On U.S. oil patches stretching along the Rockies and Great Plains, trailers hitched to trucks back up toward well pads to capture natural gas and convert it on the spot into electricity.
The trailers — carrying pipes, generators and computers — are called "mining rigs.” But their owners aren’t there to drill for oil. They are using stray natural gas unwanted by oil companies to power their search for another treasure: cryptocurrencies like bitcoin.
Cryptocurrencies are virtual coins exchanged without middlemen, such as central banks, to purchase goods and services. Extracting the currency from cyberspace, however, requires vast amounts of often-expensive electricity. Supercomputers must run constantly in a race against other "miners” to solve complex math problems in order to unlock digital vaults holding the currency.