270 December 2010, Vol. 22, No. 12 Lipid Technology

DOI 10.1002/lite.201000068

Feature Camelina ( L.) oil as a biofuels feedstock: Golden opportunity or false hope?

Bryan R. Moser Bryan R. Moser is research chemist at United States Department of Agriculture1, Agricultural Research Service, National Center for Agricultural Utilization Research, 1815 North University Street, Peoria, Illinois, USA, 61604, Tel: 1-309-681-6511, Fax: 1-309-681-6524, E-mail: [email protected]

Summary Camelina (Camelina sativa L.) is a promising sustainable alternative energy crop belonging to the Brassicaceae (mustard) family. Camelina has several favorable agronomic characteristics which give it potential to significantly enhance domestic biofuels production. With high seed oil content as well as high yield of oil per hectare, camelina can be efficiently processed into high quality renewable fuels such as ( methyl esters) as well as renewable diesel and jet fuels using existing technologies. This review summarizes the attributes of camelina along with conversion of the lipid fraction into advanced renewable biofuels.

Introduction cyanobacteria), animal fats, and various low-value waste materi- als such as used cooking oils, greases, and soapstocks. With Traditional oilseed feedstocks for production of alternative die- regard to oilseeds, desirable agronomic characteristics include sel fuels primarily include (referred to as canola in adaptability to local growing conditions (rainfall, soil type, lati- North America), soybean, palm and sunflower oils. Regional tude, etc.), high seed oil content, high density of seeds per hec- availability generally dictates which lipids are to be utilized for tare, compatibility with existing farm infrastructure, low agri- production of liquid transportation fuels. Hence, rapeseed/ cultural inputs (water, fertilizer, pesticides), definable growth canola is principally used in Europe along with sunflower oil, season, uniform seed maturation rate, fallow lands compatibil- palm and coconut oils predominate in the tropics, and soybean ity, adaptability to rotate with conventional commodity cash oil and animal fats are most commonly used in the United crops, and commercial outlets for agricultural byproducts such States. However, even combined these feedstocks do not replace as meal [3]. Fuels prepared from biological feedstocks that meet a significant percentage of petroleum diesel fuel (petrodiesel) all or most of the above criteria hold the greatest promise as consumption worldwide. For instance, a recent study estimated alternatives to petroleum-derived fuels. that only 6% of petrodiesel demand would be satisfied if all U.S. soybean production were dedicated to biodiesel [1]. Addition- ally, refined commodity vegetable oils account for approxi- Camelina mately 80% of the cost to produce biodiesel, therefore necessitat- ing exploration of less expensive alternatives. Lastly, production Camelina [Camelina sativa (L.) Crantz], also known as false flax or of biofuels from traditional food crops has generated consider- gold-of-pleasure, is a broadleaf oilseed flowering plant of the able political controversy and debate, thus further fueling the Brassicaceae (mustard) family that grows optimally in temperate need for inexpensive alternative non-food energy crops. In sum- climates. Other more common members of this family include mary, the need for alternatives to classic energy feedstocks such important food crops such as broccoli, Brussels sprouts, cabbage, as petroleum and commodity food lipids is a result of the contin- cauliflower, collards, kales, kohlrabi, radish, rapeseed/canola, ued drive toward sustainability and independence among rutabaga, turnip and various mustards. Camelina can be grown energy-consuming nations. in a variety of climatic and soil conditions as a spring or summer annual or as a biannual winter crop. Cultivated in Europe spora- dically since the Bronze Age, camelina has several beneficial Desirable characteristics of oilseed feedstocks agronomic attributes: a short growing season (85–100 days), compatibility with existing farm practices and tolerance of cold A recent report identified several feedstock categories that hold weather, drought, semiarid conditions, and low-fertility or sal- the most promise as sources of biofuels: perennials grown on fal- ine soils. Camelina also has lower water, pesticide, and fertilizer low lands, crop residues, sustainably harvested wood and forest requirements than other traditional commodity oilseed crops residues, double crops and mixed cropping systems, as well as (rapeseed/canola, soybean, and sunflower, for example). More- municipal and industrial wastes [2]. Feedstocks belonging to over, camelina is well adapted to the more northerly regions of these categories presumably do not compete with food produc- North America, Europe, and Asia. As such, it may serve in a rota- tion and have much lower life-cycle greenhouse gas emissions tional cycle in the Northern Hemisphere where winter wheat than traditional fossil fuels. Many of these categories are applic- (Triticum spp.) is typically planted, thus facilitating disruption of able to production of alternative diesel fuels. undesirable weed and pest cycles [3,4]. Some estimates indicate In general, there are four major lipid feedstock categories for that the northern U.S. state of Montana alone could support alternative diesel fuels: oilseeds, single-celled organisms (algae, between 0.8 and 1.2 million hectares of camelina per year. Com-

