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The consideration of economics during the processing of biofuels
The consideration of economics during the processing of biofuels
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Siddharth Jain1 and Deepak Verma2 1 Department of Mechanical Engineering, College of Engineering Roorkee, Roorkee, India, 2 Department of Mechanical Engineering, Graphic Era Hill University, Dehradun, India
20.1
General
Continued use of petroleum-sourced fuels is now widely recognized as unsustainable because of depleting supplies and the contribution of these fuels to the accumulation of carbon dioxide in the environment. Renewable, carbon-neutral, transport fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable and carbon-neutral alternative to petroleum fuels. Unfortunately, biodiesel from oil crops, waste cooking oil, and animal fat cannot realistically satisfy even a small fraction of the existing demand for transport fuels. As demonstrated here, microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Like plants, microalgae use sunlight to produce oils but they do so more efficiently than crop plants. Oil productivity of many microalgae greatly exceeds the oil productivity of the best-producing oil crops. Approaches for making microalgal biodiesel economically competitive with petrodiesel are discussed in this chapter [1].
20.2
Introduction
The global energy sector consumes both renewable as well as nonrenewable energy resources for energy needs. The percentage consumption of each resource in the world indicates that currently oil, being the main energy resource for the transport sector, is the largest resource being consumed and accounts for about 34% of total energy consumption. Coal and natural gas are ranked second and third in terms of energy resources that are consumed after petroleum oil, and contribute about 25% and 21% of total energy consumption, respectively. Biomass and refuse consumption have been reported to be 11%, while nuclear energy consumption is 6.4%. The consumption of hydroelectricity and other renewable energy sources, except biomass, is about 2.6% of total energy consumption in the world market. However, in the near future this percentage consumption of each resource will vary because Biomass, Biopolymer-Based Materials, and Bioenergy. DOI: https://doi.org/10.1016/B978-0-08-102426-3.00020-5 © 2019 Elsevier Ltd. All rights reserved.
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of their exhaustible nature, limited supply, and environmental constraints. Hence, there is a need to give more emphasis on the use of renewable energy resources. The energy consumption pattern from 1990 2008 is projected to show an increase in energy consumption of the world market from all energy sources over the projection period of 2008 35. Fossil fuels are expected to continue supplying much of the energy used worldwide. Although liquid fuels (mostly petroleum-based) remain the largest source of energy, their share of world marketed energy consumption will fall from 34% in 2008 to 29% in 2035, as projected high world oil prices would lead many energy consumers to switch over to other type of fuels than liquid fuels when feasible options become possible. Renewable energy is the world’s fastest-growing form of energy and the renewable share of total energy use has increased from 10% in 2008 to 14% in 2035 [2]. World use of petroleum and other liquids will grow from 85.7 million barrels per day in 2008 to 97.6 million barrels per day in 2020, and 112.2 million barrels per day in 2035. The growth in liquid fuels use is in the transportation sector, where, in the absence of significant technological advances, liquid fuels continue to provide much of the energy demands. Liquid fuels remain an important energy source for transportation, industrial, and other sectors. Despite rising fuel prices, use of liquid fuels for transportation increases by an average of 1.4% per year or a 46% overall increase from 2008 to 2035. The transport sector accounts for 82% of the total increase in liquid fuel consumption from 2008 to 2035, with the remaining portion of the growth is attributable to the industrial sector. The use of liquid fuels declines in the other end-use sectors and for electric power generation. To meet the increasing world demand, liquid fuel production (including both conventional and unconventional supplies) has increased by a total of 26.6 million barrels per day from 2008 to 2035. Increasing volumes of conventional liquids (crude oil and lease condensate, natural gas plant liquids, and refinery gain) from OPEC countries contribute 10.3 million barrels per day to the total increase in world liquid production and conventional supplies from non-OPEC countries add another 7.1 million barrels per day. Unconventional resources (including oil sands, extra-heavy oil, biofuels, coal-to-liquids, gas-to-liquids, and shale oil) from both OPEC and non-OPEC sources grow by an average of 4.6% per year over the projection period. Sustained high oil prices allow unconventional resources to become economically competitive, particularly, when geopolitical or other―above ground—constraints limit access to prospective conventional resources. World production of unconventional liquid fuels, which totaled only 3.9 million barrels per day in 2008, increases to 13.1 million barrels per day and accounts for 12% of total world liquid fuels supply in 2035 [1,2]. The largest components of future unconventional production are 4.8 million barrels per day of Canadian oil sands, 2.2 and 1.7 million barrels per day of United States and Brazilian biofuels, respectively, and 1.4 million barrels per day of Venezuelan extra-heavy oil. These four contributors to unconventional liquid fuels supply account for almost three-quarters of the increase over the projection period. Energy use in the transportation sector includes the energy consumed in moving
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people and goods by road, rail, air, water, and pipeline. The transportation sector is second only to the industrial sector in terms of total end-use energy consumption. The transportation share of world total liquids consumption increases from 54% in 2008 to 60% in 2035, accounting for 82% of the total increase in world liquids consumption. Thus, understanding the development of transportation energy use is the most important factor in assessing future trends in demand for liquid fuels. World oil prices reached historically high levels in 2008, because of a strong increase in demand for transportation fuels, particularly in emerging non-OECD economies. Non-OECD energy use for transportation increased by 4.1% in 2007 and 6.4% in 2008, before the impact of the 2008 09 global economic recession resulted in a slowdown in transportation sector activity. Even in 2009, non-OECD transportation energy use grew by an estimated 3.3%, because many non-OECD countries (in particular, but not limited to the oil-rich nations) provide fuel subsidies to their citizens. With robust economic recovery expected to continue in China, India, and other non-OECD