Don’t forget, Mr. Diesel originally made the diesel engine with peanut oil in mind as the fuel. Until he died under mysteriously circumstances after which shortly the petros turned it into a petroleum-using product. I believe the figure leading that man was none other than Peter Paul Bush.
But seriously, I’ve seen quite a few diesels, old benzes, running around on fast food oil. Just requires an inexpensive converter. Hell, I’ve even seen a Hummer atop a mountain on that stuff. So, definitely a viable alternative.
But again, I believe the real issue is consumption habits more than anything else as a first obstacle to tackle. That and mileage standards.