Introduction
The modern world relies on huge amounts of energy to sustain itself. For decades, the energy demands of the world have been met primarily by fossil fuels. However, this major energy source will not be able to meet the energy demands of the world for an indefinite period of time since fossil fuels are experiencing rapid depletion. Scientists and policy makers have been looking for alternative energy sources to replace fossil fuels. One potential solution is biofuels, which are a renewable energy source that can provide for mankind’s energy needs indefinitely if properly exploited. This paper will evaluate ethanol, which is the primary biofuel in many countries. The paper will highlight the process of obtaining ethanol from corn and discuss why ethanol is the best biofuel.
Obtaining Ethanol from Corn
Dry milling is the primary means of process corn into ethanol and 82% of the corn used for ethanol production is processed using this method. In this method, the corn is first passed through a mill where it is crushed into flour. This flour is mixed with water to form a mash and enzymes are added to help change the starch contained in the flour into the simple sugar dextrose (Moreau & Singh, 2011). To help maintain a favorable pH level, ammonia is added to the enzyme rich mash. The mash is heated to kill some of the bacteria in readiness for the fermentation process. After this, the mash is taken to a fermenter where yeast is added to facilitate fermentation. The fermentation process begins and the sugar in the mash is converted into ethanol and CO2. This process takes between 40 and 50 hours after which the product is ready for distillation (Moreau & Singh, 2011). The distillation process separates the ethanol from the sludge and further distillation is done to achieve the desired concentration. The ethanol is then dehydrated through a sieve system and after blending with a denaturant; the product is ready for use as a fuel (Moreau & Singh, 2011). Ethanol is generally blended into gasoline at the 10% level although it can be used in purer forms in vehicles that have been specially designed to accommodate the higher ethanol content.
Is Ethanol the Best Biofuel?
Ethanol is by far the most exploited biofuel in the world. As of the year 2011, ethanol had become a significant player in vehicular fuel contributing about 10% of the gasoline consumption in the US. While ethanol remains to be the most used biofuel in developed nations, it is not the best biofuel for a number of reasons. To begin with, a large proportion of the ethanol is produced in inefficient ways due to the source material (Adnadjevic, 2012). While ethanol can be produced from other sources including sugarcane and sorghum, ethanol production in the US relies almost exclusively on corn. Approximately 12.9 billion gallons of ethanol were produced in the US in 2011, and of this amount, 99% was obtained from corn. Ethanol production from corn suffers from low efficiency since the corn has to be fermented and distilled.
Ethanol suffers from some technical disadvantages compared to fossil-based fuels. Ethanol burns at a faster rate than gasoline meaning that a vehicle will consume more ethanol than gasoline. Compared to fossil-based gasoline, ethanol has a lower heating value making it difficult to start cars in cold weather when fuel with high ethanol content is used. In addition to this, ethanol is hygroscopic and more corrosive leading to engine maintenance issues (Adnadjevic, 2012). The negative impact of ethanol on vehicle engines has led to concerns related to vehicle warranties when higher percentage ethanol blends are used.
The energy efficiency of the corn-to-ethanol production process has also posed significant problems to the wide scale adoption of ethanol as an alternative to fossil-based fuels (Adnadjevic, 2012). The corn cultivation process is energy intensive. For large-scale cone production, high mechanization, which is achieved using fossil fuels, is utilized. In addition to this, farm inputs such as fertilizers require energy to produce. The energy used in the transportation efforts further reduces the energy efficiency of ethanol. Significant energy is used in the transportation of feedstock to the ethanol plant for processing. After ethanol processing is completed, energy is utilized to transport the finished product to the user. The significant transportation energy costs incurred by ethanol can be reduced by the implementation of dedicated pipelines to transport ethanol to distribution centers.
