how to make bio diesel

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How to Make Bio Diesel

Last Updated: December 27, 2021 References

wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, 23 people, some anonymous, worked to edit and improve it over time. This article has been viewed 283,770 times. Learn more...

Biodiesel is an alternative fuel for diesel engines made from vegetable oil and/or animal fat. Since it is derived from renewable organic materials and has been shown to reduce certain harmful emissions when burned compared to conventional diesel, biodiesel has received wide attention as a "green" source of energy. Here are steps to synthesize this renewable fuel yourself.

Preparations

• A good work place will be well-ventilated and have clear access to running water, eye-wash stations, fire extinguishers, spill containment supplies, a fire alarm and a telephone to use in case of emergencies.

• When making biodiesel, you should also wear a heavy-duty apron, chemical-resistant gloves (butyl rubber is best when handling methanol and lye) and protective goggles or eyewear. The gloves should come up to your elbows or have cuffs you can pull over your long-sleeve shirt.

• Avoid using peanut oil, coconut oil, palm oil, tallow, and lard. These sources of oil solidify at relatively high temperatures. Biodiesel usually has a lower melting point than the oil it's made from [2] X Research source , but these oils can still be difficult for beginners.
• Also avoid olive oil. It, peanut oil, palm oil, tallow, and lard all contain more acids than in the recommended neutral oils. These extra acids can interfere with the reactions that take place to create the biodiesel.
• It's also possible to use waste vegetable oil which has been used for cooking. However, waste oil should be filtered to remove particulates, then allowed to settle for 24 hours to separate the oil from any water or other impurities. Pure oil will be clear and bright, with no sediment. [3] X Research source

• The ensuing reaction between the methanol and lye produces sodium methoxide. Sodium methoxide cannot be allowed to sit for long, as it degrades in the presence of moisture.

• Again, be attentive - the sodium methoxide will degrade rapidly, so proceed to the next step as soon as the lye is completely dissolved.

• As the reaction proceeds, two products are formed - biodiesel and glycerin.

• The mixture should separate into two layers - biodiesel and glycerin. Because biodiesel is less dense than glycerin, it should float, forming the top layer.

• Separate the top layer from the bottom by pouring it off very carefully or using a baster or pump.

• If you don't want to waste your glycerin, consider pouring it on a compost heap to increase the rate of decomposition or using it to make soap. Consult our wikiHow on Making Glycerin Soap for more information.

Community Q&A

• Wear safety glasses !! Thanks Helpful 4 Not Helpful 0
• Work near a sink with running water. Thanks Helpful 3 Not Helpful 0
• Use glass (not plastic) containers. Methanol can react with plastics, altering the course of the reaction. Thanks Helpful 2 Not Helpful 0

• Lye is corrosive to skin. Keep a bottle of vinegar on hand - in the event you splash any lye on your skin, rinse the area immediately with vinegar to neutralize the chemical, then rinse with water. Thanks Helpful 40 Not Helpful 9
• Handle methanol with extreme care. Methanol is the most dangerous chemical used to produce biodiesel. It is extremely flammable and can be caused to burn or explode with a single spark. It is also poisonous and can cause blindness if inhaled or ingested. Thanks Helpful 24 Not Helpful 5
• Keep the work area clear of distractions. Do not attempt to synthesize biodiesel around children or animals. Thanks Helpful 29 Not Helpful 8
• Do not bring any food or drink into the work area. Thanks Helpful 27 Not Helpful 11
• Consult your owner's manual or vehicle manufacturer before using biodiesel in a vehicle. Biodiesel can harm vehicles that are not built to run on it. Thanks Helpful 13 Not Helpful 4

Things You'll Need

• Long-sleeve shirt
• Heavy duty apron
• Chemical-resistant gloves
• Protective goggles or eyewear
• 1 liter (0.3 US gal) vegetable oil
• 3.5 grams sodium hydroxide (lye)
• 200 ml methanol
• Glass blender w/low speed option or other glass mixing apparatus
• Digital scale (for measuring 3.5 grams)
• Graduated cylinder or measuring cup (for measuring 200 ml)
• Glass container marked for measuring 1 liter (0.3 US gal)
• Glass container that will hold at least 1.5 liters (0.4 US gal)(2-quart glass pitchers work well)

You Might Also Like

• ↑ https://farm-energy.extension.org/biodiesel-production-principles-and-processes/
• ↑ http://journeytoforever.org/biodiesel_make.html#start
• ↑ https://www.popularmechanics.com/cars/hybrid-electric/a4717/4332200/
• ↑ https://www.youtube.com/watch?v=TC9h78b2RM4
• ↑ https://www.motherearthnews.com/green-transportation/biodiesel/home-biodiesel-production-zm0z15aszmar
• https://www.sciencedaily.com/releases/2016/04/160420111146.htm

About This Article

To make bio diesel, make sure that you're working in a clinical lab setting such as a laboratory at a college or research institution. Additionally, make sure you wear a heavy-duty apron, chemical-resistant gloves, and protective eyewear. In order to start, mix methanol in a glass blender. Then, add lye to the methanol and allow it to dissolve. While waiting, heat vegetable oil to 130 degrees Fahrenheit, then add it to the mixture and blend it for 30 minutes. Finally, allow the mixture to sit until the biodiesel floats to the top. To learn how to extract the bio diesel from the container, keep reading! Did this summary help you? Yes No

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How to Make Biodiesel From Vegetable Oil

Juanmonino / Getty Images

• Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
• B.A., Physics and Mathematics, Hastings College

Biodiesel is a diesel fuel that is made by reacting vegetable oil (cooking oil) with other common chemicals. Biodiesel may be used in any diesel automotive engine in its pure form or blended with petroleum-based diesel. No modifications are required, and the result is a less-expensive, renewable, clean-burning fuel.

Here's how to make biodiesel from fresh oil. You can also make biodiesel from waste cooking oil, but that is a little more involved, so let's start with the basics.