nations, growing demand for raw materials, manufactured goods, and business and personal travel is projected to support fast-paced growth in energy use for transportation both in the short and long term. High oil prices and the economic recession had more profound impacts in the OECD economies than in the non-OECD economies. OECD energy use for transportation declined by an estimated 1.6% in 2008, followed by a further decrease estimated at 1.8% in 2009, before recovering to 0.7% growth in 2010. Indications are that the return of high world oil prices and comparatively slow recovery from the recession in several key OECD nations will mean that transportation energy demand will continue to grow slowly in the near to mid-term. Moreover, the United States and some other OECD countries have instituted a number of policy measures to increase the fuel efficiency of their vehicle fleets. OECD transportation energy use grows by only 0.3% per year over the entire projection period. Energy is a critical factor in developing countries for economic growth as well as for social development and human welfare, and has a vital contribution in all developmental activity. The economic development of many countries is hindered due to a paucity of energy. Over two billion people in the world are still deprived of electrical energy. The conventional sources of energy are not enough to provide energy to the developing world, as energy usage has doubled owing to rising populations, expanding economies, energy-intensive industries, urbanization, a quest for modernization, and improved quality of life. At the same time, the world energy scenario depicts a grim picture. The adverse effects on the environment caused by the production and consumption of energy have also resulted in severe environmental impacts across the globe. The by-products of conventional energy sources, such as SO2, NOx, CO2, and other air pollutants cause acid rain and health problems to people. The greenhouse gases (GHG) have exacerbated global warming. According to data collected by Frances Moore of the Earth Policy Institute, emissions of GHG grew 3.1% from 2000 to 2006. The five largest emitters of energy-related CO2 are China, the United States, the European Union, India, and Russia, and together they account for almost two thirds of global CO2 emissions. Without clean energy solutions to reduce the world’s carbon footprint, CO2 emissions could double between
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2000 and 2030. At this rate, it would be impossible to avoid an increase in temperature of 3 C above the preindustrial era. A less than 2 C increase in temperature would cause dangerous climate change [1]. World energy-related CO2 emissions have increased from 30.2 billion metric tons in 2008 to 35.2 billion metric tons in 2020 and 43.2 billion metric tons in 2035—an increase of 43% over the projection period. With strong economic growth and continued heavy reliance on fossil fuels expected for most non-OECD economies under current policies, much of the projected increase in CO2 emissions occurs among the developing non-OECD nations. In 2008, non-OECD emissions exceeded OECD emissions by 24%, while they are projected to exceed OECD emissions by more than 100% by 2035. Furthermore, with respect to total GHG emissions in absolute terms, a study estimates that India’s emissions in 2031 will be between 4.0 billion metric tons of CO2-eq to 7.3 billion metric tons of CO2-eq [1]. Apart from these environmental and social problems, conventional energy sources are not sustainable and nonrenewable in nature. These limited reserves are likely to be exhausted in the near future. The fluctuating prices of petroleum products are also a matter of real concern. Therefore, alternative energy sources will be the need of the hour. Renewable energy sources are the least costly and most feasible solution, as they are unlimited, inexhaustible, environmentally friendly, and sustainable energy resources. The limited supply, exhaustible nature, and environmental concerns with fossil fuel resources, have resulted in the search for ecofriendly and inexhaustible renewable energy sources all around the world due to their various benefits. One of the major feedstocks for biodiesel is soy oil or any other vegetable oil. Animal fats can also be used, but as pointed out that animal fats can produce more by-products that cause issues (i.e., free fatty acids which can cause soap formation). Jatropha is another oil used for biodiesel production. Second-generation biodiesel can be produced from algae, and the use of algae for biodiesel production is a growing market. Fig. 20.1 shows a breakdown of the various feedstocks used to make biodiesel from June 2010, and predicts the growth of biodiesel production in the near future. Feedstock is the primary cost involved in producing biofuel. Figs. 20.2 and 20.3 show the challenges of the economics behind biodiesel production. Fig. 20.2 shows the breakeven price of biodiesel plotted with the actual biodiesel price. Most years, the biodiesel price and breakeven price were the same. But, in 2011 and 2013, the biodiesel sold at a higher price than the breakeven price, a good indicator for demand. In Fig. 20.3, we can see that, in most years, the ULSD price was lower than biodiesel, by B$1 per gallon, but in late 2013 and 2014, the price was almost the same and the margin between the two was much narrower. Again, this suggests a greater demand for biodiesel as well as the costs becoming closer to the processing of petrodiesel [1 5]. Most of the information we are looking at is based on soy oil production. Biodiesel can be produced in ways other than transesterification and can be produced from other sources, such as algae. The reason for producing biodiesel using other methods would be to reduce the oxygenate from the biodiesel, mainly so that the biodiesel can be used as jet fuel, as jet fuel cannot have oxygenates in it.
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45
billion liters 40 35 Biomass-based (2nd generation)
30
Jatropha
25
Non agric, (animal fats)
20
Vegetable oil
15 10 5 0
2007-09 2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Figure 20.1 Global biodiesel production by feedstock.
6.00 5.50
Biodiesel price
Price ($/gal.)
5.00 4.50 4.00
Breakeven price = 7.55S0 + 0.60
3.50 3.00 2.50 2.00 2007
2008
2009
2010
2011
2012
2013
2014
Source: AMS (biodiesel price)
Figure 20.2 Weekly biodiesel price and breakeven price at an Iowa plant, 2007 14.
The reason behind using algae is because of the advantages of (1) using land areas that would not be able to grow terrestrial plants, (2) the ability of algae to produce much greater amounts of oil per land mass than plants like soy, and (3) algae plants take in much greater amounts of CO2 and could be located near a power plant to utilize emissions from the flue gases. However, as you will see from data in Table 20.1, costs of oil from algae are still fairly high. One of the useful aspects of
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Biomass, Biopolymer-Based Materials, and Bioenergy
7.00 Biodiesel price
Price ($/gal.)