Alternative Biofuels
In addition to ethanol, there are a number of alternative biofuels that can be utilized. One of these is Biodiesel, which is the type of biofuel produced from a number of organic based oils including animal fats, vegetable oils, and waste restaurant grease and oils. Commercially, biodiesel is obtained primarily from soybean oil derived from the soy plant through the trans-sterification process. In the trans-sterification process, the oil is catalyzed using alcohol (Fortenbery & Deller, 2013). The oil product from this process is then catalyzed with methanol through the esterification process. The oil product is then converted into fatty acids and later Alkyl esters that can be used as fuel. This process is highly efficient with a conversion rate of 98%. The energy required to convert the raw oil into biodiesel is low since the process takes place at a low temperature and pressure. Fortenbery and Deller (2013) confirm that biodiesel production does not require exotic materials of construction making it possible for individuals to carry out this process locally. However, large-scale production of biodiesel makes use of specialized units in order to increase the efficiency of the fuel generation process.
Another biofuel is methane, which is produced from the microorganism decomposition of organic matter. Methane is produced through the anaerobic digestion of bio wastes in the absence of air. The resulting biogas consists of methane and carbon dioxide in proportions that may vary from 50%methane and 50% CO2 to 70%methane and 30%CO2 depending on the method employed (Hnain, Cockburn & Lefebvre, 2011). Methane gas can be produced and collected on a small-scale or large-scale. In small-scale methane production, farmers can use methane digester units to produce biogas from the farm animal waste. The gas produced has high methane content that can be used directly to produce heat or light or compressed to run engines. For methane to be considered as a potential alternative to fossil fuels, it needs to be produced on a large scale. Large-scale production of methane gas can be done through city sewage plants or landfills (Hnain, et al., 2011). These sites produce methane gas passively as the organic matter breaks down. The gas production can be accelerated by use of a digester and then captured for use as fuel. In addition to these methods, methane can be produced from the residues of other biofuel production systems. Methane can be produced from the byproducts of a corn-grain ethanol production plant. Once corn has been used to produce ethanol in the method described above, the residue product can be used as feedstock for a digester to produce methane. The methane gas produced from the various methods is then compressed to reduce its volume and then used as fuel for vehicles.
Reason for using the Alternatives
Methane
The overall gains from methane biofuel use in terms of energy production and pollution mitigation are great. Using methane would significantly lower greenhouse gas emissions made though the passive release of this gas from landfill sites. The waste system of modern society contains a considerable amount of organic material that decomposes at landfill sites releasing gases into the atmosphere. A large percentage of this gas is methane, which is a potent greenhouse gas. By capturing this gas and exploiting it as a biofuel, the gas would generate economic value while at the same time reducing greenhouse gas emissions (Hnain, et al., 2011).
Methane avoids the competition for food and arable land resources that characterize ethanol production. Hnain et al. (2011) asserts that using waste products as a feedstock for heterotrophic biofuel production is a manageable strategy in terms of providing a reliable feedstock supply that does not compete with food resources. In addition to this, the feedstock for methane production does not come from arable land or require water resources. Methane can therefore be produced without a negative impact on the food-crop production capacities of the country.
Biodiesel
Biodiesel can operate in any diesel engine with little or no modification and offers almost similar horsepower and torque. A significant advantage of biodiesel is that it can be used in its pure form without necessitating changes to the vehicle engine structure. As such, this fuel can be used to replace fossil-based fuels entirely without requiring vehicle manufacturers to make significant adjustments to the engines (Fortenbery & Deller, 2013). This is not the case with ethanol, which is primarily used as an additive to gasoline. For ethanol to be used in its pure form, specialized engines have to be used. Most of the vehicles currently in use do not have engines that can accommodate pure ethanol use. When used as a diesel additive, the engine benefits from the high lubricating properties of biodiesel as well as ability of biodiesel to clear the engine due to its solvent properties. For this reason, biodiesel use is supported by most motor-vehicle warranties since it does not lead to the adverse effects that using ethanol might cause.
