7. Co-products The “guiding truth” is that if biofuel production is conversion of algal biomass to other biofuels has already considered to be the primary goal, the generation of other been discussed (see Chapter 6); this chapter will focus on co-products must be correspondingly low since their the non-fuel co-products. generation will inevitably compete for carbon, reductant, and energy from photosynthesis. Indeed, the concept of Under the biorefinery concept (Exhibit 7.1), the production a biorefinery for utilization of every component of the of industrial, high-value and high-volume chemicals from biomass raw material must be considered as a means to amino acids, glycerol, and nitrogen-containing components enhance the economics of the process. This chapter will of algal biomass becomes feasible (Mooibroek et al., 2007) address these options and discuss how some of them and must be considered in determining the economics of are better opportunities as they will not readily saturate the process. corresponding markets in the long term. The use of terms such as “high volume” or “high value” This chapter will also address within the context of the can be extremely subjective, as a “high value” product biorefinery the possibility of coupling biomass cultivation to a fine chemical producer might be well over several with CO mitigation (for carbon credits) and wastewater 2 dollars/lb, but considerably under a dollar for a commodity treatment (for nutrient removal) to provide additional producer. For the purposes of the Roadmap, a reasonably benefits to the technology, without invoking competing co- valued chemical is defined as one that will cost roughly products. $0.30 - $1.00/lb, and can be produced at a volume of roughly 100 - 500 x106 lbs/yr. Using appropriate technologies, all primary components of algal biomass – carbohydrates, fats (oils), proteins and 7.1 Commercial Products from a variety of inorganic and complex organic molecules – can be converted into different products, either through Microalgae and Cyanobacteria chemical, enzymatic or microbial conversion (see Chapter 6). The nature of the end products and of the technologies A large number of different commercial products have been to be employed will be determined, primarily by the derived from microalgae and cyanobacteria. As summarized economics of the system, and they may vary from region to in Exhibit 7.2, these include products for human and animal region according to the cost of the raw material (Willke and nutrition, poly-unsaturated fatty acids, anti-oxidants, Vorlop, 2004). Moreover, novel technologies with increased coloring substances, fertilizers and soil conditioners, and efficiencies and reduced environmental impacts may have a variety of specialty products such as bioflocculants, to be developed to handle the large amount of waste that biodegradable polymers, cosmetics, pharmaceuticals, is predicted to be generated by the process. The topic of polysaccharides, and stable isotopes for research purposes. Exhibit 7.1 An overview of the biorefinery concept Biorefinery Aquaculture Primary Refinery Industry Conversion Carbohydrates Raw biomass, wastewater, CO Products and 2 Complex residues from Fats Substances conversion Special substances: processes pigments, dyes, flavors, aromatic essences, Inorganics Proteins enzymes, hormones, etc. Heat, electricity Energy Modified from Kamm and Kamm, 2007 7. Co-products 61 By definition, these existing markets (and associated Spirulina, Tetraselmis, and Thalassiosira. Both the production plants and distribution channels) are for high- protein content and the level of unsaturated fatty value products or co-products from algae, not commodity acids determine the nutritional value of microalgal products. Yet the existing fossil fuels market is and the aquaculture feeds. The market size, currently at ~700 future algal-based biofuels market (designed in part to million US$, is expected to expand significantly. supplant the fossil fuels market) must be commodities • Animal Feed Additive: Microalgal biomass has also based to meet required volumes at price points acceptable been used with good results (i.e., better immune to the consumer. With the possible exception of the existing response, fertility, appearance, weight gain, etc.) as market for microalgal biomass for animal nutrition and a feed additive for cows, horses, pigs, poultry, and soil fertilizer, the biofuels markets will involve volumes even dogs and cats. In poultry rations, microalgal (of biomass, product, etc.) and scales (sizes and numbers biomass up to a level of 5 - 10% (wt.) can be safely of commercial plants) that are significantly less