If it continues on its current speculative trajectory, Bitcoin could not only spell the downfall of the US dollar, as some predict, but also that of the world’s power grid. The clean-energy future of this planet hangs in the balance, says Grist. \n \nValued at US$1,000 just over a year ago, a single bitcoin was worth more than US$15,000 at the beginning of December. One hundred US dollars’ worth of bitcoins in 2011 are now worth nearly US$4 million.\n \nThere’s an environmental threat behind the cryptocurrency, and that has to do with “mining,” the increasingly complex mathematical process by which new bitcoin units are “created.” That process requires greater and greater amounts of computing power and, therefore, huge quantities of electricity. A single bitcoin transaction requires the daily energy equivalent to powering nine US homes. \n \n“Already,” writes Grist, “the aggregate computing power of the bitcoin network is nearly 100,000 times larger than the world’s 500 fastest supercomputers combined.” The computing network required to keep bitcoin going absorbs the yearly equivalent of 31 terawatt-hours, which is more energy than what 150 countries world individually consume. Each day’s bitcoin intake amounts to approximately 450 gigawatt-hours — the same amount of electricity that the entire country of Haiti uses in one year.\n\n\nIf that trend continues, it will put an unbearable strain on electricity demand. By July 2019, predicts Grist; the network will require more than the total electricity output of the US, and by February 2020, it will use the same amount as the whole world does today.\n \nThat is unsustainable, claims Grist columnist Eric Holthaus, and if we don’t curtail that exponential growth, the world will be forced to revert to fossil fuels to generate power, thereby making climate change all the worse.