United Airlines has a history of trying to incorporate non-tradition fuels into its fleet. This year, they have announced plans to integrate sustainable biofuels (derived from farm waste and animal fats) into a portion of their operations from Los Angeles, mostly flights to San Francisco, a major hub of theirs (LAX-SFO). The first of these was in July. The airline cites a 30%-70% biofuel/petroleum ratio and claims a 50% reduction in carbon emissions (life cycle basis) at a price similar to petroleum-derived jet fuel.
I hope this experiment works. LAX to SFO is a very busy corridor, so United will have plenty of flight data to examine!