Renewable Energy Technology class trip to CU Boulder Biodiesel Workshop, April 9, 2005

James Taulman, Instructor

On April 8-10, 2005 Justin Boyd, a student in the EnS 483 Renewable Energy Technology class, traveled with English instructor Bret Swanson and me to Boulder to attend a workshop on biodiesel presented by the Colorado University Biodiesel organization there. Presenters were workshop directorTim Guiterman, Evan Belser, John Bush, Steve Sherman, and Paul Glasgow. About 36 people from all over the Midwest attended, 5 of whom currently use biodiesel fuel.

Tim Guiterman gives an overview of biodiesel production, use, and environmental benefits.

Biodiesel fuel, currently mixed 20% to 80% petroleum diesel and sold commercially, is available at one retail pump each in Denver and Boulder where it sells for about $3.40/gallon. Most commercial biodiesel fuel is made from soybean crops. About 50,000 gallons of B20 are currently being used annually at the University of Colorado, Boulder in a number of buses, recycling trucks, garbage trucks and other diesel vehicles. Some 10,000 gallons of B100, 100% biodiesel, are also being used in farm machinery and vehicles in the Boulder area.

Advantages of biodiesel fuel over petroleum diesel include a higher energy cost to yield ratio of 1 to 2.5, compared to 1 to 0.67 for petroleum and 1 to 0.5 for gasoline. This ratio refers to the energy required to produce the product versus the energy obtained when the fuel is consumed. Biodiesel also produces far fewer air pollutants as products of combustion: just 2% of the nitrogen oxide molecules, 1% of the particulates, and only ½ the carbon monoxide of normal diesel fuel.

But the greatest advantage of biodiesel fuel is that it is produced from vegetable oil and is part of the current ecological cycling of carbon through plants, animals, and back to the atmosphere, a cycling that is going on all the time and is natural and beneficial. Carbon dioxide produced from burning biodiesel fuel puts CO₂ back into the atmosphere that was only withdrawn recently by the plants from which the oil was made. And that CO₂ would have been returned to the atmosphere through plant decomposition or natural burning anyway. CO₂ produced from burning fossil fuels essentially puts new carbon into the atmosphere, because carbon sequestered in mineral deposits millions of years ago is not part of the current carbon cycle on earth. That fossil fuel burning is what is increasing greenhouse gases and producing an extra warming of the earth that we are experiencing now.

Evan Belser gives the group instructions in the lab preparation of biodiesel from veggie oil.

After getting a wealth of information in the classroom on the history and current use and benefits of biodiesel fuels, as well as the chemical reactions required to produce biodiesel, it was time to go over to the chemistry lab and make some ourselves. The CU Biodiesel crew had the lab all set up with stations, allowing the class to work in small groups and get good hands-on experience. Each station had 2 liter jars of veggie oil, one containing pure palm oil and the other waste fryer grease, as well as the needed beakers, tubing, and safety equipment. We handled methanol under a vent hood and wore protective gear in measuring out the lye to be used as a catalyst in the reaction.

Vegetable oil is an unsaturated fat consisting of glycerol and 3 fatty acids, called a triglyceride molecule. The basic reaction that produces biodiesel fuel from veggie oil is one in which a catalyst consisting of a strong base, NaOH or KOH, breaks apart the triglyceride molecule. Methanol is added to bond with the free fatty acids to produce the biodiesel fuel and the glycerine settles out and is drained off.

Our instructors put the chemical explanations on the board to help us understand the process.

The base and methanol are mixed together first to make a solution that will allow the easier addition of these 2 components to the veggie oil. That mixture of methanol and NaOH is called methoxide. It is a toxic stew that must be handled carefully. For pure veggie oil standard amounts of NaOH and methanol have been determined to give the correct proportions for the reaction. We used 3.5 grams of NaOH in 220 ml of methanol for each liter of veggie oil.

Our jar of pure palm oil after processing and then 30 minutes later, showing the separation of the biodiesel fuel on top and the glycerine layer at the bottom. The CU crew made up test batches ahead of time to show us the result of using different amounts of reactants. On the right is a batch made with less than optimum amount of the lye catalyst. Some veggie oil, and probably mono and diglycerides, remain in this batch that were not broken down during processing.

Biodiesel fuel is normally made from waste fryer grease, since that used oil is available free at many restaurants and only needs to be filtered and processed to make diesel fuel. The proper amount of NaOH has to be determined for each batch of waste fryer grease, since differing amounts of impurities are present depending on what has been cooked in that particular batch of grease. We did a titration on a small sample of our waste oil before processing the liter quantity, adding the methoxide solution to the waste oil and watching for a color change in an indicator solution that had been added to the oil.

Bret Swanson looks on as his teammates titrate the waste oil sample and agitate it to mix in the methoxide.

Our group did the same operation with our sample of waste oil; here Justin Boyd adds the methoxide mixture carefully, noting how much was required to produce a color change. That amount is then extrapolated to the proper proportion to add to the liter jar.

