A Study into the Feasability of Sustainible sources of Bio-Fuels

 

by

 

Seth T. Jenkins

 

 

Introduction

     A mark of the growth of any civilization is the increase of its energy needs and the specialization of transportation services to distribute products and resources to diffuse populations. While this may have been expressed in the increase of horses and sea craft for the Roman Empire, in the current world today our society utilizes fossil fuels for the transportation of goods, services, and general persons. The U.S., having only 5% of the world’s population, consumes 25% if the world’s petroleum, 43% of gasoline, and 23% of its natural gasses (1). These products are used for transportation, energy production, and heating of individual homes. This kind of specialization can be dangerous as all three of these energy sources, as they are currently being produced, are non-renewable and are purified from irreplaceable sources. Another growing source of energy and fuel production that is aggressively being researched and pursued is known as bio-fuel production. Bio-fuel is in essence "solid, liquid, or gaseous fuel that is derived from relatively recently dead biological material" (wikipedia) and differs only from conventional petroleum fuels in that the carbon atoms utilized are from more recently alive organisms and in some cases have fewer impurities when processed. What also makes bio-fuels appear increasingly attractive is that un-like many petroleum products they are bio-degradable and renewable (1). This is an important point, in that fears of increased carbon dioxide releases into the Earth's atmosphere will cause climate change and economic damage. Using carbon from recently living tissue recycles the carbon dioxide present in the atmosphere as opposed to releasing chemically fixed carbon in petroleum.

     Biodesiel is a biofuel produced from animal and plant fats utilizing trans-esterfication of fatty acids. This is accomplished by mixing the fats in set proportions with alcohols (methyl- or ethyl-) and a catalyst to speed the reaction. Traditionally alkali or acidic catalysts have been used but recent research has shown that metal and protein catalysts are also feasible (1). The primary concern for the production of biofuels is the source from where the oil is obtained. Many initial steps at producing biofuels such as ethanol from corn and other starch rich plants have met with skepticism in that there energy yield is significantly lower that conventional petroleum (4) and the cost of production and its possible economic side effects can likewise not be ignored (5). More recent studies have indicated that our wastes may be utilized to produce our own fuel sources (2). Research has shown that oil can be extracted from used coffee grounds, fruit rinds, vegetable products, and more importantly used vegetable oils (2). The key importance to extracting oils from these sources is that the market value has already been paid and in many cases money is spent to remove and process these wastes for simple destruction. Utilizing these sources for fuel would not only produce another source of revenue from the products, but remove the cost of process sing them as wastes (2). These "first generation" biofuels (wikipedia) are key in reducing the costs associated with the production of these fuels, and until economic forces rally with the production of these biofuels they will not likely become feasible.

     Another potential source of natural oils for bio-fuel production is algal biomass (1). Algae is a low-input high yield crop that can theoretically produce oils at a rate 30x higher that soybeans per acre (1). This is a rather generous estimate, however, but it does allude to the impracticality of growing soy and maize for the general purpose of fuel production. Algae for use in biofuels can be grown at standards much lower than those imposed on algae meant for human consumption, and possible sources of phosphates and nitrates for its growth may possible come from human feaces. Currently human waste is disposed of by processing and dumping into water sheds and rivers. The result of this is the eutrification of streams and lakes, such as Lake Erie. Many of the problems associated with the disposal of human waste could be alleviated and even profited from by utilizing these nutrient sources for the production of algal biofuels (1). The main goal of all the above mentioned processes is to produce fuel form renewable and safe forms of plant oils. I would go further and say that a possible goal would be to further reduce our waste products by taking what is now casually disposed of and producing not only a renewable source of fuel but a lessening of our environmental impact by further recycling of our wastes.

 

 

Bio-Fuel Production 

          Bio-fuels, like most other chemical fuel sources utilized by humans, center on the burning of carbon compounds for the release of energy. Unlike fuel derived from fossil sources of carbon (i.e. petroleum) Bio-fuels are processed from recently living plants that sequester carbon from atmospheric CO2 to form complex chemical bonds. Various sources of bio-fuels have been utilized for energy production and for use in transportation. Three of the most common sources of bio-fuels produced are Ethanol, Bio-gasses, and Bio-diesel (1,6). These compounds all are the result of the breakdown of carbon compounds produced by living organisms. They vary by the complexity of their carbon-chain length. For Bio-gasses (primarily Methane produced by bacterial breakdown of waste products) the resulting fuel is a single carbon molecule. Ethanol, produced from fermenting starches produced by primarily cereal crops, is formed with a two carbon chain and as a fuel source it can produce slightly more energy than the combustion of methane alone. Bio-diesel, produced from long chain fatty acids, varies in its carbon length but can be tailored to specific lengths depending on the oil used to produce the fuel. However, the resulting fuel varies from 16 to 22 carbon atoms and can release the most energy per volume of all three mentioned bio-fuels (3). (See Table 2)