Materials for Making Biodiesel

• 1 liter of new vegetable oil (e.g., canola oil, corn oil, soybean oil)
• 3.5 grams (0.12 ounces) sodium hydroxide (also known as lye). Sodium hydroxide is used for some drain cleaners. The label should state that the product contains sodium hydroxide ( not calcium hypochlorite, which is found in many other drain cleaners).
• 200 milliliters (6.8 fluid ounces) of methanol (methyl alcohol). Heet fuel treatment is methanol. Be sure the label says the product contains methanol (Iso-Heet, for example, contains isopropyl alcohol and won't work).
• Blender with a low-speed option. The pitcher for the blender is to be used only for making biodiesel. You want to use one made from glass, not plastic because the methanol you will use can react with plastic.
• Digital scale to accurately measure 3.5 grams, which equals 0.12 ounces
• Glass container marked for 200 milliliters (6.8 fluid ounces). If you don't have a beaker, measure the volume using a measuring cup, pour it into a glass jar, then mark the fill-line on the outside of the jar.
• Glass or plastic container that is marked for 1 liter (1.1 quarts)
• Widemouthed glass or plastic container that will hold at least 1.5 liters (2-quart pitcher works well)
• Safety glasses, gloves, and an (optional) apron

You do not want to get sodium hydroxide or methanol on your skin, nor do you want to breathe the vapors from either chemical. Both are toxic. Please read the warning labels on the containers for these products. Methanol is readily absorbed through your skin, so do not get it on your hands. Sodium hydroxide is caustic and will give you a chemical burn. Prepare your biodiesel in a well-ventilated area. If you spill either chemical on your skin, rinse it off immediately with water.

How to Make Biodiesel

• You want to prepare the biodiesel in a room that is at least 70 degrees F because the chemical reaction will not proceed to completion if the temperature is too low.
• If you haven't already, label all your containers as "Toxic—Only Use for Making Biodiesel." You don't want anyone drinking your supplies, and you don't want to use the glassware for food again.
• Pour 200 milliliters methanol (Heet) into the glass blender pitcher.
• Turn the blender on its lowest setting and slowly add 3.5 grams sodium hydroxide (lye). This reaction produces sodium methoxide, which must be used right away or else it loses its effectiveness. (Like sodium hydroxide, it can be stored away from air/moisture, but that might not be practical for a home setup.)
• Mix the methanol and sodium hydroxide until the sodium hydroxide has completely dissolved (about 2 minutes), then add 1 liter of vegetable oil to this mixture.
• Continue blending this mixture (on low speed) for 20 to 30 minutes.
• Pour the mixture into a widemouthed jar. You will see the liquid start to separate out into layers. The bottom layer will be glycerin. The top layer is biodiesel.
• Allow at least a couple of hours for the mixture to fully separate. You want to keep the top layer as your biodiesel fuel. If you like, you can keep the glycerin for other projects. You can either carefully pour off the biodiesel or use a pump or baster to pull the biodiesel off of the glycerin.

Using Biodiesel

Normally, you can use pure biodiesel or a mixture of biodiesel and petroleum diesel as a fuel in any unmodified diesel engine. There are two situations in which you definitely should mix biodiesel with petroleum-based diesel:

• If you are going to be running the engine at a temperature lower than 55 degrees Fahrenheit (13 degrees C), you should mix biodiesel with petroleum diesel. A 50:50 mixture will work in cold weather. Pure biodiesel will thicken and cloud at 55 degrees Fahrenheit, which could clog your fuel line and stop your engine. Pure petroleum diesel, in contrast, has a cloud point of -10 degrees Fahrenheit (-24 degrees C). The colder your conditions, the higher the percentage of petroleum diesel you will want to use. Above 55 degrees Fahrenheit, you can use pure biodiesel without any problem. Both types of diesel return to normal as soon as the temperature warms above their cloud point.
• You will want to use a mixture of 20% biodiesel with 80% petroleum diesel (called B20) if your engine has natural rubber seals or hoses. Pure biodiesel can degrade natural rubber, though B20 tends not to cause problems. If you have an older engine (which is where natural rubber parts are found), you could replace the rubber with polymer parts and run pure biodiesel.

Biodiesel Stability and Shelf Life

You probably don't stop to think about it, but all fuels have a shelf life that depends on their chemical composition and storage conditions. The chemical stability of biodiesel depends on the oil from which it was derived.

Biodiesel from oils that naturally contain the antioxidant tocopherol or vitamin E (e.g., rapeseed oil) remain usable longer than biodiesel from other types of vegetable oils . According to Jobwerx.com, stability is noticeably diminished after 10 days, and the fuel may be unusable after two months. Temperature also affects fuel stability in that excessive temperatures may denature the fuel.

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How to Make Biofuel at Home: From Crop to Car

Home-brewed biofuels can run a tractor, pickup truck, or car. Learn how to make biofuel at home, including how much land you’ll need for growing biofuel crops.

I moved to Missoula in December 2006 to enter the environmental studies graduate program at The University of Montana. There I found an active community motivated by the desire for self-sufficiency. I soon was introduced to the people and activities at one of the local hubs of sustainability, the Program in Ecological Agriculture and Society (PEAS) farm.

The PEAS farm is managed collaboratively by the University and the nonprofit Garden City Harvest. The farm is run by student interns, volunteers, and a director from the environmental studies program. The nine-acre farm emphasizes sustainability and provides an opportunity to contribute to the local food pantry. On an annual basis, the farm provides 20,000 pounds of vegetables to the food bank and 80 Community Supported Agriculture (CSA) members who pay an annual “subscription” to receive a weekly share of the produce throughout the season.

Initially, my interest was piqued by the farm’s focus on promoting local food systems. In addition to planting, weeding, and harvesting vegetables, I built fences, planted trees, fixed sprinklers, moved rocks, and fed livestock. The more involved I became, the more I realized that every aspect of the farm related to my graduate work in some way. Over time, my interest in sustainable fuel sources and making biodiesel has grown.

With a vision of helping others achieve greater self-sufficiency, PEAS students have started a study to test the viability of running a tractor on vegetable oil produced on the farm. We hope the benefits of running a tractor on vegetable oil will help small-scale farmers achieve self-reliance, expand their markets for oilseed crops, and reduce their environmental footprint.

Biodiesel or Straight Vegetable Oil?

In the 1890s Rudolf Diesel designed the original diesel engine to run on vegetable oil, but modern diesel engines are intended to run on petroleum diesel. For those interested in making biodiesel for diesel engines, the world of biofuels offers two options: biodiesel or vegetable oil. Using biodiesel requires modifications to the vegetable oil itself; using straight vegetable oil requires modifications to the diesel engine.

Both biofuels have pros and cons, plus complicated nuances to their use and production. But for those with enough patience and enthusiasm to embrace biodiesel or veggie oil fuel, the rewards can be great.

For starters, straight vegetable oil is too thick to burn in a standard diesel engine. In cool weather, it becomes thick as butter, clogging fuel lines and injectors. But a diesel vehicle can be modified to run on straight vegetable oil by using either a dual-tank or single-tank fuel system.

