Canada's McGill University believes that metal powders could be the key to clean energy in the future.

For the last 20 years, researchers at McGill have been studying how metal powders, such as iron, could be used as an alternative fuel source that produces zero carbon emissions. When burned, these powders are capable of producing more energy than an equivalent volume of gasoline. In lieu of carbon dioxide, the process releases only iron oxide, or rust, which is environmentally benign. What's more, the exhaust can be collected...