Biodiesel "Conversion Kit" for Diesel Jeep Liberty?

A reader recently sent me an email asking whether his diesel-engine Jeep Liberty needed a "conversion kit" to enable his Jeep's use with biodiesel....

John,

Great article, I learned a lot, and I think I just saved a lot of money too. I am going to check out this vehicle (reader attaches a picture) next weekend.

I want a Jeep Liberty diesel, not many out there. I was planning to pay for a "biofuel conversion" but now I'm not so sure. This Jeep looked interesting because it had a separate tank, which is also confusing. Why would you need separate tanks, any idea? Curious what your opinion is.

Second, I was planning to buy B100 diesel at the local truck stop, do you see any problem with that with this vehicle or a normal Jeep Liberty diesel? I any event I'm going to subscribe to your newsletter.

Thanks!

My Answer

Dear Reader,

Thanks for the note! And thanks for reading my article about why you don't need to buy a biodiesel "conversion kit" for your diesel engine car or truck.

I had a look at the advertisement for the diesel Jeep you mention. It seems the second (white) tank behind the back seat is the one designed to hold the biodiesel fuel. You would want to use this to hold ONLY 100% (or near 100%) biodiesel, because if you had a spill from this tank, your whole crew cabin would stink of diesel fumes. After you get this vehicle, I suggest you remove the spare white tank and line the back portion of the crew compartment with a plastic spill-proof lining AND/OR place the tank itself into an open-top spill-proof container - kind of like a battery box that keeps the acid from a portable battery from spilling when the vehicle it serves gets jostled. Either method would help contain a biodiesel spill. If ever there was a spill - while biodiesel is easier in some ways to clean up than a nasty petrol spill, the grease never really goes away - especially if it soaks into your vehicle's cabin carpet.

One other reason you also want to keep your biodiesel in the cabin is to help keep it warm. In the event of winter use, the crew cabin in your Jeep will be warmer than outside ambient air, where your Jeep's stock fuel is located. While it's good to keep the biofuel nice and warm, it's unlikely the hot air from your cabin heater will heat the biofuel tank within a few minutes. Even a small fuel cell would take a long time to heat up - perhaps hours. For this reason, it's good to use an anti-gelling additive such as the kind I recommend in my article. As my article states, there is no reason to buy a biodiesel "conversion kit." Those things are scams. While some of them do actually work, the alternative given in my article is much less costly, and easier to implement.

Why is biodiesel fuel temperature a concern? You probably already know that biodiesel gels up easily in colder temperatures, and will not move through fuel lines or other systems once frozen. It's difficult to say exactly at what temperature biodiesel will gel up. It depends on many factors, such as:

* The biodiesel's natural source. I have known folks to use biodiesel derived from many natural sources such as: corn oil, canola oil, rice oil (not recommended as a piston-engine fuel), rapeseed oil, jatropha, coconut oil - the list goes on. Biofuel derived from these sources all have chemical and physical properties peculiar unto themselves. It goes without saying that each one of these forms of oil will gel at different temperatures. Into what kind of substance they gel into is also a big question. Some may gel as a goopy semi-solid, and others may gel into a more or less solid substance (like ice).

* Whether the fuel is blended. If the biofuel you use is blended with other compounds such as the one I recommend in my article will determine it gel point.

* Whether thebiodiesel is recycled. If you use 100% biodiesel - also known as "B100" - from a truck stop, this most likely has not been recycled from a previous use, such as restaurant fryer grease. Instead, the fuel most likely has been captured directly from its natural source. For example most biodiesel fuel in the US is derived from corn seed that's been pulverized and pressed to capture its oil content for use as fuels and lubricants. This is a commercial application for biodiesel fuel. It should be accepatble to run this as a petroleum-based fuel alternative in your diesel engine. After all, it's been manufactured for sale on the public market. The other non-commercial common source of biodiesel is recycled from a previous use, such as the restaurant fryer grease I mentioned earlier. This kind of furel is most commonly associated with "home-brew" technology such as the kind I use. Most of the biodiesel I've run originally served as fryer grease from a Chinese restaurant. When I burn it, the exhaust fumes smell like egg rolls! Just kidding! While I can't say this is true in all cases, I've found the gel point for this kind of biofuel to vary somewhat. I would imagine this is due to what kind of oil is being used, what crop it came from, when it was harvested, and how long it was used to fry food. I find that the darker grease (used for a really long time in the fryer) tends to gel at relatively higher temperatures - somewhere around 50 °F, as opposed to ~40 °F for more "pure" forms of vegetable oil.

Another reason for having another fuel tank is obvious. More fuel on-hand means fewer stops between fill-ups. This could come in handy if you're planning a long trip into the country.

Anyway, I hope that answers your questions! Have fun with your new biodiesel rig!