Make your own biodiesel

Anybody can make biodiesel. It's easy, you can make it in your kitchen -- and it's BETTER than the petro-diesel fuel the big oil companies sell you. Your diesel motor will run better and last longer on your home-made fuel, and it's much cleaner -- better for the environment and better for health. If you make it from used cooking oil it's not only cheap but you'll be recycling a troublesome waste product. Best of all is the GREAT feeling of freedom, independence and empowerment it will give you. Here's how to do it -- everything you need to know.

Three choices
1. Mixing it
2. Straight vegetable oil
3. Biodiesel
Biodiesel
Where do I start?
What's next?
The process
Our first biodiesel
Biodiesel from new oil
Biodiesel from waste oil
Removing the water
Washing
Using biodiesel
Safety
How much methanol?
Ethyl esters -- making ethanol biodiesel
Reclaiming excess methanol
More about lye
How much lye to use?
Basic titration
Better titration
Accurate measurements
pH meters
Phenolphthalein
pH meters vs phenolphthalein
High FFA levels
Deacidifying WVO
No titration?
The basic lye quantity -- 3.5 grams?
Mixing the methoxide
Test batches
Stock methoxide solution
How much glycerine? Why isn't it solid?
PET bottle mixers
Viscosity testing
How the process works
What are Free Fatty Acids?
Iodine Values
-- High Iodine Values
-- Talking about the weather
Which method to use?
Why can't I start with the Foolproof method?
Quality
Quality testing
Cetane Numbers
National standards for biodiesel
-- standards and the homebrewer
-- standard testing
Biodiesel in gasoline engines
Home heating
Lamps and stoves
Other uses
Identifying plastics

Three choices

There are at least three ways to run a diesel engine on bio-power, using vegetable oils, animal fats or both. All three work with both fresh and used oils.

Use the oil just as it is -- usually called SVO fuel (straight vegetable oil);
Mix it with kerosene (paraffin) or diesel fuel, or with biodiesel;
Convert it to biodiesel.

The first two methods sound easiest, but, as so often in life, it's not quite that simple.

1. Mixing it

If you're mixing SVO with petroleum diesel or kerosene you're still using fossil-fuel -- cleaner than most, but still not clean enough, many would say. Still, for every gallon of vegetable oil you use, that's one gallon of fossil-fuel saved, and that much less carbon in the atmosphere.

People use various mixes, 30% petro-diesel and 70% vegetable oil, or a 50/50 mix. Some people just use it that way, start up and go, others say it needs at least pre-heating and probably a two-tank system too, like SVO (see below), and we agree with that. The same goes for mixes with vegetable oil and biodiesel. In both cases, you might get away with just using it as-is with an older Mercedes 5-cylinder IDI diesel, which is a very tough and tolerant motor -- it might not like it but you probably won't kill it. Otherwise, it's not wise.

To be safe, you're going to need what amounts to an SVO system with fuel pre-heating anyway. You'll use much less petro-diesel or biodiesel by using it in the second tank for start-ups and stops rather than mixing it 50/50. (See next.) Or just use 100% biodiesel and don't bother with extra tanks and pre-heating the fuel. (See after next.)

Mixes are a poor compromise. But they do have advantages in cold weather. Some kerosene or #1 diesel mixed with biodiesel lowers the temperature at which it starts to gel, and a mix with biodiesel will do the same for an SVO system.

Message to the Biofuel mailing list:

"I stuck 3 litres of pure rapeseed oil from my local supermarket straight into the tank of my 1998 VW Caddy van. There were about 3-4 litres of dino-diesel in the tank. Once the dino had cleared the fuel lines, I was running on about 50% dino to 50% oil. The only differences I noticed were: A) the engine ran about 10 deg C cooler; B) the exhaust smelt like a roadside burger bar. Apart from that, no problems! As the weather is finally starting to warm up here, I may increase the oil/diesel ratio and see that happens. -- Nick"

Reply:

"One thing that will happen is that your cold starts will begin to deteriorate. Then your filter will probably start plugging. Then your injectors will likely, in time, get coked up. Then the spray pattern will be wonky. Then you'll set the stage for ring sticking, glazing of the cylinder walls, increased lube oil consumption and eventual engine failure -- if you can continue to get the thing started in the morning. More than 20% or so in the diesel is not a good plan for more than short term 'experiments'. Unfortunately, you're not doing anything new here, Nick, and if it was as easy as running high percentages of SVO in diesel, and being able to maintain reliability, we'd all have gone that way long ago. Regards, Edward Beggs, Neoteric Biofuels Inc"

