Main properties / characterization of fats used in experiments
This chapter presents one method to obtain the renewable “biodiesel” energy source thru animal fats transesterification with high free fatty acid content. The authors tested different methods to produce biodiesel from waste animal fats. The purpose of research was to use the byproduct from the meat industry, the wastes in form of fats with high free fatty acid contend (FFA), fats that cannot be used in other sectors, like supplement in animal food, due to high contamination and FFA content.
The research underlines a correlation between social-economic development and air quality in an urban area. We also intend to improve the knowledge in the field of alternative fuels, field not well covered in Romania, especially if the waste management and potential are in sight. The relevance of this research theme in the knowledge development is related to the fact that studies regarding environment protection are not an objective but a dynamic process that requires adequate instruments and concrete actions in the frame of a coherent legislative frame. (Popescu, 2009)
The chapter will follow three directions: first will describe the research conducted in order to obtain an “receipt” to produce the biodiesel from waste animal fats; second will describe the pilot installation constructed to improve the biodiesel production receipt and third will describe some research conducted in order to prove (or validate) the positive impact on the urban environment if the biodiesel in used in stead of regular diesel.
In a broad sense,
Among the available alternative energy sources, including hydro, solar, wind etc. to mitigate greenhouse emissions, using biofuels is the only carbon-based sustainable option. It is increasingly understood that 1st–generation biofuels (produced primarily from food crops such as grains, sugar beet and oil seeds) are limited in their ability to achieve targets for oil-product substitution, climate change mitigation, and economic growth. Their sustainable production is under review, as is the possibility of creating undue competition for land and water used for food and fibre production. A possible exception that appears to meet many of the acceptable criteria is ethanol produced from sugar cane. The cumulative impacts of these concerns have increased the interest in developing biofuels produced from non-food biomass.
With exception of hydroelectricity and nuclear energy, the major part of all energy quantities consumed worldwide comes from petroleum, charcoal and natural gas. However, these sources are limited, and will be exhausted by the end of this century. Thus, looking for alternative sources of energy is of vital importance.
Vegetable oils and animal fats are a renewable and potentially inexhaustible source of energy with an energetic content close to diesel fuel. The physical characteristics of fatty acid ester (bio-diesel) resulted in the end of the transesterification are very close to those of diesel fuel and the process is relatively simple. Furthermore, the methyl or ethyl esters of fatty acids can be burned directly in unmodified diesel engines, with very low deposit formation.
Transesterification is the general term used to describe the important class of organic reaction where an ester is transformed into another through interchange of the alkoxy moiety. When the original ester is reacted with an alcohol, the transesterification process is called alcoholysis.
The general transesterification reaction equation is:
To meet rising energy demands and compensate for diminishing petroleum reserves, fuels such as bio-diesel and bio-ethanol are in the forefront of alternative technologies. It is well known that transport is almost totally dependent on fossil-, particularly petroleum-, based fuels such as gasoline, diesel fuel, liquefied petroleum gas, and natural gas. An alternative fuel to petro-diesel must be technically feasible, economically competitive, environmentally acceptable, and easily available. Accordingly, the viable alternative fuel for compression-ignition engines is bio-diesel.
Thus, it is obvious that the transesterification is an equilibrium reaction and the transformation occurs essentially by mixing the reactants. However, the presence of the catalyst (typically a strong acid or base) accelerates considerably the adjustment of the equilibrium. In order to achieve a high yield of the ester, the alcohol has to be used in excess.
Several aspects, including the type of catalyst (alkaline or acid), alcohol/fat molar ratio, temperature, purity of the reactants (mainly water content) and free fatty acid content have an influence on the curse of the transesterification.