6.00 5.00 4.00 3.00 2.00
ULSD
1.00 0.00
2007
2008
2009
2010
2011
2012
2013
2014
Date Source:OPIS
Figure 20.3 Weekly ultra-sulfur diesel (ULSD) and biodiesel price at Chicago, 2007 14. Table 20.1 Comparison of photobioreactor and raceway production methods Variable
Photobioreactor facility
Raceway pond
Annual biomass production (kg) Volumetric productivity (kg/m3/d) Areal productivity (kg/m2/d) Biomass concentration in broth (kg/m3) Dilution rate (d21) Area needed (m2) Oil yield (m3/ha) Annual CO2 consumption (kg) System geometry
100,000
100,000
1535
0.117
0.048 4.00
0.035 0.14
0.384 5681 136.9 183,333
0.250 7828 99.4 183,333
132 parallel tubes/unit; 80 m long tubes; 0.06 m tube diameter 6
978 m2/pond; 12 m wide, 82 m long, 0.30 m deep 8
Number of units
Source: Chisti, Y., Biotechnology Advances, 2007.
growing algae is it can be grown in water sources that can contain salt or some sediment—even though water usage may be high, some of the water may be separated out and used again. The following data are from an overview review article on producing biodiesel from algae, from 2007. In Table 20.1, Chisti compared production of biodiesel from PBR and an open raceway pond, to show differences in production [5].
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As can be seen, the PBR can produce more oil for a number of reasons, but costs associated with the PBR are higher. It is estimated that the cost to produce algae oil on a scale of 10,000 tons is $0.95 per pound. This particular article estimated that the cost of producing biodiesel from algae would range from $10.60 to $11.13 per gallon. The processing costs for palm oil would be B$0.53 per gallon, and the processing costs for soybean oil would be $3.48 per gallon. A slightly more recent report, a project to estimate the price of biodiesel, indicates prices from $10.66 per gallon to as high as $19.16 depending on location and oil production. Yet another computer-simulated estimate provided by some studies [6,7] shows a cost to produce algal oil at $0.25 1.61 per pound, not too far from the costs to produce soybean oil ($0.35 0.38 per pound). They also estimated the cost of biodiesel from algae oil to be $2.35 per gallon, less than a gallon of ULSD. However, they may not have included algae harvesting costs in this estimate. Therefore, you can see that biodiesel from microalgae is a long way from being a reality, yet it probably has a future if the costs can be brought down due to the benefits [6]. Therefore, how does biodiesel compare to ethanol as a fuel? Ethanol from corn has become big business in the United States. It is known that ethanol from corn has a NEB ratio greater than 1 and this is improving, and that production of ethanol from corn is the least expensive in the United States. The amount of ethanol produced in 2014 was 13 billion gallons per year and it is a $30 billion a year industry. It makes up 10% of the gasoline pool, although the US government has mandated that the gasoline pool can utilize up to 10% ethanol, and companies get tax credits for using ethanol. Because of the high price of gasoline due to oil prices, demand for gasoline fell, and this has made it more difficult for ethanol producers to continue selling ethanol at the level that they had over the last several years. Recently, the EPA examined whether to raise the ethanol limit to 15%, but because of the drop in oil prices, the EPA has been reconsidering this and has not set levels for 2015. According to the most recent statistics, there are 145 biodiesel facilities in the United States that provide more than 2.60 billion gallons of biodiesel per year (in 2010, the production of biodiesel was less than 0.4 billion gallons per year, which is an order of magnitude increase). Biodiesel makes up about 5% 6% of the diesel fuel pool. Biodiesel plants tend to be smaller and more evenly distributed across the United States than ethanol.
20.3
Biomass energy
Biomass, a product of photosynthesis, includes all new plant growth, residues and wastes such as rotation trees, herbaceous plants, fresh water and marine algae, aquatic plants, agricultural and forest residues, kitchen and city garbage, night soil, sewage, etc. Furthermore, biodegradable organic effluents from canneries, sugar mills, slaughterhouses, meat packing factories, breweries, distillers, etc., are also
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categorized as biomass resources. To meet the growing demand for energy, it is necessary to focus on efficient production and use of biomass resources to meet both traditional and high energy demand. The biomass production for fuel, food, fiber, and fodder, requires sustainable land use and integrated planning approaches at all levels in the country. The proper selection of a site and tree plant species suitable to different agroclimatic conditions can open new avenues for integrated land-use planning and land management for the production of maximum biomass in minimum time at low cost. Such strategies allow a synergistic increase in food crop yield and decreased fertilizer applications, while providing a local source of energy and employment. The estimated potential of various biomass resources are: biomass energy 16,900 MW, cogeneration 5000 MW, and energy from waste (MSW, etc.) 2700 MW. Utilization of biomass for power generation is handicapped due to its production being labor-intensive, scattered availability, seasonal availability, localized price sensitivity, lack of automatic feed control, tedious handling, high moisture, low energy, and low bulk density (30 180 kg/m3) with substantial transportation costs. A wide variety of conversion technologies can be used to produce energy from biomass. Some are simple and some are well developed, while others are at different stages of development. The choice of a particular process is determined by a number of factors such as location of resources, its physical condition, the economics of compacting processes, and the availability of a sustainable market for the product [6,8].
20.3.1 Biofuel Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels, and various biogases. Although fossil fuels have their origin in ancient carbon fixation, they are not considered biofuels by the generally accepted definition because they contain carbon that has been “out” of the carbon cycle for a very long time. Biofuels are gaining increased public and scientific attention, driven by factors such as oil price spikes, the need for increased energy security, concern over GHG emissions from fossil fuels, and support from government subsidies.
20.3.1.1 Liquid fuels The two main types of liquid biofuel are biodiesel and bioethanol. Biodiesel can be blended with diesel, and bioethanol is primarily blended with petrol. Currently the majority of vehicle engines are designed to run on blends of at least 5% 10% biofuel.