The dual-tank system requires one tank for diesel and another for vegetable oil — plus a system to switch from one fuel to the other. The engine starts on diesel fuel, but switches to run on vegetable oil after heat produced by the engine warms the vegetable oil to about 160 degrees Fahrenheit. Before shutting off the vehicle, diesel fuel is cycled through the fuel lines to purge the system of vegetable oil. (For more information, see  Would you use Veggie Oil to Fuel Your Vehicle? ) Because diesel fuel is required for starting the vehicle and clearing the lines before shutdown, a dual-tank system is better suited to vehicles that run for extended periods or distances.

A single-tank system preheats the vegetable oil using electric heat (plus the additional heat produced by the engine when it’s running) and uses modified injectors and glow plugs that are optimally suited to ignite and combust vegetable oil. (New diesel engines have precise fuel requirements that need to match the chemistry of the oil, but older engines have a better tolerance for a range of vegetable oils.)

Considering the frequent start-and-stop nature of our small-farm work, we decided a single-tank system would be the appropriate choice to run vegetable oil in our tractor.

Fuel for the Farm

Thanks in part to a grant from the National Center for Appropriate Technology, an organization that promotes technologies that conserve energy and resources, we have retrofitted a Kubota tractor with an  Elsbett single-tank fuel system to run on straight vegetable oil produced in eastern Montana. (Elsbett is a German company that manufactures conversion kits and engines designed to run on straight vegetable oil.) The performance of this tractor is being measured and compared with the performance of two similar tractors used on comparable farms nearby. One of these tractors uses a biodiesel blend; the other uses petrodiesel.

If we confirm that a single-tank system is a viable option for running a tractor on straight vegetable oil, we plan to grow an oilseed crop and produce our own fuel. We estimate we’ll need to devote about 5% of our cropland to oilseed (probably canola) production annually to provide enough oil to power the tractors. Others estimate it would require up to 30 percent of a farm’s land to produce enough fuel to make a farm self-sufficient.

How to Make Biofuel at Home

The PEAS farm also houses a biodiesel processor to convert used cooking oil to biodiesel for the Garden City Harvest tractor (and originally for our Kubota). The facility provides a safe location for students to make biodiesel and store the supplies used in the process. Since its arrival at the farm, several students (including me) have taken advantage of this resource to produce fuel for their own vehicles.

Last summer, I participated in my first biodiesel experiment. It was intimidating, but the process was relatively straightforward. Basically, biodiesel is produced by a chemical reaction involving vegetable oil, methanol, and potassium hydroxide or another catalyst. Glycerol is a byproduct of the process.

We took 20 gallons of used fryer oil (from a local restaurant), strained out the food particles, and pumped the oil through a series of braided hoses and copper valves into a recycled water heater. As the oil cycled through the processor, we took a sample and tested it to determine the amount of potassium hydroxide we would need to add to the used oil.

We added the necessary ratio of methanol to the potassium hydroxide. When the processor brought the oil temperature to 130 degrees, we added the chemicals to the processor and allowed it to cycle for two hours. The chemicals and heat transformed the used oil into biodiesel. When the reaction was complete, we unplugged the processor.

As the oil cooled overnight, a dense layer of glycerol settled to the bottom of the tank. The next morning we drained off the glycerol, which contains methanol and other contaminants that must be removed prior to composting. (Some people use it to make soap after it’s detoxified.)

The last stage of the process was to transfer the biodiesel to a separate barrel to “wash” it. The washing process is done by applying a light mist of water to the top of the biodiesel. The suspended impurities in the biodiesel adhere to the water drops as they percolate to the base and are drained from the tank. At this point, the home-brewed biodiesel is ready to use in any diesel engine. From 20 gallons of used fryer oil, we produced 16 gallons of biodiesel.

Fuel quality issues from incomplete reactions sometimes can cause problems with home-brewed biodiesel. At the PEAS farm, the process of brewing quality biodiesel has evolved through trial and error. Thanks to the careful attention of our home-brewers, we have not experienced any fuel-related problems using biodiesel produced at the farm.

Biofuels: Pros and Cons

• Biodiesel combustion emits less carbon monoxide, carbon dioxide, and hydrocarbons than combustion of a similar amount of petrodiesel. (The U.S. Environmental Protection Agency previously stated that nitrogen oxide emissions from biodiesel were higher than from petrodiesel, but that research is being re-examined.)
• For many, there’s an economic appeal to making biodiesel. Making biodiesel for about a dollar per gallon or less was relatively easy for us. Utilizing salvaged materials, the biodiesel processor at the PEAS farm was put together for about $150. Local restaurants give away used vegetable oil, and methanol can be purchased for $4 per gallon.
• The cost of vegetable oil has risen significantly (a major concern for commercial biodiesel producers). But for those considering straight vegetable oil as a fuel, new vegetable oil is not the only option. Many restaurants will give you used vegetable oil, which needs to be thoroughly filtered before use — but it’s free.
• The drawback is the initial cost of converting an engine. The Elsbett single-tank conversion kit installed in the farm tractor cost $1,200 and is comparable in price to other single-tank modifications. Dual-tank systems cost about $1,000, but require a bit more labor.
• The legal issues concerning use of veggie oil as a fuel and home production of biodiesel are complicated and vary from state to state. You need to register with the federal government and pay fuel taxes (probably state and federal) on the biodiesel you produce. Laws concerning straight vegetable oil are changing, but it’s still technically not approved for use as fuel by the EPA. And your state may require you to register to collect waste vegetable oil.

So far, the use of straight vegetable oil has demonstrated promise as a fuel alternative for our Kubota tractor. And I’m burning home-brewed biodiesel in my 1981 Mercedes diesel station wagon without any problems. Whenever possible, I ride my bike, walk, or carpool. But when I drive, I feel good knowing my car is running on recycled vegetable oil processed at the same farm where I raise veggies.

Do you have enough land for food and fuel?

If you want to grow biofuels to run your tractors, how many acres would you need to devote to fuel crops? This question was tackled in the Sunshine Farm study, conducted by The Land Institute in central Kansas from 1992 to 2001. Sunshine Farm is The Land Institute’s 160-acre organic research farm with 49 acres of cropland. Based on measurements of fuel use and crop yield, the researchers found that the farm would need to use 30 percent of its crop area to grow soybeans and sunflowers that would be used to make biodiesel to run its 70-horsepower diesel tractor. To provide fuel for the farm’s pickup truck would require another 15 percent.

