Bitcoin: electricity consumption comparable to that of Poland

In 2024, the price of bit­coin soared, reach­ing its highest levels since its cre­ation. Bit­coin is the most widely used crypto­cur­rency. Its mar­ket cap­it­al­isa­tion reached over $1.3 tril­lion on Octo­ber 21, 2024, com­pared with Ethereum’s $321 bil­lion just behind. One bit­coin is worth over $67,000 (as of Octo­ber 21, 2024). This surge has an envir­on­ment­al cost, which is also rising sharply. “Bit­coin is based on block­chain tech­no­logy: by defin­i­tion, com­puters per­form identic­al cal­cu­la­tions (around 15,000 times) to ensure the network’s secur­ity,” explains Jean-Paul Dela­haye. “The pro­tocol used for bit­coin has a very high energy cost; it’s an envir­on­ment­al waste.”

The annu­al elec­tri­city con­sump­tion ded­ic­ated to bit­coin min­ing [Editor’s note: the pro­cess by which bit­coins are issued and gen­er­ated] is com­par­able to that of Poland. It is estim­ated at 155 TWh per year to 172 TWh per year (or 162 TWh per year accord­ing to the Cam­bridge Centre for Altern­at­ive Fin­ance). The Inter­na­tion­al Energy Agency (IEA), mean­while, estim­ates that crypto­cur­ren­cies would have con­sumed 110 TWh of elec­tri­city by 2022, or 0.4% of annu­al glob­al demand¹.

As a res­ult, bitcoin’s car­bon foot­print is sig­ni­fic­ant, and some sci­ent­ists are warn­ing of the urgent need for action². In 2021, bitcoin’s envir­on­ment­al foot­print sud­denly increased. While the major­ity of miners were based in China (73%), the coun­try decided to ban bit­coin min­ing on its ter­rit­ory³. Most of the activ­ity is now relo­cated to Kaza­kh­stan and the United States. The car­bon foot­print of bit­coin min­ing is dir­ectly linked to the green­house gases released dur­ing the pro­duc­tion of the elec­tri­city that powers the com­puters per­form­ing the cal­cu­la­tions. The more car­bon-intens­ive the country’s elec­tri­city mix, the high­er bitcoin’s car­bon foot­print. The share of renew­able ener­gies power­ing bit­coin min­ing has fallen from 41.6% to 25.1% fol­low­ing the massive relo­ca­tion in 2021. In 2022, the Cam­bridge Cen­ter for Altern­at­ive Fin­ance estim­ates the share of renew­ables at 37.6% includ­ing nuc­le­ar power and 26.3% exclud­ing nuc­le­ar power ⁴. As a res­ult, CO₂ emis­sions from bit­coin min­ing are estim­ated at 77, 85 or even 96 mil­lion tonnes of CO₂ per year, depend­ing on the source. By com­par­is­on, France’s equi­val­ent CO₂ emis­sions (all green­house gases com­bined) will amount to 385 mil­lion tonnes in 2023.

But the envir­on­ment­al impact of bit­coin min­ing is not lim­ited to green­house gas emis­sions. In 2024, an art­icle pub­lished in the journ­al Cell Reports sus­tain­ab­il­ity⁵ estim­ates the water foot­print of the crypto­cur­rency. The author estim­ates that it will amount to 1.5 bil­lion litres of water in 2021. The cul­prit? The use of water for the cool­ing sys­tems of the serv­ers used for min­ing, and indir­ect use to pro­duce elec­tri­city via the cool­ing of ther­mo­elec­tric power sta­tions. Oth­er authors arrive at dif­fer­ent estim­ates based on the envir­on­ment­al foot­print of elec­tri­city pro­duc­tion in the coun­tries host­ing bit­coin miners. Their estim­ates are much high­er, due to the inclu­sion of evap­or­a­tion from hydro­elec­tric dams. They estim­ate bitcoin’s water foot­print at 1,650 bil­lion litres between Janu­ary 2020 and Decem­ber 2021 (the equi­val­ent of 660,000 Olympic swim­ming pools), or around 800 bil­lion litres per year. “I find the decision to include evap­or­a­tion from hydro­elec­tric dams in the water foot­print of bit­coin min­ing a del­ic­ate one,” says Jean-Paul Dela­haye. “It’s dif­fi­cult to dis­tin­guish between water used for bit­coin and oth­er uses.” As for the land foot­print, for the same peri­od it was estim­ated at 1,870 km².

It is dif­fi­cult to accur­ately cal­cu­late the envir­on­ment­al impact of bit­coin min­ing. There is no register of the machines used for min­ing and their exact energy con­sump­tion. “How­ever, we do have a min­im­um estim­ate, which is enough to show that energy con­sump­tion is excess­ive,” asserts Jean-Paul Dela­haye. The estim­ates are based on the “hash” com­put­ing power of the net­work – known to with­in a few per­cent – and on the min­im­um con­sump­tion by the best machines to pro­duce 1 hash, which is an optim­ist­ic view of the hard­ware in use. “There are two main meth­od­o­lo­gies that have been developed in recent years to assess the energy con­sump­tion of the bit­coin net­work, one based on eco­nom­ic sim­u­la­tions and the oth­er on tech­no­lo­gies,” explains Chris­ti­an Stoll. “But they pro­duce sim­il­ar res­ults”. And with the rise in the price of bit­coin, the fore­casts are fairly pess­im­ist­ic: even if the rela­tion­ship is not uni­form, the high­er the price of bit­coin – remem­ber that it will reach record levels in 2024 – the high­er the energy con­sump­tion will be⁶.

Bitcoin’s high energy con­sump­tion is linked to the way it works, as Jean-Paul Dela­haye explained in a pre­vi­ous art­icle: “The issue and cir­cu­la­tion of bit­coin is man­aged by a net­work of com­puters that oper­ates in a decent­ral­ised man­ner. Each com­puter on the net­work holds a copy of the “block­chain”, a file sum­mar­ising all the inform­a­tion on the con­tent of all the bit­coin accounts and all the trans­ac­tions car­ried out on the net­work. To encour­age new com­puters to take part in man­aging the bit­coin net­work, a reward is dis­trib­uted every 10 minutes to one of them in a com­pet­i­tion called proof of work. We know this pro­cess as “min­ing”, and it is pre­cisely this pro­cess that involves a sig­ni­fic­ant expendit­ure of elec­tri­city.” In 2021, around 2.9 mil­lion com­put­ing devices were ded­ic­ated to bit­coin min­ing. “Over the past 2 years, Eth­ereum has switched from a proof-of-work pro­tocol to a proof-of-stake pro­tocol: this has reduced the network’s energy con­sump­tion by at least a factor of 100,” points out Jean-Paul Dela­haye. By improv­ing trans­par­ency and reg­u­la­tion, devel­op­ing altern­at­ive energy-sav­ing crypto­cur­ren­cies and adopt­ing green­er block­chain val­id­a­tion pro­to­cols, the sci­ent­ists are call­ing for sev­er­al levers to be activ­ated to reduce bitcoin’s envir­on­ment­al footprint.

Anaïs Marechal