Each Bitcoin transaction uses 4,200 gallons of water — enough to fill a swimming pool — and could potentially cause freshwater shortages

i strongly urge skepticism when reading articles about the environmental impacts of bitcoin. I am not saying that bitcoin is a sensible use of resources - rather that the claims made about the environmental impacts are often overstated and based on models extrapolated to absurdity. For example, see https://doi.org/10.1038/s41558-018-0321-8 where Mora, Camilo et al suggested that "Bitcoin Emissions Alone Could Push Global Warming Above 2°C". Then read Implausible projections overestimate near-term Bitcoin CO2 emissions by Masanet et al.
Again - the environmental impacts of cloud computing in general and bitcoin in particular are something we should be concerned about. But there are a number of researchers who have made wild claims that should be treated with a critical eye.
- (Checking if outbound federation is back)
  Yeah, if they had said 10 gallons, I'd buy that, but a whole swimming pool of water would be worth far more than a transaction fee I'd expect.
- Yeah, generally miners will set up in places with cheap electricity. And excluding places like Azerbaijan, those sources are generally renewables.
  
  Yeah. Right now, the cost of a Bitcoin transaction is around $65 US. That price includes all of the expenditures that the miners have made on resources (electricity, water, rental costs for the space they're using, hardware depreciation, etc.), as well as whatever bit of profits it takes to keep miners in business. That puts a cap on whatever environmental impact the transaction is having.

These data centers consume water for cooling systems
How does a data center consume water? Doesn't every liter that enters as freshwater leave as slightly warmer freshwater? What am I missing here?
- Some of the water is evaporated so it doesn't leave as a liquid.
  
  That's unlikely in a closed heat exchange system. Maybe some additional evaporation because the water is slightly warmer. But unless I'm missing something, it seems very misleading to suggest that a Bitcoin transaction uses 16 kilolitres because of evaporation. Napkin math, it would require about 10 megawatt/hours of energy to evaporate that much water (please correct me if I'm wrong). I'm not a Bitcoin fanboy, I just don't like BS.
- Swamp coolers.
  Fans blow over water to lower the pressure, causing evaporation to occur at room temperature.
  Evaporating water absorbs heat from its surroundings without raising the water's temperature as it undergoes a phase change. It absorbs nearly 20 times more heat than it would from being heated from 50 degrees F to 100 degrees.
- Aquafers do not refill as quickly as industry sucks them dry. It’s not just a Bitcoin or even a cloud computing problem, but the author is using this fact to make Bitcoin look even more ridiculous.

Ok thats not even remotely accurate. wtf is this clickbait shit. You can argue that bitcoin is bad for the environment but if you're gonna invent statistics at least make is plausible.

These calculations are a bit off IMO. They factor the total amount of mining and divide it by the number of transactions.
However, the amount of mining is not dependent on the amount of transactions.
I'm not a fan of bitcoin due to the wasteful proof of work mechanism but 'blaming' the transactions is not really fair IMO, especially because people don't really use bitcoin as a payment method anymore. It's just used by speculators now.
- Wasteful and unsustainable.
- However, the amount of mining is not dependent on the amount of transactions.
  Entertain my ignorance on this for a second, but isn't there some sort of dependence here? Like not a strictly casual dependence, but if transactions were, say, to magically halve for a few days, would that not affect the mining required and thus the total energy expenditure of the mining?
  (Obviously the limit case would show this to be true, in that in the absence of any transactions at all, mining would cease. But I'm after something a bit more clearly casually related, somewhat like supply and demand in the marketplace – consumption of beef driving more supply and more methane, e.g.)
  
  No, transactions piggyback on the mined blocks but if there are no transactions mining still happens.
  
  @janguv
  @Zworf @technology
  The mining isn't based on transactions, the mining is set to target a 10 minute block time, the difficulty changes based on how much mining capacity there is.
  If a block takes less than 10 minutes the difficulty goes up. If it takes more the difficulty goes down.
  Each block has a maximum capacity of 2500 transactions, which is why gas is used to prioritize who gets added in a block.
  There have been many blocks with zero transactions.
  (May bot be correct #)

False. Mining is what uses electricity (and water) in bitcoin, not transactions. Adding more transactions does not add to the cost. Calculating consumption per transaction is misleading as the two are not related.
What does add to the cost is complexity, and complexity is calculated based on number of miners in the network in order to achieve the sweet spot of 1 block every 10 mins (if i remember correctly). If there's a lot of competition, each miner will have to use more electricity to win.
- Finally someone that get's it

That's not how this works, that's not how any of this works. BS clickbait
- Care to expand?
  
