Christian Stoll and colleagues, Technical University of Munich, Germany, have used the data offered because of the IPO (initial public offering or stock market launch) of the three major manufacturers of Bitcoin mining hardware, Bitmain, Ebang, and Canaan, in 2018 to gain more insight into the electricity and CO₂ consumption of Bitcoin calculations.

The team found that in November 2018, the annual power consumption of the Bitcoin network was around 45.8 TWh. To meet this demand, more than five large power plants have to run at full load throughout the year. Since 2016, energy consumption increased relatively steadily, from 345 MW at the end of 2016 to 5,232 MW at the end of 2018. This is because the crypto calculations to be solved are becoming increasingly difficult.

68 % of the computing power in the Bitcoin network comes from Asia, especially from China. A good half of the Chinese mining facilities are in the hydropower-supplied south. The other half works in northern China where coal-fired power supplies a large part of the energy. Bitcoin miners in China, therefore, consume 550 g CO₂ per kWh.

17 % of the computing power of the Bitcoin miners is in Europe and 15 % in North America. In total, the Bitcoin system produces between 22 and 22.9·10⁶ t CO₂ per year. The CO₂ footprint of the cryptocurrency thus corresponds to that of a small country or the city of Hamburg in Germany, or Kansas City in the US. In the list of global emitters, the CO₂ equivalent of the Bitcoin lies between rank 82 and 83.

There are more significant factors for climate change, but the CO₂ footprint is so large that the researchers recommend to discuss more about where to locate crypto-mining.

• The Carbon Footprint of Bitcoin,
  Christian Stoll, Lena Klaaßen, Ulrich Gallersdörfer,
  Joule 2019.
  https://doi.org/10.1016/j.joule.2019.05.012