             Energy production by each bio-fuel is important to consider for the possible sustainability of a fuel source. Although it is easier to produce methane from wastes most current public vehicles do not utilize methane as a fuel source, likely due to its low energy per volume. Recent trends in fuel production have created a new class of fuel called E-85, a mixture of 85% Ethanol and 15% associated hydrocarbons (10). This fuel recently gained popularity in some European countries and many hoped that it could reduce the carbon footprint of private vehicles that currently burned gasoline. However, comparison tests on E-85 fuel efficiency found that it preformed only 72% as efficient as gasoline(10) . This, combined with the energy required to produce ethanol from plant-based crops, makes the cost of using E-85 as a transportation fuel greater than that or modern petroleum based fuels. While used on a small scale ethanol fuels can help to reduce carbon impact but ultimately the market could not produce ethanol fuel on a level consummate with the current consumption of fuels in the United States. In order for a replacement or alternative to petroleum based fuels to be successful, it must be practical to produce the fuel at rates near or at current consumption.

             Bio-diesel is a fuel produce via trans-esterification of fatty acid oils.(See Fig. 1) These oils can come from a variety of sources and the purified fuel can run efficiently in most standard diesel engines (1,2,3). Conversion kits can be utilized to further improve the efficiency of the fuel and in general bio-diesel runs cleaner than conventional diesel fuel and better lubricates the engine prolonging engine life. The transition to bio-diesel as a primary fuel source would be much easier than using methane or pure ethanol to power engines for transportation. Their would be only the need to produce more diesel engines and not necessarily design and produce a new class of engine for using methane gas or ethanol. The energy contained in Bio-diesel is approximately equal to that of conventional petroleum based diesel which would also help the consumer accept a possible shift in the predominate fuel used in the market. The rest of this paper will focus on bio-diesel production and consider it as the likeliest source of renewable and sustainable energy.

 

Sources of Bio-fuels 

For the feasibility of bio-diesel as a replacement for petroleum based fuel it must be able to be produced in sufficient quantities for current market usage. The United States currently consumes 178 million tonnes of diesel fuel annually and the world consumption of diesel fuel is estimated to be approximately 934 tonnes per year(1). In order for the world market to accept a alternative fuel source their must be methods to not only produce reliable amounts of the fuel but have numerous sources so that the energy productions do not hinge on a single crop or production method. While all bio-diesel production centers on esterification of oils the sources of those oils can vary(2,3,6,9). Three potential sources of oil being researched and utilized by private industry are virgin oils produces from plants, used cooking oils/waste product oils, and oils produces by the industry scale growing of algae. These sources have a variety of benefits and costs but each can produce large amounts of bio-diesel for market use.

 

 

Virgin Oils

             Virgin oils are oils extracted directly from oil crops such soybeans, rapeseed and oil palm (1,2,3). These oils are not used for any other purpose than production of bio-diesel. This allows for easier production of the fuel as fewer impurities exist in virgin oil when compared to waste cooking oil (see below). The oil produced in this method is already employed by many industry bio-diesel producers to crease the bio-fuel but the primary setback is the cost. Pure oil extracted from modern oil crops is expensive and the land usage and energy to produce the crops is much higher than buying petroleum based fuels. The primary problem with this fuel, however, is the necessity of land for the production of the oil. Currently exploited farmland can not produce sufficiently quantities of virgin oil to supply the fuel needs of the Unites States (6). This makes using virgin oil an unlikely source of oil for bio-diesel production.

 

 

Used cooking oil

             Used cooking oils have been looked at as a potential source for bio-diesel production (2,3,9). Already many private citizens have taken to producing their own bio-diesel from waste oil and powering their own vehicles. Using waste cooking oil to produce bio-diesel has several advantages over using virgin oil. The cost of the oil in terms of growing the actual plant and extracting the oil is offset by the utilization of oil that is already paid for and used. In essence, the cooking oil was bought and its utility was expended. Most restaurants change their cooking oil every 3 or 4 weeks although the times can vary (1). When changing the oil in their fryers, restaurants often have to pay to dispose of the oil which adds yet another source of income to reduce the price of the waste cooking oil. In many cases private citizens can get their waste oil for free. While these features help to reduce the cost of the oil the cooking process can add a number of impurities. The high heat and addition of foods (i.e. potatoes, fish, and cornmeal batter) can create a number of hydrolytic and oxidative compounds (1). For economic reasons the oil is used several times and can be left heated 24 hours a day for several weeks. This addition of impurities can interfere with the esterification of the oil, a problem that using virgin oil lacks. However, optimization of the trans-esterification reaction can overcome these limitation and still result in yields of over 90%, although likelihood of adverse or unwanted products forming (i.e. soap) is increased (2,9).

