The Deepwater Horizon; mountaintop-removal coal mining; global warming and glacial melting from the burning of fossil fuels. You might expect the man in charge of United States energy security to be glum about the future, but despite his intense concerns regarding carbon emissions, Steven Chu is optimistic that science may yet bail us out. The first physicist to take the post, and the first Nobel laureate (for work using lasers to cool and trap atoms), Chu has $39 billion in Recovery Act dollars to dole out and an unprecedented opportunity to foster big ideas. In the near term, he says, simple measures like energy-efficient homes and white-painted roofs could make a major dent in our carbon budget. For the future, look to radical solutions like glucose-based fuels, smart storage, or tiny mass-produced nuclear power plants. His sunniest prediction: Our economy could be largely carbon-neutral by 2050.