One popular process for producing bio diesel from fats/oils is transesterification of triglyceride by methanol (methanolysis) to make methyl esters of straight-chain fatty acids. The purpose of the transesterification process is to lower the viscosity of oil. The transesterification reaction proceeds well in the presence of some homogeneous catalysts such as potassium hydroxide (KOH), sodium hydroxide (NaOH) and sulphuric acid or heterogeneous catalysts such as metal oxides or carbonates. (Popescu, 2009)
The transesterification process of the fresh fats and vegetable oils is an easy one with no complications. It is more difficult to control the transesterification process when the raw materials are waste fats with animal origin and very high content of free fatty acids. The scope of this paper is to provide an receipt, based on authors experiences, to succeed in the transformation of waste fats to bio-diesel and to use the energy contents of waste fats, that otherwise must be incinerated/destroyed in special conditions with high costs, as an renewable energy source.
2. Experiments to obtain a “receipt” for biodisel production from waste fats
In this paragraph the properties of 11 old fats sample provided by the same manufacturer will be presented. It may be interesting to mention that the fats were originally produced to be used as a food in animal farms. The qualities of the fats are below the in force in Germany at the time of experiments, GROFOR - that stipulates the acceptable limits for the quality of animal food - and that is a very good reason and argument to try to use the fats for bio-diesel production. Measurements have been made for: iodine number (DGF-Methoden C-V 11b), sulfuric ash (DIN 51 575), total contamination (DIN 51419-A), peroxide number, kinematic viscosity (DIN 51 562 part 1) and free fatty acid (DIN 51 558 part 1). In Table 1 a synthesis of the old fat proprieties used in experiments are given.
The fat must be heated until it becomes liquid and then might be filtered. Two stages (acid-catalyzed stage and base-catalyst stage) should be accomplished. (Trent, 2002)
For a successful reaction the oil must be free of water. There are two common methods of removing the water content:
Boiling the water off: heating to 100 °C. As the heat raises the water, it separates out and falls to the bottom. The water is then drained out to avoid steam explosion. The temperature (> 100 °C) should be maintained until no bubbles are rising any more.
Settling the water out: This method saves energy. The fats must be heated to 60 °C and to keep this temperature for 15 minutes. After this one pours the fats into a settling tank and lets it settle for at least 24 hours. The water will separate and fall to the bottom.
The following strategy/receipt must then be fulfilled, step-by-step, for accomplishing successfully the fats preparation. First described is the acid-catalyzed stage, giving the basic acid stage reaction.
Bellow is given the First stage (acid-catalyzed stage), in detail:
Measuring the volume of oil/fats to be processed (preferably in liters).
Heating the oil/fats to 55 °C - all solid fats must be melted.
Measure out the methanol and add 0.1 liter of methanol for each liter of oil/fats (10 % by volume). Add the methanol to the heated oil.
Mixing for 5 minutes; the mixture will become murky because of solvent change (methanol is a polar compound, oil is strongly non-polar and a suspension will occur).
Adding for each liter of oil/fats the quantity of 1 milliliter of 95-97 % sulfuric acid (H2SO4). A graduated eyedropper, a graduated syringe or a pipette should be used.
Mixing gently at low rotation speed (rpm), while keeping the temperature at 55 °C. The rotation of the stirrer should not exceed 500 to 600 rpm.
Maintaining the temperature at 55 °C for 50 minutes then stop heating. Continuing stirring.
Preparation of the sodium methoxide that consists of adding 0.1 liter of methanol for each liter of oil/fat (10 % by volume) and 3.1 grams of 99 % pure sodium lye (NaOH) per liter of oil/fat. Finally mixing the lye into the methanol until the lye is completely dissolved.
Pouring half of the prepared methoxide into the mixture after 1.5 hours (oils only or oils plus fats) or 2 hours (for fats that are solid at room temperature). This will stop the acid-catalyzed reaction and prevent ester back splitting. Mixing for 5 more minutes, then stop.
Allowance to the mixture to settle for 6 to 12 hours, then draining off the glycerin. (the brown or dark brown compound at the bottom).
Bellow is given the Second stage (base-catalyzed stage), in detail:
Heating the mixture to 55 °C. Make sure that any remaining room-temperature solid fats are melted.