Ethanol Ethanol, also called ethyl alcohol, alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a solvent, and as a fuel. In common usage, it is
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often referred to simply as alcohol or spirits. Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline. Bioethanol is a form of renewable energy that can be produced from agricultural feedstocks. It can be made from common crops such as sugar cane, bagasse, miscanthus, sugar beet, sorghum, grain, switch grass, barley, hemp, kenaf, potatoes, cassava, fruit, molasses, corn, stover, grain, wheat, sweet potatoes, straw, cotton, other biomass, as well as many types of cellulose waste and harvestings, whichever has the best well-to-wheel assessment. There has been considerable debate about how useful bioethanol will be in replacing gasoline. Concerns about its production and use relate to increased food prices due to the large amount of arable land required for crops, as well as the energy and pollution balance of the whole cycle of ethanol production, especially from corn. Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns. Cellulosic ethanol offers promise because cellulose fibers, a major and universal component in plant cell walls, can be used to produce ethanol. According to the International Energy Agency (IEA), cellulosic ethanol could allow ethanol fuels to play a much bigger role in the future than previously thought. The basic steps for large-scale production of ethanol are: microbial (yeast) fermentation of sugar, distillation, dehydration, and denaturing (optional). Prior to fermentation, some crops require saccharification or hydrolysis of carbohydrates, such as cellulose and starch into sugars. Saccharification of cellulose is called cellulitis. Enzymes are used to convert starch into sugar.
Biodiesel Biodiesel refers to a vegetable oil or animal fat-based diesel fuel consisting of longchain alkyl (methyl, propyl, or ethyl) esters. Biodiesel is typically made by chemically reacting lipids [e.g., vegetable oil, animal fat (tallow)] with an alcohol. Biodiesel is made from vegetable oils and animal fats. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates (PM), carbon monoxide (CO), and hydrocarbons (HC) emitted by diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe. Energy and the environment are both vital for sustainable development. New initiatives for reduction of GHGs are being taken all over the world. The utilization of biodiesel can help in directly substituting fossil fuel consumption, leading to a reduced reliance on crude oil imports and improvements in the environment. For the last 5 years, the use of blends of biodiesel with diesel, to the extent of 5% 10% in the European Union (EU) and the United States, has been rising with policy supports. The world use of vegetable oils for biodiesel production has been estimated at about 3 MT or just less than 3% of global vegetable oil production. Major users are the EU (mainly rapeseed oil) and the United States (mainly soybean oil). The usage of vegetable oil for biodiesel has been rising in EU at about 30% annually over the last 5 years. The demand for diesel fuel for the transport sector in
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Biomass, Biopolymer-Based Materials, and Bioenergy
India is growing at a high annual growth rate of 2.1% on one hand, and increasing import and exhaustion of limited indigenous production has led to increased attention on biodiesel on the other hand. Biodiesel is receiving great attention worldwide as an alternative fuel for diesel engines as it has shown almost the same engine performance with reduced emissions compared to diesel fuel.
20.4
Improving the economics of microalgae biodiesel [6,8]
The cost of producing microalgae biodiesel can be reduced substantially by using a biorefinery-based production strategy, improving capabilities of microalgae through genetic engineering, and advances in engineering of photobioreactors: G
G
G
Biorefinery-based production strategy; Photobioreactor engineering; Enhancing algal biology.
Molecular level engineering can be used to potentially: Increase photosynthetic efficiency to enable increased biomass yield in light; Enhance biomass growth rate; Increase oil content in biomass; Improve temperature tolerance to reduce the expense of cooling; Eliminate the light saturation phenomenon so that growth continues to increase in response to increasing light level; 6. Reduce photoinhibition that actually reduces the growth rate at midday light intensities that occur in temperate and tropical zones; 7. Reduce susceptibility to photo-oxidation, which damages cells. 1. 2. 3. 4. 5.
20.5
Conclusion
As demonstrated here, microalgal biodiesel is technically feasible. It is the only renewable biodiesel that can potentially completely displace liquid fuels derived from petroleum. The economics of producing microalgal biodiesel need to improve substantially to make it competitive with petrodiesel, but the level of improvement necessary appears to be attainable. Producing low-cost microalgal biodiesel requires primarily improvements to algal biology through genetic and metabolic engineering. Use of the biorefinery concept and advances in photobioreactor engineering will further lower the cost of production. In view of their much greater productivity than raceways, tubular photobioreactors are likely to be used in producing much of the microalgal biomass required for making biodiesel. Photobioreactors provide a controlled environment that can be tailored to the specific demands of highly productive microalgae to attain a consistently good annual yield of oil.
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References [1] Acie´n Ferna´ndez FG, Garcı´a Camacho F, Sa´nchez Pe´rez JA, Ferna´ndez Sevilla JM, Molina Grima E. A model for light distribution and average solar irradiance inside outdoor tubular photobioreactors for the microalgal mass culture. Biotechnol Bioeng 1997;55:701 14. [2] Acie´n Ferna´ndez FG, Garcı´a Camacho F, Sa´nchez Pe´rez JA, Ferna´ndez Sevilla J, Molina Grima E. Modelling of biomass productivity in tubular photobioreactors for microalgal cultures. Effects of dilution rate, tube diameter and solar irradiance. Biotechnol Bioeng 1998;58:605 11. [3] Acie´n Ferna´ndez FG, Ferna´ndez Sevilla JM, Sa´nchez Pe´rez JA, Molina Grima E, Chisti Y. Airlift-driven external-loop tubular photobioreactors for outdoor production of microalgae: assessment of design and performance. Chem Eng Sci 2001;56:2721 32. [4] Chisti Y, Moo-Young M. Improve the performance of airlift reactors. Chem Eng Prog 1993;89(6):38 45. [5] Chisti Y, Moo-Young M. Clean-in-place systems for industrial bioreactors: design, validation and operation. J Ind Microbiol 1994;13:201 7. [6] Chisti Y, Moo-Young M. Bioprocess intensification through bioreactor engineering. Trans I Chem E 1996;74A:575 83. [7] Richardson JW, Johnson MD, Zhang X, Zemke P, Chen W, Hu Q. A financial assessment of two alternative cultivation systems and their contributions to algae biofuel economic viability. Algal Res 2014;4:96 104. [8] Chisti Y, Halard B, Moo-Young M. Liquid circulation in airlift reactors. Chem Eng Sci 1988;43:451 7.
