When running a power system to supply electrical energy to homes and businesses, engineers strive to satisfy three objectives: providing a reliable service, minimizing the cost of providing this energy, and facilitating the use of renewable energy sources. Unfortunately, these objectives conflict. My research focuses on techniques that achieve the optimal balance between these three essential goals. In particular, using advanced optimization techniques, my students and I explore how flexibility resources (such as demand-side participation, energy storage and agile generating units) should be deployed and operated. This is the essence of what has recently been called the "smart grid".