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
Poor man's titration
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.

 

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.)

See also Making lye from wood ash.

Our first biodiesel

This was just an investigative project for us when we made our first biodiesel more than five years ago in Hong Kong. Most of the equipment was improvised. Apart from chemicals and some beakers, syringes and things, the only thing we bought was a set of scales.

We got about 60 litres of used oil (WVO --waste vegetable oil) from Lantau Island's local McDonald's. There were four 16-litre cans of it, a mix of used cooking oil and residual beef and chicken fats. Two of the tins were solidified, the other two held a gloppy semi-liquid. We warmed it up a bit on the stove (to about 50 deg C) and filtered it through a fine mesh filter, and then again through coffee filter papers, but it was quite clean -- very little food residue was left in the filters.

 

Used cooking oil from McDonald's.

We'd also bought 10 litres of the cheapest new cooking oil we could find -- we don't know what kind of oil it was, the tins only said "Cooking Oil" -- and used this for our first experiment.

It worked, but we've learnt a lot since then. Now it's easy to make high-quality biodiesel every time without fail. And we don't use open containers for processing now, and neither should you -- and mix the methanol in closed containers too.

Practices, knowledge, technology, equipment and safety measures have all improved tremendously in the last five years since we brewed our first batch, thanks mainly to the collaborative work of thousands of biofuellers worldwide at the Biofuel mailing list and other Internet forums.

As a Biofuel list member said in 2002: "I just want to say how important what you all are doing here is. Closed-system fuel production, on a local or small regional scale, tied to local resources, using accessible technologies, and dependent on entrepreneurial innovation combined with open-source information exchange -- it's AWESOME. Keep up the good work everyone, before the planet fries."

Biodiesel from new oil

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Make your first test-batch using new oil (fresh, virgin, uncooked). Follow the instructions below, but use 1 litre of oil instead of 10 litres, and 200 ml of methanol instead of 2 litres, with 3.5 grams of lye. Check the quality of your biodiesel with this basic quality test.

 

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We had difficulty finding pure methanol in Hong Kong, and eventually paid the very high price of US$10 per litre for 5 litres from a wholesale chemical supply company. It has to be 99% pure or better. (See How much methanol?)

In the US, for small test batches, you can get DriGas from the hardware store. One type of DriGas is methanol, another is isopropanol, make sure to get the methanol one.

We used 2 litres of methanol to 10 litres of vegetable oil, and 3.5 grams of pure, granular lye (sodium hydroxide) per litre of oil -- 35 grams for 10 litres. (See More about lye.)

You can get lye at most hardware stores (Red Devil lye in the US). Shake the container to check it hasn't absorbed moisture and coagulated into a useless mass, and make sure to keep it airtight.

We had to be quick measuring out the 35 grams of lye required -- summer humidity in Hong Kong is usually about 80% at 30 deg C or more, and the lye rapidly got wet, making it less effective.

We mixed the lye with the 2 litres of methanol in a strong, heatproof glass bottle with a narrow neck to prevent splashing. It fumed and got hot, and took about 15 minutes to mix. See Methoxide the easy way. (Use closed containers for mixing methoxide.)

This mixture is sodium methoxide, an extremely powerful base which enjoys eating stuff like human flesh -- take full safety precautions when working with sodium methoxide, have a source of running water handy.

 

Midori checks the temperature of the oil.

Meanwhile we'd warmed the 10 litres of new oil in a steel bucket on the stove to about 40 deg C (104 deg F) to thin it so it mixed better. In fact, 55 deg C (131 deg F) is a better processing temperature. Don't let it get too hot or the methanol will evaporate. (Methanol boils at 64.7 deg C, 148.5 deg F.)

We'd made a wooden jig with a portable vice clamped to it holding a power drill fitted with a paint mixer to stir the contents of the bucket. This did a good job without splashing.

Stirring well, we carefully added the sodium methoxide to the oil. The reaction started immediately, the mixture rapidly separating into a clear, golden liquid on top with the light brown glycerine settling out at the bottom. We kept stirring for an hour, keeping the temperature constant. Then we let it settle overnight.

The next day we syphoned off 10 litres of biodiesel, leaving two litres of glycerine in the bottom of the bucket.

Biodiesel from waste oil

This is more appealing than using new oil, but it's also more difficult.

First, check for water content. Used oil often has some water in it, and it has to be removed before processing. See Removing the water, below.

Waste oil needs more catalyst than new oil to neutralize the Free Fatty Acids (FFAs) formed in cooking the oil, which interfere with the transesterification process.

