Journal of Chemical, Biological and Physical Sciences. Biodiesel-Renewable Fuel, Environmental Implications and Its Handling

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1 February April 2013, Vol. 3, No. 2, E- ISSN: Journal of Chemical, Biological and Physical Sciences An International Peer Review E-3 Journal of Sciences Available online atwww.jcbsc.org Section D: Environmental science CODEN (USA): JCBPAT Review Article Biodiesel-Renewable Fuel, Environmental Implications and Its Handling M.Sakunthala 1, V.Sridevi 2*, K.Vijay kumar 3 and K.Rani 4 1 Centre for Biotechnology, Department of Chemical Engineering, Andhra University, A.P, India, 2* Department of Chemical Engineering, Andhra University, A.P, India, 3 Department of chemical Engineering, Andhra University, A.P, India, 4 Centre for Biotechnology, Department of Chemical Engineering, Andhra University, A.P, India, Received: 4 March 2013; Revised: 15 March 2013; Accepted: 18 March 2013 Abstract: Several attempts have been made by researchers across the globe to counter the effects of the growing information related to the finite nature of the present fossil fuel reserve and the associated hazards. Biofuel has gained global popularity in this respect as a biomass based fuels that have been tipped as a timely candidate. This review strictly focuses on biodiesel of all biomass derived biofuel. Biofuel production from renewable sources is widely considered to be one of the most sustainable alternatives to petroleum based fuels and a viable means for environmental and economic sustainability. Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable, and nontoxic fuel. Several processes for biodiesel fuel production have been developed, among which transesterification using alkali-catalysis gives high levels of conversion of triglycerides to their corresponding methyl esters in short reaction times. This process has therefore been widely utilized for biodiesel fuel production in a number of countries. Keywords: Biodiesel, Biofuel, Catalyst, Renewable sources, Transesterification J. Chem. Bio. Phy. Sci. Sec.D, 2013, Vol.3, No.2,

2 HISTORY OF BIODIESEL Dr. Rudolf Diesel actually invented the diesel engine to run on a myriad of fuels including coal dust suspended in water, heavy mineral oil, and, vegetable oil. Dr. Diesel s first engine experiments were catastrophic failures. But by the time he showed his engine at the World Exhibition in Paris in 1900, his engine was running on 100% peanut oil. Dr. Diesel was visionary. In 1911 he stated The diesel engine can be fed with vegetable oils and would help considerably in the development of agriculture of the countries which use it. In 1912, Diesel said, The use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time. No doubt, this statement has come to stay. Since Dr. Diesel s untimely death in 1913, his engine has been modified to run on the polluting petroleum fuel we now know as diesel. Nevertheless, his ideas on agriculture and his invention provided the foundation for a society fuelled with clean, renewable, locally grown fuel. Today throughout the world, countries are returning to using this form of fuel due to its renewable source and reduction in pollution 1. THE NEED FOR RENEWABLE FUELS The earth contains a wide variety of carbon reservoirs that can be harnessed to meet societal power requirements in the form of gaseous, liquid, and solid fuels, with liquid fuels being of most importance. The modern world has come to rely almost exclusively on fossil based reserves, a non-renewable resource, for production of liquid fuels. However, the cost and politics of being totally dependent on these reserves is getting progressively more expensive from both a strategic and sociological standpoint. A renewable source of fuels is required for meeting the future energy needs of the United States and the world. Unfortunately, politics and policy tend to be crisis management oriented resulting in a lag in the development of alternative fuels. The strategic and economic adverse impacts of the United States being so dependent on unstable petroleum reserves has finally pressured the leadership of the United States to pursue domestic resources of energetic products capable of economically and technically supporting the country s energy needs. INTRODUCTION Biodiesel has become more attractive recently because of its environmental benefits and the fact that it is made from renewable resources. The cost of biodiesel, however, is the main hurdle to commercialization of the product. The used cooking oils are used as raw material, adaption of continuous transesterification process and recovery of high quality glycerol from biodiesel by-product (glycerol) are primary options to be considered to lower the cost of biodiesel. There are four primary ways to make