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Make your own biodieselSpanish version -- Versión en español
Three choices Three choicesThere are at least three ways to run a diesel engine on biofuel using vegetable oils, animal fats or both. All three are used with both fresh and used oils.
The first two methods sound easiest, but, as so often in life, it's not quite that simple. 1. Mixing itVegetable oil is much more viscous (thicker) than either petro-diesel or biodiesel. The purpose of mixing straight vegetable oil (SVO) or blending it with other fuels and solvents is to lower the viscosity to make it thinner so that it flows more freely through the fuel system into the combustion chamber. 2. Straight vegetable oilStraight vegetable oil fuel (SVO) systems can be a clean, effective and economical option. 3. Biodiesel or SVO?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. BiodieselConverting the oil to biodiesel is probably the best all-round solution of the three options (or we think so anyway). Where do I start?Start with the process, NOT with the processor. The processor comes later. What's next?Learn, one step at a time. It's all quite simple really, very few biodiesel homebrewers are chemists or technicians, there's nothing a layman can't understand, and do, and do it well. But there is a lot to learn.
Thousands of ordinary people have done this without any other help, and so can you. You don't need anyone to show you how, and you don't need to find another biodieseler in your area first so you can see their set-up in action. Not all biodiesel brewers are the same, not all make quality fuel (though they might think they do). There's a fair chance you'd just be picking up someone else's bad habits. "Your website is very well done. I appreciate the layers of technical complexity. You have progressively more technical information layered in an escalating and logical fashion. I like the links as each new item is introduced, the user can click for more specific information on a topic and it opens in a new window. This eliminates the tediousness of having to constantly backtrack to where the new concept was introduced." Close the new window when you're finished with it and you're back where you were. Keep going. The processBiodiesel is made from vegetable and animal fats and oils, or triglycerides -- three chains of fatty acids joined by a glycerine molecule. The biodiesel process replaces the glycerine with methanol, forming fatty acid methyl esters (FAME), the technical name for biodiesel. The glycerine sinks to the bottom and the biodiesel floats on top and can be syphoned off. We recommend KOH, especially for beginners. Make your first test batchHere's what you need:
See Accurate measurements Using a blender. Use a spare blender you don't need or get a cheap second-hand one -- cheap because it might not last very long, but it will get you going until you build something better.
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![]() Used cooking oil from McDonald's. |
![]() Simple, safe, efficient biodiesel processors you can build cheaply and easily |
Make your first test-batch using one litre of new oil (fresh, uncooked). Follow the instructions above. Check the quality of your biodiesel with these quality tests.
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 Methanol suppliers)
We used sodium lye drain-cleaner (NaOH, sodium hydroxide) bought in small plastic containers at a local hardware store, not always very fresh. (We recommend using potassium hydroxide, KOH, instead of NaOH. See More about lye.)
We used 2 litres of methanol to 10 litres of vegetable oil, and 3.5 grams of NaOH per litre of oil -- 35 grams for 10 litres. (It's better to start with smaller one-litre test batches.)
We had to be quick measuring out the 35 grams of lye required. Lye is very hygroscopic, it absorbs moisture from the air; 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. (See More about lye.)
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. (Use closed containers for mixing methoxide! See above, Mixing the methoxide.)
This mixture is sodium methoxide, a powerful corrosive base -- take full safety precautions when working with sodium methoxide, have a source of running water handy.
Meanwhile we'd warmed the 10 litres of new oil in a 20-litre steel oil drum to about 40 deg C (104 deg F) to thin it so it mixed better (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.)
Midori checks the temperature of the oil.
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 oil drum. This did a good job without splashing. (Not advised, it's dangerous to use sparking electric motors such as those in drills for processing with open containers. See "Simple 5-gallon processor" for a much better way.)
Stirring well, we carefully added the sodium methoxide to the oil. The reaction started immediately, the mixture rapidly transforming into a clear, golden liquid. 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 by-product in the bottom of the drum.
This is more appealing than using new oil, but it's also more complicated.
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.
Then, check the acid content, by titration.
