Making Biodiesel in a cold environment can bring with it several challenges. The oil is thicker and likes to gel, the glycerin likes to get thick, it’s possible to get a poorly reacted batch due to heat loss, and water washing can just be a complete nightmare.
So, we figured we’d share some of our tips & tricks for successfully making the good stuff when the temperatures are low.
1- Use The Right Collection Pump
Cold weather can thicken oil making it really difficult to pump. Most small 12 volt pumps pretty much croak & die in cold weather, so be sure to get one that’s up to the job.
If you’re pumping vegetable oil and it’s still somewhat liquid, either our 25 GPM Electric Transfer Pump or our Heavy Duty Gas Powered 25 GPM Transfer Pump would be great options! If the oil gets really thick, go with the Gas Engine pump as it has more power & torque.
While both vegetable oil and motor oil get thick when they get cold, motor oil tends to stay liquid no matter how cold it is outside. When the vegetable oil turns hard as a brick, it’s obvious–the stuff isn’t going to move! But with motor oil, it just gets thicker but never really goes solid, giving the illusion that “yeah, it’ll pump!”
In reality, thick, cold motor oil is an absolute bear to transfer and can stress high speed electric motors quite a bit. With the gas engine powered model or our 12 GPM electric model, you’ll have quite a bit more torque and power to move it–even when it’s really thick & really cold!
2- Get The Water Out Of The Oil Before Processing It
In the winter, water in the oil seems to be 10x worse. It’s harder to get rid of (because it’s cold in the room), it thickens the oil even more, and it makes for a mess when you try and react it into Biodiesel.
We’ve found the easiest (and relatively cheapest) method for getting the water out is through heat and circulation. You basically heat the oil up to about 80 to 100 Deg. F, and then circulate & spray it into a thin layer in an open top container. Building one is a breeze! You can even use a 55 gallon drum with a pump, a heater, and one of our Dry Pro nozzles! Click here to see a cool set of plans for how to build this cool dewatering tank. We even offer a complete dewatering tank kit to build your own too!
To test the oil for water content, we really like using our Deluxe Water Test Kit! The kit works with a chemical called Calcium Hydride that reacts with any water in the oil to produce hydrogen gas. The gas registers as pressure inside the vessel on the gauge. The reading is then compared to a chart and converted into water content as either parts per million or percentage water content.
For oil being processed into Biodiesel, we like the water content to be no higher than about 2500 PPM (0.25%). If the oil titrates above a 6 using KOH Titration Solution, then we recommend getting the water content under 1500 PPM (0.15%) as it will help the batch react more completely and potentially produce less soaps (which makes it easier to water wash).
In order to make a good batch of Biodiesel from the oil, you’ll need to adequately filter it. In the winter, this can especially be a chore because the thickened oil doesn’t like to go through a filter very well. To make it easier, we recommend heating the oil up in a 55 gallon drum with a heavy duty band heater. You just need to get it warm enough so that it flows well, typically that’s above about 70-80 deg. F
Once heated, run the oil through a filter to remove all the junk out of it. In the winter we find that our 55 gallon stainless steel drum filters do exceptionally well. These filters filter not only through the bottom but also through the sides; which makes it easier for the oil to flow through them faster. For producing Biodiesel, we recommend going with 400 micron or smaller. Also, if the oil still acts stubborn while going through the filter, you can use a heat gun on the filter itself to heat it up; which will melt any stubborn oil and let it flow through easier.
4- Titrating The Oil
Another problem area in the winter is titrating cold oil. The problem is that the thickened oil doesn’t like to dissolve into the isopropyl alcohol creating more of a glob of oil sinking to the bottom of your titration cup. To help deal with this issue, we recommend taking a small sample of oil and heating it up a bit. This can be done in the microwave, with a heat gun, or believe it or not, by simply holding the oil in it’s container in your hand for a few minutes.
Also, be sure that the isopropyl alcohol is also warm enough to dissolve the oil as well. Typically, it needs to be above 65 deg. F; usually typical ambient room temperature will work. Once the oil and the alcohol are warm, then mix them together and ensure that the oil dissolves into the alcohol. If you see globs on the bottom, then either the oil or the alcohol is still cold; which will cause a bad reading. Once the oil and alcohol dissolve well, perform a titration 3 times and then take the average between all three.
5-Insulate Your Biodiesel Processor & Wash Tanks
If you’re processing your oil into Biodiesel in an unheated room, we highly recommend insulating your Biodiesel processor & wash tanks. We insulated our BioPro 190 Automated Biodiesel Processor several years ago with a really cool product called ArmaFoil and have been really impressed with the results.
