Just an off the wall question. I am in the market for a new truck and am waffling between diesel and ones that can burn higher levels of ethanol. It got me started thinking about making your own fuel. Which would be easier to manufacture on your own, bio-diesel or ethanol?

Hard to say, I've read a lot about biodiesel, not much about ethanol.

I think the main challenge with ethanol is getting the last of the water out of it - it can't be done by simple distillation.

On the other hand, biodiesel requires methanol to manufacture. You can scavenge the excess at the end of the process, but you do consume most of it.

On the other, other hand, a diesel can also be modified to burn straight vegitable oil. Not sure you'd want to do that to a brand new vehicle.

It is solely out of curiosity sparked by a random thought. I have no idea how to make bio-diesel, but I have seen alcohol distilled (I can't say where, but I did drink some of it!). I do not know how they would compare or if the effort would be prohibitively time and resource intensive.

Perhaps it would be wise to invest in some PV technology now, and get an electric car a bit later

Yeah, it's an interesting question. (Assuming, hypothetically, the zombie apocalypse, or a really tough year in the stock portfolio, or an equivalent whatever -- LOL).

Ethanol is ridiculously easy to produce, in a dilute form, from anything with sugars. This can include waste materials (that would otherwise enrich the pig). Getting it to a motor vehicle friendly concentration is considerably more difficult, requiring substantial inputs of energy. Still, it should be possible. Though ethanol has considerably less energy per volume than gasoline, and home-brew would have less still.

Biodiesel, on the other hand, is based on plant oils -- fats.
These are the hardest things to produce. They are very hard on the land, they require layers of processing depending on the source, and then IIRC require methanol to process into a clean fuel. In other words, it's a crackpot proposition. In genuinely hard times, nobody with any sense will turn high-value food into fuel. You will instead feed the raw fat to your pig (or yourself, as needed).

The most direct option for producing fuel suited to an internal combustion engine is biomass burned externally to heat more biomass in a closed process. The result is a mixture of hydrogen, carbon monoxide, and traces of methane and various acids -- all quite flammable. This arrangement, though not exactly handy, has been in use for the better part of a century. Though IMO, it's handier for stationary use (run a small generator for example).

As far as motor fuel goes, I don't see N.America running out of natural gas for several decades, provided we can distribute the stuff. And natural gas burns quite well in internal combustion engines.

Having experimented with both, I can give a definite answer: it depends on what resources you have available.

As already stated, ethanol can be made from any sugar and sugar can be made from any starch (google "spit beer") but getting it pure enough to run a vehicle takes a lot of effort. I worked with a small company once to try and build a solar-heated distillation unit but the flow was never stable enough for a high-purity output. We ended up concentrating it down with a solar still and then had to switch over to a traditional still coupled with azeotroping it with benzene to make a usable fuel. Getting the benzene or something similar would be very difficult in a "made by hand" world.

The guy two doors down from me spent a few years playing with biodiesel fuel for two old Mercedes. Grease/fat/oils can be obtained from both plant and animal sources with medium amounts of effort, methanol is the main product of the destructive distillation of wood (easy to do at home), and sodium hydroxide can be obtained from leaching hard wood ash. One can replace the methanol with ethanol for a slightly inferior product but also easier to make. The trick with biodiesel is getting enough oil to run your truck any distance. There are lots of different oil-press plans on the internet, my favorite involves a welded frame and a hydraulic jack. Squeeze the sunflower seeds, peanuts, or even acorns and watch the oil ooze out...then repeat a bunch more times. Sidenote: the white, waxy coating on the outside of Chinese tallow trees can be made into a good biodiesel. We have TONS of those trees all over Houston.

The actual reaction involved in making biodiesel is even simpler than making alcohol and the "clean-up" of the fuel to make it ready for your vehicle is also easier but somewhat heat and time dependent plus you end up with a lot of waste glycerol and caustic water, both of which currently are difficult to legally dispose.

Conclusion: it depends on what feedstock you have access too. My personal preference is biodiesel because the equipment and raw materials to produce it are easier for ME to obtain. What's easier for you?
-Blast

Chinese tallow trees??!! Well, dang. There are more things in heaven and earth ...

Might be enough to keep the Dietz lanterns going. Not sure about the Kenworth.

But I do approve of all mad experiments in this direction. And if I had an old Mercedes that would run on recycled KFC, I would absolutely drive it around for my own amusement. I hope it could handle the entrained salt content.

Thinking about my current vehicles, though, I'm not sure alternate home-made fuels would sit well. The days of the dumb, carbeurated gasoline engine are long gone. Now it's all about efficiency, fuel injection and sensors up the wazoo. Would they run on 80% home-brew ethanol (and 20% water)? I'm doubtful.

My instructor for basic electronics + electronics lab had an old diesel that he ran on used fryer oil. Smelled like Mickey D's from blocks away!

Two people I know who tried the biodiesel stuff collects used oil from restaurants and such, but as more people doing it and more companies pay for used oil the sources are drying up.

Pressing enough oil yourself to run a car engine is pretty unrealistic.

The only commercial product I've ever seen (and apparently caught very little traction, even in California) were these:

http://www.microfueler.com/default.aspx

I liked the idea, but I think at the end of the day, the up-front costs and the costs of "feeding" the Fueler actually cost more that what you could just drive to the pump.

Also, I don't think this thing would like Iowa Winters all that much.