When President Obama visited Northwestern University in October, he gave a shout-out to a cool new project there: turning solar energy into liquid fuel. The Solar Fuels Institute initiative, headed by professor Dick Co, aims to replicate photosynthesis with an artificial tree (see rendering) to produce clean fuel for your car; a prototype should be ready by the end of next year. Here’s how it would work.

Step 1: Capture sunlight

Most solar panels convert sunlight directly into electricity without storing any. Engineers have created a device that uses photocatalytic panels to absorb and hold solar energy.

Step 2: Add water

The energy will split H₂O into positive charges (hydrogen ions) and negative charges (oxygen). The resulting atoms will then be stitched back together as O₂ and H₂ molecules.

Step 3: Toss in carbon dioxide

Once CO₂ (the same thing we breathe out and the stuff plants have been collecting for millennia) has been added—voilà!—natural hydrocarbons.