The story of how Texas was brought to its knees by crippling cold weather leaving millions without power is a complex one, yet entirely predictable and avoidable. The details matter, so it is important to know the long story, but let’s start with the short version: For years, Texas’ grid operator (ERCOT) has overestimated the ability to maintain a reliable grid without a sufficient supply buffer, known as a “reserve margin.” That margin is the difference between demand for electricity and what the grid can produce. When demand exceeds production, you get blackouts. That buffer has been shrinking because reliable...