Biodiesel Safety Tips

Producing homemade biodiesel offers many benefits, as long as you keep safety in mind. Check out these helpful biodiesel safety tips before you get started.

Sunflower oil

Making biodiesel can be a rewarding experience, as long as you are prepared to undertake it safely.

Photo by Fotolia/HappyAlex

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Lyle Estill and Bob Armantrout offer the benefit of their cumulative experience in the biodiesel field in Backyard Biodiesel (New Society Publishers, 2015). Designed to be accessible to everyone, from readers with no prior technical expertise to alternative energy buffs, Backyard Biodiesel covers everything you need to get up and running quickly and safely. The following excerpt is from chapter 12, "Safety."

You can purchase this book from the MOTHER EARTH NEWS store: Backyard Biodiesel.

Knowledge Facilitates Biodiesel Safety

The more you know about what you’re doing, the easier it is to anticipate and avoid accidents. Although making biodiesel is relatively easy, the chemicals we work with can be extremely dangerous if mishandled. Methanol is highly flammable and toxic. NaOH and KOH are highly caustic and can combust when wet. Even used fryer oil and biodiesel can cause dangerous conditions if handled improperly. Take the time to learn the safe way to handle and store all your materials, and you’ll sleep better at night.

Engineered Versus Administrative Controls

In order to reduce the hazard presented by materials and processes, controls are used. Engineered controls are those that are designed and built to isolate people from hazards. A lock on your workshop to keep children away from hazardous materials is an example of an engineered control, as is a timer or float switch that ensures that a tank won’t overfill and spill. Although engineered controls require investment, they are usually well worth the expense. And they are not foolproof.

Administrative controls are rules or procedures that help isolate people from hazards. No smoking in the shop would be an example of an easy administrative control to reduce the risk of fire. Properly labeling materials is another good example of an easy administrative control designed to enhance safety. One long-standing rule at Piedmont prohibits beverages in laboratory spaces. If you are not drinking in the space, you are less likely to take a swig of isopropyl alcohol, thereby saving a trip to the emergency room.

A combination of both engineered and administrative controls is typically used to help minimize the risk of personal injury or property damage.

Material Safety Data Sheets

Material Safety Data Sheets (MSDS) exist for all the hazardous materials used in fuel making. These detail all the health, safety and environmental information for the material in question. Search for the material name followed by MSDS (e.g., Methanol MSDS) to find them free online. Take a few minutes and read the details of the hazards, suggested personal protective equipment and first aid measures for each chemical you plan to work with.

Personal Protective Equipment

Personal protective equipment (PPE) like gloves, safety glasses and respirators are useful in guarding yourself from hazards while making fuel. A box of 100 nitrile disposable lab gloves will last for months and cost as little as $8 purchased online. Gloves are a good idea when handling caustic and methanol, and optional when handling used fryer oil and biodiesel. Reusable washable gloves can be great for handling waste oil containers and general work around the shop.

Wear clothing appropriate for your activity: closed-toed shoes, long sleeves and long pants, headwear that will provide some protection from a spill or splash. Consider using a chemical-resistant apron for mixing and transferring methoxide. Avoid clothing or jewelry that is too loose fitting or dangles and creates an opportunity to get hung up on equipment or becomes a distraction at a crucial moment.

Safety glasses or a full-face shield are a must when working with methanol or caustic in any quantity, whether performing a 27/3 test, a titration or mixing methoxide. Get a good pair of safety glasses, goggles or a face shield, depending on what is comfortable. Make sure they fit well and do not need constant attention to keep them from slipping. Regular corrective lenses or sunglasses really don’t provide enough protection against splashes — don’t count on them as PPE.

Respirators are good to use when pouring production quantities of caustic, as well as when pouring methanol and mixing the methoxide. Caustics can emit dust into the air that can get in your eyes and settle on sweaty skin, causing a chemical burn. A full-face shield with respirators will keep this out of your lungs and eyes and reduce the risk of methanol inhalation. Be aware that due to the small size of methanol molecules, they are not entirely filtered out by a respirator, so design your process to limit the amount of methanol released into the workspace. Change cartridges at least once a year or when they are compromised by exposure to a large chemical release.

Gloves, safety glasses and a full-face shield respirator with organic vapor cartridges can be bought online for about $160, a small price to pay to preserve your health and safety.