Adding the second half of the prepared sodium methoxide to the heated mixture and start mixing at the same low speed of not more than 500 to 600 rpm. Mix for 1 hour.
Allow settling for 6 to 12 hours.
Drain off the glycerin. The biodiesel is now obtained.
Final stage is represented by the washing out the biodiesel and the pH of the FAME (fatty acid methyl ester) should be known. The receipt comprises the following steps: Put the FAME in one vessel with ½ water or the same quantity of water as the FAME to wash. The FAME and water must have the same temperature (room temperature). The water pH must have as many units under 7 as the FAME pH is above 7. Use strong vinegar to obtain lower pH for water. Use compressed air to create bubbles in the vessel ho contains the FAME/water mixture. Let it bubble for up to 6 hours. The bubbles will carry the water up. When this water falls down again, it washes the soaps and surplus methanol out of the FAME and the vinegar neutralizes the remaining lye. After settling for 12 hours the water will fall to the bottom, turning completely white and the bio-diesel will look much lighter in color now (Figure 3).
In Table 2 are presented the chemicals (CH3OH – methanol, H2SO4 – sulphuric acid, NaOH – sodium hydroxide, KOH – potassium hydroxide) and their concentration values used in the tests for producing the bio-diesel.
The most successful test was No 6, realized with an extra-step with KOH. The viscosity of the bio-diesel obtained was 5.3 mm2/s. Also test No 7 was a partial success. It should be mentioned that for the last step (KOH) for No 6 it was used just 188.28 g collected at the end of the second step. Figure 3 is a view over samples from biodiesel No 6. Note the lighter colors and no depositions.
Implementing the process described above results in the process flow shown in the figure 4.
Based on the experiments described above and on the derived flow chard of the process, the pilot station presented in figure 5 was built at “Politehnica” University of Timisoara. The control of the installation and transesterification process is fully automated and design to use waste animal fats from meat processing industry. The ration between raw fats introduced and biodiesel produced is up to ~ 50% for waste fats with the FFA content higher than 12% and is getting higher as the FFA content in the raw material decreases. The installation capacity is 20 liters of fats and the processing time is from 3 to 10 hours, depending on the FFA content of the fats
3. Advantages in the use of biodiesel in an typical urban vehicles fleet
Air pollution is a major concern for all nations, with a higher or lower development level. The rapid increase of the industry sector and urban development had generated substantial quantities of substances and poisonous materials, witch are, mostly evacuated in the atmosphere. The human society was not willing to recognize that the environment has only a limited capacity to process all this waste, without major changes. As a consequence we are able to observe disfunctionalities in the health degree, deterioration of flora and fauna, materials, buildings, in parallel with the lost of natural resources. Each of us is a polluter but also a victim of pollution. (Ghani, 2009)
The scope of this paragraph focuses on the utilization of the bio-diesel in a comparative study regarding air quality impact of its utilization as main fuel in a real fleet in urban area, in comparison to the present situation, when fossil diesel is used.
Further examples of how air quality might be determined by numerical modeling in order to establish if new industrial sources (that are also polluting sources) might affect the quality of air. One knows that the total air concentration is a sum of the natural pollution and the induced anthropic pollution. In order to modernize a city it is necessary to build new industrial area that are simultaneously also polluting. By numerical simulation the strategy might be optimized. (Silva, 2010)
In the next paragraph and figures is presented the simulation in the case that all diesel engines are using the bio-diesel fuel, for one major Timisoara crossroad, M. The values for emission factors both for diesel and bio-diesel fuels are extracted from Corinair database and traffic structure and meteorological date were measured
The software used was CALROADS with modeling code CALINE 4 (US EPA approved) and the areas studied were Michelangelo crossroad and Marasti crossroad, both major polluting area point in the city of Timisoara. The traffic surveillance and cars characterizations have been conducted for the time frame considered in both crossroads. The medium number of cars in both intersections was around 45 000 vehicles/day (about 30% diesel powered vehicles). The diesel emission factors have been taken from Corinair database.