biodiesel, direct use and blending, micro emulsions, thermal cracking (pyrolysis) and transesterification. The most commonly used method is transesterification of vegetable oils and animal fats. The transesterification reaction is affected by molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats. The mechanism and kinetics of the transesterification show how the reaction occurs and progresses.the increases of world energy demand and greenhouse gas emissions have been concerning all sectors since last decades. Fossil fuels are starting to reveal their limitations as an energy source; both literally, as resources are depleted, and through their contributions to climate change. The result of this revelation is that the search for clean renewable fuels has been gathering momentum, in a bid to continue to meet our huge population s energy demands in the future. One of the most attractive responses regarding the alternative sources is biofuels. Biodiesel, however, is made from renewable resources, is biodegradable and nontoxic, and has a higher flash point than normal diesel. In addition, biodiesel increases lubricity (even at blends as low as 3% or less), which prolongs engine life and reduces the frequency of engine 1565 J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,

3 part replacement. Another significant advantage of biodiesel is its low emission profile and its oxygen content of 10-11%. Biodiesel is called the environmentally friendly biofuel since it provides a means to recycle carbon dioxide. In other words, biodiesel does not contribute to global warming. Increasing concerns regarding environmental impacts, the soaring price of petroleum products together with the depletion of fossil fuels have prompted considerable research to identify alternative fuel sources. Biofuel has recently attracted huge attention in different countries all over the world because of its renewability, better gas emissions and its biodegradability. Table 1 shows a brief comparison of the ASTM standards for diesel and biodiesel. As can be seen, biodiesel exhibits characteristics that are comparable to traditional diesel fuel. Table-1: Values for the American Society for Testing and Materials (ASTM) Standards of Maximum Allowed Quantities in Diesel and Biodiesel property diesel biodiesel Standard ASTM D975 ASTM D6751 composition HC a (C10-C21) FAME b (C12-C22) Kin. viscosity (mm 2 /s) at 40 C specific gravity (g/ml) flash point ( C) cloud point ( C) -15 to 5-3 to 12 pour point ( C) -35 to to 16 Water (vol %) Carbon (wt %) Hydrogen (wt %) Oxygen (wt %) 0 11 Sulfur (wt %) Cetane number HFRR c (µm) BOCLE d scuff (g) 3600 >7000 a Hydrocarbons. b Fatty acid methyl esters. c High-frequency reciprocating rig. d Ball-on cylinder lubricity evaluator. ADVANTAGES OF THE USE OF BIODIESEL Some of the advantages of using biodiesel as a replacement for diesel fuel are 3 6 : Renewable fuel, obtained from vegetable oils or animal fats. Low toxicity, in comparison with diesel fuel. Degrades more rapidly than diesel fuel, minimizing the environmental consequences of biofuel spills. Lower emissions of contaminants: carbon monoxide, particulate matter, polycyclic aromatic hydrocarbons, aldehydes. Lower health risk, due to reduced emissions of carcinogenic substances. No sulfur dioxide (SO 2 ) emissions. Higher flash point (100 C minimum) J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,

4 May be blended with diesel fuel at any proportion; both fuels may be mixed during the fuel supply to vehicles. Excellent properties as a lubricant. It is the only alternative fuel that can be used in a conventional diesel engine, without modifications. Used cooking oils and fat residues from meat processing may be used as raw materials. Figure1: Classification of biofuels 2 DISADVANTAGES OF THE USE OF BIODIESEL There are certain disadvantages of using biodiesel as a replacement for diesel fuel that must be taken into consideration: Slightly higher fuel consumption due to the lower calorific value of biodiesel. Slightly higher nitrous oxide (NOx) emissions than diesel fuel. Higher freezing point than diesel fuel. This may be inconvenient in cold climates. It is less stable than diesel fuel, and therefore long-term storage (more than six months) of biodiesel is not recommended. May degrade plastic and natural rubber gaskets and hoses when used in pure form, in which case replacement with Teflon_ components is recommended. It dissolves the deposits of sediments and other contaminants from diesel fuel in storage tanks and fuel lines, which then are flushed away by the biofuel into the engine, where they can cause problems in the valves and injection systems. In consequence, the cleaning of tanks prior to filling with biodiesel is recommended J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,

