Possible Route to Hydrocarbon Fuel from Air
The normal process is to burn a hydrocarbon and get CO2. A possible novel new process would turn the CO back into a Hydrocarbon. 
CO2 ==> CO ==> Hydrocarbon ... just add concentrated sunlight! Pretty neat!
"... research team from Sandia National Laboratories is building a prototype ... to chemically “reenergize” carbon dioxide into carbon monoxide ... carbon monoxide could then be used to make hydrogen or ... combustible fuel, such as methanol or even gasoline, diesel and jet fuel."
"... Counter Rotating Ring Receiver Reactor Recuperator (CR5, for short), ..."
"... “Sunshine to Petrol” (S2P). “Liquid Solar Fuel” is the end product — the methanol, gasoline, or other liquid fuel made from water and the carbon monoxide produced using solar energy."