This is a somewhat pessimistic number, as larger tractors pulling wider farm implements (which could be shared among a number of small farms) are more energy efficient — up to about twice as efficient. Also, the farm’s truck got only about 13 miles to the gallon, so a more efficient vehicle would have a significant impact on fuel use.

A farm’s tillage practices also can make a big difference. The Sunshine Farm used conventional tillage, which involves many passes with tractors and heavy equipment. Fuel usage could be reduced significantly by using reduced tillage techniques that also minimize soil loss, maintain soil quality and reduce greenhouse gas emissions from the soil.

The environmental impact of producing biofuels locally as part of diversified, sustainable small farm operations is different from the mass production of biofuels. Oil crops produced on a large scale (such as palm oil) are causing significant deforestation and contributing to global warming. There are also significant concerns surrounding the use of food plants (corn and soybeans) to produce fuels.

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How to Make Biodiesel With a Commercial Kit

"Make your own diesel for 70 cents a gallon," the Internet ad claimed. I was tired of paying for 30 gallons of regular diesel each week to fill my pickup, so I downloaded the instructions. It wasn't long before I was sucking used fry oil out of tanks behind a restaurant, and mixing it with lye and methanol in a 5-gallon bottle before pouring it into an old water heater.

Two hours later, I opened the valve at the bottom of the heater and black goo oozed from the hose, a biodegradable substance called glycerin. Before long the glycerin drained and gave way to a thin, clear, amber liquid: I had my first batch of biodiesel.

I made that first batch of fuel five years ago. If you factor in all the time I spent making the homebuilt biodiesel processor (a converted electric water heater) and experimenting with the design (some batches went, umm, less than perfectly--I had to replace two injection pumps on my truck), my experience with DIY fuels was often a frustrating and, occasionally, very expensive process.

Since then, the biodiesel industry and the technology have evolved. With the professionally engineered biodiesel systems available today, the process is simpler, safer, takes less time and yields more consistent results. So I decided to try one of the commercially available processors--it came boxed with all of the equipment and reagents needed to turn out consistent, high-quality biodiesel fuel. The FuelMeister processor used here has five fewer valves than the eight in my old homemade one. It also mixes the lye and methanol inside the tank to prevent the chance of dangerous spills.

Biodiesel Safety

Yes, you can make biodiesel in a plastic bucket with little more than some drain cleaner, gas-line de-icer and a wooden spoon, if you know what you're doing. But it can be dangerous. Splashing lye and/or methanol into your eyes can blind you. And electrical pumps unattended in the presence of hundreds of gallons of flammables will make your local fire marshall understandably nervous. In addition, poor-quality product will damage your very expensive diesel-injection pump. Our advice? Research biodiesel production properly before doing the mad-scientist routine.

2. Next we need to titrate to see how acidic the oil is. Add a small amount of phenolphthalein indicator dye to a carefully prepared mixture of methanol and sodium hydroxide. Add a sample of the acidic waste oil to the mix with a calibrated pipette.

3. Trickle in a prepared basic reagent until the mixture stays purple for 10 seconds of swirling. The quantity of reagent you add here determines the amount of methoxide (methyl alcohol/sodium hydroxide mixture) to add to the oil to complete the transesterification process. It takes some simple math or a look-up table to calculate the amount.

There's quite a bit of chemistry involved in transforming vegetable oil into biodiesel, in a process known as transesterification. Vegetable oil (VO) is made up of chains of fatty acids held together by glycerol molecules. Methanol breaks those chains of fatty acids apart. The corrosive, alkaline lye (sodium hydroxide, although you can also use potassium hydroxide) breaks the glycerol (a heavy alcohol) off those chains and the methanol (a light alcohol) in turn takes the place of the glycerol, leaving shorter, lighter, more combustible molecules. The result is an oil that burns well as a direct replacement for petroleum-based diesel fuel, with 12 to 15 percent glycerin left over at the bottom of the tank. The lye acts only as a catalyst in this case, and isn't consumed in the process.

On the other hand, waste vegetable oil (WVO) , like we get out the back door of restaurants, is somewhat acidic because it has free fatty acids, which are produced during heating and cooking. Fortunately, that acidity is neutralized by the extremely alkaline lye essential to the transesterification. Adding lye converts free fatty acids to a form of soap, most of which will drain out with the glycerin. The remaining soap is removed in the wash. Of course, we have to be sure that the amount of alkaline lye is just enough to counterbalance the acidity, or we wind up with poor-quality fuel.

5. Drain the glycerin from the bottom until you get lighter-colored, thinner biodiesel pouring from the valve. Then use water to wash the excess methanol, lye and soapy residue from the biodiesel. The water will settle to the bottom of the vessel in a few hours, where you can drain it out.

6. Allow the fuel to air out for a day or two with the top off to let any cloudiness (caused by a small amount of remaining water) dissipate.

You can't make biodiesel if you don't have a couple of high-quality restaurants in your area. Greasy spoons need not apply. That's because the more pure the WVO is, the better the biodiesel. Restaurants that overcook their food, don't change their oil frequently or cook lots of frozen food will have oil with high free-fatty-acid content.

As for water, less is better. As little as 5 percent in the WVO can leave you with a batch of soapy glop instead of biodiesel in your processor. You don't want to deal with the mess of cleaning up, so care in selecting feedstock will pay off in the long run. Heat a couple of ounces of the WVO in a frying pan. If it sizzles, there's too much water. This water can be removed by heating the oil to above 220 degrees in an open container, and then letting it cool down. But that consumes a lot of energy, and you'll need to baby-sit the whole business because of the danger of fire. Best just to find higher-quality WVO.

Busy restaurants are like food-cooking assembly-lines. They heat their oil at the same time, at the correct temperature, and fry about the same amount of food every day. They also change their cooking oil at the same time and in the same way every week. Other places aren't as careful, and their oil gives me less, and poorer quality, biodiesel per batch. I get almost all my WVO from two local restaurants, and I've never had water in the oil. Biodiesel processing has become popular. Restaurants used to be thrilled when I took the old oil away without charging them. Now WVO is a commodity not unlike crude oil. When regular diesel is about $2.50 a gallon, I pay $0.30 per gallon. When diesel was $4.85 a gallon, I paid $0.60 a gallon.