A compelling rationale for adopting biodiesel is that it has a lower carbon footprint compared to fossil fuels. Biodiesel produces lower carbon emissions than fossil diesel since it has a higher hydrogen and oxygen content and lower carbon content (Galatola, 2008). Unlike ethanol, which requires significant energy resources in its production, biodiesel requires low energy to produce. Its carbon footprint is significantly lower than that of ethanol. This energy source therefore helps to mitigate the greenhouse gas emissions attributed to vehicular sources.
Challenges Associated with the Alternatives
While biodiesel and methane can be used as alternative biofuels to ethanol, the two have a number of significant challenges.
Biodiesel Challenges
Just like corn-produced ethanol, biodiesel also competes with food supply of vegetable oil. In addition to this competition, biodiesel reduces the food production when farmers switch from food-crops to oilseed crops. Biodiesel can be produced from waste vegetable oil and animal oil but commercially, these sources are unfeasible (Fortenbery & Deller, 2013). More reliable sources such as soybeans are therefore used for biodiesel leading to the competition with food crops since soy plantations take up arable land that could have been used for food crop production.
While biodiesel is a feasible alternative fuel, it has the major disadvantage of lower energy content compared to diesel. This makes biodiesel unfavorable for use in transportation means that that require a high engine output such as trucks and trains. Biofuel also has a higher viscosity and this poses a number of important challenges during operation. Research indicates that the viscosity of biodiesel at low temperatures might be unacceptable since it is associated with piston ring sticking and severe engine deposits (Fortenbery & Deller, 2013). The higher viscosity of biodiesel results in pumping difficulty when the vehicle is in operation. Fuel pumps may therefore have to be modified for use with biodiesel or if standard pumps are used, the efficiency of the vehicle is reduced. In addition to this, biodiesel will lead to significant engine degradation. Biodiesel is also blamed for increased vehicle maintenance cost. Use of biodiesel leads to higher copper strip corrosion and cold start problems thereby increasing risk of engine malfunction.
Methane Challenges
Methane presents significant technical problems since the supply system has to be significantly modified to enable methane storage and handling. Unlike ethanol, which can be sold at service stations using any existing pump, special pumps are needed for the delivery of methane to the end-user. Significant investments in infrastructure therefore have to be made before methane can be used widely as a fuel for vehicles (Adnadjevic, 2012). In addition to this, cars have to be adapted to dual fuelling and in cases where optimum use of methane is preferred, significant engine modification has to take place.
In spite of its perceived advantages, methanol is a toxic product and it can be lethal if ingested. Research indicates that methanol vapors are poisonous and up to five times as toxic as ethanol (Adnadjevic, 2012). This toxicity combined with the high solubility of methanol has led to concerns that fuel spills might lead to ground water pollution
Challenges in the Development of Biofuels
Biofuels have been presented as feasible alternatives to the fossil fuels that currently play a dominant role in energy production all over the world. However, the viability of this alternative is hampered by some significant challenges that will have to be addressed for biofuels to effectively replace petroleum-based products.
Technical Challenges
The first significant challenge for biofuels is that most sources require fossil fuels in their production. These fossil fuels are used for cultivation of plant matter for biofuel production, to provide heat for the biofuel processing and finally to transport the biofuels to the market. If biofuels are to completely replace fossil fuels, advances have to be made to remove fossil fuel use from all steps in the production and distribution of biofuels. Galatola (2008) observes that progress in biofuel use has been hampered by the lack of significant infrastructure. In spite of the significant advantage that using biofuels will bring, some sources such as methane cannot use the available petroleum infrastructure. Specialized fueling stations have to be made to accommodate this fuel and investing in new filling stations is a difficult task. For biodiesel and ethanol, dedicated pipelines need to be built to facilitate the efficient transportation of these fuels.