5 It must be noted that these disadvantages are significantly reduced when biodiesel is used in blends with diesel fuel. BIODIESEL PRODUCTION PROCESS Biodiesel is defined as the mono-alkyl esters of vegetable oils or animal fats. Biodiesel is produced by transesterifying the parent oil or fat to achieve a viscosity close to that of petro diesel. The chemical conversion of the oil to its corresponding fatty ester (biodiesel) is called transesterification. Biodiesel is a biofuel commonly consisting of methyl esters that are derived from organic oils, plant or animal, through the process of transesterification. The biodiesel transesterification reaction is very simple 7. Triglyceride + 3 Methanol Catalyst Glycerine + 3 Methyl Esters (Biodiesel) An excess of methanol is used to force the reaction to favour the right side of the above equation. The excess methanol is later recovered and reused. Biodiesel production requires a feedstock (fat or oil) and an alcohol. In most cases, a catalyst also is present. Depending on the quality of the feedstock, either esterification or transesterification reactions are used for biodiesel production (see FAPC Fact Sheet FAPC-149 Biodiesel Glossary for definition of the terms). Most of the current biodiesel production operations use base catalysis (transesterification). Sodium hydroxide (NaOH), potassium hydroxide (KOH) and sodium methoxide (CH 3 ONa) are the most common catalysts for transesterification. Sodium methylate (sodium methoxide) is more effective than NaOH and KOH as a catalyst, but it is more expensive. Sodium methoxide is sold as a 30 percent solution in methanol for easier handling. Base catalysts are very sensitive to the presence of water and free fatty acids. The amount of sodium methoxide required is 0.3 to 0.5 percent of the weight of the oil. ENVIRONMENTAL IMPLICATIONS OF BIODIESEL USE Biodiesel does not contain chemically hazardous materials 8. However, it does contain chemicals that do impart oxygen loading on receiving environments. Therefore, long-term leakage or large spills into the environment can cause adverse impacts due to excessive oxygen utilization causing anaerobic (septic) conditions to become established. Environmental release of biodiesel is considered much less of an environmental security issue than the release of petroleum diesel because of the ease of biodegradation associated with the biodiesel 9, 10. Additionally, biodiesel is not considered a toxic compound due to its oil-base (i.e. not petroleum). The US Biodiesel Board (2003) reports that studies show that the use of biodiesel reduces exotic (derived from outside of the biosphere) carbon dioxide flux into the biosphere by over 75% because of recycling of the carbon dioxide within the biosphere. Carbon monoxide production on a life cycle basis is reduced by approximately 35%. Measurements of particulate matter emissions from diesel-run buses indicate a reduction of particulates by over 60%. Soot (the black smoke released during rpm increases) within the same tests were reduced by over 80%. Sulfur dioxide and methane releases have been documented to be reduced by over 8% and 3%, respectively. Nitrogen oxide releases were approximately 9% higher than those measured from combustion of petroleum diesel fuel. Wastewater production and hazardous waste generation during processing of biodiesel over petroleum diesel is approximately 80% and 95%, respectively, lower. Sharp (1998) 11 reports similar emission numbers for the burning of neat biodiesel within a Cummins N14 diesel engine. He estimates reductions in hydrocarbons, carbon monoxide, and particulates in excess of 95%, 45%, and 30%, respectively. However, he also measured a 13% increase in nitrogen emissions. Additionally, his results included data to show a 90% decrease in polycyclic hydrocarbon release J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,

6 Since biodiesel contains no aromatic compounds, it is far more environmentally friendly than petroleum derived diesel which does contain many aromatic compounds 12. The lack of aromatic compounds within biodiesel reduces the extent of polycyclic aromatic compounds formation during combustion within diesel engines. Tyson (2001) 8 reports that biodiesel degrades within the environment approximately four times faster than petroleum diesel. In terms of long-term human health benefits, Canada Clean Fuels (2003) reported that the use of B100 would reduce cancer cases due to diesel combustion by over 90%. They also state that using B20 would reduce this risk by approximately 25%. Note with regard to direct human handling issues, biodiesel appears to be relatively passive outside of reported skin and eye irritation when directly contacted. Ignition is a safety issue that should be evaluated as part of a site