than those used as a partial replacement for conventional proteins associated with the existing high-value algae-derived (Spoalore et al., 2006). The main species used in products. animal feed are Spirulina, Chlorella and Scenesdesmus. The market for microalgal animal feeds, estimated Therein lies a major conundrum associated with the to be about 300 million US$, is quickly growing. nascent algal-derived biofuels market: in the long term, However, it is important to note that since the flue massive lipid production dominates; yet in the short term, gas from coal-fired power plants that will be used co-products of higher value in the marketplace must be to supply carbon dioxide to the cultures will contain pursued in order to offset the costs of production of algal- significant amounts of lead, arsenic, cadmium and derived biofuels. Although it is clear that co-products may other toxic elements, the resulting non-oil algal improve the economic viability of some algae processes biomass is very likely to be unsuitable for use as an in the short-term, the goal of the industry is to produce animal feed, particularly given the fact that algae transportation fuels below their market price, thereby are known to be effective at metal absorption. increasing fuel supplies without drastically increasing price. This situation, is anticipated to continue until 1) a sufficient Polyunsaturated Fatty Acids (PUFAs) number of the challenges outlined earlier in the Roadmap Microalgae can also be cultured for their high content for biofuel production have been overcome and associated in PUFAs, which may be added to human food and life cycle costs are reduced to realize sustainable biofuel animal feed for their health promoting properties production at volumes and pricepoints that meet consumer (Benemann, 1990; Radmer, 1994 and 1996). The most demands or 2) new co-products that are low cost and have commonly considered PUFAs are arachidonic acid (AA), very large potential markets are developed. docohexaenoic acid (DHA), γ-linolenic acid (GLA), and eicosapentaenoic acid (EPA). AA has been shown to be Food and Feed synthesized by Porphyridium, DHA by Crypthecodinium • Human Health Food Supplement: The consumption of and Schizochytrium, GLA by Arthrospira, and EPA by microalgal biomass as a human health food supplement Nannochloropsis, Phaeodactylum and Nitzschia (Spolaore is currently restricted to only a few species, e.g., et al., 2006). However, only DHA has been produced thus Spirulina (Arthospira), Chlorella, Dunalliella, and far on a commercial scale by microalgae. All other PUFAs to a lesser extent, Nostoc and Aphanizomenon are more cost-effectively produced from non-algal sources (Radmer, 1996; Pulz and Gross, 2004; Spolaore et (e.g., GLA from evening primrose oil). Although small, al., 2006). the DHA oil market is quickly growing, having presently a retail value of 1.5 billion US$. The production includes ca. 3,000 t/yr Spirulina; ca. 2,000 t/yr Chlorella; ca. 1,200 t/yr Dunaliella; ca. Anti-Oxidants 600 t/yr Nostoc; and ca. 500 t/yr Aphanizomenon. The market, currently at about 2.5 billion A number of anti-oxidants, sold for the health food market, US$, is expected to grow in the future. have also been produced by microalgae (Borowtizka, 1986; Benemann, 1990; Radmer, 1996). The most prominent • Aquaculture: Microalgae are also used as feed in the is β–carotene from Dunaliella salina, which is sold either aquaculture of mollusks, crustaceans (shrimp), and as an extract or as a whole cell powder ranging in price fish (Benemann, 1990; Malcolm et al., 1999). Most from 300 to 3,000 US$ per kg (Spolaore et al., 2006). The frequently used species are Chaetoceros, Chlorella, market size for β–carotene is estimated to be greater than Dunaliella, Isochrysis, Nannochloropsis, Nitzschia, 280 million US$. Pavlova, Phaeodactylum, Scenedesmus, Skeletonema, 62 7. Co-products Coloring Agents the related carotenoids lutein and zeaxantin, have also been used in the feed of carp and even chicken (Puls and Microalgae-produced coloring agents are used as natural Gross, 2004; Spolaore et al., 2006). Phycobiliproteins, dyes for food, cosmetics, and research, or as pigments i.e., phycoerythrin and phycocyanin, produced by in animal feed (Borowitzka, 1986; Benemann, 1990). the cyanobacterium Arthrospira and the rhodophyte Astaxanthin, a carotenoid produced by Hematococcus Porphyridium, are used as food dyes, pigments in pluvialis, has been successfully used as a salmon feed to cosmetics, and as fluorescent reagents in clinical or research give the fish meat a pink color preferred by the consumers laboratories (Spolaore et al., 2006). (Olaizola, 