The 40-gallon processor we used here costs nearly three grand. We saved about $1.20 a gallon over the current price of petro-diesel, if you don't count the $2995 price tag for the processor. That means we'd have to make 62 or more batches to pay back the investment, or one batch every six days--for a year. A couple of batches can be fun, but spending every Saturday with greasy hands can get to be a chore. You'll also need to set up a place to store the WVO, the methanol and the biodiesel, all of which are flammable, and a place to work. Don't forget you'll also need to dispose of leftover poor-quality WVO, a fair amount of glycerin and the occasional batch of glop. There's an excess of methanol and alkali remaining after the transesterification, and commercial biodiesel producers recover the methanol and use it for the next batch. Your local authorities may have an opinion as to the proper, legal disposal of glycerin.

You'll still need to run a fair amount of conventional mineral diesel in your tank along with your home-brew fuel, especially in the winter when low temperatures turn even the best-quality biodiesel into jello.

Also, the current crop of direct-injection diesels don't fare well on concentrations of bio higher than 10 percent. Why? To thermally purge the diesel particulate filter (DPF), the injection system periodically injects fuel into the cylinder during the exhaust stroke to raise exhaust temperatures high enough to ignite the carbon inside the DPF. The carbon simply burns off, leaving the DPF ready to filter out more particles. Biodiesel, more viscous than mineral diesel, sticks to the cylinder walls and washes past the rings into the crankcase. This can dilute the engine oil, potentially causing engine damage. Most car manufacturers prohibit the use of more than 10 percent biodiesel if you expect any warranty protection. Biodiesel works best in older diesel vehicles with precombustion-chamber mechanical injection.

Caveats aside, you can make diesel fuel sustainably while also reducing pollution. Getting a good supplier of WVO when fuel prices are low should ensure an adequate supply when demand rises. Biodiesel stores very well in a cool, dry place if you squirt a little nitrogen from a welding supply shop into the top of the barrel. Making a lot of the stuff now might be one way to have your own little investment in home-brew biodiesel futures as regular diesel prices climb.

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Sustainable Living on a Small Farm the Permaculture Way

Best Bio Diesel Making: How to Make Bio Diesel at Home

June 5, 2017 By Meg Howe Leave a Comment

Tired of spending all your money on fuel?  Bio Diesel making yourself is an alternative that can save you big money.

Increasing fuel prices spurred on by peak oil have sparked a surge in commercial biodiesal production, as well as a lot of buzz around home made bio diesel.

And why not?

It’s very satisfying to make your own bio diesel and fill up your tank with something that cost you peanuts to produce (typically around 70c a gallon or 15c a liter depending largely on what you pay for the waste oil).

How to Make Bio Diesel

Concise Guide to Making Your Own Biodiesel Processor for under $100, Plus Biodiesel Recipe , and Full Instructions. To make your own bio diesel all you need is some Bio Diesel Making equipment and a few readily available ingredients like water, methanol, lye and vegetable oil.

Both methanol and lye can be bought at large hardware stores or shopping centers. Methanol, a fuel used in most model aircraft, is available in small quantities as fuel line antifreeze. Lye or caustic soda (NaOH) is an common drain cleaner.

These substances are potentially hazardous, and must be kept out of reach of children and used with care!

Why biodiesel?

Biodiesel is made from vegetable oil that is liquid at room temperature (rather than shortening or animal fat).

Though it is possible to run diesel vehicles on straight vegetable oil, they need to be modified first.

Bio Diesel Making, on the other hand, is the same vegetable oil chemically changed so that it will run any standard diesel engine without any modification of the vehicle necessary.

However, in cold climates biodiesel will solidify in which circumstances it is recommended to use a biodiesel/petroleum diesel blend.

Where to make you own biodiesel

Your Bio Diesel Making equipment can be set up anywhere…with a few provisos.

If it isn’t a closed system (these type of kits are more expensive) it will give off fumes so put it where there’s good ventilation, like in a sheltered spot outside. Be aware of the neighbours too! They may not appreciate your fumes!

If you live in a built up area, invest in a closed system biodiesel processor.

How long does it take to make your own bio diesel?

Naturally, Bio Diesel Making  will take you longer when you are just learning. Expect to get quicker as you go.

Then there’s the different processing methods which vary in the time they take.

As a general guide, it could take about a day to collect your oil and get the process started, and about 15 minutes a day over 3 or more days to finish off a batch of home made biodiesel.

What sort of Bio Diesel Making equipment will I need?

There’s quite a range of biodiesel stills out there.

What you go for will depend on the amount of home made biodiesel you wish to make, the quality you are after (all steel tanks and fittings cost more than plastic versions) and your neighbours.

If your choices are limited to a closed system because you need to avoid the production of odorous fumes, then expect to pay more.

If an open system would suit you fine, you can even make you own biodiesel processor from a purchased kit or from scratch.

The ingredients used in home made bio diesel

Ingredients for the biodiesel recipe are easy to find and comprise alcohol (usually methanol), lye (which is also known as caustic soda or sodium hydroxide), and vegetable oil (new or used).

The usual oils used for Bio Diesel Making re those that are liquids at room temperature.

So home made bio diesel can be achieved with such oils as soy, canola, peanut and palm.

However, algae biodiesel wins hands down when it comes to productivity, and is shaping up to become the future of biodiesel.

Back to the now…

Most Bio Diesel Making equipment and recipes can’t cope with the oils that are solid at room temperature, such as animal fats or hydrogenated oils (shortening).

Since many restaurants prefer oil over shortening for their frying, it is not that hard to find the two or three small restaurants willing to sell you their used oil cheaply that you will need to become independent of gas stations forever.

The Process for Making Bio Diesel

Biodiesel is most commonly made by chemically altering an organic oil through the use of a catalyst (such as lye which is also known as caustic soda or NaOH) and an alcohol, typically Methanol.

These chemicals react to break down the oil molecules and replace their glycerine portion with an alcohol. The glycerine falls to the bottom and is drained off leaving biodiesel.

Biodiesal Safety

Methanol is a poison which can cause blindness or death if inhaled, absorbed through your skin, or ingested.

Cartridge respirators will not prevent you breathing it in, so use in a well ventilated area.

Methanol is also highly flammable.

Lye (caustic soda, NaOH, lye) is highly caustic. It can cause severe burns if it touches your skin, and death if ingested.

Precautions when Bio Diesel Making:

• Wear appropriate clothing – long-sleeved shirt, full shoes and trousers, chemical proof gloves, apron, and face shield or eye protection.
• Take care to avoid inhaling any vapors given off by the home made biodiesel process.
• Have running water at hand to rinse off any splashes.
• Keep kids, visitors and pets away from ingredients and processing equipment.

Here’s the same process broken down into the basic steps:

Note : It is important to keep water out of the process at all stages until instructed to add at the washing stage!!!!

