My roommates brother makes biodiesel out of cooking oil he gets for free from a local waterpark cook stand. He uses that in his excursion and sells the lye(bi-product) to some soap maker for alittle profit. But its kinda complicated to do the whole process.
Now, e85. Yes its true about the energy content to gallon ration, but its an all around better fuel if your engines pcm is flashed to run the stuff. Not many cars roll of the assembly line ready to run e85. My electronics teacher at school drag races on the side. He has an old school monte carlo with a 500ci motor, massive supercharger and all the works. He was running 100 octane(i think) and decided to retune and run e85. He gained a lot of top speed he claims, and ended up shaving 4-5 tenths off his best times on the 100 octane.
Its not an all around better fuel. It takes a lot of energy to make it. More than a gallon of gas goes into the production of making a gallon of E85. So does something like 9 gallons of water get used to make a gallon of E85.
So with that said, its horrible for the environment. It uses corn, where that land could be used to grow something else, but corns in demand so they grow it to make ethanol.
From an emissions standpoint, yeah, it burns cleaner than gas, but keep in mind that every gallon of E85 you "save" the planet with, has already in effect used a gallon of gas (or some sort of a fossil fuel to cook the mash they make the ethanol out of).
Its just a lose lose fuel. Im a car enthusiast, and I wouldnt mind playing around with it because it IS like running race gas (octane rating of like 108) but its not doing the environment any favors.
Just like people who buy hybrid cars like a Prius or anything hybrid anymore. Theres so much energy required to make all the batteries those things run on, and so much more energy required to dispose of the batteries, that any fuel econ saving you get is negated by the damage youve already done to the enviroment.
Now diesel, I agree has tons of potential. If we were more like europe, you could get fuel efficient diesel motors in like damn near anything we sell (little civics, subarus, smaller trucks, etc). But our EPA pretty much sucks, so we dont.