2003; Spolarore et al., 2006). Astaxanthin, and Exhibit 7.2 Summary of microalgae commercial products market MARKET SIZE SALES VOLUME COMMERCIAL PRODUCT REFERENCE (TONS/YR) (MILLION $US/YR) BIOMASS Health Food 7,000 2,500 Pulz&Gross (2004) Pulz&Gross (2004) Aquaculture 1,000 700 Spolaore et al., (2006) Animal Feed Additive No available information 300 Pulz&Gross (2004) POLY-UNSATURATED FATTY ACIDS (PUFAs) ARA No available information 20 Pulz&Gross (2004) Pulz&Gross (2004) DHA <300 1,500 Spolaore et al., (2006) PUFA Extracts No available information 10 Pulz&Gross (2004) GLA Potential product, no current commercial market Spolaore et al., (2006) EPA Potential product, no current commercial market Spolaore et al., (2006) ANTI-OXIDANTS Pulz&Gross (2004) Beta-Carotene 1,200 >280 Spolaore et al., (2006) Tocopherol CO Extract No available information 100-150 Pulz&Gross (2004) 2 COLORING SUBSTANCES Pulz&Gross (2004) Astaxanthin < 300 (biomass) < 150 Spolaore et al., (2006) Phycocyanin No available information >10 Pulz&Gross (2004) Phycoerythrin No available information >2 Pulz&Gross (2004) FERTILIZERS/SOIL CONDITIONERS Fertilizers, growth promoters, Pulz&Gross (2004) No available information 5,000 soil conditioners Metting&Pyne (1986) 7. Co-products 63 Fertilizers which occurs in high concentrations in brown seaweeds, is considered recalcitrant to ethanol fermentation since Currently, macroalgae (i.e., seaweeds) are used as a plant the redox balance favors formation of pyruvate as the end fertilizer and to improve the water-binding capacity and product (Forro, 1987). mineral composition of depleted soils (Metting et al., 1990). Microalgal biomass could in principle serve the same purpose. Furthermore, plant growth regulators could be 7.3 Potential Options for the derived from microalgae (Metting and Pyne, 1986). Recovery of Co-products Other Specialty Products Co-products from algal refineries should address one There are a number of specialty products and chemicals of these three criteria to be commercially viable and that can be obtained from microalgae. These include acceptable: bioflocculants (Borowitzka, 1986), biopolymers and biodegradable plastics (Philip et al., 2007; Wu et al., 2001), 1. Identical to an existing chemical, fuel, or other product. cosmetics (Spolaore et al., 2006), pharmaceuticals and In this instance, the only issue is price. The production bioactive compounds (Burja et al., 2001; Metting and Pyne, cost of the new product must be equivalent to the 1986; Olaizola, 2003; Singh et al., 2005; Pulz and Gross, material it replaces and to be competitive typically, it 2004), polysaccharides (Benemann, 1990; Borowitzka, must be produced at a cost 30% lower than the existing 1986; Pulz and Gross, 2004), and stable isotopes for material (shutdown economics). This sets a high bar research (Benemann, 1990, Radmer, 1994; Pulz and Gross, but has been achieved for some chemicals and proteins/ 2004). The market for these specialty products is likely to nutritional products. be very small due to their specialized applications. 2. Identical in functional performance to an existing chemical, fuel or other product. Here price is a major 7.2 Commercial Products factor, but the source of the material can often provide from Macroalgae some advantage. This occurs with natural oils which manufacturers in many cases would prefer if the costs Macroalgae possess high levels of structural were comparable, or with replacements such as algal polysaccharides that are extracted for their commercial proteins for distillers dried grains from corn dry grind value (Exhibit 7.3). They include alginate from brown ethanol processing. Price becomes less of an issue if algae and agar and carrageenen from red algae. Alginate, the product can be labeled “organic” and thus saleable at a premium. Exhibit 7.3 Global value of seaweed products per annum (McHugh, 2003) PRODUCT VALUE Human Food (Nori, aonori, kombu, wakame, etc.) $5 billion Algal hydrocolloids Agar (Food ingredient, pharmaceutical, biological/microbiological) $132 million Alginate (Textile printing, food additive, pharmaceutical, medical) $213 million Carrageenen (Food additive, pet food, toothpaste) $240 million Other uses of seaweeds Fertilizers and conditioners $5 million Animal Feed $5 million Macroalgal Biofuels Negligible TOTAL $5.5-6 BILLION 64 7. Co-products 3. New material with unique and useful functional production systems, it may be difficult to identify large performance characteristics. In this case, the issues enough markets for potential co-products. Therefore, one are less related to costs and more to the functional option would be to convert as much of the