GRANBURY, TEXAS — Cheryl Shadden cannot sleep. The 61-year-old nurse, who works at hospitals giving patients anesthesia, says she is kept up at night by the nonstop mechanical whir of fans spinning to cool tens of thousands of computers.  Shadden lives in Granbury, Texas, about 40 miles southwest of Fort Worth, with her seven dogs, … Continue reading Texas Leaders Worry That Bitcoin Mines Threaten to Crash the State Power Grid