• Heat your waste oil to 248°F (120°C) to remove any water. If water is present it will spit, perhaps violently, so take care! Once it stops spitting, then the water has been removed. Allow it to cool.
• Filter your waste vegetable oil. Let it settle first so the worst impurities drop to the bottom.
• Pour waste vegetable oil into the “processor”. You can use a storage hot water system or even an old washing machine that has a heating element for this!
• Heat the oil to between 130 and 135°F (54 and 57°C).
• Do a test titration to see how much lye (caustic soda i.e. NaOH) and methanol you’ll need for the batch. This is because each batch of waste oil will be different in its concentration of free fatty acids (FFA), and it is all important to have the correct amount of ingredients to ensure your home made bio diesel works out properly. Titration involves reacting a small sample of waste oil with a measured amount of lye. The pH shows when the FFA is all used up.
• Mix the correct amount of lye and methanol in a separate container. It will give off methoxide, a poisonous gas so TAKE CARE not to breath in the vapours!!!!
• First ensure the oil is below 140°F (60°C) as methanol boils at around 150°F (65°C). Then add the lye/methanol mix to the oil in the “processor” and mix thoroughly for 20 minutes to encourage the chemical reaction.
• Allow time (about 8 hours) for the resulting biodiesel and glycerin to separate.
• Drain off glycerin layer. This biodiesal byproduct can be used to make soap!
• Use water to gently wash the biodiesel layer to remove any remaining glycerin and   impurities. Take care not to agitate roughly or you’ll end up with mayonnaise!

Concise Guide to Making Your Own Biodiesel Processor for under $100, Plus Biodiesel Recipe , and Full Instructions.

• 11. Allow time for the washed biodiesel and water to separate.
• 12. Drain off the water layer.
• 13. Drain off the biodiesel into a storage container.
• 14. Washed biodiesel is cloudy. All it needs now is a day or so to dry and settle and it will become clear.
• 15. Put the biodiesel into your diesel vehicle’s fuel tank and drive away!

That’s all there is to Bio Diesel Making. Hey, it’s not rocket science!

But if you ever do strike problems, there are a heap of biodiesel groups and forums with knowledgable people who can help you solve them.

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Fuel Your Survival: How to Make Biodiesel

When the grid goes down, life changes.

One of the key skills it pays to acquire is learning how to make alternative fuels, such as biodiesel, because it can be used as fuel in a diesel engine and as a primary source of fuel for generators at a remote bugout location or refuge. It also has a number of other uses, including as fuel for your oil-fired heaters and lamps.

Not only does biodiesel have multiple uses, it is also one of the easier types of alternative fuels to make because of the simple process involved and the ready availability of the source materials.

Here’s how to do it.

Six Simple Steps

Making biodiesel is a simple process; but it is one that requires precise measurements and caution in handling the materials used to make this alternative fuel.

Step #1: Assemble All Your Materials

You will need the following materials to make your biodiesel, and you should have them all on hand and ready to use when you begin. You don’t want to have to step away to get your measuring spoons or find propane for your stove.

• waste vegetable oil (WVO) or pure vegetable oil
• methanol (methyl alcohol)
• measuring spoons
• measuring cup
• 1-quart glass container
• half-gallon (2-liter) clear plastic container, such as a 2-liter soda bottle
• protective rubber gloves
• protective eyewear
• protective apron
• heater to warm your waste or pure vegetable oil, such as a propane stove or electric burner
• metal pot to heat your waste or pure vegetable oil

Note: Anything that comes in contact with the lye must be a non-reactive vessel. A non-reactive vessel is one that does not oxidize or release metal ions when exposed to something very acidic (such as lemon juice or tomatoes) or very basic (such as lye). For this reason, you should avoid vessels made from aluminum, copper, or cast iron. Your best bet is to use something made from glass, plastic, or ceramic.

This procedure requires good ventilation, so doing it in a well-ventilated room—or preferably outside—is necessary. For this article, we are doing it outside.

Step #2: Heat the WVO

Pour 4 cups of WVO into a metal pot or saucepan and heat it to between 130 and 140 degrees Fahrenheit—any hotter than this, and you run the risk of melting your mixing container.

Step #3: Make the Sodium Methoxide

While the WVO is heating, pour 1 cup (or 250 ml) of methanol (methyl alcohol), followed by 1½ teaspoons of lye (sodium hydroxide), into a glass container that uses a non-reactive lid. Place this lid on the glass container and shake or swirl the container to thoroughly mix the methanol and lye. Water and other contaminants might settle to the bottom of your heating vessel as you heat the WVO.

Step Four: Combine the Heated WVO and the Sodium Methoxide

Pour the heated WVO into a half-gallon (2-liter) plastic bottle. Take care to ensure that no water or other contaminants are poured into your mixing container. Then, add the methanol/lye mixture (sodium methoxide). Do this slowly to avoid splattering or spilling. Use a funnel for pouring each of these liquids into the half-gallon container.

Place the lid on the container and shake it vigorously for 20 to 30 seconds to fully mix the two liquids. Then, set the bottle down and wait.

Step Five: Transesterification (Separating the Biodiesel From the Glycerin)

Through a process called “transesterification,” the WVO and sodium methoxide mixture will separate into two liquids—biodiesel and glycerin. The glycerin will be a thin layer of darker liquid that, due to its greater density, will sink to the bottom of the container. The lighter biodiesel will remain on top. The separation should be evident within 30 to 45 minutes, but it will take two to three days for all the glycerin to separate from the biodiesel. So, set the container somewhere it will not be disturbed or knocked over and let the chemistry do its thing.

Step Six: Remove the Glycerin

Depending on the purity of your WVO, the biodiesel produced will be approximately 85 to 100 percent of the amount of WVO.

The next step is to remove the glycerin from the container. If you left the container with the opening up so the glycerin settles to the bottom, you can pour off the biodiesel, leaving some of it in the container. Alternatively, if you store the container with the opening down, the glycerin will settle next to the opening, and you can slowly loosen the lid until the darker layer of glycerin starts to flow out.

Once clear liquid (biodiesel) starts to flow out, you can close the lid. The glycerin can be added to your compost to help with decomposition or it can be used to make soap.

Transformation Complete

You now know the basics of how to transform vegetable oil into biodiesel. Do some more reading on the Internet about other methods that use different chemicals and also research how to build or where to buy a biodiesel production system so you can make this fuel in larger quantities and at a lower cost. (See sidebars 2 and 3 for some suggested websites.)