lipid-extracted performance and potentially enhanced performance of biomass into energy, which could then be either sold on the new product. the open market or used on-site in the various biorefinery operations. There are at least five different options for recovering economic value from the lipid-extracted microalgal biomass The most promising energy recovery technology, both (Exhibit 7.4). These are: from a practical and economic perspective, is the anaerobic digestion of lipid-extracted biomass. Anaerobic digestion of • Option 1 – Maximum energy recovery from whole (i.e., non-extracted) micro and macroalgal biomass the lipid extracted biomass, with potential has been successfully demonstrated, with reported methane use of residuals as soil amendments yields of about 0.3 l per gram volatile solids (Huesemann • Option 2 – Recovery of protein from the lipid- and Benemann, 2009). The economic value of the produced extracted biomass for use in food and feed methane is equivalent to about $100 per ton of digested • Option 3 – Recovery and utilization of non-fuel lipids biomass, which is significant in terms of reducing the overall cost of liquid biofuels production. The residuals • Option 4 – Recovery and utilization of carbohydrates remaining after anaerobic digestion could either be recycled from lipid-extracted biomass, and the glycerol as nutrients for algal cultivation or could be sold as soil from the transesterification of lipids to biodiesel fertilizers and conditioners, as is currently already done for • Option 5 – Recovery/extraction of fuel certain waste water treatment sludges (see http://www.unh. lipids only, with use of the residual biomass edu/p2/biodiesel/pdf/algae_salton_sea.pdf). as soil fertilizer and conditioner Each option and its associated technologies and future In addition to anaerobic digestion, thermochemical research needs are discussed below. conversion technologies, such as pyrolysis, gasification, and combustion, could also be potentially considered for the recovery of energy from the lipid-extracted biomass Option 1. Maximum Energy Recovery from the (see Chapter 6). These technologies are able to convert Lipid-Extracted Biomass, with Potential Use of a much larger fraction of biomass into fuels. However, Residuals as Soil Amendments these technologies are still in the testing and development Given the large amounts of lipid-extracted biomass residues stage, and because of their large energy inputs (temperature that will likely be generated in future microalgal biofuels and pressure), could have poor or even negative energy balances (Huesemann and Benemann, 2009). Nevertheless, Exhibit 7.4 Overview of the five Recycle Nitrogen Gases Algal Biomass potential options for the recovery and use of co-products Option 1 Extract Lipids Energy for Fuel Burn Residue Ash/ Soil Amendments Option 5 Soil Fertilizer/ Conditioners Dry Residue Processing Proteins as Option 2 Food/ Feed Supplement Co-Products Processing Option 3 Non-Fuel Surfactants/ Bioplastics Lipids Chemical/ Biological Conversion Option 4 Carbohydrates Ethanol/ Butanol/ Glycerol Chemical/ Biological Conversion 7. Co-products 65 the thermochemical conversion of lipid-extracted biomass Option 3. Recovery and Utilization of Non-fuel Lipids has the potential advantage that the resulting nitrogen- It is well known that microalgae can synthesize a variety containing gases (e.g., ammonia and nitrous oxides) could of fatty acids with carbon numbers ranging from C to C , be recycled into the microalgal culture ponds, thereby 10 24 depending on the algal species and culturing conditions reducing the expense for nitrogen fertilizers. Furthermore, (Hu et al., 2008). Since the generation of gasoline, jet fuel, the mineral-rich ash generated by these thermochemical and diesel substitutes will require specific ranges of carbon processes could possibly be used for nutrient recycle or as a chain length, it will be necessary to either separate the soil amendment. product into the appropriate range or rearrange the carbon chains through catalytic cracking and catalytic reforming. Option 2. Recovery of Protein from the Lipid-Extracted It may be worthwhile, however, to separate specific Biomass for Use in Food and Feed lipids present in the algal oil that have utility as chemical Following the extraction of lipids from the microalgal feedstocks for the manufacture of surfactants, bioplastics, biomass for liquid biofuel production, the protein fraction and specialty products such as urethanes, epoxies, from the residual biomass could be extracted and used as lubricants, etc. a food and feed supplement. As was pointed out above, the market for animal