Beneath the Himalayas, rivers fed by ancient glaciers supply the tiny kingdom of Bhutan with immense stores of hydroelectricity. The renewable resource has become an economic engine, accounting for 30% of the country’s gross domestic product, and fueling the homes of nearly all of its 800,000 residents. But for the past few years, Bhutan’s royal government has been quietly devising a new use for these reserves: powering its very own bitcoin mine.