20
Siddharth Jain1 and Deepak Verma2 1 Department of Mechanical Engineering, College of Engineering Roorkee, Roorkee, India, 2 Department of Mechanical Engineering, Graphic Era Hill University, Dehradun, India
20.1
General
Continued use of petroleum-sourced fuels is now widely recognized as unsustainable because of depleting supplies and the contribution of these fuels to the accumulation of carbon dioxide in the environment. Renewable, carbon-neutral, transport fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable and carbon-neutral alternative to petroleum fuels. Unfortunately, biodiesel from oil crops, waste cooking oil, and animal fat cannot realistically satisfy even a small fraction of the existing demand for transport fuels. As demonstrated here, microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Like plants, microalgae use sunlight to produce oils but they do so more efficiently than crop plants. Oil productivity of many microalgae greatly exceeds the oil productivity of the best-producing oil crops. Approaches for making microalgal biodiesel economically competitive with petrodiesel are discussed in this chapter [1].
20.2
Introduction
The global energy sector consumes both renewable as well as nonrenewable energy resources for energy needs. The percentage consumption of each resource in the world indicates that currently oil, being the main energy resource for the transport sector, is the largest resource being consumed and accounts for about 34% of total energy consumption. Coal and natural gas are ranked second and third in terms of energy resources that are consumed after petroleum oil, and contribute about 25% and 21% of total energy consumption, respectively. Biomass and refuse consumption have been reported to be 11%, while nuclear energy consumption is 6.4%. The consumption of hydroelectricity and other renewable energy sources, except biomass, is about 2.6% of total energy consumption in the world market. However, in the near future this percentage consumption of each resource will vary because Biomass, Biopolymer-Based Materials, and Bioenergy. DOI: https://doi.org/10.1016/B978-0-08-102426-3.00020-5 © 2019 Elsevier Ltd. All rights reserved.
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of their exhaustible nature, limited supply, and environmental constraints. Hence, there is a need to give more emphasis on the use of renewable energy resources. The energy consumption pattern from 1990 2008 is projected to show an increase in energy consumption of the world market from all energy sources over the projection period of 2008 35. Fossil fuels are expected to continue supplying much of the energy used worldwide. Although liquid fuels (mostly petroleum-based) remain the largest source of energy, their share of world marketed energy consumption will fall from 34% in 2008 to 29% in 2035, as projected high world oil prices would lead many energy consumers to switch over to other type of fuels than liquid fuels when feasible options become possible. Renewable energy is the world’s fastest-growing form of energy and the renewable share of total energy use has increased from 10% in 2008 to 14% in 2035 [2]. World use of petroleum and other liquids will grow from 85.7 million barrels per day in 2008 to 97.6 million barrels per day in 2020, and 112.2 million barrels per day in 2035. The growth in liquid fuels use is in the transportation sector, where, in the absence of significant technological advances, liquid fuels continue to provide much of the energy demands. Liquid fuels remain an important energy source for transportation, industrial, and other sectors. Despite rising fuel prices, use of liquid fuels for transportation increases by an average of 1.4% per year or a 46% overall increase from 2008 to 2035. The transport sector accounts for 82% of the total increase in liquid fuel consumption from 2008 to 2035, with the remaining portion of the growth is attributable to the industrial sector. The use of liquid fuels declines in the other end-use sectors and for electric power generation. To meet the increasing world demand, liquid fuel production (including both conventional and unconventional supplies) has increased by a total of 26.6 million barrels per day from 2008 to 2035. Increasing volumes of conventional liquids (crude oil and lease condensate, natural gas plant liquids, and refinery gain) from OPEC countries contribute 10.3 million barrels per day to the total increase in world liquid production and conventional supplies from non-OPEC countries add another 7.1 million barrels per day. Unconventional resources (including oil sands, extra-heavy oil, biofuels, coal-to-liquids, gas-to-liquids, and shale oil) from both OPEC and non-OPEC sources grow by an average of 4.6% per year over the projection period. Sustained high oil prices allow unconventional resources to become economically competitive, particularly, when geopolitical or other―above ground—constraints limit access to prospective conventional resources. World production of unconventional liquid fuels, which totaled only 3.9 million barrels per day in 2008, increases to 13.1 million barrels per day and accounts for 12% of total world liquid fuels supply in 2035 [1,2]. The largest components of future unconventional production are 4.8 million barrels per day of Canadian oil sands, 2.2 and 1.7 million barrels per day of United States and Brazilian biofuels, respectively, and 1.4 million barrels per day of Venezuelan extra-heavy oil. These four contributors to unconventional liquid fuels supply account for almost three-quarters of the increase over the projection period. Energy use in the transportation sector includes the energy consumed in moving
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people and goods by road, rail, air, water, and pipeline. The transportation sector is second only to the industrial sector in terms of total end-use energy consumption. The transportation share of world total liquids consumption increases from 54% in 2008 to 60% in 2035, accounting for 82% of the total increase in world liquids consumption. Thus, understanding the development of transportation energy use is the most important factor in assessing future trends in demand for liquid fuels. World oil prices reached historically high levels in 2008, because of a strong increase in demand for transportation fuels, particularly in emerging non-OECD economies. Non-OECD energy use for transportation increased by 4.1% in 2007 and 6.4% in 2008, before the impact of the 2008 09 global economic recession resulted in a slowdown in transportation sector activity. Even in 2009, non-OECD transportation energy use grew by an estimated 3.3%, because many non-OECD countries (in particular, but not limited to the oil-rich nations) provide fuel subsidies to their citizens. With robust economic recovery expected to continue in China, India, and other non-OECD nations, growing demand for raw materials, manufactured goods, and business and personal