The Signa bike runs on fuel cells. But instead of having to carry hydrogen next to your butt, it uses a new, clever and safe method: it runs on cells full of a sand-like powder. You just have to add water.
The powder is sodium silicide, an inert, safe substance that is not dangerous at all. When you add water to the cell, hydrogen gas is produced, which generates electricity. The cells are 0.7kg and are hot-swappable, which means that you can plug another right in after you reach its maximum 48km run.
According to the company, they are working in making this cells more powerful so they can be integrated in cars. [Wired]