Biodiesel can be a useful resource for you and your family, and it can also be quite a valuable resource you can trade during bleaker times, when you need something you don’t have or can’t do yourself.

Larry Schwartz is an experienced outdoorsman, prepper, hunter, shooter, and instructor who enjoys passing on his love and knowledge of the outdoors, the shooting sports, and how to “be prepared” through his writing and workshops on a wide variety of topics. He is a longtime and regular contributor to several of Engaged Media’s publications.

Biodiesel 101

One of the first alternative fuel engines was created by Rudolf Diesel, the German scientist for whom diesel fuel and diesel engines are named. Diesel saw the usefulness of non-petroleum-based oils as sources of power and foresaw today’s biofuel marketplace.

When asked about its usefulness, he said, “The use of vegetable oils for engine fuels may seem insignificant today, but such oils may become, in the course of time, as important as petroleum.”

In 1898, he was granted a U.S. patent for a diesel engine he designed for farmers to use so they could grow their own fuel in the form of peanuts and peanut oil.

The Science Behind Biodiesel

Biodiesel in all its forms starts with animal fat or vegetable oil, which are tri-glycerides composed of glycerin and fatty acids. The addition of lye (sodium hydroxide) to the fat or oil breaks the fatty acids from the molecules’ glycerin “backbone.” Adding methanol (methyl alcohol) to the mix gives the free fatty acids something to bond to.

The new molecule made of the fatty acids and methanol is called “biodiesel.” It is a simple process when using pure ingredients, but it can get more complicated if your source materials are contaminated (for example, if you are using old cooking oil or if there is water mixed in with the oil). These are not insurmountable obstacles; they just require some additional steps to “clean” the oil.

The following websites provide information about how to make or where to buy biodiesel kits and production facilities:

www.instructables.com/id/Make-Your-Own-Biodiesel-Processor

www.b100supply.com

www.homebiodieselkits.com

www.biodieselsolutions.com

www.diyfuel.com

www.officialbiodiesel.com

The following websites and organizations are excellent sources for information about making biodiesel in larger amounts, as well as how to “clean” the impurities from it:

www.biodieselcommunity.org

www.biodiesel.infopop.cc/eve

www.journeytoforever.org

Editor’s note: A version of this article first appeared in the December 2015 print issue of American Survival Guide.

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Backyard biodiesel.

Convert vegetable oil into a liter of biodiesel fuel.

• Time Required!: Six hours over three days
• Print this Project

By Rob Elam

It’s easy to make a small batch of biodiesel that will work in any diesel engine, from a model airplane engine to the family car. You don’t need any special equipment — an old juice bottle will serve as the “reactor” vessel — and on such a small scale you can quickly refine your technique and perform further experiments. After a few liters’ worth of experience, you’ll know if you’ve been bitten by the biodiesel bug.

The principle behind biodieseling is to take vegetable oil (either new or used), and process it into a fuel that’s thin enough to spray from a regular diesel engine’s fuel-injection system. This is done chemically, by converting the oil into two types of compounds: biodiesel, which shares the original oil’s combustibility, and glycerin, which retains the oil’s thick, viscous properties. Drain away the glycerin, and you’re left with a fuel that you can pour into any diesel vehicle with no further modification.

Once you get to the far side of the learning curve, making biodiesel is very much like cooking. In fact, a commercial biodiesel production plant shares more in common with a large-scale bakery than a petroleum refinery. There’s organic chemistry involved in baking a cake, but most bakers wouldn’t consider themselves organic chemists.

Project Steps

Biodiesel homebrewing safety.

While biodiesel is safe to handle and store, the homebrewing process involves flammable, poisonous, and caustic chemicals, alcohols, and lye.

Keep all chemicals clearly labeled, sealed, and out of reach of children and pets. When handling methanol and lye, wear long sleeves, safety glasses, and gloves made out of nitrile — or, even better, PVC.

Wash the gloves after each use, and be careful not to touch your skin or eyes. Keep a water hose nearby in case of skin contact. Methanol can be absorbed through the skin, so wash immediately with water if contact occurs. Immediately flush lye off skin with water or vinegar.

Methanol fumes are poisonous, so wear a mask, or hold your breath while pouring, and work outside or with good ventilation.

Filter and De-water your oil

If you’re using new oil, you can skip to Step #5. But if you’re starting with waste oil from a restaurant fryer, it will contain food particles, water, and free fatty acids (FFAs) — contaminants that you need to remove or adjust for. The FFAs make the oil more acidic, (a.k.a. rancid), which counters the effect of the lye.

You can compensate for this by adding more lye into the main reaction later, but you need to perform a titration test beforehand in order to determine how much extra lye you’ll need.

Start with more than one liter of oil, since the following steps will slightly reduce your oil’s volume.

Warm the oil to about 95ºF in a pot on an electric hot plate (don’t use a gas burner, here or anywhere else in this project), then filter it through a few layers of cheesecloth in a funnel (or use a coffee filter).

Heat the oil to 140ºF and maintain the temperature for 15 minutes.

The water will fall to the bottom, so you’ll risk steam explosions if the temperature gets too high. Pour the oil into a bottle or other vessel and let it settle for at least 24 hours. This removes water, which would produce soap in your batch. If you see water at the bottom (it will be dirty, not clear), don’t pour it back out with the oil.

Test your oil to determine its acidity

Dissolve one gram of lye in one liter of distilled water (0.1% lye solution), or use an equivalent ratio to make a smaller amount.

This is your reference test solution, which you can store sealed and re-use for later batches.

In a small jar, dissolve 1ml of slightly warm oil in 10ml of isopropyl alcohol.

Stir until clear, then add two drops of phenolphthalein solution.

Using a graduated syringe or dropper, add your reference test solution drop-by-drop into the oil/alcohol solution, keeping track of how much you’re using. The more acidic the oil, the more you’ll need to add.

Stir constantly, and continue adding solution until the mixture stays pink for ten seconds.

Note the number of milliliters of lye solution you used; this is the number of extra grams of lye you’ll need to add per liter of oil.

This process is called “titration,” and it’s a standard method of determining a solution’s acidity.

Process the oil

This is the main chemical reaction that produces the biodiesel.

First, calculate how much lye you need.

If you’re using new oil, use 5 grams of NaOH or 7 grams of KOH per liter.

With used oil, use these amounts plus one gram for every milliliter of solution you used in the titration step 7.

For example, if it took 1.5ml of lye solution to turn the mixture pink, use 6.5g of NaOH or 8.5g of KOH.

Measure your lye into a clean Mason jar.