Refined fats and oils have a Free Fatty Acid (FFA) content of less than 0.1%. Used oil has more FFA, sometimes much more. FFAs are formed in cooking the oil, the longer and hotter the oil has been cooked the more FFAs it will contain. FFAs interfere with the transesterification process for making biodiesel. With waste oil you have to use more lye to neutralise the FFAs. The extra lye turns the FFAs into soap which drops out of the reaction along with the glycerine by-product.
It's essential to titrate the oil to find out how much FFA it contains so you can calculate exactly how much extra lye will be required to neutralise it.
This means determining the pH -- the acid-alkaline level (pH7 is neutral, lower than 7 is increasingly acidic, higher than 7 is increasingly alkaline). Use an electronic pH meter or phenolphthalein solution (from a chemicals supplier). pH test strips are less accurate than pH meters or phenolphthalein.
You can also use red cabbage juice, which changes from red in a strong acid, to pink, purple, blue, and finally green in a strong alkali, or one of the other plant-based pH indicators. See Natural test papers -- Cabbage, Turmeric, Brazil, Dahlia, Elderberry, Indigo, Litmus, Rose, Rhubarb.
Most people use a pH meter or phenolphthalein solution, and that's what we recommend.
We used phenolphthalein solution when we started making biodiesel in 1999. Phenolphthalein is colourless up to pH 8.3, then it turns pink (or rather magenta), and red at pH 10.4. When it just starts to turn pink and stays that way for 15 seconds it's reading pH 8.5, which is the measure you want.
Phenolphthalein lasts about a year. It's sensitive to light, store it in a cool, dark place.
Don't be put off or frightened away by titration. It's not difficult, thousands of non-chemist biodiesel makers have learnt how to do it without difficulty and use it every time they make biodiesel. Just follow the directions, step by step. See also:
Titration
Dissolve 1 gm of lye (KOH or NaOH) in 1 litre of distilled water to make 0.1% w/v lye solution (weight-to-volume).
Keith checks the pH of the waste oil.
In a smaller beaker, dissolve 1 ml of the oil to be tested in 10 ml of pure isopropyl alcohol (isopropanol).
Warm the beaker gently by standing it in some hot water, stir until all the oil dissolves in the alcohol and turns clear. (Wooden chopsticks make good stirrers for titration.)
Add 2 drops of phenolphthalein solution.
Using a graduated syringe or a pipette, add 0.1% lye solution drop by drop to the oil-alcohol-phenolphthalein mixture, stirring all the time. It might turn a bit cloudy, keep stirring. Keep on carefully adding the lye solution until the mixture just starts to turn pink (magenta) and stays that way for 15 seconds.
Take the number of millilitres of 0.1% lye solution you used and add the basic amount of lye needed to process fresh oil -- 3.5 grams for NaOH or 4.9 grams for (pure) KOH. This is the number of grams of lye you'll need per litre of the oil you titrated. (Don't worry that you seem to be adding millilitres to grams, that's the way it works.)
Our first titration took 6 ml of 0.1% NaOH solution (not very good oil), so we used 6 + 3.5 = 9.5 grams of NaOH per litre of oil.
NOTE: Beginners should avoid poor-quality oil like this for their first test-batches with used oil.
Find a source of oil that titrates at about 2.5 ml of 0.1% NaOH solution or less, not more than 3.5 ml. Leave overcooked oils with higher titration levels for later when you have more experience.
Try to get a selection of used oils from different restaurants -- if you're friendly and polite and tell them what it's for they usually won't mind giving you a couple of litres. Find out what kind of oil they use. (This might not be the best time to suggest collecting large amounts of oil for full-scale production, leave that for later, unless they suggest it first.)
Start by titrating the samples. Use low-titration oil for your first used oil test batches, move on to higher titration levels and different kinds of oil as you gain experience.
If you have difficulties at first, it could be due to the kind of oil you're using -- see above, Which oil is best?
If not, then see What should you do if your fuel doesn't pass the wash-test? and How to use the quality tests, as with new oil.