Whether you use ArmaFoil, double-foil backed bubble wrap, water heater insulation, spray foam, or some other insulation, the key point here is to do it! We’ve seen people use everything from sleeping bags & foam, to blankets & bungee cord. As long as your processor is covered on the sides with insulation, it’s going to help!
As an example of how effective this is, one day we measured the temperature of some oil prepped for processing in our BioPro 190 with a laser thermometer at 130 Deg. F. When we measured through the glass window at the bottom, we could read about 100 Deg. F, however, when we pointed it at the high tech insulation we used, it read 78 Deg. F. That means the insulation was doing it’s job of keeping the heat IN the processing tank.
When securing insulation to metal or poly tanks, we’ve found the HVAC metalized duct tape works best! Also, be sure & clean the exterior of your tank before applying the insulation. Otherwise, the tape won’t stick and the insulation will soon fall off. When insulating a poly tank, it’s always a good idea to leave a small slit down the side uninsulated so that you can still see the liquid level in your tank. No wider than 1″ should do just fine.
6- Heat Your Biodiesel Back Up BEFORE Water Washing
If you water wash your Biodiesel in an unheated room, be sure to bring the heat of the Biodiesel back up to at least 80 to 100 Deg F before attempting to water wash it. If you’re water washing with really cold water (say water temp below 50 Deg. F), I’d recommend heating the Biodiesel to 100-110 Deg. F (remember, the cold water will be like taking a cold shower–it’s going to cool the Biodiesel down as it flows through it REALLY FAST!).
If you’re using a BioPro Automated Processor, it’s pretty easy. I just flip the HEAT switch on before I start reacting a batch of oil and I don’t turn it back off until the batch is finished. This trick keeps the heat running even when the glycerin is settling out so that the Biodiesel is nice & hot when you wash it (it also makes the glycerin flow out of the tank easier too–especially if NaOH (Sodium Hydroxide, Lye) was used.
For other style processors, you can utilize heavy duty electric band heaters, inline heaters connected to a pump that circulates the oil past a heating element, or even something as simple as a drop in heater. The key here is to keep the temperature of the Biodiesel between 80 to 110 deg. F during all the washing. Keep a thermometer handy and measure the temperature periodically to ensure you’re not dropping below 80 deg. F
IMPORTANT NOTE: If you are washing in a plastic tank and plan on heating it with a drop in heater, be careful not to let the heater tough the sides of the plastic tank anywhere; the hot element can melt the tank really fast and make a big mess (and potentially even a fire). Also, if you’re heating in a plastic tank, we strongly recommend monitoring the tank to make sure you don’t heat it too hot. Plastic tanks don’t hold up well much past 140 to 160 deg. F, so watch the temperature carefully. If you need an easy way to do this, grab one of our 12″ long stem thermometers and attach it to the tank so that it’s reading the Biodiesel temperature at all times.
7 – Wash Heated Biodiesel With Luke-Warm Water
Use luke-warm water (80 to 100 Deg F) to wash your Biodiesel with. Especially if you’re using softened water or washing a batch of Biodiesel that was reacted with Potassium Hydroxide.
Really hot water (water above 130 deg F) can tend to cause foaming and even exacerbate emulsions. Particularly if you’re using water that’s been softened by a household water softener. This is especially true when washing batches reacted with Potassium Hydroxide (KOH). Soaps formed from KOH tend to “suds up” much easier than Sodium Hydroxide reacted batches. If the Biodiesel itself is nice and warm, it doesn’t seem to be as much of an issue, but it can still occur if the water spraying onto it is too hot.
There’s also a few tricks for keeping emulsions at bay. The first one is to add some vinegar to your wash water or Biodiesel that you’re washing. Usually a gallon of vinegar to every 50 gallons of Biodiesel is a good starting point. The slightly acidic vinegar helps to keep the soaps from mixing with the water to the point of causing an emulsion. The second tip is that if you do unfortunately create an emulsion, all is not lost. Simply grab some rock salt, dissolve it in water, and add it to your emulsion and watch the emulsion melt right before your eyes! It’s a pretty cool trick and it works really well! Check out our full article on how this works.
8- Test Biodiesel For Soap Content To Identify When Done Washing
The reason we wash Biodiesel is to remove any soap that was formed during the production process. Typically, this takes about 3 water washes to get to the point where most of the soaps have been removed. Once you’re wash water starts to come out clear, it’s time to test the fuel for soap content to see if it’s ready to be dried.
A really simple test I recommend for checking gross soap levels in Biodiesel is called The Shake-Em Up Test.
The test is performed by pulling a sample of the fuel you’re washing and mixing it 50/50 with some distilled water in a glass container (any small drink container or even mason jar will work). Shake the container up well and then allow it to sit for about an hour. After about an hour, inspect the water that’s settled to the bottom. If the water is mirky or milky looking, you need keep on washing. However, if the water is nice and clear, then you’ve removed the majority of the soap from the Biodiesel.