feed (cattle, pigs, poultry, fish, and Option 4. Recovery and Utilization of Carbohydrates pets) is already very large and growing (estimated to rise from Lipid-Extracted Biomass, and the Glycerol from the to approximately 60 million tons per year for distillers dry Transesterification of Lipids to Biodiesel grains plus soluble (DDGS)) (Berger and Good, 2007). The current price for DDGS ranges from $110 - 150 per ton After the extraction of lipids, the residual microalgal (http://www.ams.usda.gov/mnreports/sj_gr225.txt). Since biomass may contain sufficient levels of carbohydrates that protein is generally the key and often limiting ingredient could be converted through anaerobic dark fermentations in animal feed, supplementation with microalgal proteins to hydrogen, solvents (acetone, ethanol, and butanol), and could be advantageous. Furthermore, human nutrition may organic acids (formic, acetic, propionic, butyric, succinic, also benefit from supplementation with microalgal proteins. and lactic) (Huesemann and Benemann, 2009; Kamm and Kamm, 2007; Kawaguchi et al., 2001). Hydrogen and The byproduct material, which contains proteins, might ethanol could be used as biofuel, while butanol and organic make a useful animal feed. However, feeding studies acids could serve as renewable feedstocks for the chemicals indicate that algae cannot be used as a high percentage industry. For example, butanol is a valuable C compound 4 of feed, due to issues such as taste of the meat or eggs, for chemical synthesis of a variety of products, including and interactions with animal digestion. Furthermore, the polymers that are currently produced from fossil oil- overall size of the animal feed market is small, relative derived ethylene and propylene, thus butanol could serve to the amount of byproduct that would be produced, and as a renewable substitute (Zerlov et al., 2006). Similarly, the individual local markets for animal feed are often not succinate is an intermediate in the production of a variety located adjacent to areas where algae may be produced. As of industrial surfactants, detergents, green solvents and a result, byproduct markets are likely to be overwhelmed, biodegradable plastics (Kamm and Kamm, 2007). Lactic and byproduct prices will be greatly depressed versus acid, which can be converted into polypropylene oxide, current levels. is the starting material for the production of polyester, polycarbonates and polyurethanes; it is also used in the In addition, it may be possible to recover important industrial production of green solvents, and its applications enzymes such as cellulases or other industrial enzymes include the pharmaceutical and agrochemical industries from the lipid-extracted biomass. However, this option (Datta et al., 1995). would require the use of specially selected or engineered microalgal strains capable of producing these enzymes. The Glycerol, a byproduct of the transesterification of market for industrial enzymes, specifically cellulases for microalgal lipids to biodiesel, could also be anaerobically pretreating lignocellulosic feedstocks prior to fermentation fermented to the above mentioned and other end products to fuel ethanol, is potentially very large. Assuming that (a) (Yazdani and Gonzalez, 2007). Furthermore, glycerol microalgal cellulases could be provided at a cost of less could be converted by certain bacteria to 1,3-propanediol, than $0.20 per gallon ethanol; (b) approximately 100 grams which is used in the formulation of a variety of industrial of cellulase are needed per gallon of ethanol; and (c) at products such as polymers, adhesives, aliphatic polyesters, least 10.5 billion gallons of lignocellulosic ethanol will be solvents, antifreeze, and paint (Yazdani and Gonzalez, produced by 2020, the projected market for cellulases is 2007; Choi, 2008). Finally, glycerol could be used to generate electricity directly in biofuel cells (Yildiz and potentially very large, i.e., 1 billion kg. 66 7. Co-products Kadirgan, 1994). Once again, the issue of scale enters in. microalgal metabolites, including sugars and complex Production of 1 billion gallons of biodiesel will result in carbohydrates; and the development of genetic engineering the formation of more than 400,000 tons of glycerol (http:// tools to improve yields of desired products, including www.biodieselmagazine.com/article.jsp?article_id=377). carbohydrates, if desired. As the current production levels for biodiesel (700 million gallons in 2008) already has the market for glycerol Option 5. Recovery (Extraction) of Fuel Lipids Only, with saturated, additional capacity from algal lipids may find it Use of the Residual