Test batches with used oil
Make small, one-litre test batches. Use the same procedure as with new oil, see above.
Measure out the lye and mix it with the methanol to make sodium methoxide or potassium hydroxide -- it will get slightly hotter and take a little longer to mix as there's more lye this time. Make sure the lye is completely dissolved in the methanol. (See above, Mixing the methoxide.)
Carefully add the methoxide to the warmed oil while stirring, and mix for an hour. Settle for 12-24 hours, then syphon or decant off the biodiesel.
Check the quality of your biodiesel with these quality tests.
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 two or three times at first, until you've had more practice and perfected your technique.
With poor-quality oils that have high titration levels do bracket tests as well. Do everything you can to improve the accuracy of your measurements so you get consistent results.
Read on, and you'll learn how to make high-quality biodiesel every time, without fail. (It's a LONG time since we made jelly!)
The production rate with our first batches was less than with new oil, ending with 8-9 litres of biodiesel instead of 10. With care and experience the production rate improves.
When you're confident that you can get good results every time, even using oil from different sources, then it's time to scale up the process to provide your fuel needs. Now that you have a feel for the process and know what to expect, you'll have a much better idea of what sort of processor you want than if you'd started off building the processor (as many do) rather than learning the process first.
"Understanding of the process is vital to operate the plant." -- Prof. P.V. Pannir Selvam, Technology Center, Department of Chemical Engineering, Universidade Federal do Rio Grande do Norte (UFRN), Brazil, Biofuel mailing list, 15 Apr 2007
See Biodiesel processors.
However, one-litre test batches are not just something for beginners. It's a basic technique you'll always use. Many experienced biodiesel makers do test batches with each batch of oil. Many not only titrate the oil every time to calculate the right amount of lye to use, they also do "bracket" tests in sequence, followed by wash tests. You learn a lot that way, your fuel gets better, life gets easier.
In fact life is already easier -- people who start off making 40-gallon batches often never learn the accuracy and discipline that comes from making one-litre test batches first. Their fuel quality suffers for it, and when they encounter that inevitable "problem batch", they suffer for it too.
But if you've followed the instructions here carefully, you'll be familiar with all the variables, you'll have good methodology, and you'll be in a much better position to trouble-shoot a problem batch successfully.
Keep a Biodiesel Journal -- make notes, keep records. Get some small glass jars and keep samples of all your batches, clearly labelled and cross-referenced to the notes in your journal. You won't regret it.
When scaling up from small test-batches to a full-sized processor, be aware that the process will probably need some adjusting. All the various processing methods use averages and approximations because processors and conditions vary so widely. Blenders especially agitate much faster than any full-scale processor, a real processor will probably take longer to achieve the same result. Use the fuel quality tests to fine-tune the process to your particular processor. See Scaling up.
Water in the oil interferes with the lye catalyst, especially if you use too much lye, and you can end up with a batch of 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 so. If it's still not crackling by 60-65 deg C (140-149 deg F) there should be 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 (or for a week or two). Pump the oil out from the top, leave the bottom 90% for removal later and re-settling.
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 and the more acidic the oil, the more water it's likely to contain, and the more difficult it will probably be to remove the water.
Biofuel list member Joe Street adds:
Although Dale's points about unknown solutes in waste vegetable oil and their ability to lock up water are true I have found that practically speaking oil (even terrible oil) can be reliably dried to the point of being reacted without problems by the process of heat and vacuum.
Heating the oil to reaction temperature (I use 58 deg C, 136 deg F) and pulling a vacuum to 27 inches of mercury immediately before the reaction has allowed me to remove water beyond what falls out by heating alone.
I estimate that oil at 55-60 deg C can contain as much as 10,000 PPM (that's 1%) water. I have experimented with some extremely saturated oils (titrations up to 11 ml with 0.1% KOH) which require ridiculous amounts of catalyst when attempting base-only conversions. Although I cannot get complete conversions in these cases, drying the oil by heating and vacuum has allowed me to do this and still avoid problems with soap formation. (I am also very careful with my caustic and methanol.) Using a known temperature and a vacuum gauge is a very repeatable way of drying oil.
