ECONOMIC ANALYSIS OF SMALL SCALE BIODIESEL PRODUCTION
Students: Scott Haase, Benjamin Craig
Mentor: Ann Goebel
Department: Manufacturing Engineering Technology
Abstract
Biodiesel is becoming a demanded consumer automotive alternative fuel used in diesel vehicles today. A developing trend is toward small scale biodiesel production in which all work is done by the final consumer. A limited source exists of commercially available production systems and has resulted in most systems being designed and built by the user. Our initial research has shown biodiesel to be the least costly alternative to petroleum diesel after as few as 8 months of system use. This research examines the economic viability of building and producing biodiesel using a small-scale production system versus buying consumer petroleum diesel. During production, measurements were taken to determine labor hours, energy consumed and total cost of system construction. These results were used to generate an economic view of biodiesel production.
Slide 1
Biodiesel is a renewable alternative to conventional petroleum diesel fuel. It is derived from vegetable oil such as corn or soybean oil. The final product of biodiesel from the production process can be used in any conventional diesel engine without any modifications. Biodiesel is already produced in large refineries on a large scale and is available for general consumption. We choose to study the production of biodiesel on a small scale. Small-scale production is typically done by the people who will use the fuel in the end. This allows for flexibility in production size and allows for production at the point of consumption. Small-scale production also entails lower start up costs and results in a lower final cost of the fuel.
Slide 2
In our initial research we look at several different case studies and design projects preformed by small-scale producers. In our research we found several benefits in using biodiesel over petrol diesel. Production cost of a gallon of biodiesel averaged $0.65. The environmental impact caused by biodiesel was significantly lower than that of petrol diesel. The net carbon release into the atmosphere caused by biodiesel is near zero due to the fact that the plants used to produce biodiesel also absorb carbon out of the atmosphere. Particulate emissions are also significantly lower.
Slide 3
This is a schematic of the design that we used for our biodiesel production unit. The waste vegetable oil is heated in tank one to remove excess water. The oil is than pumped and filtered on its way to tank two where it is reacted with potassium hydroxide and ethanol. After it has been agitated, it is then moved to tank three to be cleaned with water and air bubbles. The biodiesel is then ready for use.
Slide 4
This is a picture of out actual apparatus. Tanks one and two are shown in this picture, tank three is not shown.
Slide 5
The plumbing is built in two sections. The first part is a pump and filter assembly run between the first and second tanks. The assembly has a 1” steel pipe running into the bottom of the first tank that has a screen covering the entry end to prevent large particles form entering the reaction tank. The vegetable oil is drawn up the pipe by a hand-operated pump and then forces the oil through a filter to remove any additional particulates and water. The oil then enters the reaction tank through a bung in the top of the tank.
The second part of the plumbing is used to remove product from the reaction tank. Directly under the tank is a series of three valves that allow for three different configurations. The first is all closed. The configuration is used when the reaction is in process and plumbing isn't being used. The second configuration is used as a drain. This configuration is used when draining off glycerin or other by-products. The third configuration is for pumping. This configuration allows fluid to leave the tank flow to a pumping column where the fluids can be pumped up and out to a third tank. This is used when removing the finished biodiesel from the reactor tank as it moves to the bubble-washing tank.
Slide 6
The framework and support structure is built from structural steel. The base for the drums was made form angle steel cut into the general shape of the barrel bottom. The legs of the structure were made from 1” square tube steel. Lengths of rebar steel attached between the legs and base supported the legs.
Slide 7
The electrical and heating system is into tank one exclusively. The heating is accomplished by two heating elements. The larger one runs at 1100W and is submerged in the tank. The second element is held to the bottom of the barrel by steel straps welded to the tank. On both ends of this element are attached thermal fusses and both ends of the element are covered by junction boxes. The ends are connected to the main circuit by 12-gage wire shielded by aluminum conduit. The conduit is connected to the main electoral box where the majority of the electrical system is houses. A schematic of the circuit is shown below.
Both elements are connected to limiting controls. The larger element is connected to thermostatically controlled limit switch while the smaller element is connected to a high limit switch. Both elements are run through current-limiting fuses.
Slide 8
The agitator assembly is built onto the lid of the reactor tank. The agitator itself is comprised of two steel fins welded onto the end of a rotating shaft. The shaft runs through the top of the barrel where it is stabilized by two barring assemblies. At the top of the shaft is a pulley wheel that is connected by a belt to the drive motor that is mounted to the apparatus frame.
Slide 9
This is a chart to help illustrate the processes that occur when producing biodiesel. The feedstock oil can be either new or used. After the oil is prepared for the reaction, either ethanol or methanol is then reacted with the use of catalysis. We choose to use ethanol. Ethanol is safer to work with and is produced in the local region. Also, because ethanol is produced from corn, it is a renewable resource.
There are some problems with using ethanol. Ethanol can be more sensitive to the reaction process with the vegetable oil. Ethanol is also more sensitive to variables such as pH and water in the vegetable oil. We've seen that this is true in our own experiments. So far no successful full-scale batch has been produced using ethanol. We have had a successful ½ liter sized test batch of methanol. We are continuing to work on this problem and are taking measures to refine our process by keeping tighter control over the pH of the feedstock oil, and water content in any of the reagents. Also blending ethanol with some amount of methanol. Is our next area we will be exploring help control the reaction.
Slide 10
These are the cost figures that we collected when constructed our production system.
Slide 11
These are the cost figures that we collect when running our production system.
Slide 12
To better illustrate how our findings could be applied to a real life situation, we looked at what could be possible here on the campus of MnSU if biodiesel production was implemented.
We obtained estimates of MnSU's annual diesel fuel consumption as well as the annual cooking oil consumption. Using the theoretical yield that Ben talked about in the last slide we have determined that 32.3% of the diesel used on campus could be replaced with biodiesel. By adding up the costs of each type of fuel it was determined that the university could save around $165 yr. While this is a very modest amount we think that the effort would be justified because of other benefits including fulfillment of environmental responsibilities and possible savings in costs associated with the disposal of waste oil.
Slide 13
Because we have been unable to produce biodiesel, cannot conclude whether system is economically justifiable at this time. It is important to remember that our research ongoing. Because the process has been tried and documented, confident we will produce biodiesel in the near future.