Algoritem za overovitev transakcij z bitcoini je neverjetno računsko in energetsko potraten. Bitcoin transakcija tako porabi, po oceni iz l. 2015, približno 5000 krat več energije kot transakcija z uporabo Visa kreditne kartice.
Koliko električne energije torej trenutno gre za rudarjenje bitcoinov? Po oceni Digiconomist.net je ta na letni ravni trenutno kar strašljiva – primerljiva s porabo električne energije celotne Danske. V oceni Digiconomist.net je glavna predpostavka ekonomska, da namreč bitcoin rudniki okoli 60% svojega dohodka porabijo za operativne stroške. To se sliši kar smiselno, saj primer energijsko učinkovitega novega rudnika na Kitajskem kaže na okoli 20% operativne stroške za električno energijo, kar je verjetno spodnja meja. Po tej oceni gre tako 0.15% globalne proizvodnje električne energije za rudarjenje bitcoinov…
Nekaj izsekov iz “A Deep Dive in a Real-World Bitcoin Mine” na Digiconomist.net
The 21,000 Bitcoin mining machines represented “nearly 4% of the processing power in the global Bitcoin network” at the time, and together with the Litecoin mining machines the mine generates about $250,000 in revenue daily. The mining machines are powered with electricity coming mostly from the nearby coal-fired power plants, and costing only four cents per kilowatt-hour after a 30% discount by the local government. In exchange for this discount, the profit from the mine is taxed. The total daily electricity bill amounts to roughly $39,000, meaning the facility consumes around 40 megawatts of electricity per hour.
Bitmain’s Inner Mongolia mine teaches us that the carbon footprint of a single Bitcoin transaction could be equal to that of being a passenger during one hour of flying a Boeing 747-400, or driving a Hummer for 200 kilometers (~120 miles).
Izseki iz “Bitcoin Energy Consumption Index” na Digiconomist.net:
Number of U.S. households that could be powered by Bitcoin: 3,030,415
Number of U.S. households powered for 1 day by the electricity consumed for a single transaction: 7.93
Bitcoin’s electricity consumption as a percentage of the world’s electricity consumption: 0.15%
To put the energy consumed by the Bitcoin network into perspective we can compare it to another payment system like VISA for example. Even though the available information on VISA’s energy consumption is limited, we can establish that the data centers that process VISA’s transactions consume energy equal to that of 50,000 U.S. households. We also know VISA processed 82.3 billion transactions in 2016. With the help of these numbers, it is possible to compare both networks and show that Bitcoin is extremely more energy intensive per transaction than VISA.
Izsek iz “The Ridiculous Amount of Energy It Takes to Run Bitcoin” na IEEE Spectrum:
Vranken says doing today’s calculations would “consume way more power than is generated on the entire planet” if it were done using the CPUs available when Bitcoin launched in 2009. What has prevented such disruption is a series of hardware upgrades: Miners began abandoning the CPU for the more-efficient graphics processing unit around 2011, and by 2013, chipmakers were producing application-specific integrated circuits (ASICs) just for bitcoin mining.
Today’s state-of-the-art Bitcoin ASICs complete a 256-bit hash 100 million times as fast and with one-millionth the energy of a 2009-vintage CPU, Vranken says. Yet more efficiency gains are possible by optimizing data centers from the ground up to power and cool bitcoin-mining ASICs [PDF] [see “Why the Biggest Bitcoin Mines Are in China,” coming soon in this issue].
The problem is that chip efficiency gains are slowing [see “Moore’s Law Might Be Slowing Down, But Not Energy Efficiency,” IEEE Spectrum, April 2015] and, according to Vranken, are losing ground against Bitcoin’s exponentially rising exchange rate and rates of hash computation. Another Dutch researcher, Sebastiaan Deetman, says an “enormous increase in hash rate” over the last year or so has likely pushed Bitcoin’s global draw closer to 700 MW.
And if the hash computations accelerate further? In that case, Deetman, who is a doctoral candidate in industrial ecology at Leiden University, sees Bitcoin power demand ballooning 20-fold—to 14 gigawatts—by 2020. If that happens, Bitcoin will be using as much electricity as Denmark.