In figure 6 an example of road traffic structure measured in the Michelangelo crossroad is given. The figure shows the traffic structure over one hour period from a typical day in a time frame with medium traffic intensity.
The road traffic measurements and fleet characterization has been done over a week period, the results for total road traffic in the Michelangelo crossroad is given in table 3.
In figure 6 the road traffic structure is given for one hour period, for the Michelangelor crossroad, as the concentrations resulted after the simulations are one hour mean values.
The formulas used to calculate the emission factors for CO, NOx and particles is in accordance to Corinair methodology and the estimated results for diesel and biodiesel are calculated. (EMEP, 2007)
|Day||Road traffic [veh. tot.]|
In the formulas above
Emission factors for biodiesel fuel (B100 blend), for each vehicle, are:
|Pollutant||Fuel||Maximum obtained value|
4. Conclusion and discussions
With exception of hydroelectricity and nuclear energy, the major part of all energy is produced from petroleum, charcoal and natural gas. However, these sources are limited, and will be exhausted by the end of this century. Thus, looking for alternative sources of energy is of vital importance.
Vegetable oils and animal fats are renewable and potentially inexhaustible sources of energy with an energetic content close to diesel fuel. The physical characteristics of fatty acid ester (bio-diesel) resulted in the end of the transesterification are very close to those of diesel fuel and the process is relatively simple. Furthermore, the methyl or ethyl esters of fatty acids can be burned directly in unmodified diesel engines, with very low deposit formation.
It is quite visible from Figures 7, 8 and 9 the advantages of using bio-diesel in diesel engines and that if all diesel engines will use bio-diesel fuel the reduction of emitted CO and particle concentration is up to 50%.
As it is known the crude oil world reserves will not last forever and it is necessary to obtain alternatives fuels for piston engines. Another aspect is the more decent impact of these fuels on the environment. The search for alternative fuels is on wide spread in all developed countries.
The advantage of bio-diesel as an alternative fuel relies first of all on its physical properties, similar with those of diesel fuel so that bio-diesel can be used directly in diesel engines with no essential modification. Second advantage is the very low impact on environment, and the third advantage is the accessibility of the breeding materials like old animal fats and a large variety of vegetable oils.
The tests described above are a real success and a step forward in developing new alternative fuels for piston engines.
This paper brings in attention an example of possible strategy in order to meet the general EU strategy concerning the RES utilization and percentage support for the total energy consumption by 2020. Also, gives an example on how numerical simulations with software approved by international institutions can be used by local urban and environment authorities in order to control pollutants emissions in urban or industrial areas, with an emphasis on sustainable and eco-friendly urban development. The advantage of numerical simulations is given by fast results, low cost and possibility to evaluate different pollution reduction scenarios.
Worldwide, there is a growing interest in the use of solid, liquid and gaseous biofuels for energy purposes. There are various reasons for this, such as:
Political benefits (for instance, the reduction of the dependency on imported oil);
Employment creation – biomass fuels create up to 20 times more employment than coal and oil; and
Environmental benefits such as mitigation of greenhouse gas emissions, reduction of acid rain and soil improvements.
The advantage of biofuel as an alternative fuel relies first of all on its physical properties, similar with those of diesel fuel so that biofuels (biodiesel or buthanol) can be used directly in diesel engines with no essential modification. Second advantage is the very low impact on environment, and the third advantage is the accessibility of the breeding materials like old animal fats and a large variety of vegetable oils.
In this respect, knowledge exchange as well as the creation of conductive market mechanisms and legislation is essential for a more widespread introduction of biomass and biofuels energy systems.
All tests presented where successfully made by the authors in the frame of several projects of the hosts, “Politehnica” University of Timisoara and T.U. München with the financial support of Alexander von Humboldt Foundation, Romanian National Council for Scientific Research and Balkan Environmental Association for which deep thanks are expressed.