The source of China's electricity -- largely coal-fired power plants -- is also a major reason for its poor air quality.
As the aftermath of Hurricane Sandy shows, the grid that provides our electricity can be a fragile thing. Building a modern, more resilient version will cost hundreds of billions of dollars. But most agree it's essential to a cleaner, more energy-efficient future.
It's a challenge confronting California and the nation, as well as other nations -- notably China, where the aging grid is already proving to be an obstacle to "greening" that nation's energy production. Reporter: Marjorie Sun