Just a couple of notes about performing the Shake-Em Up test in cold weather
1) Use distilled water if you have it. If not, tap water will do, but minerals in the water can sometimes throw the test
2) Use warmed Biodiesel and warm or luke-warm water.
3) Let the bottle settle in a room where the temperature is above 65 deg. F
While a Shake-Em Up test does a fairly good job of letting you know if there’s still a lot of soap in the fuel, it’s doesn’t let you know just how much soap is actually there. To identify what the actual soap levels are, you’ll need to perform a Soap Titration Test on the fuel. We carry a full line of Soap Test Kits that easily let you measure the soap levels very accurately.
For many years the Shake-Em Up test was the only one recommended to test for soap levels. However, because the test is subjective (“Yep! Water looks clear!”), it’s not very good at letting you know what the actual sooap levels are. So, why should you care about this? Well, soap in Biodiesel is one of the leading causes of plugged fuel filters. Soap in Biodiesel also has the tendency to get thick and coagulate when it’s cold. So, if you’re planning on using your Biodiesel during cold weather, it’s extremely important to ensure you have removed as much of the soap as possible.
The ASTM Standard for Biodiesel doesn’t really have soap limits in it directly, but they do specify limits for Sodium and Potassium; which are believed to come from elevated soap levels in the fuel. So, by performing a soap titration test on your fuel, you’ll know if you truly have the soap levels low enough to start drying.
Dry Washing Note:
Performing a soap titration test on fuel that has been dry washed is particularly important. This is because it’s extremely difficult to see the soaps in dry washed fuel. Because no water is used to wash the fuel, the Biodiesel may appear to be nice and clear, but can still be loaded with soap. So, if you dry wash your fuel; and particularly if you plan on using the Biodiesel in colder weather, I can’t stress strongly enough, SOAP TEST YOUR FUEL!
9- Drying Washed Biodiesel
Biodiesel needs to be adequately dried before it can be used in diesel engine vehicles or home heating appliances. This is particularly important when it’s being used in colder temperatures. The reason is that if it still has water, the water can drop out of the fuel and really cause havoc on your fuel system. However, drying Biodiesel in the cold can be somewhat of a challenge. So, just like drying the oil, we recommend utilizing a heat, circulate, and spray method.
This can be accomplished in your processing or wash tank, or by building a special drying tank such as our oil/biodiesel drying tank.
The reason this method works so well is that it creates much more surface area with the Biodiesel to come in contact with the ambient air; which then helps allow the moisture to evaporate faster out of the Biodiesel.
In other words, the secret is in the spray pattern. As the Biodiesel thins out and is sprayed into a vessel, air both below and above the Biodiesel allow the moisture to evaporate up and away! If you’d prefer not to build a dedicated drying tank, you can still get away with spraying the fuel using a Dry Pro nozzle to get the same effect; even if it’s in your processing or washing tank!
Just like drying oil, you’ll want to get the temperature of the Biodiesel up nice & hot. In the case of drying Biodiesel, we recommend getting it to anywhere between 80 and a 130 deg. F. The hotter the better (allowing for considerations for the vessel you’re drying it in ie. don’t heat it hotter than the tank can handle). In order for this method to work effectively, it’s extremely important that the top of the vessel be open to the air. Otherwise, as water evaporates and rises it’ll simply hit the top of the vessel, condense, and fall back into the Biodiesel making it wet again. So make sure you have a nice, wide opening at the top if you plan to use the Heat/Circulate/Spray method.
Also, you can speed the drying process up by blowing air across the top of the vessel. This will create a low air pressure above the drying tank and the moisture will get sucked up and away. We’ve seen it speed up the drying by quite a bit!
Biodiesel Water Limits:
As with drying oil, this is where using a Deluxe Water Test Kit really comes in handy! Use it to measure the water content of your finished Biodiesel. The ASTM Limit for water in Biodiesel is no more than 500 PPM (0.05%), so be sure & test to make sure you’re within that specification. As indicated above, getting all the water out of Biodiesel is extremely important in cold weather. Otherwise, it can contribute to icing in the fuel lines, fuel tanks, and fuel filters plus, water can also cause corrosion to occur in the fuel system itself. Suffice it to say, you want to get as much of it out as possible.
10- Test The Gelpoint Of Your Biodiesel
One simple test you can do on the Biodiesel you produce is to measure the temperature that it gels at. A simple method for doing this test is to take a jar of your Biodiesel and place it outside where you park your vehicle. Then, as it gets cold outside, watch the jar each morning to see if it’s gelling up. Placing a thermometer nearby is also helpful too!