             The major limitation to using used or waster cooking oil is the actual amount of cooking oil available. Estimations of the availability of cooking oil produced by the entire European Union only reach a maximum of 1 million tonnes per year (1). While a substantial amount of fuel can likely be produced from used cooking oil it is not available in quantities abundant enough to supply the demand. Even if 100% recovery of fuel were possible, the entire used oil production of the EU per year could not even approximate the demands of the fuel consumed in the US over a period of one month. Taking into account additional sources of oils from products such as used coffee grounds and orange peals the consumption of fuel is simply too great for this method to succeed. While these methods can produce significant amounts of renewable bio-diesel fuel, in order to be truly sustainable another source of oil must be utilized.

 

 

Algal Oil Production

             The major drawback of utilizing oil from modern oil crops (such as soybean, rapeseed, and oil palm) is the large amount of space required to grow the crops and the additional cost of fertilizers, pest control and irrigation. Utilizing algae to produce oil for use in the production of bio-diesel is likely the only truly sustainable method of production (6). While the oil content in the current oil crops can vary from 5% to 20% mass of dry weight some algae can be stimulated by intense light and limiting nutrients to produce oil in excess of 70% dry weight. (see table 2). Algal growth is also much faster than the traditional oil crops and algae can double approximately every 24 hours. The major limitations to algal growth are CO2, nutrient and light availability. These can be overcome by utilizing Photo bioreactors.

             Photo bioreactors are large assemblages of tubes or sheets of plastic that allow algae to be exposed to increased concentrations of light (12). The Photo bioreactors are also closed systems, which allow for the increase of CO2 concentrations to greater than atmospheric levels and the control over nutrients present in the system. This allows for a greater control over the algae which can increase oil yield. The Photo bioreactors can also help reclaim water and prevent water loss due to evaporation. With the control of the nutrients and high intensity light exposure estimations have been made that the entire fuel consumption of the U.S. could be met with oil produced from algae by using only 5% of currently exploited farmland. This seems relatively minor when considering the oil palm, which can yield 20% oil per dry weight, would require nearly 50% of currently exploited farmland to supply the same oil.(See table 1)

            Algal derived oil for use in the production of bio-fuels has several advantages when compared to conventional petroleum based fuels. The algal oil has all the advantages of the vegetable oils in that it is biodegradable, renewable and sequesters carbon dioxide from the atmosphere (6). As a bio-fuel it burns cleaner than conventional diesel and can help to lubricate the diesel engine more effectively than regular diesel. The greatest advantage to the algal oil production is its compact nature compared to the vegetable oil production. The algae can be grown in compact plots that produce large amounts of oil. This oil can be extracted on site and transferred into bio-fuel immediately. This is advantageous over conventional petroleum based fuels in that petroleum fuel must be transported to a refinery and treated by extremely high temperatures (11). This process, although efficient at producing several different types of fuel and associated oil products, is costly and can be dangerous. The necessary heat and fractionation of the refinery “cracking towers” also make them highly centralized. With algal oil their can be several different sites that produce oil and bio-fuel for dispersal to local gas stations. This is advantageous for it reduces the cost and hazard of transporting crude oil and gasoline to and from refineries, respectively. 

 

Table 1- From Christi, Yusef 2007

 

 

 

Table 2- Comparision of Oil % yield of various crops (from  Kulkarni and Dalai, 2006)

 

 

 

 

Figure 1- Transesterfication of fatty acid into glycerol and free hydrocarbon. 

 

Bio-Diesel Policy

             Numerous methods of Bio-diesel production have been researched and there exists a possibility for the sustainable production of renewable and carbon neutral fuel. However, this fuel source will not likely be realized unless the government intervention is applied (5,7,8). Currently petroleum fuels are among the most heavily subsidized products in the U.S. This makes the ability for Bio-Diesel to out compete petroleum fuel producer difficult, as the support of the U.S. government is clear. However, it is also possible that is actual cost of petroleum fuel production were internalized then bio-fuel production could become a cheaper and cleaner alternative. To reduce the economic impact of changing the source of such a largely utilized product and profitable industry it would be only prudent that the petroleum producing organizations take over the bio-fuel production industry(7). The petroleum fuel industry is ideal for the production and distribution of bio-fuel in that they already have money, influence, and the equipment necessary for the transportation and sale of fuel. In will however require government intervention to encourage the petroleum fuel producers to switch to bio-fuels as some dissenters (i.e. OPEC) are likely to resist change.