travel is projected to support fast-paced growth in energy use for transportation both in the short and long term. High oil prices and the economic recession had more profound impacts in the OECD economies than in the non-OECD economies. OECD energy use for transportation declined by an estimated 1.6% in 2008, followed by a further decrease estimated at 1.8% in 2009, before recovering to 0.7% growth in 2010. Indications are that the return of high world oil prices and comparatively slow recovery from the recession in several key OECD nations will mean that transportation energy demand will continue to grow slowly in the near to mid-term. Moreover, the United States and some other OECD countries have instituted a number of policy measures to increase the fuel efficiency of their vehicle fleets. OECD transportation energy use grows by only 0.3% per year over the entire projection period. Energy is a critical factor in developing countries for economic growth as well as for social development and human welfare, and has a vital contribution in all developmental activity. The economic development of many countries is hindered due to a paucity of energy. Over two billion people in the world are still deprived of electrical energy. The conventional sources of energy are not enough to provide energy to the developing world, as energy usage has doubled owing to rising populations, expanding economies, energy-intensive industries, urbanization, a quest for modernization, and improved quality of life. At the same time, the world energy scenario depicts a grim picture. The adverse effects on the environment caused by the production and consumption of energy have also resulted in severe environmental impacts across the globe. The by-products of conventional energy sources, such as SO2, NOx, CO2, and other air pollutants cause acid rain and health problems to people. The greenhouse gases (GHG) have exacerbated global warming. According to data collected by Frances Moore of the Earth Policy Institute, emissions of GHG grew 3.1% from 2000 to 2006. The five largest emitters of energy-related CO2 are China, the United States, the European Union, India, and Russia, and together they account for almost two thirds of global CO2 emissions. Without clean energy solutions to reduce the world’s carbon footprint, CO2 emissions could double between
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2000 and 2030. At this rate, it would be impossible to avoid an increase in temperature of 3 C above the preindustrial era. A less than 2 C increase in temperature would cause dangerous climate change [1]. World energy-related CO2 emissions have increased from 30.2 billion metric tons in 2008 to 35.2 billion metric tons in 2020 and 43.2 billion metric tons in 2035—an increase of 43% over the projection period. With strong economic growth and continued heavy reliance on fossil fuels expected for most non-OECD economies under current policies, much of the projected increase in CO2 emissions occurs among the developing non-OECD nations. In 2008, non-OECD emissions exceeded OECD emissions by 24%, while they are projected to exceed OECD emissions by more than 100% by 2035. Furthermore, with respect to total GHG emissions in absolute terms, a study estimates that India’s emissions in 2031 will be between 4.0 billion metric tons of CO2-eq to 7.3 billion metric tons of CO2-eq [1]. Apart from these environmental and social problems, conventional energy sources are not sustainable and nonrenewable in nature. These limited reserves are likely to be exhausted in the near future. The fluctuating prices of petroleum products are also a matter of real concern. Therefore, alternative energy sources will be the need of the hour. Renewable energy sources are the least costly and most feasible solution, as they are unlimited, inexhaustible, environmentally friendly, and sustainable energy resources. The limited supply, exhaustible nature, and environmental concerns with fossil fuel resources, have resulted in the search for ecofriendly and inexhaustible renewable energy sources all around the world due to their various benefits. One of the major feedstocks for biodiesel is soy oil or any other vegetable oil. Animal fats can also be used, but as pointed out that animal fats can produce more by-products that cause issues (i.e., free fatty acids which can cause soap formation). Jatropha is another oil used for biodiesel production. Second-generation biodiesel can be produced from algae, and the use of algae for biodiesel production is a growing market. Fig. 20.1 shows a breakdown of the various feedstocks used to make biodiesel from June 2010, and predicts the growth of biodiesel production in the near future. Feedstock is the primary cost involved in producing biofuel. Figs. 20.2 and 20.3 show the challenges of the economics behind biodiesel production. Fig. 20.2 shows the breakeven price of biodiesel plotted with the actual biodiesel price. Most years, the biodiesel price and breakeven price were the same. But, in 2011 and 2013, the biodiesel sold at a higher price than the breakeven price, a good indicator for demand. In Fig. 20.3, we can see that, in most years, the ULSD price was lower than biodiesel, by B$1 per gallon, but in late 2013 and 2014, the price was almost the same and the margin between the two was much narrower. Again, this suggests a greater demand for biodiesel as well as the costs becoming closer to the processing of petrodiesel [1 5]. Most of the information we are looking at is based on soy oil production. Biodiesel can be produced in ways other than transesterification and can be produced from other sources, such as algae. The reason for producing biodiesel using other methods would be to reduce the oxygenate from the biodiesel, mainly so that the biodiesel can be used as jet fuel, as jet fuel cannot have oxygenates in it.
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45
billion liters 40 35 Biomass-based (2nd generation)
30
Jatropha
25
Non agric, (animal fats)
20
Vegetable oil
15 10 5 0
2007-09 2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Figure 20.1 Global biodiesel production by feedstock.
6.00 5.50
Biodiesel price
Price ($/gal.)
5.00 4.50 4.00
Breakeven price = 7.55S0 + 0.60
3.50 3.00 2.50 2.00 2007
2008
2009
2010
2011
2012
2013
2014
Source: AMS (biodiesel price)
Figure 20.2 Weekly biodiesel price and breakeven price at an Iowa plant, 2007 14.
The reason behind using algae is because of the advantages of (1) using land areas that would not be able to grow terrestrial plants, (2) the ability of algae to produce much greater amounts of oil per land mass than plants like soy, and (3) algae plants take in much greater amounts of CO2 and could be located near a power plant to utilize emissions from the flue gases. However, as you will see from data in Table 20.1, costs of oil from algae are still fairly high. One of the useful aspects of
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7.00 Biodiesel price
Price ($/gal.)