If you notice that the Biodiesel has gelled, then it’s a good time to note it. Given enough cold nights, you’ll be able to get a good feel for the temperature at which your Biodiesel gels at. In general, oils that are less dense (Canola & Safflower Oil) tend to gel at lower temperatures than oils that have higher density’s (Soybean, Peanut, Olive, & Coconut Oils). You can lower the temperature at which your Biodiesel gels at by adding kerosene or petro diesel to it. You can see what blend level is ideal for your area by creating several blends in separate bottles and leaving them outside and watching them over several days. Given some time, you’ll be able to find the optimal blend of Biodiesel to kerosene/diesel fuel that will keep your fuel from gelling on you.
Several years back, we did a biodiesel gel point study. We made Biodiesel from several different kinds of oils, placed samples of them outside, and then let winter in Utah happen. The results were pretty drastic! Our Canola Biodiesel sample by far did the best while our Peanut Oil sample gelled really fast! The Soybean Biodiesel sample was pretty close to our Peanut Oil Biodiesel sample, while the Corn Oil Biodiesel sample was about middle of the road.
A note about anti-gel additives:
In general, diesel fuel anti-gel additives have no effect on lowering the gel temperature of Biodiesel. Study after study has born this out. While there are anti-gel additives on the market that specifically list Biodiesel as a fuel they will treat, most people find that the results are minimal at best and that any benefit afforded by using the anti-gel additive isn’t worth the money paid for the additive. In other words, diesel fuel or kerosene work much better and are much cheaper than any Biodiesel anti-gel additive available on the market. In our own testing we did see decent results with Amsoil Cold Flow Improver, but it wasn’t a significant effect.
My general recommendations are to start with a 50/50 mix of Biodiesel to diesel fuel and test from there. The oil you’re using to make Biodiesel from may vary somewhat, but by testing the gel point of your Biodiesel as well as what blend works best for your climate, you can help avoid getting stuck on the side of the road with a gelled up fuel filter in the cold.
11- Filter Finished Biodiesel
Our final tip for making Biodiesel in cold temperatures is to filter your finished fuel through a Biodiesel compatible fuel filter. We filter our fuel through a 10 micron GPI fuel filter attached right to the side of our BioPro 190 Automated Biodiesel Processor and have seen really good results with it.
We make sure our fuel is well washed so we average about 2,000 to 3,000 gallons through our filter before we have to swap it out. Pre-filtering your Biodiesel through fuel filters also saves money too! Our GPI Fuel Filters or our Golden Rod fuel filters are typically a heck of a lot cheaper than the on board vehicle fuel filters. They’re also a lot more convenient to replace when one plugs up vs. plugging the one on your vehicle on the road somewhere.
As for what micron fuel filter to pre-filter with, we recommend identifying what the micron rating on your vehicle fuel filter is and then filter down to at least that level. For example, our GPI & Golden Rod fuel filters both filter down to 10 microns. If you need to go smaller, we recommend using one from the Bio-Tek line of Cim-Tek branded fuel filters. They even offer them in a water separating version called a Cim-Tek Bio-Tek Microglass Hydroglass fuel filter.
Adding one of these fuel filters to a fuel transfer pump is a breeze too! Our Golden Rod fuel filters come with the mounts built into them and our GPI fuel filters can be ordered with a mount that connects right up to any 3/4″ hose fitting.
Since fuel filters are so inexpensive to purchase and easy to install, we highly recommend using them all the time. Plus, if you use them to pre-filter your Biodiesel through in colder weather, it’ll be just one more preventative step you can take in keeping your fuel from gelling up on you in your vehicle.
What To Do If Fuel Gels Up:
Sometimes no matter what steps you take to make your Biodiesel, it still gets so cold outside that the Biodiesel can gel up on you. If this happens, all is not lost. Simply move your vehicle into a heated garage, point a heat gun or even a hair blow dryer at the fuel filter and heat it back up, or even use a “trouble-lamp” (metal caged lightbulb on the end of an extension cord) near the fuel filter to warm it back up enough to get the engine running again.
We also offer a really nice line of fuel filter heaters as well that can help keep you running Biodiesel in high blends even when it’s cold outside.
Check out our video we did highlighting these cold weather Biodiesel tips & tricks as well!
Running Biodiesel In The Cold In this article we highlight some tips & tricks for running your rig on Biodiesel when it’s cold outside.
Four Test Kits Every Biodiesel Producer Should Own Highlights four test kits that will help you make great Biodiesel
So, there you have it! Our tips & tricks for successfully making Biodiesel in the cold! We’ve had several customers all over the world successfully make and use Biodiesel all winter long by using these simple, easy to follow tips. So, if you’re up to brewing in the cold, now you know how! Happy brewing!