Additionally, it’s a good idea to get maximum ventilation through your workspace while methanol vapors are present. Please remember that methanol vapors are flammable and toxic, so using an electric fan to try to remove high concentrations of methanol is a bad idea. Much better to not have the methanol escape your process to begin with. If using a fan, place it well away from the source of methanol fumes and blow air into the room rather than using it as an exhaust fan and risk pulling flammable vapors into the fan.

Here are some details on recommended PPE, based on my personal use. These items are available from a variety of online sellers:

Lab gloves: Kimberly-Clark, Blue Nitrile Powder-free Exam Gloves, Model 53103, box of 100, $24 from Amazon.
Chemical handling gloves: Wells Lamont 167L Heavyweight PVC Fully Coated Gloves, $8 from Amazon. These are great for measuring bulk KOH and methanol, as well as methoxide mixing.
Safety glasses: for everything except mixing and adding methoxide, Uvex S1600 Bandit Safety Glass, black frame, clear lens, $9 from Amazon. These fit over my small prescription glasses.
Full-face mask with organic vapor cartridges: 3M Fullface piece Reusable Respirator 6900 — get the right size! About $100 from Amazon; 3M Multi-Gas/Vapor Cartridge/Filter 60926, 2 pack, $24 from Amazon. Remember, no respirator cartridge will remove methanol vapors entirely. I use this setup in a well-ventilated shop and keep methanol fumes at a minimum.
Chemical-resistant apron: Steelman 77050 black chemical-resistant apron, $23 from Amazon.

Location, Location, Location

Do not make biodiesel in any building that is attached or part of your house. Period.

If you doubt the wisdom of this advice, please take a moment and Google the words “biodiesel home fire images” and take a moment to reflect. It’s best to make fuel in a shop space that is not physically connected to your house. If you plan on making fuel through the winter, you’ll probably want a heated space, depending on your climate. When considering heat sources for your biodiesel shop, remember that methanol emits flammable vapors. You can, of course, just turn off your building’s heat when you are reacting or washing and may have methanol fuel present.

The folks at Springboard Biodiesel, producers of the BioPro™ processor, have done extensive testing and analysis of its unit’s methanol emissions and claim that it can safely be used in a typical home garage. I certainly believe this is possible, having run one of their BioPro 190s numerous times in two different lab spaces at our local community college. That being said, if I had one at home, I would put it out in my pole barn just to be on the safe side.

Oil collection, dewatering and biodiesel production are typically messy operations. Fuel production also drives the need to store caustics and methanol onsite. These are not the kind of activities or materials that fit well in a suburban attached home garage. Your spouse, your kids and your pets will appreciate not having to trip over or come in contact with this when getting out of the car and heading into the house.

Basic Housekeeping

A clean and uncluttered workspace goes a long way to providing a safe environment for your fuel making. Keeping cords and hoses from becoming trip hazards is part of a good design. Store any unused extension cords coiled and hung out of the way. Keep unused hoses coiled and, if possible, hooked end to end to prevent any liquid from leaking out.

It is good practice to entirely empty any hose before storing it to prevent leaks as well as to prolong its life. I like to use camlock fittings since they provide a fluid-tight connection to my processing equipment and allow me to store my hoses with the male end plugged into the female end to prevent leaks and contamination from dust, bugs, etc.

Maintain a clean toolbox by always degreasing your tools before putting them back in the toolbox. They are going to get greasy, but there’s absolutely no reason to contaminate your toolbox so that every tool is greasy all the time. It really only just takes seconds to clean tools before replacing them.

Don’t let glycerin by-product pile up in or outside your shop. This happens to most fuel makers at some point and has caused a few fines, fires and divorces. It is imperative to find a method of disposing of or using your glycerin by-product before you start to generate it. If at some point your situation changes and you start to stockpile homeless glycerin, I advise you to stop making fuel until you find an alternative.

Keeping your mind uncluttered is important as well. Don’t bring your cell phone into your workspace, and if you do, don’t answer it. This distraction may be all it takes to help you forget that you have a pump running, causing an overflow spill. Also, of course, drinking, drugs and hazardous materials don’t mix.

Spill Prevention and Control

As any of us with grease collecting or biodiesel making experience knows, spills happen fast and clean up slow. It’s best to develop habits that help you prevent spills.