  Whether the energy consumption of an action is justified depends on the efficiency of the energy use, the practical aim of the action, whether it would replace any more or less efficient actions, and the energy source.
  Simply stating it has no purpose and that the energy use of Bitcoin is somehow analogous to mass water wastage, does not seek to investigate whether Bitcoin's energy use is justified. It's disingenuous and reactionary.

Because of these transactions, many countries, such as the United States, could face freshwater shortages if the currency becomes more widely adopted.
False.
Blocks get mined (secured) with the same amount of power no matter the number of transactions in each.
Interesting that an article like this would come out right as Bitcoin's value is going up and the US SEC is considering approval of several Bitcoin ETFs.

I do wonder how this compares to current payment processors (Visa, Mastercard, Paypal, etc)
- What I found.. 1 Bitcoin transaction takes ~700 kWh of power, where as 100,000 Visa transactions use ~150 kWh.
  https://www.statista.com/statistics/881541/bitcoin-energy-consumption-transaction-comparison-visa/
  
  I don't think that's really equivalent. They are averaging the energy usage of mining and usage across the number of transactions. The overwhelming majority of that energy would be on mining.
  What is the equivalent of mining in terms in VISA transactions? How much energy does that use? What is the marginal cost of a Bitcoin transaction? If you're including Bitcoin mining in your per-transaction costs, shouldn't you include the entire operating costs of VISA, along with the partners they rely on like banks, mints, and even physical mines?
  Bitcoin is not a 1:1 equivalent of anything in the traditional financial world, so coming up with a meaningful comparison is difficult. It's a little bit currency, a little bit transaction processing, a little bit "mining", and a little bit banking. Despite the hype, I don't think it's a full replacement for any one of those things.
  
  But does it account for manufacturing of the plastic cards, delivering it to the user, and the added expense of the extra weight when carrying it around? /s
- Well my understanding is that visa, MasterCard ECT. Are far more efficient in terms of energy and transaction time when compared to Bitcoin and Ether. Visa uses about a quarter of the power per 100,000 transactions.
  So I would assume that would mean fewer data center computers to cool and therefore less water used per transaction
  
  By design.
  Bitcoin has pretty much no incentive to make the transactions efficient. The load is distributed to other people (their customers), and their biggest customers have a perverse incentive to want the transactions to be as inefficient as possible in order to discourage competition.
  Vista et al have to pay for their own transactions, so keeping it light is simple cost savings and totally rational.
  
  Sorry, I’ve not kept up to date with crypto, but wasn’t ethereum due to move from computational mining to staking? Wouldn’t that be a lot more efficient, or is that not a thing yet?
  
  Most importantly, VISA, MasterCard, etc. are far more profitable for VISA, MasterCard, etc. stock holders.

700kWh per transaction? That's absurd amount of power. That's 70 EUR of energy per one transaction at current (EU) exchange price.
Is there anyone here knowledgeable enough about this issue to say whether those numbers are correct, or just an overestimate? It feels wrong.
- They are insanely off, yes.
- The number varies a little bit (I've seen estimates 600-1200 kWh) but this is well within an order of magnitude of being correct. It's the nature of the competitive mining network and the proof of work system: if you can spend more computing power (i.e. energy) than everyone else there are lucrative mining rewards to be had. At the same time adding more computing power to the network doesn't add more transaction processing power, because mining difficulty is constantly adjusted to keep the speed more or less constant.
  This naturally leads to exorbitant power consumption per transaction. Note that most of this power is not being purchased at EU exchange prices (mining naturally moves to where electricity can be had for cheap to maximize profits).
  