            With both the dependence of a large majority of economic activities (i.e. shipping, transport, private transportation for work) coupled with a very large consumption of fuel and the power and influence that petroleum fuel manufactures have over the market it is imperative that government steps in and encourages the shift from conventional fossil fuels to sustainable bio-fuels. In Europe, the governmental support for bio-fuel has been varied and at times hostile. Countries like France, Germany and Italy have produced significant amounts of bio-fuels in excess of their consumption while other countries such as the United Kingdom consume bio-fuels in excess of their production (7). American companies are currently exploring the possibilities of bio-fuel production and the U.S. government is recently increasing initiatives to support more renewable fuel sources.

The National Bio-Fuels Action Plan, published in 2008, outlines a multiple faceted investigation into the feasibility of ethanol based bio-fuels from cellulose feedstock plants, such as corn (8). While it is unlikely that such initiatives will truly be successful, based on the amount of ethanol required to replace petroleum fuels, more money is being spent in the investigation of bio-fuels as a potential replacement or supplement to petroleum fuels. While this might seem counter productive, any involvement by the government in the legislation over use of fuel is a benefit over none. In order to successfully institute the change of bio-fuel as the primary fuel source in the U.S. their must be governmental support in the form of subsidies and the creation of an end-user market. Without proper subsidization bio-fuel will never be able to out compete petroleum based fuels, as they are heavily subsidized all over the world (7). Also, a proper market of bio-diesel compatible vehicles must be established. Without this the bio-diesel market will be limited to commercial transportation and only individuals owning diesel vehicles will be able to utilize the non-petroleum based fuel. Governments must therefore both encourage the production of affordable diesel cars with the capability of utilizing Biodesiel and either remove the subsidies associated with petroleum fuel production or equally subsidize the production of bio-fuels (5).

 

 

Conclusions

            As the Nations of the World continue to exploit natural resources the ultimate demand on limited resources will grow. In instances where the consumption outweighs the replacement via natural means, those limited resources will become scarcer and eventually non-existent. Petroleum fuel, which is based on crude oil extracted from fossilized plant material, is not replenished quickly and current sources are rapidly depleting while the demand is rapidly increasing. Logically, the sources for the production of fossil fuels will eventually be gone while the demand for those fuels remains. The economic well being of all nations is closely tied to production of energy for heat, transportation, and power. Without a reliable and renewable fuel source our current standard of living and economy is doomed for failure.

            Renewable sources of fuel are available and the methods to convert the raw oils and associated compounds into bio-fuels are available. Production of Bio-diesel from oil extracted from algae is possible and the oil can be produced in quantities that are consummate with the current consumption of fuel in the United States. As the largest consumer of fuel in the world, if the U.S. can create a sustainable and renewable fuel market then the rest of the world can likewise supply themselves. This will take not only the support of the government in the form of subsidies for the production of the bio-fuel but also the producers of automobiles and the current Fuel producing corporations. While a substantial amount work remains to be done in order to fully creating a renewable fuel market the ability is clear and already private individuals and small companies are utilizing the technology to produce renewable bio-fuels. If the nations of the world can follow suite, then we will be able to produce fuel that will not release additional CO2 into the atmosphere but rather sequester CO2 and create a closed system that will supply the world with the energy it needs and not pollute the ecosystem in the process.

 

  

 

Citations:

 

1)Vasudevan, P., &  Briggs, M. (2008). Biodiesel production-current state of the art and challenges. JOURNAL OF INDUSTRIAL MICROBIOLOGY & BIOTECHNOLOGY, 35(5), 421-430.

 

2)Lang, X., Dalai, A., Bakhshi, N., Reaney, M.,  & Hertz, P. (2001). Preparation and characterization of bio-diesels from various bio-oils. BIORESOURCE TECHNOLOGY, 80(1), 53-62.

 

3)Lebedevas, S., Vaicekauskas, A., Lebedeva, G., Makareviciene, V., Janulis, P.,  & Kazancev, K. (2006). Use of waste fats of animal and vegetable origin for the production of biodiesel fuel: Quality, motor properties, and emissions of harmful components. ENERGY & FUELS, 20(5), 2274-2280.

4) http://zfacts.com/p/436.html

5) UN report on Bio-fuels http://esa.un.org/un-energy/pdf/susdev.Biofuels.FAO.pdf 

6)Chisti, Yusef, "Bio-diesel from Micro Algae" 2007

7) Thuijl, E. Van and Deurwaarder, E.P. "European Biofuel policies in Reterospect." 2006

8) National BioFuels Action Plan, September 2008

9) Mangesh G. Kulkarni, and Ajay K. Dalai, "Waste Cooking oil-An Economical source for Biodiesel: A review"

10) http://www.edmunds.com/advice/alternativefuels/articles/120863/article.html 

11)http://en.wikipedia.org/wiki/Refinery

12)http://www.youtube.com/watch?v=7Ih-DLurcZA