Make a habit of reviewing your setup before starting the pump on a liquid transfer, whether it’s used cooking oil, methanol, methoxide, glycerin, wash water or finished fuel. My method is to start from the end that I’m pumping from and point with my finger all the way along the route of transfer, looking for loose connections and making sure that valves are in the desired position. I also ensure that the tank I’m pumping into has enough space (headspace) to prevent overfills from the amount of liquid being transferred. I go through these rituals every time before transferring any liquid anywhere.

Make it a habit to not walk away from pumps when they are transferring liquid.

I’m a great believer in Oil-Dri Premium Absorbent ($10 at Lowe’s for a 25-pound bag). In my shop, I like to keep a spill kit handy composed of a 5-gallon bucket mostly filled with Oil-Dri, and a dustpan and whisk broom sitting on top. When the inevitable spill happens, I can immediately pour some Oil-Dri on the spill before it gets tracked around the shop. Pour on a generous amount, fully covering the spill and give it time to absorb. Then sweep up the material into the dustpan and reuse it by putting it back into the 5-gallon bucket, unless it is totally saturated. I can usually reuse the material a few times before bagging it for disposal and refilling the bucket with fresh absorbent.

Material Storage

Proper storage of your chemicals is important to promote safety and to maintain their quality. Best storage practices include proper labeling and containers that keep the material safely contained, protect the integrity of the material and are ergonomically sound. Buying chemicals in bulk will save money, but allowing the material to degrade due to bad storage will likely cost you even more. Understanding the nature of the material to be stored, as well as what container materials are compatible, will help you make informed choices.

The materials you will routinely store include used fryer oil, methanol, caustic (KOH or NaOH), waste glycerin, used wash water and finished biodiesel. Let’s look at the nature of the hazards and proper storage techniques for each.

Used Fryer Oil

The hazards associated with used fryer oil are its combustibility, the slip hazard when it spills and your risk of injury while moving a heavy load. A 55-gallon drum of oil weighs about 400 pounds — not something to be trifled with. Although not flammable per se, used oil is combustible and would stoke any fire that breaks out in your shop if its container melts and leaks.

Collected used fryer oil should be kept in containers, typically Type 2 plastic (HDPE), like the cubies for transporting new fryer oil a, 5-gallon buckets, 55-gallon drums and 270-gallon IBC’s (caged poly totes). Used fryer oil should be properly labeled and dewatered upon arrival at your shop to keep it from further degrading due to biological breakdown of the schmutz (food particles and water) it contains. Once settled and dried, keep your incoming feedstock out of the sun and at room temperature or lower for the best shelf life.


Methanol, probably the most dangerous material you’ll routinely use, is highly flammable and toxic. It can also be safely stored in HDPE plastic containers or steel drums. Five-gallon plastic carboys are great to transport and store methanol in before use, available online at Amazon or Uline for about $20.

Methanol is hygroscopic, that is, it will draw water to itself. So keep your stored methanol tightly sealed at all times that you are not dispensing it. Otherwise, it will start to pull moisture out of the atmosphere and will become contaminated with water over time. You can test the purity of methanol using a hydrometer, a tool for measuring specific gravity (SG). The SG of pure water is 1.000 at 20°C (68°F), while the SG of methanol at the same temperature is 0.7913. By measuring the SG of your methanol, you can determine the purity with a little math. Here’s the formula for use at 20°C (68°F):

% Purity = 100 − (B – 0.7913) / 0.002087
B = SG of your sample at 20°C (68°F)

You can buy a complete methanol test kit online from Utah Biodiesel Supply for $85.

If using a metal 55-gallon drum to store your methanol, you should electrically ground it. Static electricity can build up in your container due to fluid movement, and the resulting spark can cause an explosion or fire. Ground your metal drum by using a clip to the drum that’s wired to a properly deployed copper ground rod. If using a pump to transfer your methanol, make sure it is explosion-proof and rated for methanol. Better yet, use an air-powered pump or a hand-crank pump to dispense your methanol.