Add 220ml of methanol, cover securely, and tip the jar to make sure the lid doesn’t leak.

Then swirl or shake the jar gently until the lye dissolves fully. This will take a few minutes, and the jar will become slightly warm in the process.

This mixture is the methoxide solution, and it’s dangerous stuff; you’ll need to wash the Mason jar lid after you’re done with your batch, or its seal will dissolve. (Some regular homebrewers prepare methoxide ahead of time and store it in #2 HDPE plastic.)

Warm a liter of your oil up to 130ºF. Let it cool down if the temperature gets too high.

Pour the oil into a large bottle, add the methoxide solution, cap tightly, and shake like crazy for about five minutes.

The contents might change color a couple of times.

Set this mixture aside, and admire.

In half an hour or so, you should see a darker, dirty, glycerin layer start to sink toward the bottom, and a larger, lighter, biodiesel layer rise to the top. This is a good time to clean up.

If you’re sure your bottle won’t leak, you may want to let it settle upside-down, so you can drain the glycerin out by cracking the bottle cap. Or you can lay it sideways to make it easier to pour off the biodiesel.

Let the liquids continue to settle overnight.

Separate, wash, and dry your biodiesel

Your bottle now contains biodiesel, glycerin, mono- and di-glycerides, soap, methanol, lye, and possibly a little leftover oil (triglycerides). The glycerides are all oil-soluble, so they’ll reside predominantly in the upper, biodiesel layer. The thin layer of glycerin, which is water-soluble, will sink.

Depending on the oil and catalyst you used, it might be either liquid or solid. Soap, methanol, and lye, which are also water soluble, will be mixed throughout both layers — although some of the soap can sometimes form its own thin layer between the biodiesel and glycerin.

If you see more than two layers, or only one, then something’s wrong — possibly excessive soap or monoglyceride formation. These are both emulsifiers, and in sufficient quantities they will prevent separation. In this case, check your scales, measurements, and temperatures. You can reprocess the biodiesel with more methoxide, or try again with fresher oil (or new oil). If you can, shake the bottle even harder next time.

In an engine, glycerin droplets in biodiesel will clog fuel filters, soap can form ash that will damage injectors, and lye can also abrade fuel injectors. Meanwhile, methanol has toxic and combustible fumes that make biodiesel dangerous to store. You don’t want any of these contaminants in your biodiesel. If you left your biodiesel to settle undisturbed for several weeks, these water-soluble impurities would slowly fall out of the biodiesel (except for the methanol). Washing your biodiesel with water removes the harmful impurities, including the methanol, much faster.

Unfortunately, washing will not remove the invisible, oil-soluble mono- and di-glycerides. These are a problem in rare instances when large amounts of certain types of monoglycerides crystallize. This can clog fuel filters and injectors, and cause hard starts, especially in cold weather. High-quality, commercial biodiesel has very low levels of mono- and di-glycerides, which is the ideal for biodiesel homebrewing.

You can roughly test for the presence of mono- and di-glycerides in your own batch by processing it a second time, as if it were vegetable oil, starting with step 2 again. If more glycerin drops out, then your first reaction left some unfinished business behind.

Pour the biodiesel layer off the top, into another bottle.

Don’t pour off any of the glycerin, as it makes washing difficult; better to leave a little biodiesel behind.

If you let the bottle settle upside-down, drain the glycerin from the bottom.

Gently add some warm distilled water to the biodiesel.

Rotate the bottle end over end, until the water starts to take on a little bit of white soapiness, which may take a few minutes.

Do not shake the bottle. You want to bring water and biodiesel into contact, without mixing it too vigorously. The biodiesel contains soap, and if you overdo the agitation, the soap, biodiesel, and water will make a stable emulsion that won’t separate.

Turn the bottle upside-down, crack the cap, and drain away the soapy water.

If you’re using a soft drink bottle with a narrow neck, you can plug the opening with your thumb instead of using the cap.

Add more warm water and keep repeating the sloshing and draining process. Each time there will be less soap, and you can mix a little more vigorously.

If you go too far and get a pale-colored emulsion layer between the biodiesel and white, soapy water, don’t drain it away; it’s mostly biodiesel. Just keep washing and diluting until the water becomes clear and separates out quickly.

It takes a lot of water. But if the emulsification layer persists, try applying heat, adding salt, and adding vinegar, in that order.

After draining the last wash water away, let the biodiesel sit to dry in open air until it’s perfectly clear, which may take up to a couple of days. In general, the better your washing, the faster the fuel will clear.

If you’re in a hurry, you can dry the fuel faster by heating it at a low temperature. As with the evaporation method, the fuel is done when it clears.

If you can read a newspaper through the biodiesel, it’s dry and ready to pour into a vehicle. Congratulations — you’re done!

Biodiesel Chemistry (background information)

Vegetable oil is a triglyceride, which means that its molecule consists of a glycerin “backbone” with three fatty acids attached, forming a shape like a capital letter E. To make biodiesel, we add lye and methanol. The highly caustic lye breaks the three fatty acid branches off of the glycerin backbone. These free fatty acids then bond with the methanol, which turns them into fatty acid methyl esters — otherwise known as biodiesel. The freed glycerin, which is heavier, sinks to the bottom, leaving the fuel (and lye) on top. Wash the lye out of the upper layer, and you have pure biodiesel.

But it’s not that simple. With some triglyceride molecules, only one or two fatty-acid branches break off, which leaves mono- or di-glyceride molecules (shaped like capital Ts or Fs), rather than free glycerin. At the same time, mixing methanol and lye produces some water — and oil, water, and lye mixed together make soap. With all of these incomplete and competing chemical reactions, your batch will inevitably contain soap, water, leftover lye, methanol, and mono- and di-glycerides, along with the nice biodiesel and glycerin. Mono- and di-glycerides are emulsifiers, so they prevent mixed liquids from separating, making it harder to extract biodiesel. The picture gets even muddier when you use waste vegetable oil rather than pure oil, since it contains free fatty acids, water, and countless random contaminants from all those French fries.

These by-products are bad for an engine, potentially causing micro-abrasions that damage fuel injectors or clog fuel filters. But you can remove them by washing or cooking the biodiesel in various ways, or by processing the incompletely converted biodiesel again, as if it were vegetable oil. In extreme cases, you’ll end up with a thick, soapy mass that never separates. All biodieselers wind up with a batch of this glop sooner or later. Fortunately, you can use it to make a good, grease-cutting soap — which is something that all biodiesel homebrewers need to have on hand.

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