We learned that using too much NaOH catalyst results in bonding of the lye with fatty acids to produce soap before methanol can bond with them to make biodiesel. It is also better to use too much methanol rather than too little, so that no free fatty acids or veggie oil remain in the finished product.

Potassium hydroxide, KOH, is less toxic than sodium hydroxide, NaOH, and is sometimes used to make biodiesel, particularly in small home processors. We let both of our batches settle and saw the glycerine drop out and form a layer at the bottom and the biodiesel fuel separate into the clear layer above it.

Tim answers questions as a group waits for their batches to settle.

After taking a lunch break it was time to go back to the classroom to learn more about the nuts and bolts of setting up a home processor to make biodiesel fuel. Steve Sherman described his own home processor in detail and gave valuable advice on dos and don’ts for building and operating a home processor. We then boarded a bus and drove up in to the mountains to Gold Hill to look at Steve’s processor in person.

Our bus blows a radiator hose just a few miles from Steve’s house.

Our bus decided to take a little smoke (steam) break on the trip up to Gold Hill. This turned out to be a fortuitous event, though, as class participants used the time to get to know one another better, to discuss personal experiences and share information and make new contacts in this small but enthusiastic segment of the renewable energy community. A fresh bus was sent up and those of us who were still determined to see Steve’s processor set up continued on to his house.

The hot water heater that makes up the heart of Steve Sherman’s biodiesel processor

Steve and others have found that a used hot water heater is a good container on which to base the home processor. He draws a vacuum in the hot water heater and then sucks his filtered waste oil into the tank. Next the internal heating element and the thermostat on the heater are used to heat the oil up to about 55° C (being careful not to let the oil temperature get over 60° C, since methanol boils off at 64.5°). After mixing the methoxide in a smaller high density polyethelene, HDPE #2, container he then adds that to the heated oil with a recirculating pump. The batch is circulated and mixed for about an hour.

Simple plumbing on the processor. The silver pump in back is the vacuum pump that brings the interior of the hot water heater tank to about 18 atmospheres in order to draw in the grease. The blue pump is a recirculating pump to mix in the methoxide into the oil batch.

The mixture is then allowed to sit over night, about 8 or more hours. This allows time for the glycerine to separate from the biodiesel. The next day the glycerine is drained out the bottom of the tank. Steve emphasized the importance of also draining out a couple of gallons extra once the outflow changed from glycerine to biodiesel. This lowest layer of biodiesel still has many impurities in it and it can be cleaned separately and then added later to the biodiesel batch.

The remaining bulk of biodiesel fuel is then subjected to a wash in which further impurities are removed. It is important to remove the biodiesel and to conduct the washing step in another tank in order to keep water out of the main biodiesel mixing tank. Water can be sprayed on the top surface of the biodiesel. It then sinks to the bottom, being heavier than the oil, and picks up impurities along the way. A bubble machine can also be placed in the bottom of the washing tank, submerged in a layer of water that has been added to the biodiesel and sits on the bottom. Bubbles produced in this water layer will rise to the top and burst at the surface, then the tiny water droplets will sink back to the bottom, cleaning the biodiesel as the pass through it.

This washing process is usually done several times and is finished when the waste water drained off is very clear in appearance.

Drums holding Steve’s methanol and the waste oil used to make biodiesel

Steve listed the advantages of using a water heater for the home processing tank rather than a metal drum or other container:

The hot water heater can hold a vacuum, allowing oil to be sucked into the tank rather than having to be poured or pumped

An internal heater is already present

It is insulated

Drain connections are already present

It is a sealed vessel and vapors are contained

A thermostat is present allowing accurate control of mixture temperatures

Steve collects waste oil from local restaurants and lets a batch sit for a week or so to give larger debris and impurities a chance to settle out. He also lets his finished biodiesel fuel sit for a week or so to allow further settling of impurities before finally filtering it and using in his car. He recommends carrying a small titration test kit to the restaurant and taking the time to test a batch of oil on site. Sometimes the a restaurant’s waste oil is so dirty or damaged that it is not worth bringing home. It saves a lot of time and trouble to determine that before the oil is ever collected from the restaurant.

The diehards in the class who waited out the bus swap and finally made it to Steve Sherman’s home at Gold Hill. The snow we saw during the breakdown had stopped by this time and the day turned out very nice. (The weather for the trip home Sunday was a different story!) The biodiesel log cabin processing room is on the left. CU Biodiesel director, Tim Guiterman is at far left. Host Steve Sherman is on one knee with orange coat.

This workshop was a wonderful introduction to the technology of making biodiesel fuel and the benefits that this natural, renewable fuel offers to our oil saturated society. The CU Biodiesel guys did a great job of covering all the information and planning the lab exercises so thoroughly that we were all able to successfully make 2 batches of biodiesel and really understand what we were doing. We left with enough knowledge to safely set up a home processor. Now back home I’m on the lookout for a used hot water heater and am planning to build a processor in the garage. Next I’ll have to sell the gas truck and get a diesel!

For further information about CU Boulder’s biodiesel organization and for links to more biodiesel sites, check out the CU Biodiesel web site: http://www.cubiodiesel.org/.