(See: Joe Street's processor)
Short of vacuum, start with heating the oil to 60 deg C and settling it, as Aleks Kac recommends, and if that doesn't give satisfactory results, try boiling the water off, as Mike Pelly recommends. Then try a small 1-litre test batch first.
If you still have difficulties, try to find a source of better-quality oil.
Or try using a glycerine pre-wash to lower the Free Fatty Acid level and dry the oil (see below, Glycerine pre-wash).
Or try this: Deacidifying WVO.
Many people filter their WVO before making biodiesel, but filtering takes time and energy, and there's really no need to filter it.
Settling the oil works just as well or better, and if it contains any water the water will settle out too.
If it's poor quality oil with a high titration level, heat it first, as in de-watering (above), and then let it settle.
If you don't have time to wait for the oil to settle, usually 1-2 weeks, it could be worth increasing the WVO supply and reserves to make the time.
If in collection you keep ahead of your processing rate, oil has a chance to settle. I have found that oil that has been sitting for several weeks is very dry if carefully decanted. Settling also results usually in oil which is spectacularly clear when observed in a glass container (you can read fine print through it) which means it is quite clean, perhaps cleaner than filtering may give you.
-- Joe Street, Biofuel mailing list, July 2006
I recently helped someone get off the ground making biodiesel. He's a tinkerer, and came up with an elaborate filtering/dewatering system. I repeatedly suggested that he trust gravity. He was away for about 10 days and when he came back he called to tell me that he couldn't distinguish the oil from the top half of an unfiltered cubie from his filtered oil. Getting rid of his filtering setup has made room for a settling tank.
-- Tom Kelly, Biofuel mailing list, April 2006
This is how Tom does it:
I allow the WVO to settle in cubies for a week. (A cubie is the 4.5 gal (17.7L) plastic container that veg oil is delivered to restaurants in.) I then pour the top 80% of each cubie into a 55 gal drum and consolidate the bottom 20% of 5 cubies into 1. Most of this will be ready for the barrel the next week. I have 4 WVO barrels. One is settled, two are settling, and one is being filled. I pump WVO out of the settled barrel from the top 3/4. This oil is very clear and requires very little drying.
We do it much the same way, settling the WVO first in the 18-litre metal cans it's supplied in here, then pouring it from the top. What's left at the bottom is re-settled.
We use a 55-gal (200-litre) steel drum for storage, but we don't pump the WVO out from the top. The drum has a bottom drain fitted with a 6"-high 3/4" standpipe (15cm-high x 1.9cm), which leaves any sediment on the bottom of the drum undisturbed.
Every now and then we drain the drum to the top of the standpipe, then remove the standpipe and drain the drum completely, sediment and all. The "bottoms" are resettled the same way, first in 18-litre metal cans.
The final sediment can be used as fire-starter, or added to the compost pile.
Simple gravity settling works well with oils titrating up to 3.5 ml NaOH solution and more.
The higher the titration level, the more water, impurities and suspensions the oil is likely to contain and the longer it will take to settle. For higher titration levels, heat the oil to 60 deg C (140 deg F), maintain the temperature for 15 minutes, then allow to cool, and let it settle.
There's no need to filter your biodiesel before using it either.
If you make the biodiesel properly, everything that a filter might remove will be in the by-product layer, not the biodiesel.
The biodiesel should be ready for instant consumption if it's clear and bright and without sediments.
-- Jan Warnqvist, Biofuel mailing list, Aug 2005
If the WVO has been filtered or settled to clear, any solid particles that get as far as the processor are small and won't affect the processing. During processing and settling, all unfiltered solids drop out into the glycerine by-product layer.
Settle it properly, separate the by-product carefully, wash, dry, and use. No need to filter it.
Badly processed biodiesel with poor conversion and too much soap might contain sediments in suspension, but if it's properly made it will be without sediments. Keep your processing fine-tuned by making test batches and using the quality tests.
People often want to "speed up" the process in the hopes of making it more efficient, and that often means taking short-cuts with settling times.