You have to titrate the oil to determine the FFA content and how much lye will be required to neutralize it. This means determining the pH -- the acid-alkaline level (pH7 is neutral, lower values are increasingly acidic, higher than 7 is alkaline). An electronic pH meter is best, but you can also use pH test strips (or litmus paper), or phenolphthalein solution (from a chemicals supplier).

We also thought of using red cabbage juice, which changes from red in a strong acid, to pink, purple, blue, and finally green in a strong alkali (see Natural test papers -- Cabbage, Brazil, Dahlia, Elderberry, Indigo, Litmus, Rose, Rhubarb, Turmeric). We didn't have a pH meter then so we used phenolphthalein solution. Phenolphthalein is colourless up to pH 8.3, then it turns pink (or rather magenta), and red at pH 10.4.

 

Keith checks the pH of the waste oil.

Dissolve 1 gm of lye in 1 litre of distilled water (0.1% w/v lye solution). In a smaller beaker, dissolve 1 ml of the cooled oil in 10 ml of pure isopropyl alcohol. Warm the beaker gently by standing it in some hot water, stir until all the oil dissolves in the alcohol and turns clear. Add 2 drops of phenolphthalein solution.

Using a graduated syringe, add 0.1% lye solution drop by drop to the oil-alcohol-phenolphthalein solution, stirring all the time, until the solution starts to turn pink and stays that way for 10 seconds. Take the number of millilitres of 0.1% lye solution you used and add 3.5. This is the number of grams of lye you'll need per litre of oil. (See Better titration.)

Our first titration took 6 ml of 0.1% lye solution (not very good oil), so we used 6 + 3.5 = 9.5 grams of lye per litre of oil: 95 grams for 10 litres.

Then proceed as with new oil: measure out the lye and mix it with the methanol to make sodium methoxide -- it will get even hotter and take longer to mix, as there's more lye this time. Make sure the lye is completely dissolved in the methanol.

Carefully add the sodium methoxide to the warmed oil while stirring, and mix for an hour. Settle overnight, then syphon off the biodiesel.

The first five times we did this, using 10 litres of waste oil each time, we got biodiesel (a bit darker than the new oil product) and glycerine three times, and twice we got jelly. The answer is to be more careful with the titration: do it twice, just to be sure. Read on, and you'll learn how to make high-quality biodiesel every time, without fail.

The production rate was less than with new oil, ending with 8-9 litres of biodiesel instead of 10. The acid-base Foolproof method, developed since, will get much higher production rates with heavily-used oil.

Check the quality of your biodiesel with this basic quality test.

For a more detailed description of making biodiesel from WVO, see Mike Pelly's method.

Removing the water

Water in the oil will interfere with the lye, especially if you use too much lye, and you'll end up with jelly. Test first for water content -- heat half a litre or so of the oil in a saucepan on the stove and monitor the temperature with a thermometer. If there's water in it it will start to "snap, crackle and pop" by 50 deg C (120 deg F) or less. If it's still not crackling by 60 deg C (140 deg F) there's no need to dewater it.

See Mike Pelly's recommendations: Removing the water.

Here's another way, from Aleks Kac -- it uses less energy and doesn't risk forming more Free Fatty Acids (see below) by overheating. Heat the oil to 60 deg C (140 deg F), maintain the temperature for 15 minutes and then pour the oil into a settling tank. Let it settle for at least 24 hours. Make sure you never empty the settling vessel more than 90%.

Here's what Biofuel mailing list member Dale Scroggins says about water removal:

Water in vegetable oil can exist as free water, which will eventually settle to the bottom of a vessel; as suspended droplets, which may settle if the oil is heated, or the droplets are coalesced; and as water in solution with other impurities in the oil. Free water is the easiest to remove. The droplets are removed most efficiently by coalescing and draining. Suspended droplets that cannot be coalesced and water in solution are more problematic.

Boiling off the water is more difficult than it appears on the surface. Colligative properties of solutions (and some mixtures) can make removal of the last traces of water almost impossible. Water mixed with oil will not boil at the same temperature and pressure as pure water. As water is removed, more heat or lower pressure will be required to remove more water. If the oil contains salts or semi-soluble fatty acids, distillation is even more difficult.

As the percentage of water in the solution decreases (its molar fraction) its vapor pressure will continue to drop. Lowering pressure in the system alone may be insufficient to sustain vaporization when the solution becomes concentrated (the molar fraction of the solute greatly exceeds that of the solvent). Results will vary depending upon the nature of the water-soluble impurities in the oil. Few solutions are ideal, in terms of Raoult's law, and in used vegetable oil, there is no way to know what solutes are in the oil.