  I just hope bitcoin will finally die. It's literally just wasting absurd amount of energy, only to allow scammers to scam billions of dollars from victims, and regular people to steal from eachother by investing into it. I mean, if the only use of bitcoin by now is for speculation and investment, then it means that any dollar you made, you literally stole from someone else who will be left with useless bitcoin once it's all over. There's no value, and with the ledger getting bigger and bigger, and bitcoin more expensive to mine, it will eventually be worthless. And we all know it, so anyone who makes thousands of dollars, there's someone who probably financially ruined himself by making a wrong and stupid investment at the wrong time.
  I hate crypto so much :D.
- It's incorrect. I would comparing to fuel consumption in a car based on how many times you turned. If you make more turns on your way, it would seem your car is more efficient, when in reality there's very little relation between turns and fuel usage, just like there is little relation between number of blocks mined and transactions.
- It's an overestimate. Right now the total cost per transaction is around 82 US dollars, which at current exchange rates is 75 Euros. That cost covers everything - electricity, rent for the building, salary for staff, taxes, depreciation of mining equipment, and whatever profit is required to keep the miners in business. I don't know what proportion of miner costs actually goes to electricity but I expect it'll likely be much less than 70 Euros.
  Perhaps someone got that 700 kWh figure by doing the reverse calculation - looking at how much a transaction cost and then assuming that all goes toward electricity.

As tradition I won't read the actual article and only comment on the headline - while BTC is a massive energy waste, it seems unlikely that each transaction would waste so much cooling water. Maybe each mined block, but each block should contain thousands of transactions

Not only is the science underlying all these findings completely non-existent, they only "guesstimate" what the water usage of what every thing that uses water is; then blindly divide that by the transaction volume per time period.
Not only is that method highly flawed; it's incorrect. Computers do more than mine crypto; and 1 transaction typically costs not even 1 tenth of a percent of most miners' overall computer resources. This is due to the fact that many miners are utilizing either a GPU or FPGA style device to power optimize and optimize the mathematics necessary to secure a transaction.
- That might have been true a decade ago. But GPUs and FPGAs have long been obsolete for mining Bitcoin.
  Mining is happening on custom silicon in large-scale operations. They specifically observed several of those large-scale operations in multiple nations and extrapolated out. I don't see how that methodology is flawed.

OP, your "news" article sucks. It's just clickbait

When the alternative to prove of works (vouched by those hoarding compute resources) is prove of stake (vouched by those who can afford to park piles of money), both are suck for their own reasons.

Not even a mention of lightning? I have no idea if it works as I’ve been hearing both yes and no for several years, but writing such an article without mentioning what at least theoretically would be the solution just seems bad.
- Last I saw Lightning was pretty much DOA, it's been around for many years and almost nobody's using it. At the time I was checking there was an order of magnitude more activity transferring Bitcoin on Ethereum using WBTC tokens than using Lightning on Bitcoin itself.
  
  Yeah I made a bitcoin payment recently and I was very suprised to learn that my wallet (CakeWallet) doesn't support Lightning payments at all. So I had to do it the old way.
  Very weird because bitcoin advocates always pushed it as the holy grail. But I guess bitcoin as an actual payment method is just really too niche for it to take off.
  
  See, that's another "no", but then I read just as convincing "yes" posts, and I just don't care enough to make my own research, so I have Schrödinger's lightning network ;)
  But any way, it would have to be mentioned in a serious sticker.

It's a necessary sacrifice to push more ponzi schemes
- It's actually a scam pushed by Big Water to get you to use more water and line their pockets.

I don't understand some things in the water consumption.
Why do they need to humidify the air for the datacenter?
Why is there water consumption for cooling? Aren't they recirculating water used for watercooling? Or are they using f*ing tap water then throwing it out?
Water for electricity production, kinda, yes. Could be indirectly attributed to their water consumption as they are using the electricity produced by the sources using water.
- Why do they need to humidify the air for the datacenter?
  Static electricity. Humidified air dissipates static charges before they can build up enough to arc and cause damage to sensitive components.
  
  I worked in a "datacenter" where the humidifier function for the HVAC unit was turned off because it leaked under the floor into an adjoining office when it was trying to humidify. Management refused to fix the unit due to the cost, and saw no issue with running the room with relative humidity in the teens all winter. Madness.
  
  Yeah and too much is bad too, because it can condense on coolers. I've been told it's also bad for bearings in HDDs when it's too low.
  Of course in a datacenter being low on humidity is a much more likely thing as there is nothing to emit humidity (e.g. humans).

- Lol

ok then just use salt water. You're welcome nerds!

The people that care about this sort of thing are incapable of fixing it- and the people that could fix it- don’t care.
My advice? Get used to it. This is the new normal.
- Or make it illegal. Why waste so many resources on something that doesn't produce any value for society?