book
CONCEIÇÃO, A. F. & ROCHA, V. E. M. Blockchain: Conceitos básicos. Independent edition. Apr. 2020.
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