Biomass as Soil Fertilizer exceedingly difficult to find uses. and Conditioner In case none of the above mentioned four options are It may also be possible to extract microalgal economical, i.e., the recovery and use of energy, proteins, polysaccharides for use as emulsifiers in food and industrial non-fuel lipids, and carbohydrates is not cost-effective, it applications (Mooibroek et al., 2007). Finally, microalgal is possible to revert to the most simple option (Option 5), carbohydrates could be recycled into pulp and paper which involves the extraction of only fuel lipids and the streams, substituting for lignocellulosic materials derived subsequent use of the biomass residues rich in nitrogen and from forestry resources. organic matter as soil fertilizer and conditioners. As was mentioned above, the market for organic fertilizer is large As was the case with Option 3, this option will also require and potentially growing. R&D efforts as discussed under Chapter 2, Algal Biology; specifically, these are the development of high throughput technologies for the quantitative characterization of References Benemann, J.R. (1990). Microalgae products and production: An overview. Developments in industrial microbiology. Journal of Industrial Microbiology. Suppl. No. 5. (31), 247-256. Berger, L.L., D. L. Good. (2007). Distillers dried grains plus solubles utilization by livestock and poultry in corn-based ethanol in Illinois and the U.S. A Report from the Department of Agricultural and Consumer Economics, University of Illinois, Champaign-Urbana. Borowitzka, M.A. (1986). Microalgae as sources of fine chemicals. Microbiological Sciences. 3(12), 372-375. Burja, A.M., B. Banaigs, E. Abou-Mansour, J.G. Burgess, and P.C. Wright. (2001). 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Science Publishers, New Hampshire. Kamm, B. M. Kamm. (2007). Biorefineries – multi product processes. Advances in Biochemical Engineering/Biotechnology. (105),175-204. Kawaguchi H, K. Hashimoto, K. Hirata, K. Miyamoto. (2001). H2 production from algal biomass by a mixed culture of rhodobium marinum A-501 and lactobacillus amylovorus. Journal of Biosciences Bioengineering. (91), 277-282. McHugh, D. J. (2003). A guide to the seaweed industry. Food and Agriculture Organization. Metting, B., J.W. Pyne. (1986). Biologically active compounds from microalgae. Enzyme Microbial Technology. (8), 386-394. Metting, B., W.J. Zimmerman, I. Crouch, J. van Staden. (1990). Agronomic uses of seaweed and microalgae. Introduction to Applied Phycology. SPB Academic Publishing, The Hague, Netherlands. 589-627. 7. Co-products 67 Mooibroek, H., N. Oosterhuis, M. Giuseppin, M. Toonen, H. Franssen, E. Scott, J. Sanders, A. Steinbüchel. (2007). Assessment of technological options and economical feasibility for cyanophycin biopolymer and high-value amino acid production. Applied Microbiology Biotechnology. (77), 257-267. Olaizola, M. (2003). Commercial development of microalgal biotechnology: From the test tube to the marketplace. Biomolecular Engineering. (20), 459-466. Philip, S., T. Keshavarz, I. Roy. (2007). Polyhydroxyalkanoates: Biodegradable polymers with a range of applications. Journal of Chemical Technology and Biotechnology. (82), 233-247. Pulz, O., W. Gross. (2004).Valuable products from biotechnology of microalgae. Applied Microbiology and Biotechnology. (65), 635-648. Radmer, R.J., B.C. Parker. (1994). Commercial applications of algae: Opportunities and Constraints. Journal of Applied Phycology. (6), 93-98. Radmer, R.J. (1996). Algal diversity and commercial algal products. BioScience. 46(4), 263-270. Singh, S., B.N. Kate, U.C. Banerjee. (2005). Bioactive compounds from cyanobacteria and microalgae: An overview. 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Bacterial acetone and butanol production by industrial fermentation in the Soviet Union: Use of hydrolyzed agricultural waste for biorefinery. Applied Microbiology and Biotechnology. (71), 587-597. 68 7. Co-products 8. Distribution and Utilization Distribution and utilization are challenges associated with It is also anticipated that gasoline and diesel range fuels virtually all biofuels. Although the biofuel product(s) from algae will not require significant distribution system from algal biomass would ideally be energy-dense modifications during or after processing in the refinery. and completely compatible with the existing liquid transportation fuel infrastructure, few studies exist that While the demonstration flights mitigate some address outstanding issues of storing, transporting, infrastructure concerns, other distribution aspects pipelining, blending, combusting, and dispensing algal