A variation on this theme is adding a solvent to the veg oil to lower the viscosity -- usually 3% white spirit (a.k.a. mineral turpentine, Stoddard solvent, turpentine substitute). This raised a lot of interest after it was publicized on a British TV program -- "just add a spoonful". It also raised a lot of scepticism: "'experimental' at best" was the view of experienced SVO users, and "steer well clear". We agree. Work on blends of SVO with other solvents, such as butanol and ethanol, is still experimental. Go ahead and experiment, but there are no guarantees.

2. Straight vegetable oil

Straight vegetable oil (SVO) systems can be a clean, effective and economical option.

Unlike biodiesel, with SVO you have to modify the engine. The best way is to fit a full single-tank SVO system with different injectors and glowplugs, injector pump adjustment, fuel pre-heating, temperature controls and extra filters. With the German Elsbett single-tank SVO system you can use petro-diesel, biodiesel or SVO, in any combination. Just start up and go, stop and switch off, as usual.

There are also two-tank systems which only pre-heat the oil, to make it thinner. You have to start the engine on ordinary petroleum diesel or biodiesel in one tank to warm it up, then switch to SVO in the other tank, and switch back to petro- or biodiesel before you stop the engine, or you'll coke up the engine and the injectors.

More information on straight vegetable oil systems here.

3. Biodiesel

Biodiesel has some clear advantages over SVO: it works in any diesel, without any conversion or modifications to the engine or the fuel system -- just put it in and go. It also has better cold-weather properties than SVO (but not as good as petro-diesel -- see Using biodiesel in winter). Unlike SVO, it's backed by many long-term tests in many countries, including millions of miles on the road.

Biodiesel is a clean, safe, ready-to-use, alternative fuel, whereas it's fair to say that many SVO systems are still experimental and need further development.

On the other hand, biodiesel can be more expensive, depending what you make it from and whether you're comparing it with new or used oil (and where you live). And, unlike SVO, it has to be processed -- you have to make it. But the large and rapidly growing worldwide band of homebrewers don't seem to mind -- they make a supply every week or once a month and soon get used to it. Many have been doing it for years.

And anyway, you have to process SVO too, especially WVO (waste vegetable oil, used, cooked), which many people with SVO systems use because it's cheap or free for the taking. WVO has to be filtered and dewatered, and probably should be deacidified.

Biodieselers say, "Well, if I'm going to have to do all that I might as well make biodiesel instead." But SVO types scoff at that -- it's much less processing than making biodiesel, they say. To each his own.

x	Needs processing	Guaranteed trouble-free	Engine conversion	Cheaper
Biodiesel	Yes	Yes	No	Sometimes
SVO/WVO	Less	No	Yes	Usually

Biodiesel

Converting the oil to biodiesel is probably the best of the three options (or we think so anyway).

You could simply buy your biodiesel instead. Most major European vehicle manufacturers now provide vehicle warranties covering the use of pure biodiesel -- though that might not be just any biodiesel. Some insist on "RME", rapeseed methyl esters, and won't cover soy biodiesel in the US, but this seems to be more a trade-related issue than a quality-control one. Germany has more than 1,500 filling stations supplying biodiesel, and it's cheaper than ordinary diesel fuel. It's widely used in France, the world's largest producer. Virtually all fossil diesel fuel sold in France contains between 2% and 5% biodiesel. New EU laws will soon require this Europe-wide. Some states in the US are legislating similar requirements. There's a growing number of US suppliers. Biodiesel is more expensive than ordinary diesel in the US but sales are rising very fast and prices will drop in time. In the UK biodiesel is taxed less than petrodiesel and it's available commercially.

But there's a lot to be said for the GREAT feeling of independence you'll get from making your own fuel (and it's more than just a feeling -- it's real!).

If you want to make it yourself, there are several good recipes available for making high-quality biodiesel, and they all say what we also say: some of these chemicals are dangerous, take full safety precautions, and if you burn/maim/blind/kill yourself or anyone else, that will make us very sad, but not liable -- we don't recommend anything, it's nobody's responsibility but your own.

