Bitcoins
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The process of mining new bitcoin is now so intensive that computers carrying out the process are using nearly as much electricity as the entire country of Ireland.

A new study by economist Alex de Vries estimates that bitcoin mining consumes at least 2.55 gigawatts of electricity and, by the end of the year, that will have risen to 7.67 gigawatts - as much as Austria consumes in the same period.

Mining the cryptocurrency involves computers solving complex mathematical problems. As the amount of bitcoin left to mine grows smaller and smaller, the problems become increasingly complex, meaning they require an even greater amount of computing power.

'Half a million PlayStations'

Due to the secretive nature of mining, the research is based on speculative figures. The cryptocurrency's network is estimated to have around 10,000 connected nodes, but a single node in the network can represent either one or many machines.

"A hashrate of 14 terahashes per second can either come from a single Antminer S9 running on just 1,372 watts, or more than half a million PlayStation 3 devices running on 40 megawatts," the research says.

The study is the first time that estimates of bitcoin's energy consumption have been peer reviewed and it has sparked calls to address the environmental impact of mining the digital asset. De Vries also runs the Digiconomist blog, which hosts the Bitcoin Energy Consumption Index.

Some experts have queried the study's findings, claiming it is the latest example of overblown concerns about the strain that computers put on the electricity network.
"The worry is that those are two numbers that are picked out of the air," Stanford researcher Jonathan Koomey said. "There may be some basis for them, but it's a very unreliable way to do these kinds of calculations, and nobody who does this for a living would do it like that. It's odd that someone would.

"For two decades, people have been eager to overestimate electricity use by computing," he added. "My concern is that we simply don't have adequate data to come to the strong conclusions that he's coming to."