Don't do it -- life is easier with longer settling times, for the WVO, for the by-product to separate after processing, and for the wash-water to separate, especially after the final wash.
Actually what people speeding up the process usually want isn't more efficiency, it's more production. Probably they need a bigger processor, or two processors in parallel, rather than trying to make gravity hurry. Extra washing and settling tanks also help.
We don't have much time for centrifuges either, for similar reasons.
Again, people want to "speed up" the process by using a centrifuge instead of settling (or instead of washing, in some cases).
We've had a number of reports that centrifuges give poor results compared with normal settling, and especially compared with washing -- washing centrifuged fuel has yielded very soapy wash-water, so obviously the centrifuging didn't work very well.
We have laboratory test results of "finished" biodiesel made here in Japan in a $70,000 commercial processor. The finished fuel was washed and dried, and then it was centrifuged, and then samples were sent to the lab for testing. But the centrifuged fuel didn't come close to the standards requirements.
Our biodiesel surpasses the standards requirements though, made in a $100 homebuilt processor, with no need for a centrifuge.
You don't need a centrifuge. As with filtering, if you want more production get a bigger processor, or run two processors in parallel, add more settling and washing tanks.
From Biofuel mailing list member Chris Tan: "Good use for your glycerine cocktail", 6 Oct 2007:
Here's a good use for your glycerine cocktail before finally giving it away. My father came up with the idea that you can use the glycerine cocktail to dry your waste vegetable oil. And it works. Glycerine is hygroscopic enough to pull moisture out as it settles down so you don't have to heat or boil the oil to dry it. And as a bonus, most of the catalyst ends up in the glycerine cocktail so it neutralizes the Free Fatty Acids (FFAs) in the waste oil.
What we do is use at least 10/90 weight ratio: 10kg of glycerine for 90kg of waste oil. It is possible to bring the FFA level to zero if you use large amounts of glycerine (if you happen to have accumulated large amounts).
We use an ordinary 1/2 hp clear water pump with two inlet pipes to suck in glycerine and wvo. I adjust the inlet openings to regulate the mixing. We let it settle in a dedicated separate tank for about the same time as you would settle glycerine from biodiesel, though longer is better because of the viscosity of wvo.
We pump both glycerine cocktail and oil at the same time into a separate container. The glycerine will flow at a lower rate and the the inlet opening should be adjusted so that it finishes at the same time as the oil.
You can also mix it in the processor (just make sure to drain the water-rich glycerine and soap residue afterwards). Cycle the glycerine cocktail and oil mixture twice. The time it takes will depend on the gallons per minute rate of your pump, which is not the same for viscous oil, so measure and compute the time required for one or two cycles.
If the weather is cold, warming the oil first helps for mixing as well as settling: pre-heat to about 30 deg C (86 deg F).
-- Chris Tan
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
Myth:
> I did notice that a lot of the chemistry in the book was wrong.
> His main argument seemed to be against losing the energy in
> the methanol that was washed out.
The "energy" does you no good if your particular thermodynamic cycle can't take advantage of it. What is the cetane rating of methanol?
-- Ken Provost, Biofuel mailing list, "Re: washing?"
Quite so. The cetane rating of methanol is only 3, very low. Low cetane-number fuel in a diesel causes ignition delay and makes the engine knock. The high-speed diesel engines in cars and trucks are designed to use fuels with cetane numbers of about 50. The US biodiesel standard specifies a cetane number higher than 47, the EU standard specifies higher than 51. The methanol in unwashed biodiesel doesn't "make a great fuel anyway". It's also very corrosive. The EU biodiesel standard specifies less than 0.2% methanol content.
Quality biodiesel is well-washed biodiesel. Filtering it is no use, and letting it settle for a few weeks won't help much either. Anyway washing the fuel is easy.
See Washing
You don't have to convert the engine to run it on biodiesel, but you might need to make some adjustments and you should 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 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. See: Biodiesel and your vehicle -- Compatability: Filters.
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 happen 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
Please read this whole section right to the end.