6.00 5.00 4.00 3.00 2.00
ULSD
1.00 0.00
2007
2008
2009
2010
2011
2012
2013
2014
Date Source:OPIS
Figure 20.3 Weekly ultra-sulfur diesel (ULSD) and biodiesel price at Chicago, 2007 14. Table 20.1 Comparison of photobioreactor and raceway production methods Variable
Photobioreactor facility
Raceway pond
Annual biomass production (kg) Volumetric productivity (kg/m3/d) Areal productivity (kg/m2/d) Biomass concentration in broth (kg/m3) Dilution rate (d21) Area needed (m2) Oil yield (m3/ha) Annual CO2 consumption (kg) System geometry
100,000
100,000
1535
0.117
0.048 4.00
0.035 0.14
0.384 5681 136.9 183,333
0.250 7828 99.4 183,333
132 parallel tubes/unit; 80 m long tubes; 0.06 m tube diameter 6
978 m2/pond; 12 m wide, 82 m long, 0.30 m deep 8
Number of units
Source: Chisti, Y., Biotechnology Advances, 2007.
growing algae is it can be grown in water sources that can contain salt or some sediment—even though water usage may be high, some of the water may be separated out and used again. The following data are from an overview review article on producing biodiesel from algae, from 2007. In Table 20.1, Chisti compared production of biodiesel from PBR and an open raceway pond, to show differences in production [5].
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As can be seen, the PBR can produce more oil for a number of reasons, but costs associated with the PBR are higher. It is estimated that the cost to produce algae oil on a scale of 10,000 tons is $0.95 per pound. This particular article estimated that the cost of producing biodiesel from algae would range from $10.60 to $11.13 per gallon. The processing costs for palm oil would be B$0.53 per gallon, and the processing costs for soybean oil would be $3.48 per gallon. A slightly more recent report, a project to estimate the price of biodiesel, indicates prices from $10.66 per gallon to as high as $19.16 depending on location and oil production. Yet another computer-simulated estimate provided by some studies [6,7] shows a cost to produce algal oil at $0.25 1.61 per pound, not too far from the costs to produce soybean oil ($0.35 0.38 per pound). They also estimated the cost of biodiesel from algae oil to be $2.35 per gallon, less than a gallon of ULSD. However, they may not have included algae harvesting costs in this estimate. Therefore, you can see that biodiesel from microalgae is a long way from being a reality, yet it probably has a future if the costs can be brought down due to the benefits [6]. Therefore, how does biodiesel compare to ethanol as a fuel? Ethanol from corn has become big business in the United States. It is known that ethanol from corn has a NEB ratio greater than 1 and this is improving, and that production of ethanol from corn is the least expensive in the United States. The amount of ethanol produced in 2014 was 13 billion gallons per year and it is a $30 billion a year industry. It makes up 10% of the gasoline pool, although the US government has mandated that the gasoline pool can utilize up to 10% ethanol, and companies get tax credits for using ethanol. Because of the high price of gasoline due to oil prices, demand for gasoline fell, and this has made it more difficult for ethanol producers to continue selling ethanol at the level that they had over the last several years. Recently, the EPA examined whether to raise the ethanol limit to 15%, but because of the drop in oil prices, the EPA has been reconsidering this and has not set levels for 2015. According to the most recent statistics, there are 145 biodiesel facilities in the United States that provide more than 2.60 billion gallons of biodiesel per year (in 2010, the production of biodiesel was less than 0.4 billion gallons per year, which is an order of magnitude increase). Biodiesel makes up about 5% 6% of the diesel fuel pool. Biodiesel plants tend to be smaller and more evenly distributed across the United States than ethanol.
20.3
Biomass energy
Biomass, a product of photosynthesis, includes all new plant growth, residues and wastes such as rotation trees, herbaceous plants, fresh water and marine algae, aquatic plants, agricultural and forest residues, kitchen and city garbage, night soil, sewage, etc. Furthermore, biodegradable organic effluents from canneries, sugar mills, slaughterhouses, meat packing factories, breweries, distillers, etc., are also
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categorized as biomass resources. To meet the growing demand for energy, it is necessary to focus on efficient production and use of biomass resources to meet both traditional and high energy demand. The biomass production for fuel, food, fiber, and fodder, requires sustainable land use and integrated planning approaches at all levels in the country. The proper selection of a site and tree plant species suitable to different agroclimatic conditions can open new avenues for integrated land-use planning and land management for the production of maximum biomass in minimum time at low cost. Such strategies allow a synergistic increase in food crop yield and decreased fertilizer applications, while providing a local source of energy and employment. The estimated potential of various biomass resources are: biomass energy 16,900 MW, cogeneration 5000 MW, and energy from waste (MSW, etc.) 2700 MW. Utilization of biomass for power generation is handicapped due to its production being labor-intensive, scattered availability, seasonal availability, localized price sensitivity, lack of automatic feed control, tedious handling, high moisture, low energy, and low bulk density (30 180 kg/m3) with substantial transportation costs. A wide variety of conversion technologies can be used to produce energy from biomass. Some are simple and some are well developed, while others are at different stages of development. The choice of a particular process is determined by a number of factors such as location of resources, its physical condition, the economics of compacting processes, and the availability of a sustainable market for the product [6,8].
20.3.1 Biofuel Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels, and various biogases. Although fossil fuels have their origin in ancient carbon fixation, they are not considered biofuels by the generally accepted definition because they contain carbon that has been “out” of the carbon cycle for a very long time. Biofuels are gaining increased public and scientific attention, driven by factors such as oil price spikes, the need for increased energy security, concern over GHG emissions from fossil fuels, and support from government subsidies.
20.3.1.1 Liquid fuels The two main types of liquid biofuel are biodiesel and bioethanol. Biodiesel can be blended with diesel, and bioethanol is primarily blended with petrol. Currently the majority of vehicle engines are designed to run on blends of at least 5% 10% biofuel.
