An abundance of fossil fuels combined with advances in technology to harness wind and solar power has sent energy prices crashing around the world. WSJ explains how it all happened at once. Photo illustration: Carlos Waters/WSJ (Originally Published July 21, 2020) LONDON—BP PLC is in talks to sell its London headquarters to help cover debt, punctuating the crisis facing the British oil giant and its peers as they navigate a pandemic that has decimated demand for oil. BP bought the office block in the tony Mayfair section of London almost two decades ago, a time when it and its rivals enjoyed the prospect of growing oil demand and unrivaled stock-market valuations. Then-CEO John Browne had just pulled off the largest oil deal in history at the time, a move that triggered a series of…