Wear proper protective gloves, apron, and eye protection and do not inhale any vapours. 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 if at all and it's easily avoided, just keep it at arm's length whenever you open the container. 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. This is easily arranged, and an ordinary small aquarium air-pump will do. 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 -- nothing about life is safe if you're not 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
Question: Just how dangerous is methanol?
Fact: Methanol is a poisonous chemical that can blind you or kill you, and as well as drinking it you can absorb it through the skin and breathe in the fumes.
Question: How much does it take to kill you?
Short answer: Anything from five teaspoons to more than half a pint, but nobody really knows.
Fact: Human susceptibility to the acute effects of methanol intoxication is extremely variable. The minimum dose of methanol causing permanent visual defects is unknown. The lethal dose of methanol for humans is not known for certain. The minimum lethal dose of methanol in the absence of medical treatment is put at between 0.3 and 1 g/kg.
That means it's thought to take at least 20 grams of methanol to kill an average-sized person, or 25 ml, five teaspoonsful. Or it might need more than three times as much, 66 grams, 17 teaspoonsful, or maybe more, and even then it'll only kill you if you can't reach a doctor within a day or two, and maybe it still won't kill you.
But it definitely can kill you. If you drink five teaspoonsful of pure methanol you'll need medical treatment even if it doesn't kill you. Yet people have survived doses of 10 times as much -- a quarter of a litre, half a pint -- without any permanent harm. But others haven't survived much lower doses. Getting rapid medical attention is crucial, though the poisoning effects can be slow to develop.
Authorities advise that swallowing up to 1.3 grams or 1.7 ml of methanol or inhaling methanol vapour concentrations below 200 ppm should be harmless for most people. No severe effects have been reported in humans of methanol vapour exposures well above 200 ppm.
Out of 1,601 methanol poisonings reported in the US in 1987 the death rate was 0.375%, or 1 in 267 cases. It might have been only 1 in more than a thousand cases because most cases weren't reported. Most cases were caused by drinking badly made moonshine, which is a worldwide problem.
Fiction: "Methanol is ... a very active chemical against which the human body has no means of defence. It is absorbed easily through the skin and there is no means of elimination from the body, so levels of methanol dissolved in the blood accumulate."
That's from a British website trying to sell Straight Vegetable Oil (SVO) solvent additives by frightening people with the alleged perils of biodiesel. See The SVO vs biodiesel argument
Fact: 30 litres of fruit juice will probably contain up to 20 grams of methanol, near the official minimum lethal dose. Methanol is in the food we eat, in fresh fruit and vegetables, beer and wine, diet drinks, artificial sweeteners.
Not only that, methanol occurs naturally in humans. It's a natural component of blood, urine, saliva and the air you breathe out. It's there anyway even if you've never been exposed to chemical methanol or its fumes.
Methanol is eliminated from the body as a normal matter of course via the urine and exhaled air and by metabolism. Getting rid of it takes from a few hours for low doses to a day or two for higher doses. Some proportion of a dose of methanol just goes straight through, excreted by the lungs and kidneys unchanged. The normal background-level quantities of methanol in humans are eliminated and replenished all the time as a matter of course.
Fiction: It's largely biodiesel's methanol content that's being blamed when the same British SVO website charges that biodiesel is wasteful and environmentally irresponsible.
Fact: Methanol is readily biodegradable in the environment under both aerobic and anaerobic conditions (with and without oxygen) in a wide variety of conditions.
Generally 80% of methanol in sewage systems is biodegraded within 5 days.
Methanol is a normal growth substrate for many soil microorganisms, which completely degrade methanol to carbon dioxide and water.
Methanol is of low toxicity to aquatic and terrestrial organisms and it is not bioaccumulated. (It's toxic mainly to humans and monkeys.)
Environmental effects due to exposure to methanol are unlikely. Unless released in high concentrations, methanol would not be expected to persist or bioaccumulate in the environment. Low levels of release would not be expected to result in adverse environmental effects.
