Nanotrees mimic nature, harvest sun's energy

If humans are going to mimic nature's unique way of converting sunlight into energy, we're going to need to build some very extraordinary trees.

Electrical engineers in California want to do just that. Their new "nanotree" device is made from cheap, abundant materials and uses sunlight to split water molecules into oxygen and hydrogen atoms that can be used in fuel cells to produce energy.

Hydrogen fuel cells could power everything from houses to cars. But hydrogen doesn’t exist alone in nature. The atoms have to be separated from other molecules, like water.