Caustic (KOH or NaOH)

KOH and NaOH, both strong caustics, are therefore very corrosive. The dust generated when transferring these materials can cause serious burns to your eyes and skin. Once mixed with methanol, the resulting methoxide combines the hazards of both the caustic and the methanol: it is flammable, toxic and a strong corrosive that will cause a nasty chemical burn on contact. Don’t treat these materials casually! Always take the time to put on the proper PPE (gloves, apron, safety glasses or face mask), and focus your mind and hands on the tasks at hand.

KOH and NaOH are hygroscopic; they’ll readily pull moisture from the air that will ruin their ability to act as a catalyst for transesterification. You need to keep them dry. I’ve found it’s best to store unused catalyst in plastic 5-gallon drums with airtight Gamma Seal lids, found online at US Plastics for about $8. US Plastics also has some very nice premium buckets in various colors for $8 each.

NFPA Placards

Proper labeling of your stored material may not seem important, but it is. In the event of an emergency in your shop, you’ll want the first responders (fire, ambulance, EMS personnel) to quickly understand the nature of the hazards within. Labeling is easy, and it raises your game to a more professional (and safe) level.

The US National Fire Protection Association (NFPA) created a labeling system for hazardous materials that you should use, which you probably already recognize. These “diamond on point” symbols use colors and codes to let first responders quickly assess the hazards present in order to use appropriate measures without unduly risking their own safety or that of others.

Some years ago, I created a set of NFPA signs (see the Slideshow) for the commercial biodiesel plant I was managing in Berthoud, Colorado.

The colors denote the particular type of hazard. Red (top diamond, gray) indicates flammability, blue (left diamond, black) indicates health effects, yellow (right diamond, light gray) indicates instability, and white (bottom diamond) is reserved for special hazards like oxidizers and water-reactive materials. The number indicates the severity of the hazard: 4 is the most severe, while 0 is no hazard. You can see that biodiesel has a 1 in the red square, as it is combustible but not flammable by NFPA definition. Biodiesel has no adverse health effects and is not inherently unstable from a caustic, explosive or radioactive standpoint. The label in the upper left of the sheet, the one with no material on it, is a summation of all the most hazardous aspects of the others — it has the blue 3 from the KOH, the red 3 from the methanol and the yellow 2 from the KOH. This sign goes on your exterior shop door to inform anyone entering your workspace of the cumulative nature of the hazards within.

Use these links to PDFs — one for KOH, and the other for NaOH — and print out the signs in color and label the materials in your own shop. I use 8.5-by-11-inch white plastic label stock in my home color inkjet printer and then cut them out. Papilio white waterproof vinyl, 8.5-by-11-inch sheets are 10 for $12, available online. I cover them with clear packing tape so they last longer.

Waste Glycerin

Waste glycerin from your reaction will contain most of the polar materials in your mix — methanol, glycerin, water, soap, residual caustic and some methyl esters. It is, therefore, somewhat flammable, toxic, caustic and not to be trifled with. It can be stored in HDPE plastic or steel containers, but should not be stored for long. It is also heavy — glycerin is denser than water — so containers over 5 gallons are hard to lift and carry without assistance. A 5-gallon container of glycerin bottoms will weigh over 40 pounds, and a 55-gallon drum will weigh over 500 pounds! I suggest determining the use or disposal option for your glycerin, and moving it out of your shop as often as you can, based on that. Don’t stockpile glycerin — it is dangerous, messy and will alienate your friends, family and neighbors. This point underscores the need to include methanol recovery in your fuel-making operation. The only possible uses (known to me) for glycerol containing methanol are to feed anaerobic digesters and for combustion as an industrial fuel, both of which require a legally permitted facility to receive them. When you remove the methanol from your bottoms, other options are open to you — composting, dust suppression, adding to animal feed and making soap.

Used Wash Water

Used wash water will contain methanol and soaps — meaning it’s high in biological oxygen demand (BOD) content, a measure of how polluted water is with material that will feed bacteria, algae and other critters that will pull out dissolved oxygen as they metabolize the nutrients. Used wash water should be left to settle to allow the biodiesel that it will invariably contain to rise to the top for collection and reuse. The water can be decanted off the bottom of your tank into another tank for pH balancing prior to disposal. Water pH should be neutralized with a weak acid — vinegar or diluted muriatic work well — to a pH of 7.0. If you perform methanol recovery on your methyl esters, settle and decant your wash water to remove any residual methyl esters and oil, then pH balance it. The used KOH in your treated wash water can be land applied and will act as a potassium fertilizer. Try this on non-critical plant life first!

