British police got a shock when they raided a suspected illegal cannabis farm this week: Instead of halogen lamps and weed, they found about 100 computers mining bitcoin.
Officers from the West Midlands Police forced entry into the warehouse in an area west of the city of Birmingham known as the Black Country with a drug warrant, after intelligence suggested it was being used to grow the illegal crop.
Unusual amounts of wiring and ventilation were visible on the outside of the building and a drone had measured high levels of heat rising from it—classic signs of a cannabis factory. But the officers broke in to discover a huge bank of computers in what they now suspect was a cryptocurrency mine.
They also found that the computers used stolen electricity by tapping directly into the power supply outside of the warehouse’s circuits. Police said the mine consumed thousands of pounds worth of electricity (£1 is equivalent to around $1.40).
Cryptocurrency mining, particularly for has become a lucrative business as its value has shot higher, peaking at about $60,000 per bitcoin in April. But mining the coins, where computers race to solve complex mathematical puzzles, is also hugely energy-intensive and very costly.