On the other hand, a lot of people are doing it -- it's safe if you're careful and sensible. "Sensible" also mean not over-reacting, as some people do: "I'd like to make biodiesel but I'm frightened of all those terrible poisons." In fact they're common enough household chemicals. Lye is sold in supermarkets and hardware stores as a drain-cleaner, there's probably a can of it under the sink in most households. Methanol is the main or only ingredient in barbecue fuel or fondue fuel, sold in supermarkets and chain stores as "stove fuel" and used at the dinner table; it's also the main ingredient in the fuel kids use in their model aero engines. So get it in perspective, no need to be frightened. See Safety for further information. Learn as much as you can first -- lots of information is available. Make small test batches before you try large batches (see also Test-batch mini-processor). Make it with fresh oil before you try waste oil.

Where do I start?

Start here: make a test batch of biodiesel using 1 litre of fresh new oil in a blender. If you don't have a spare blender, either get one (you can pick them up quite cheap second-hand), or try this. Or, better, make a simple Test-batch mini-processor.

Go on, do it! Get some methanol, some lye and some new oil at the supermarket and go ahead -- it's a real thrill!

Here's the recipe, just use 1 litre of oil instead of 10 litres, and 200 ml of methanol instead of 2 litres, with 3.5 grams of lye. Here's how to use a blender, and here's how to mix the sodium methoxide -- "Methoxide the easy way" (also the safe way).

What's next?

Learn. You have some decisions to make. It's all quite simple really, thousands of people are doing it, very few of them are chemists or technicians, and there's nothing a layman can't understand, and do, and do it well. But there is quite a lot to learn. You should find everything you need to know right here. We've tried to make it easy for you. You start off with the simplest process that has the best chance of success and move on step by step in a logical progression, adding more advanced features

First, here's how we started.

The process

Vegetable oils and animal fats are triglycerides, containing glycerine. The biodiesel process turns the oils into esters, separating out the glycerine. The glycerine sinks to the bottom and the biodiesel floats on top and can be syphoned off.

The process is called transesterification, which substitutes alcohol for the glycerine in a chemical reaction, using lye as a catalyst.

We use methanol to make methyl esters. We'd rather use ethanol because most methanol comes from fossil fuels (though it can also be made from biomass, such as wood), while ethanol is plant-based and you can distill it yourself, but the biodiesel process is more complicated with ethanol. (See Ethyl esters.)

Ethanol (or ethyl alcohol, grain alcohol -- EtOH, C2H5OH) also goes by various other well-known names, such as whisky, vodka, gin, and so on, but methanol is a deadly poison: first it blinds you, then it kills you, and it doesn't take very much of it. It takes a couple of hours, and if you can get treatment fast enough you might survive. (But don't be put off -- it's easy to do this safely. Safety is built-in to everything you'll read here.)

Methanol is also called methyl alcohol, wood alcohol, wood naphtha, wood spirits, methyl hydrate (or "stove fuel"), carbinol, colonial spirits, Columbian spirits, Manhattan spirits, methylol, methyl hydroxide, hydroxymethane, monohydroxymethane, pyroxylic spirit, or MeOH (CH3OH or CH4O) -- all the same thing. (But, confusingly, "methylcarbinol" or "methyl carbinol" is used for both methanol and ethanol.) In the US you can usually get it at race tracks.

Methylated spirits (denatured alcohol) doesn't work; isopropyl alcohol (rubbing alcohol) also doesn't work.

The lye catalyst can be either sodium hydroxide (caustic soda, NaOH) or potassium hydroxide (KOH), which is easier to use, and it can provide a potash fertilizer as a by-product. Sodium hydroxide is often easier to get and it's cheaper to use. If you use potassium hydroxide, the process is the same, but you need to use 1.4 times as much. (See More about lye.) You can get KOH from soapmakers' suppliers and from chemicals suppliers. Other chemicals, such as isopropyl alcohol (isopropanol) for titration, are available from chemicals suppliers.

CAUTION:
Lye (both NaOH and KOH) is dangerous -- don't get it on your skin or in your eyes, don't breathe any fumes, keep the whole process away from food, and right away from children. Lye reacts with aluminum, tin and zinc. Use glass, enamel, stainless steel or HDPE (High-Density Polyethylene) containers for methoxide. (See Identifying plastics.)