CORRESPONDENCE

Bitcoin’s alarming carbon footprint

PPC Renewables, Athens, Greece.
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The ‘mining’ process for the cryptocurrency bitcoin is power hungry, and is increasing its environmental impact as its price and popularity rise. Cryptocurrencies are generated by specialized software, used to solve complex mathematical problems that represent proof-of-work algorithms in exchange for electronic coins (see https://bitcoin.org/bitcoin.pdf).

Some estimate that the combined electricity consumption for bitcoin and ethereum mining, which together represent 88% of the total cryptocurrency market capitalization (G. Hileman and M. Rauchs http://doi.org/cj22; 2017), has already reached a staggering 47 terawatt-hours per year and is on the rise (see www.digiconomist.net). To put this into perspective, Greece’s population of 11 million consumes close to 57 terawatt-hours annually.

Moreover, 58% of all cryptocurrency mining is done in China and is typically powered by coal plants. Using the life-cycle impact-assessment methodology, I estimate that the annual carbon footprint for bitcoin and ethereum mining is comparable to that of some 6.8 million average European inhabitants — or as much as 43.9 million tonnes of carbon dioxide equivalent (see ReCiPe and IPCC 2013 methods, respectively, at go.nature.com/2nn7zzj).

In my opinion, the cryptocurrency industry is urgently in need of reform to make it environmentally sustainable.

Nature 554, 169 (2018)

doi: 10.1038/d41586-018-01625-x
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