what is the most simple backyard biodiesel method?

Hi Bob,
I got a 've rabbit diesel been holding it due to its great engine and 6liters/100km about 60mpg and $25 fill up. I believe re-
Processing bio diesel from cooking oil is messey, growing your own oil plants in temperate climate difficult. What is the easiest simplest method of back yard bio diesel?

howie story wrote:
I believe re-Processing bio diesel from cooking oil is messy, growing your own oil plants in temperate climate difficult. What is the easiest simplest method of back yard bio diesel?

Hi Howie,

Yes, making biodiesel from used fryer oil can be messy - but so can gardening, beer-brewing, and bread-making.

Processing used fryer oil (aka waste vegetable oil - WVO) is the easiest (and most cost effective) method for homebrewers. Oil can be collected from local restaurants, and good fuel can be made by following a fairly simple and well documented process - much like gardening, beer-brewing, and breadmaking.

Getting oil from purpose grown oil plants requires a lot more work and money, to grow and harvest the crops and then to press the oil from the seeds - not typically cost effective at small scale.

Around here, there is no such thing as waste vegetable oil collectable from local restaurants. It would be more properly called, "used vegetable oil headed to the biodiesel manufacturing plants". To get "waste" oil from a restaurant, you'd have to pay higher prices and offer more reliable or easier collection services than the biodiesel manufacturers that are currently hauling off the used cooking oil.

Hi Bob,

I have looked into biodiesel before (not too deeply I might add), and stopped when it seemed to me that the processes I learned about required large amounts of methanol which itself can only be manufactured in large quantity through energy intensive industrial processes.

I love the concept of utilising waste (the used oil), and was why I looked into the technology. Discovering that the amount of methanol involved can be very significant left me feeling rather disappointed.

Am I wrong in my views on biodiesel? Has technology advanced? Is there a process where the other main ingredients can be readily manufactured on a homestead (like ethanol)?

Your comments would be very much appreciated

Nick Kitchener wrote:Discovering that the amount of methanol involved can be very significant left me feeling rather disappointed.

Am I wrong in my views on biodiesel? Has technology advanced? Is there a process where the other main ingredients can be readily manufactured on a homestead (like ethanol)?

Your comments would be very much appreciated

Hi Nick,

I share your concern.

Biodiesel is term used for the fuel use of methyl esters - a product of a reaction involving methanol, fats or oil, and a catalyst typically potassium or sodium hydroxide (KOH or NaOH). Methanol is typically made as a byproduct of natural gas - often a byproduct of the petroleum industry and comes from places like Iran, Qatar, Trinidad, Equatorial Guinea , and Russia. KOH and NaOH typicaly comes from China these days.

A typical biodiesel reaction uses 22% by volume of the fat or oil to be converted - not insignificant.

Ethyl esters (made using ethanol) are another possible fuel source but the processes required to produce anhydrous ethanol (without water) are a bit daunting for homescale. The alcohol (methanol or ethanol) needs to be about 99.5% pure or better to make the reaction worthwhile. The amount of ethanol required to make ethyl esters is also greater, which is partly why it's not cost competitive commercially.

To my knowledge, there is no energy without impact - not wind, solar, hydro and certainly not biofuels. The original biofuel that powered people and farms was hay for farm animals - also not without impact but arguably more sustainable that solar, wind, hydro, and biodiesel or ethanol. I think the more we can reduce our need to commute, shop, and recreate far away from our homes, the better our lives will become. Call me a Luddite!

Although I garden daily, home brewed beer for 10 years, and my wife has been making all of our bread for about 10 years - I have never homebrewed biodiesel. I have worked with five commercial biodiesel producers so have been able to run my vehicle on B100 for the last 14 years. I'll admit that if and when I don't have access to commercial biodiesel, I have no intention of homebrewing myself - just not into it. I'd happily buy it or trade for it with someone who did though!

Same story in Europe, much of the WVO supply is tied up already, also up against legislation and sensitive modern diesel fuel systems.
Anyone who is not a diesel mechanic trying out any kind of non conventional diesel should seek professional help.

- The EGR system spits soot into your intake and the crankcase pressure relief system spits hydrocarbons into the intake. When one or both of these two different types of input are not what the manufacturer expected, it forms sludge, and that sludge kills your engine, quickly
- high EGTs will kill your turbo, bits of turbo will kill your engine
- Low viscosity will clog your pumps and filters, especially in the cold
- Change of fuel will produce wrong injector spray pattern causing loss of economy and power and possibly overheating
- Uncombusted fuel will destroy your DPF & catalyser
- Biodiesel dissolves rubber (usually only a problem with 40+ yr old cars)

All these problems can be addressed, but are not within the scope of backyard modifications. Even a DIY mechanic with a lot of knowledge is unlikely to have the equipment to adjust injectors and rebuild injection pumps. It used to be that the fuel cost savings of using WVO outweighed the maintenance and repair costs, but I'm not sure this is the case now. Waste motor oil on the other hand is freely available from mechanics in almost unlimited quantities and makes for a better fuel after less processing with less adjustments to vehicle required. If you want to experiment your first step should be to buy a car with an indirect injection normally aspirated engine that also happens to be very cheap to replace. Depending on where you live, the modifications you need to make will probably mean your car will fail emissions tests. So get your yearly test or whatever in the bag before you start.

Sounds like making biodiesel is somewhat beyond the scope of my current plans. Guess I'll need to read the book before I decide.

Ethyl esters (made using ethanol) are another possible fuel source but the processes required to produce anhydrous ethanol (without water) are a bit daunting for homescale.

Ethanol is readily dried by desiccants such as calcium sulphate (wallboard), quicklime, potassium carbonate. The sulphates and carbonates can be regenerated in an oven.