A technical problem facing ethanol is the means of transportation. Currently, ethanol is transported to various destinations using railway terminals. While this method is effective, it is not the most efficient (Adnadjevic, 2012). Pipelines would be the best way to move ethanol to various destinations. In the US, it has been impossible to use the extensive pipeline infrastructure used for petroleum products for ethanol would be contaminated by the hydrocarbon residues and water left behind by petroleum products. For pipelines to be used, the government would have to invest in a pipeline dedicated to ethanol transportation. Biodiesel also suffers from a lack of an efficient transportation system. Railroads are the primary means of transporting biodiesel since this fuel is mostly prohibited from the well-established petroleum product pipelines.
Ethical Challenges
Biofuels might have a negative impact on food production in a number of ways. To begin with, biofuel will decrease the amount of food available for human consumption if the biofuel is obtained from food sources such as corn, soy and sugarcane. This issue has already raised great concerns in the US where large-scale amounts of corn are being used to manufacture ethanol. As of the year 2011, ethanol plants were purchasing more corn than livestock producers who had until then been the main purchasers of corn. The second way through which biofuels will reduce food availability is by creating additional competition for land and water resources. Spiertz and Ewert (2009) reveal that biofuels are diverting land that could be used for food crops thereby decreasing the quantity of food produced by farmers. The potential conflict with food production is a major concern since food demand is expected to increase as the global population increases over the next decades.
Discussion and Conclusion
Making the shift from fossil fuels to biofuels is going to be a difficult task. Even so, this task is not impossible since innovations are already being made to improve the efficiency of current biofuel production methods. In addition to this, new engines are being made with biofuel use as a major consideration in engine design. For example, newer engine models are made to accommodate the use of higher levels of ethanol than the 10% limit for standard engines. Car manufacturers are already designing cars that can run on pure ethanol. However, most car engines are still incompatible with pure or high ethanol content.
The depletion of the global crude oil resources has propelled intensive research devoted to discovering alternative bio-sustainable energy sources. This paper set out to discuss biofuel as a feasible alternative to fossil fuels. It began by discussing ethanol production from corn. The paper then highlighted other biofuels that can be used in place of ethanol. These alternatives, which are biodiesel and methane, have significant merits and demerits. The paper then highlighted the overall challenges facing biofuels. From the information provided in this paper, it is clear that significant changes in the fuel delivery system and car engine designs need to be made for the switch to pure biofuel use to be made. In spite of the challenges faced by biofuels, there is significant support for the development of biofuels as a major alternative to fossil fuels. It can therefore be expected that biofuels will replace fossil fuels as the primary source of energy for the world in the future.
References
Adnadjevic, B. (2012). New Technologies in the Production of Motor Fuels from Renewable Materials. Thermal Science, 16(1), 87-95.
Baba, Y.T. & Watanabe, R. (2012). Anaerobic digestion of crude glycerol from biodiesel manufacturing using a large-scale pilot plant: methane production and application of digested sludge as fertilizer. Bioresour Technol, 140(1), 342-348.
Fortenbery, T.R., & Deller, S. (2013). The Location Decisions of Biodiesel Refineries. Land Economics, 89(1), 118-136.
Galatola, T.A. (2008). The potential of bio-methane as bio-fuel/bio-energy for reducing greenhouse gas emissions: a qualitative assessment for Europe in a life cycle perspective. Water Sci Technol, 57(11), 1683-92.
Hnain, A., Cockburn, L. & Lefebvre, L. (2011). Microbiological processes for waste conversion to bioenergy products: Approaches and directions. Environmental Reviews, 19(1), 214-237
Moreau, R., & Singh, J. (2011). Changes in Lipid Composition during Dry Grind Ethanol Processing of Corn. Journal of the American Oil Chemists’ Society, 88(3), 435-442.
Spiertz, J.H.J. and Ewert, F. 2009. Crop production and resource use to meet the growing demand for food, feed and fuel: opportunities and constraints. Netherlands Journal of Agricultural Science, 56 (1), 281-300.