Fiction: A European SVO fuel website using similar anti-biodiesel tactics claims: "Biodiesel is a chemically altered plant oil. However the process to chemically change the structure of Pure Plant Oil is a very costly operation and requires a lot of energy, as it removes the glycerine substituting it by methanol as well as adding other chemicals, making the end-product poisonous and equally hazardous as fossil diesel fuel."
Fact: There is no free methanol in washed biodiesel. All the national standards require washing. According to US EPA studies methyl esters biodiesel is less toxic than table salt and more biodegradable than sugar. It has none of the toxic or environmental hazards of fossil diesel fuel.
To put it all in some perspective, 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.
Yes, methanol is a dangerous chemical, but quite how dangerous it may be is a little hard to say, and it causes surprisingly little harm. If you're careful and sensible and treat it with caution it won't harm you either. Many thousands of biodiesel homebrewers worldwide have been using it for years without serious mishap.
In our view, the difference between methanol and the really dangerous chemicals is that although methanol is poisonous, it's a natural chemical, you'd find it in the Garden of Eden too. It's not something nature's simply never heard of before and has no way of handling and neither do you, unlike too many of the 100,000-odd "new" chemicals now in use which aren't readily biodegradable and do accumulate, and spread, and keep being implicated in cancer clusters and bizarre sexual distortions of frogs and so on and on and on.
There are no reports of carcinogenic, genotoxic, reproductive or developmental effects in humans due to methanol exposure. Its environmental effects if any are minimal and short-lived.
Biodieselers can and do use methanol safely and the biodiesel fuel we make from it is safe and clean.
-- With information from: United Nations Environment Programme / International Labour Organisation / World Health Organization: International Programme On Chemical Safety, Environmental Health Criteria 196 - Methanol, from IPCS INCHEM, "Chemical Safety Information from Intergovernmental Organizations", in cooperation with the Canadian Centre for Occupational Health and Safety (CCOHS)
http://www.inchem.org/documents/ehc/ehc/ehc196.htm
See also:
Safety (MSDS) data for methyl alcohol
http://ptcl.chem.ox.ac.uk/MSDS/ME/methyl_alcohol.html
Methanol MSDS
http://www.bu.edu/es/labsafety/ESMSDSs/MSMethanol.html
Methanol as a plant nutrient
"Methanol is a fixed-carbon nutrient source for plants." -- From "Agriculture and Methanol", Chapter 7, Methanol Production and Use, ed. Wu-Hsun Cheng and Harold H. Kung, ISBN 0-8247-9223-8, 1994 (10th printing)
"Methanol treatments of C3 plants [most food crops] have been found to result in growth improvement... As a plant source of carbon, methanol is a liquid concentrate: 1 cc of methanol provides the equivalent fixed-carbon substrate of over 2,000,000 cc of ambient air... Methanol treatments are a means of placing carbon directly into the foliage... The application of 10-100% methanol to some crops increased photosynthetic productivity... The uptake of methanol by plants in light leaves no significant residual methanol above baseline as detectable by chromotography within 15-30 minutes of penetration. Treatment with methanol is therefore an inexpensive, safe, and effective means of providing plants with a source of fixed carbon and carbon dioxide... An economical means of inhibition of photorespiration has been sought for decades, and methanol may well provide the solution... The control of photorespiration across the food crops of the world could double yields." -- Greg Harbican and Peter G., Biofuel mailing list, 8 Sep 2004. For discussion see:
http://snipurl.com/j94f
Methanol and Plants
http://snipurl.com/j94e
Use for wash water - methanol
Note however that the authors of Methanol Production and Use caution that the application of methanol to crops still requires further study before we all "rush out to spray methanol".
Most of the excess methanol used in the biodiesel process ends up in the glycerine by-product layer, and the rest stays in the biodiesel. If you don't reclaim it for re-use (you should!) the portion that's in the biodiesel gets washed out when you wash the fuel, mostly with the first wash. The first wash-water probably won't contain more than 5-6% methanol (as well as some sodium or potassium lye and some soap). You could try spraying it on half a small patch of weeds and don't spray the other half to see what happens. Choose a bright sunny day.
Next: Make your own biodiesel -- Page 2
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