The grid that transmits our electrical power needs a radical transformation. The structure of the grid has not changed fundamentally since its creation a century ago. But today’s grid faces new challenges: Clean energy sources like solar and wind are feeding more power into the grid, replacing centralized fossil fuel plants with more widely distributed and intermittent sources, while new control technologies and electric vehicles are changing the way we draw power out of the grid. How do we get from where we are today to the more flexible grid of the future? This lecture discusses new tools being developed at SLAC and Stanford for modeling and optimizing the grid. Based on massive data collection and machine learning, these methods will guide the conversion of the grid to support our 21st century energy needs.