The important thing is how well-used, or overused, the oil is. Titration will tell you that. The higher the titration result, the more water it's likely to contain, and the more difficult it will probably be to remove the water.

Start with heating to 60 deg C and settling, as Aleks Kac recommends, and if that doesn't give satisfactory results, try boiling it off, as Mike Pelly recommends. Then try processing small test batches of a liter or less first. If you still have difficulties, try to find better-quality oil.

Washing

Biodiesel must be washed before use to remove soaps, excess methanol, residual lye, free glycerine and other contaminants. Some people (fewer and fewer of them) say washing isn't necessary, arguing that the small amounts of contaminants cause no engine damage.

Read what the Fuel Injection Equipment (FIE) Manufacturers (Delphi, Stanadyne, Denso, Bosch) have to say about these contaminants:
Summary -- html
Full document -- Acrobat file, 104kb

See also: Determining the Influence of Contaminants on Biodiesel Properties, Jon H. Van Gerpen et al., Iowa State University, July 31, 1996 -- 12,000-word report on contaminants and their effects. Acrobat file, 2.1Mb:
http://www.biodiesel.org/resources/reportsdatabase/reports/gen/gen014.pdf

Quality biodiesel must be washed. No, filtering it is no use, and letting it settle for a few weeks won't help either. Anyway washing the fuel is easy, and it's well worth the trouble.

See Washing

Using biodiesel

You don't have to convert the engine to run it on biodiesel, but you do need to make some adjustments and check a few things.

Petroleum diesel leaves a lot of dirt in the tank and the fuel system. Biodiesel is a good solvent -- it tends to free the dirt and clean it out. Be sure to check the fuel filters regularly at first. Start off with a new fuel filter.

If a car has been left standing for a long time with petroleum diesel fuel in the tank the inside of the tank may have rusted (water content is quite a common problem with petro-diesel fuel). Biodiesel will free up the rust, and it could clog the particle filter inside the tank. At worst the car simply stops, starved of fuel. It's not a very common problem, but it happens.

A common warning is that biodiesel, especially 100% biodiesel, will rot any natural or butyl rubber parts in the fuel system, whether fuel lines or injector pump seals, and that they must first be replaced with resistant parts made of Viton. But rubber parts in diesel engine fuel systems have been rare or non-existent since the early 1980s -- it seldom happens, and when it does it's not catastrophic, you have plenty of warning and it's easily fixed. See: Biodiesel and your vehicle -- Compatability: Rubber.

See Biodiesel and your vehicle

Safety

Wear proper protective gloves, apron, and eye protection and do not inhale any vapors. Methanol can cause blindness and death, and you don't even have to drink it, it's absorbed through the skin. Sodium hydroxide can cause severe burns and death. Together these two chemicals form sodium methoxide. This is an extremely caustic chemical. These are dangerous chemicals -- treat them as such! Gloves should be chemical-proof with cuffs that can be pulled up over long sleeves -- no shorts or sandals. Always have running water handy when working with them. The workspace must be thoroughly ventilated. No children or pets allowed.

Organic vapor cartridge respirators are more or less useless against methanol vapors. Professional advice is not to use organic vapor cartridges for longer than a few hours maximum, or not to use them at all. Only a supplied-air system will do (SCBA -- Self-Contained Breathing Apparatus).

The best advice is not to expose yourself to the fumes in the first place. The main danger is when the methanol is hot -- when it's cold or at "room temperature" it fumes very little, and this is easily avoided. Don't use "open" reactors -- biodiesel processors should be closed to the atmosphere, with no fumes escaping. All methanol containers should be kept tightly closed anyway to prevent water absorption from the air.

We transfer methanol from its container to the methoxide mixing container by pumping it, with no exposure at all. This is easily arranged, and an ordinary aquarium air-pump will do (the same one you use for washing the biodiesel). The methoxide is mixed like this -- Methoxide the easy way, which also happens to be the safe way. The mixture gets quite hot at first, but the container is kept closed and no fumes escape. When mixed, the methoxide is again pumped into the (closed) biodiesel processor with the aquarium air-pump -- there's no exposure to fumes, and it's added slowly, which is optimal for the process and also for safety. See Adding the methoxide.

Once again, making biodiesel is 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: be careful with these chemicals -- be careful with ALL chemicals -- but there's no need to be frightened of them.

For fire risks, see Hazards


Next: Make your own biodiesel -- Page 2