Renewable rocket fuel made by genetically engineered soil bacteria

Synthetic biologists have genetically tweaked soil bacteria to make compounds containing chains of three-membered rings that are so energy dense that they outmuscle advanced rocket fuel.

Cyclopropanes boast the largest net heat of combustion per carbon among all cycloalkanes. This is because the three-membered ring forces the carbon–carbon bonds into a 60° angle, while angles in the linear alkenes in gasoline and diesel are at 109.5°. ‘The highest energy density you can get comes from the smallest cyclic compounds, which is a ring of three carbons in a triangle,’ notes Pablo Cruz-Morales at the Technical University of Denmark.