Petroleum products are a pretty convenient way to store energy. It's just unfortunate that burning the stuff releases carbon dioxide into the atmosphere. Biofuels could be a solution, but relying on natural biological processes can be difficult to scale up -- especially if we expect biofuels to try to match up with the current energy demands. Researchers are working on ways to modify biology or circumvent it with chemical engineering to make some carbon neutral hydrocarbon fuels in large quantities. Here are a few possible examples.
If you'd like to read more awesome and interesting stuff, check out this unrelated (but not entirely random!) Techdirt post