safety assessment; biodiesel is a fuel. The reader is strongly suggested to access the Material Data and Safety Sheet (MSDS) for biodiesel available from suppliers or from the world-wide web. The MSDS presents information on handling safety, first aid, and fire fighting procedures among other useful information. Note that government regulations require MSDS sheets for all chemicals used within industrial operations are on hand for employee and community member review. AIR EMISSIONS FROM BIODIESEL PRODUCTION If the oilseeds are processed (extracted or expelled) at the plant, tiny particles (particulate matter less than 10 microns in diameter, PM 10 ) are released during receipt and handling of the seeds. PM 10 could also be released during the mechanical extraction process. During the chemical extraction process and oil pre-treatment process volatile organic compounds (VOCs) are released. Some of these VOCs are known as hazardous air pollutants (HAPs), including methanol and hexane. The biodiesel reaction process units include tanks, reactors, decanters, ester washer and dryer, and distillation columns. This process will emit VOCs including hexane (when chemically extracted soybean oil is used), methanol, and/or ethanol. The biodiesel process may also utilize condensers, scrubbers, and/or a process flare to control emissions. The combustion process from the flare and boilers providing steam and energy to the process generates PM 10, VOCs, HAPs (hexane from natural gas or biodiesel combustion), carbon monoxide (CO), nitrogen oxides (NO x ) and sulfur oxides (SO x ). VOCs and HAPs could be emitted from biodiesel storage, crude glycerine storage, biodiesel load out, and the chemical storage tanks. Other emissions may result from activities not associated with the production process such as: PM 10 from the cooling towers; fugitive PM and PM 10 emissions from haul road traffic; fugitive VOC emissions from equipment leaks; PM 10, NO x, SO x, CO, and VOCs from fuel combustion in the boilers and emergency equipment (engine driven fire pumps and generators). HANDLING OF BIODIESEL The intent of this chapter is to present a summary of issues concerning the handling of biodiesel products. Note that Dr. Shane Tyson of the DOE National Renewable Energy Laboratory in Golden, CO 8 presents much more detail on mixing and storage issues in her document entitled Biodiesel Handling and Use Guidelines (DOE document NREL/TP ). The reader is referred to her document for more information concerning handling and cold weather issues. Neat biodiesel requires handling procedures similar to those utilized with vegetable oils. However, appropriate care should be taken when handling petroleum/biodiesel blends due to issues related to the petroleum fraction. Biodiesel should be stored in tanks made of compatible materials that include steel, aluminium, 1569 J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,

7 fluorinated polyethylene, fluorinated polypropylene, and Teflon 13. Materials that should be avoided include copper, brass, lead, tin, and zinc. As mentioned above, care should be taken to ensure that biodiesel does not contact rubber products, including hoses, gaskets, and seals. Biodiesel is described by Tyson (2001) 8 as a mild solvent; therefore, prolonged contact of biodiesel on painted and varnished finishes should be avoided. As noted in the performance experience discussions from this document, biodiesel tends to act as a cleansing agent; therefore, adding biodiesel to tanks that has attached solids may result in the detachment of the solid into the bulk fluid potentially causing plugging problems during fuel pumping. When storing neat biodiesel at temperatures lower than 45 o F, problems with gelling may be encountered. Biodiesel should be stored underground in most cold climates. However, if above-ground storage is used then blending with anti-gel agents or with No. 1 or No. 2 diesel fuel can be used to control gel problems, along with the use of tank heaters and/or insulation. Tyson (2001) 8 recommends that biodiesel fuels should be stored at temperatures at least 15 o F above their pour point, which is feedstock dependent characteristic (30 o F to 56 o F). If stored or mixed biodiesel form crystals due to temperatures being too low, then Tyson (2001) 8 suggest the following to remove the crystals: a. Allow ambient atmospheric conditions to warm the solution b. Force heat the fuel to above 100oF or until the crystals disappear c. Filter out the crystals, but keep them for reuse when they melt Storage stability of biodiesel is a key issue to the industry. Oxidative degradation can result in the formation of solids and gums within the fuel 8. The tendency to be unstable can be predicted via the number of unsaturated carbon-carbon bonds within the feedstock