Bitcoin has a large and rapidly growing energy and environmental footprint. The bitcoin ecosystem now uses approximately the same power as the entire country of Bulgaria, about 0.2 percent of the global total for electricity.
Bitcoin’s computing network has grown at an 1,100 percent average annual pace over the last five years. So if we project out just a few years, we get a truly massive energy demand for the new king of coins: Bitcoin would use more electricity than the entire world uses today, by 2020, if the recent growth trend in bitcoin mining power continues.
As of December 2017, the global hashrate is about 17 exahash per second (EH/s), up from just 2.5 at the beginning of the year, and up from just about 10,000 terahash per second (TH/s) at the beginning of 2014. (The hashrate is the processing speed of the bitcoin network.)