The Average Bitcoin Transaction Wastes a Full Swimming Pool of Water, Scientists Say

Down the Drain

Everytime Bitcoin is bought or sold, it wastes enough water to fill an entire swimming pool, new research shows, further evidence of the staggering environmental impact of cryptocurrencies.

The research, a study published in the journal Cell Reports Sustainability, also found that Bitcoin's water footprint is rapidly escalating, rising by 166 percent between 2020 and 2021.

Now, each transaction is estimated to expend over 16,000 liters of water. According to Alex de Vries from the Vrihe Universiteit Amsterdam, the study's sole author, that's around six million times more than what you use buying something with a credit card.

"It's sort of hard to surprise me, given how I've already worked on this topic I'm kind of used to big numbers popping up," de Vries told The Verge. "But then again, the numbers are still mind blowing even to me every time I look at it."

Cool It

Globally, Bitcoin mining used about 1,600 gigaliters — that's a billion liters times 1,600 — in 2021, and the figure could be upwards of 2,200 gigaliters this year, with the US alone accounting for up to 35 gigaliters of that consumption. The steep increase will likely be driven by Bitcoin's climbing value, which encourages more mining.

An enormous amount of water is used to cool the tireless computers that mine and process Bitcoin around the clock. It's an intensive process that devours absurd amounts of energy — as much as a small country, in fact.

That energy bill figures into de Vries's calculations. Most of its water footprint comes from the water used in generating the electricity that Bitcoin burns through, though cooling systems still formed a massive part of the total proportion.

Lowering the Stakes

It doesn't have to be this way, according to de Vries. Most cryptocurrencies including Bitcoin use what's known as "proof of work" to validate transactions on the blockchain — the "work" being the mining done by those toasty computers — which is wildly inefficient.

"You have millions of devices around the world, constantly competing with each other in a massive game of what I like to describe as 'guess the number,'" de Vries told the BBC. "All of these machines combined are generating 500 quintillion guesses every second of the day, non stop — that is 500 with 18 zeros behind it."

There is at least one major cryptocurrency, however, that works around this: Ethereum, which last year started using "proof of stake" instead of work to validate transactions without any mining whatsoever, cutting its energy bill by 99 percent.

Short of ditching crypto entirely, switching them over to more efficient systems could cause "all the electricity consumption" and "associated water consumption" to "disappear overnight," de Vries told The Verge.

Beyond that, using renewables and switching over to cooling methods that either recycle or don't use water at all could help soften crypto mining's grim environmental toll.

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