concerning algal biomass, fuel intermediates, and final fuels biomass, fuels intermediates, biofuels, and bioproducts. remain poorly studied: Being intermediate steps in the supply chain, distribution • First, the stability of the algal biomass under different and utilization need to be discussed in the context of earlier production, storage, and transport scenarios is decision points, such as cultivation and harvesting. In turn, poorly characterized, with some evidence suggesting these logistics through end-use issues influence siting, that natural bacterial communities increase the scalability, and the ultimate economics and operations of rate of algae decomposition (Rieper-Kirchner, an integrated algal biofuels refinery. As a variety of fuel 1990). In the context of a variety of culturing and products – ethanol, biodiesel, higher alcohols, pyrolysis oil, harvesting conditions differing in salinity, pH and syngas, and hydroreformed biofuels – are being considered dewatering levels, it is difficult to predict how from algal biomass resources, the specific distribution and these factors will influence biomass storage and utilization challenges associated with each of these possible transport, and the quality of the final fuel product. opportunities is discussed. • Second, an issue that impacts oleaginous microalgae feedstocks is that the transport and storage mechanisms 8.1 Distribution of algal lipid intermediates have not yet been established. It is conceivable that these “bio-crudes” Lowering costs associated with the delivery of raw will be compatible with current pipeline and tanker biomass, fuel intermediates, and final fuels from the systems. However, it is known that the presence feedstock production center to the ultimate consumer of unsaturated fatty acids causes auto-oxidation of are common goals for all biofuels. In all cases, biofuels oils (Miyashita and Takagi, 1986), which carries infrastructure costs can be lowered in four ways: implications for the producers of algae and selection • Minimizing transport distance between process units; for ideal lipid compositions. It is also known that temperature and storage material have important • Maximizing the substrate energy-density and stability; implications for biodiesel stability (Bondioli et al., • Maximizing compatibility with existing infrastructure 1995). Thus, materials and temperature considerations (e.g. storage tanks, high capacity; delivery vehicles, similar to plant lipids may be possibly taken into pipelines, dispensing equipment, and end-use vehicles); account for the storage of algae lipids (Hu et al., 2008). and • Third, depending on whether it will be dewatered/ • Optimizing the scale of operations to the parameters densified biomass and/or fuel intermediates that are to stated above. be transported to the refinery, conforming to existing standards (e.g., container dimensions, hazardous materials and associated human health impacts, and Distribution is complicated by the fact that several corrosivity) for trucks, rails, and barges is critical different fuels from algae are being considered, as to minimizing infrastructure impacts. The optimal discussed in detail in Chapter 6 (Algal Biofuel Conversion transport method(s) should be analyzed and optimized Technologies). Ethanol, biodiesel, biogas, renewable for energy-inputs and costs, within the context of gasoline, diesel, and jet fuels are all possible products where the algae production and biorefinery facilities from algal biomass. Each of these different fuels has are to be sited. These have been challenging issues different implications for distributions. Some of these fuels for lignocellulosic feedstocks (Hess et al., 2009) and appear to be more compatible with the existing petroleum can be expected to influence the economics of algal infrastructure. Specifically, jet-fuel blends from a variety biofuels as well. of oil-rich feedstocks, including algae, have been shown to be compatible for use in select demonstration flights (Buckman and Backs, 2009; Efstathiou and Credeur, 2009). 