Finished Biodiesel

Finished fuel can be stored in HDPE plastic containers, from the yellow plastic fuel jugs designed for petroleum diesel to 55-gallon poly drums to 270-gallon IBCs, where it is out of the direct sun and experiences very little daily temperature variation. One good rule of thumb is to not make more fuel than you will use in the next 30 days. Biodiesel should not be stored in steel 55-gallon drums as they are prone to rust, which clogs fuel filters and contributes to the early oxidation of your fuel.

If you follow these guidelines and are careful not to introduce particulates into your tank, you do not need a filter on your storage tank. In areas with high humidity, make sure the finished fuel container stays tightly closed to keep it dry. Every time you get to the bottom of your storage container, see if there’s any sediment buildup — there shouldn’t be with well-reacted, washed and dried fuel stored for 60 days or less.

Fire Prevention and Control

Fires caused by biodiesel production usually occur due to methanol or spontaneous combustion. Understanding how these fires occur can help you prevent them in your shop.

Methanol and its vapors are extremely flammable. Minimize the risk of fire by eliminating all sources of flames or sparks when methanol or its vapors are present. Eliminating release of methanol vapors throughout your process is a good place to start. Remember that open flames, light switches, thermostats and non-explosion-proof electric pumps are common sources of ignition in your shop.

In case of a methanol spill, remember that the fumes are toxic and their exposure is cumulative, so a number of small exposures build up in your system over time. If it’s a large spill, you may be better off leaving the shop and getting a hose to water down the spill or even calling 911 rather than risk a significant exposure or possible explosion. For smaller spills, mixing four times or more water into the spill will greatly remove the fire risk, and then you can absorb small spills with Oil-Dri.

Spontaneous Combustion

Spontaneous combustion is the cause of many biodiesel-related fires. It occurs when materials like oily rags are left in a pile. Oxidation of the oils causes their temperature to rise, and due to their insulative nature, the heat builds up until the auto-ignition temperature is reached and a fire is the result. In addition to oily rags, spent filter material (like wood chips or Magnesol) is also prone to spontaneous combustion. I am personally aware of at least six of these kinds of fires in biodiesel plants in the US, told to me by the people involved. So it really happens and is not at all uncommon.

The way to minimize the risk of spontaneous combustion is to understand and never create the conditions under which it occurs. I don’t use cotton rags for this reason. I use Oil-Dri on floor spills and wash tools and other equipment down with Simple Green and water. I do keep a roll of heavy-duty paper towels around as wipes but use them as a last resort and lay them flat between uses, and then throw them away when no longer useable.

If using shop rags, keep them in an airtight metal container to reduce the available oxygen and contain any fire that starts.

Fire Extinguishers

You should have at least one fire extinguisher, near the exit door in your shop, capable of extinguishing flammable solids, liquids and electrical fires. A 2A-10 ABC is a good choice for this purpose, available online for about $40. Additionally, you can install a heat-activated automatic fire extinguisher over your processor to activate in case a fire occurs when you’re not in your shop. They can also be bought online for about $60 (search for Flame Defender 12 kg) — cheap insurance.

When to Call 911

It’s important to know when to call 911 for help. My advice is if you think it might be a good idea, do it! Don’t hesitate if a fire that looks beyond your control has started. If you are not in a position to call, yell for help and get that person to make the call. There is no need to be a hero, and thereby become a casualty. If you encounter a fire that appears beyond your control, move away to a safe distance and call 911. In the meantime, make sure no one else comes on the scene and assumes you’re inside. Guard the site from a safe distance until help arrives.

A Valuable Resource

To close out this chapter on safety, I recommend an excellent resource created by my friend Matt Steiman, in conjunction with Pennsylvania State University, the “Biodiesel Safety and Best Management Practices for Small-Scale Noncommercial Use and Production,” published as a public service in 2007. I strongly suggest you download a copy and read it a few times as part of your ascent up the biodiesel learning curve.

Reprinted with permission from Backyard Biodiesel by Lyle Estill and Bob Armantrout and published by New Society Publishers, 2015. Buy this book from our store: Backyard Biodiesel: How to Brew Your Own Fuel.