triglycerides. Fuels containing a high number of double bonded oil and/or fats tend to oxidize more rapidly than saturated feeds. Tyson (2001) 8 states that instability increases by a factor of 1 for every unsaturated bond present on the fatty acid chain; therefore, the fatty acid C18:3 (where, CX: Y with X = number carbon atoms and Y = number of double C: C bonds), being three times more unstable than a C18). The stability test described in ASTM D 2274 can be used to assess stability characteristics of a biodiesel. Stabilizers can be added to eliminate stability problems. Biodiesel or BXX blends should not be stored beyond 6 months, until more data are made available 8, 14. Obviously, this has great implications to processing plant production scheduling and distribution planning. Biological activity within biodiesel can also pose stability problems, mostly associated with slime and solids formation. Tyson (2001) 8 recommends that biocides be considered within systems where bio growth problems have been observed. Often the bioactivity is associated with water supporting algae growth; therefore, improved housekeeping operations can be used to control algal growth 8. CONCLUSION Energy is an essential factor in industrial growth and in provision of required services that improve the quality of life of mankind. Biodiesel, of the family of biofuel, has been described in this review as a fuel with necessary potentials to replace fossil diesel in future. In recent years, biodiesel has become more attractive as an alternative fuel for diesel engines because of its environmental benefits and the fact that it is made from renewable resources. Used oils can also be utilized for making biodiesel fuel, thus helping to reduce the cost of wastewater treatment in sewerage systems and generally assisting in the recycling of resources.the trials biodiesel and its blend have undergone is a confirmatory test to all advantages including environmental benefits accrued to it thereby plays a vital role in meeting future fuel requirements. There are significant advantages in the use of biodiesel as a replacement of dieselfuel and in blends. This review also provides to the public and state and local government officials 1570 J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,

8 information regarding the biodiesel production processes and air emissions. An integral part of the permitting process is to provide opportunities for the public to understand and comment on activities that affect their environment. As the nation becomes more dependent on renewable fuels, such as biodiesel, the industry, the public, and local and state governments must have the knowledge that will prepare them for the future. The public health, welfare, and environment will be protected and economic development will continue if everyone communicates effectively and works together. REFERENCES P.S. Nigam, and A. Singh; Production of liquid biofuels from renewable resources. Progress in Energy and Combustion Science, In press. DOI: /j.pecs ; G. Knothe, R.O. Dunn, and M.O. Bagby; Biodiesel: the use of vegetable oils and their derivatives as alternative diesel fuels. In: Fuels and Chemicals from Biomass, 1st edn. American Chemical Society, New York; J. Van Gerpen, B. Shanks, R. Pruszko, D. Clements, and G. Knothe; Biodiesel production technology. National Renewable Energy Laboratory, NRRL/SR ; J. Van Gerpen, B. Shanks, R. Pruszko, D. Clements, and G. Knothe; Biodiesel analytical methods. National Renewable Energy Laboratory, NRRL/SR ; S.D. Romano, E. González Suárez, and M.A. Laborde; Biodiesel. In: Combustibles Alternatives, 2nd edn. Ediciones Cooperatives, Buenos Aires; Chun-Yen Chen, Kuei-Ling Yeh, Rifka Aisyah, Duu-Jong Lee, and Jo-Shu Chang; Cultivation, photo bioreactor design and harvesting of microalgae for biodiesel production: A critical review. Bioresource Technology, 2011, 102, S. Tyson; Biodiesel Handling and Use Guidelines, NREL Report No. TP , Golden,CO; C. Peterson, J. Cook, J. Thompson, and J. Taberski; Continuous Flow Biodiesel Production. Applied Engineering in Agriculture, 2002, 18, pp C. L. Peterson, J.L. Cook, J.C. Thompson, and J.S. Taberski; Continuous Flow Biodiesel Production. Applied Engineering in Agriculture, 2002, Vol. 18, No. 1, pp C. Sharp; Characterization of Biodiesel Exhaust Emissions for EPA 211(b). Prepared for the National Biodiesel Board, Jefferson City, MO, W.A. Majewski; Biodiesel. DieselNet Technology Guide, Active website: subscriber%20access%5d.htm, SeQuential Fuels Inc (Eugene, OR), Active website; : Clean Air Fleets, Alternatives to Conventional No. 2 Diesel Fuel. Active website: Corresponding author: V.Sridevi; Associate professor, Department of Chemical Engineering, Andhra University, A.P, India 1571 J. Chem. Bio. Phy. Sci. Sec. D, 2013, Vol.3, No.2,