8. Distribution and Utilization 69 Ethanol is another likely fuel from algae. With over Typically, compliance with specifications promulgated by 10 billion gallons per year produced and consumed organizations such as ASTM International ensures that a domestically, distribution-related issues for ethanol has fuel is fit for purpose (ASTM International, 2009a, 2009b, been studied for some time, and algal ethanol can benefit 2009c, 2009d, and 2009e). Failure of a fuel to comply with from these analyses. While not as energy dense as purely even one of the many allowable property ranges within petroleum-derived fuels, ethanol is an important fuel the prevailing specifications can lead to severe problems oxygenate that can be used in regular passenger vehicles in the field. Some notable examples included: elastomer- and special flex-fuel vehicles at up to 10% and 85% gasohol compatibility issues that led to fuel-system leaks when blends, respectively. However, considerable infrastructure blending of ethanol with gasoline was initiated; cold- investments need to be made for higher ethanol blends weather performance problems that crippled fleets when to become even more attractive and widespread. One blending biodiesel with diesel was initiated in Minnesota issue is that ethanol is not considered a fungible fuel; it in the winter; and prohibiting or limiting the use of the can pick up excessive water associated with petroleum oxygenated gasoline additive MTBE in 25 states because products in the pipeline and during storage, which causes it has contaminated drinking-water supplies (McCarthy a phase separation when blended with gasoline (Wakeley and Tiemann, 2000). In addition to meeting fuel standard et al., 2008). One possible way to address this is to build specifications, algal biofuels, as with all transportation dedicated ethanol pipelines; however, at an estimated fuels, must meet Environmental Protection Agency cost of $1 million/mile of pipeline, this approach is not regulations on combustion engine emissions. generally considered to be economically viable (Reyold, 2000). Another possibility is to distribute ethanol blends by As is true of any new fuel, it is unlikely that new rail, barge, and/or trucks. Trucking is currently the primary specifications will be developed for algal fuels in the near mode to transport ethanol blends at an estimated rate of term (i.e., at least not until significant market penetration $0.15/ton/kilometer (Morrow et al., 2006). This amount is has occurred); hence, producers of algal fuels should a static number for low levels of ethanol in the blends (5% strive to meet prevailing petroleum-fuel specifications. to 15%); as the ethanol content in the blend increases, the Nevertheless, research and technology advancements transport costs will also increase due to the lower energy may one day yield optimized conversion processes which density of the fuel. can deliver algae-derived compounds with improved performance, handling, and environmental characteristics 8.2 Utilization relative to their petroleum-derived hydrocarbon counterparts. If significant benefits can be demonstrated, new specifications can be developed (e.g., ASTM D6751 The last remaining hurdle to creating a marketable new and D7467). fuel after it has been successfully delivered to the refueling location is that the fuel must meet regulatory and customer requirements. As mentioned in Chapter 6, such a fuel is The discussion below is divided into separate sections that said to be “fit for purpose.” Many physical and chemical deal with algal blendstocks to replace gasoline-boiling- properties are important in determining whether a fuel is fit range and middle-distillate-range petroleum products, for purpose; some of these are energy density, oxidative and respectively. These classifications were selected because biological stability, lubricity, cold-weather performance, the compounds comprising them are largely distinct and elastomer compatibility, corrosivity, emissions (regulated non-overlapping. Within each of these classifications, and unregulated), viscosity, distillation curve, ignition hydrocarbon compounds and oxygenated compounds are quality, flash point, low-temperature heat release, metal treated separately, since their production processes and in- content, odor/taste thresholds, water tolerance, specific use characteristics are generally different. heat, latent heat, toxicity, environmental fate, and sulfur and phosphorus content. Petroleum refiners have shown Algal Blendstocks to Replace remarkable flexibility in producing fit-for-purpose fuels Middle-Distillate Petroleum Products from feedstocks ranging from light crude to heavy crude, oil shales, tar sands, gasified coal, and chicken fat, and are Petroleum “middle distillates” are typically used to create thus key stakeholders in reducing the uncertainty about the diesel and jet fuels. The primary algae-derived blendstocks suitability of algal lipids and carbohydrates as a feedstock that are suitable for use in this product range are biodiesel for fuel production. (oxygenated molecules) and renewable diesel (hydrocarbon molecules). The known and anticipated end-use problem areas for each are briefly surveyed below. 70 8. Distribution and Utilization