Ethanol Ethanol, also called ethyl alcohol, alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a solvent, and as a fuel. In common usage, it is
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often referred to simply as alcohol or spirits. Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline. Bioethanol is a form of renewable energy that can be produced from agricultural feedstocks. It can be made from common crops such as sugar cane, bagasse, miscanthus, sugar beet, sorghum, grain, switch grass, barley, hemp, kenaf, potatoes, cassava, fruit, molasses, corn, stover, grain, wheat, sweet potatoes, straw, cotton, other biomass, as well as many types of cellulose waste and harvestings, whichever has the best well-to-wheel assessment. There has been considerable debate about how useful bioethanol will be in replacing gasoline. Concerns about its production and use relate to increased food prices due to the large amount of arable land required for crops, as well as the energy and pollution balance of the whole cycle of ethanol production, especially from corn. Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns. Cellulosic ethanol offers promise because cellulose fibers, a major and universal component in plant cell walls, can be used to produce ethanol. According to the International Energy Agency (IEA), cellulosic ethanol could allow ethanol fuels to play a much bigger role in the future than previously thought. The basic steps for large-scale production of ethanol are: microbial (yeast) fermentation of sugar, distillation, dehydration, and denaturing (optional). Prior to fermentation, some crops require saccharification or hydrolysis of carbohydrates, such as cellulose and starch into sugars. Saccharification of cellulose is called cellulitis. Enzymes are used to convert starch into sugar.
Biodiesel Biodiesel refers to a vegetable oil or animal fat-based diesel fuel consisting of longchain alkyl (methyl, propyl, or ethyl) esters. Biodiesel is typically made by chemically reacting lipids [e.g., vegetable oil, animal fat (tallow)] with an alcohol. Biodiesel is made from vegetable oils and animal fats. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates (PM), carbon monoxide (CO), and hydrocarbons (HC) emitted by diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe. Energy and the environment are both vital for sustainable development. New initiatives for reduction of GHGs are being taken all over the world. The utilization of biodiesel can help in directly substituting fossil fuel consumption, leading to a reduced reliance on crude oil imports and improvements in the environment. For the last 5 years, the use of blends of biodiesel with diesel, to the extent of 5% 10% in the European Union (EU) and the United States, has been rising with policy supports. The world use of vegetable oils for biodiesel production has been estimated at about 3 MT or just less than 3% of global vegetable oil production. Major users are the EU (mainly rapeseed oil) and the United States (mainly soybean oil). The usage of vegetable oil for biodiesel has been rising in EU at about 30% annually over the last 5 years. The demand for diesel fuel for the transport sector in
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India is growing at a high annual growth rate of 2.1% on one hand, and increasing import and exhaustion of limited indigenous production has led to increased attention on biodiesel on the other hand. Biodiesel is receiving great attention worldwide as an alternative fuel for diesel engines as it has shown almost the same engine performance with reduced emissions compared to diesel fuel.
20.4
Improving the economics of microalgae biodiesel [6,8]
The cost of producing microalgae biodiesel can be reduced substantially by using a biorefinery-based production strategy, improving capabilities of microalgae through genetic engineering, and advances in engineering of photobioreactors: G
G
G
Biorefinery-based production strategy; Photobioreactor engineering; Enhancing algal biology.
Molecular level engineering can be used to potentially: Increase photosynthetic efficiency to enable increased biomass yield in light; Enhance biomass growth rate; Increase oil content in biomass; Improve temperature tolerance to reduce the expense of cooling; Eliminate the light saturation phenomenon so that growth continues to increase in response to increasing light level; 6. Reduce photoinhibition that actually reduces the growth rate at midday light intensities that occur in temperate and tropical zones; 7. Reduce susceptibility to photo-oxidation, which damages cells. 1. 2. 3. 4. 5.
20.5
Conclusion
As demonstrated here, microalgal biodiesel is technically feasible. It is the only renewable biodiesel that can potentially completely displace liquid fuels derived from petroleum. The economics of producing microalgal biodiesel need to improve substantially to make it competitive with petrodiesel, but the level of improvement necessary appears to be attainable. Producing low-cost microalgal biodiesel requires primarily improvements to algal biology through genetic and metabolic engineering. Use of the biorefinery concept and advances in photobioreactor engineering will further lower the cost of production. In view of their much greater productivity than raceways, tubular photobioreactors are likely to be used in producing much of the microalgal biomass required for making biodiesel. Photobioreactors provide a controlled environment that can be tailored to the specific demands of highly productive microalgae to attain a consistently good annual yield of oil.
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References [1] Acie´n Ferna´ndez FG, Garcı´a Camacho F, Sa´nchez Pe´rez JA, Ferna´ndez Sevilla JM, Molina Grima E. A model for light distribution and average solar irradiance inside outdoor tubular photobioreactors for the microalgal mass culture. Biotechnol Bioeng 1997;55:701 14. [2] Acie´n Ferna´ndez FG, Garcı´a Camacho F, Sa´nchez Pe´rez JA, Ferna´ndez Sevilla J, Molina Grima E. Modelling of biomass productivity in tubular photobioreactors for microalgal cultures. Effects of dilution rate, tube diameter and solar irradiance. Biotechnol Bioeng 1998;58:605 11. [3] Acie´n Ferna´ndez FG, Ferna´ndez Sevilla JM, Sa´nchez Pe´rez JA, Molina Grima E, Chisti Y. Airlift-driven external-loop tubular photobioreactors for outdoor production of microalgae: assessment of design and performance. Chem Eng Sci 2001;56:2721 32. [4] Chisti Y, Moo-Young M. Improve the performance of airlift reactors. Chem Eng Prog 1993;89(6):38 45. [5] Chisti Y, Moo-Young M. Clean-in-place systems for industrial bioreactors: design, validation and operation. J Ind Microbiol 1994;13:201 7. [6] Chisti Y, Moo-Young M. Bioprocess intensification through bioreactor engineering. Trans I Chem E 1996;74A:575 83. [7] Richardson JW, Johnson MD, Zhang X, Zemke P, Chen W, Hu Q. A financial assessment of two alternative cultivation systems and their contributions to algae biofuel economic viability. Algal Res 2014;4:96 104. [8] Chisti Y, Halard B, Moo-Young M. Liquid circulation in airlift reactors. Chem Eng Sci 1988;43:451 7.