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mercially, Agragen in partnership with Great Plains Oil & Table 2. Fatty acid composition (%) of camelina oil from several literature Exploration, LLC is working on genetic modification of camelina sources [7–10] to further improve desirable traits such as oil content, seed Fatty acid Carbon Leonard Moser & Zuhr & Frohlich & yield, viability in expanded growing locations, and resistance to number Vaughn Matthaus Rice disease, weeds and pests. Thus far, several patents relating to Palmitic 16:0 5.3 6.8 5.4 5.4 camelina have been developed, with several more pending. Stearic 18:0 2.5 2.7 2.5 2.6 Oleic 18:1 12.6 18.6 14.9 14.3 Linoleic 18:2 15.6 19.6 15.2 14.3 a-Linolenic 18:3 37.5 32.6 36.8 38.4 Camelina oil and meal Arachidic 20:0 1.2 1.5 1.3 1.4 11-Eicosenoic 20:1 15.5 12.4 15.5 16.8 Camelina yields anywhere from 336 to 2240 kg of seeds per hec- Eicosadienoic 20:2 2.0 1.3 1.9 tare at maturity with the lipid content of individual seeds ran- Eicosatrienoic 20:3 1.7 0.8 1.6 ging between 35 and 45 weight percent (wt%). The resulting Behenic 22:0 0.3 0.2 0.3 0.2 yield of camelina oil is thus calculated to be between 106 and Erucic 22:1 2.9 2.3 2.8 2.9 Others – 2.9 1.2 1.8 3.7 907 liters per hectare, which as seen in Table 1 at the higher end of the range. It is higher than soybean and sunflower oils but lower than rapeseed oil. The wide variability in yield is attributa- raised for human consumption, thus representing an important ble to such factors as the climate and conditions at the growing revenue stream for camelina meal. location as well as by the amount of agricultural inputs applied to the crop and the presence of pests, weeds and disease. With further genetic modification, the yield of camelina may approach that of rapeseed. Commercially, Great Plains Oil & Camelina oil as feedstock for biodiesel Exploration, LLC and Sustainable Oils, LLC are the two primary Biodiesel is defined by the American Society for Testing and commercial suppliers of camelina oil in the United States. Materials (ASTM) as “a fuel comprised of mono-alkyl esters of long-chain fatty acids” that meets the requirements of ASTM Table 1. Comparison of yields from several oilseeds standard D6751. Biodiesel can be prepared from a wide variety Camelina Rapeseed Soybean Sunflower of lipids [3]. Advantages of biodiesel include positive energy bal- ance, domestic and renewable origin, biodegradability, high flash point, excellent lubricity, low or no sulfur content, lower Seed yield (T/ha) 0.90–2.24 2.68–3.39a 2.14–2.84a 1.44–1.70a Oil content (wt%) 35–45 40–44 18–22 39–49 overall exhaust emissions versus petrodiesel, and miscibility Oil yield (L/ha)b 106–907 965–1342 347–562 505–750 with petrodiesel at all blend ratios. Poor economics and insuffi- cient supply of feedstock represent disadvantages of biodiesel a Source: Oil World Annual 2009, 1, Oilseeds 5–9 (T = metric ton = 1000 kg). Data from EU-27 from 2002–2006. along with relatively poor cold flow properties and oxidative sta- b Calculated by the author (BRM) from yield and oil content data. bility as compared with petrodiesel, as well as dilution of engine oil and elevated nitrogen oxides in exhaust emissions [3, 4]. Camelina is particularly attractive as an alternative feedstock a-Linolenic acid generally comprises between 32 and 40 wt% for biodiesel production as a result of its low cost versus com- of the fatty acid composition of camelina oil (Table 2). Other modity oils coupled with its potential to significantly enhance fatty acids in quantities above 10 wt% include linoleic, oleic, and domestic feedstock availability. 11-eicosenoic acids [4]. The acid value of crude camelina oil Biodiesel is classically prepared by transesterification of lipids extracted either by solvent (hexane) or cold press is typically in the presence of an homogenous alkali catalyst and excess between 1 and 5 mg KOH/g of oil, which is considerably lower methanol at elevated (608C) temperature [3–5]. Figure 1 illus- than many other crude plant oils. Camelina oil has been used trates a typical schematic for industrial production of biodiesel. for numerous applications including directly as an experimen- Crude feedstocks that have low free fatty acid contents (less than tal fuel for diesel transport engines, as a culinary oil, and as a 3.0 wt%) can be directly transesterified without pretreatment, biological feedstock for the experimental production of long- thereby eliminating a costly pretreatment step. Camelina is one chain wax esters for potential cosmetic and lubricant applica- such crude oil and has been successfully converted to biodiesel tions [4]. Camelina oil may also be used as an industrial source of (fatty acid methyl esters) by the classic method [5] as well as with a-linolenic acid, as it has a comparatively high content of this heterogeneous metal oxide catalysts both with and without constituent versus the commodity oils. microwave irradiation and at non-catalytic sub- and supercriti- Extraction of oil from camelina seeds by mechanical expeller cal conditions employing co-solvents with methanol. The fuel yields a meal that consists of approximately 10% residual oil, properties (cold flow properties, oxidative stability, kinematic 45% crude protein, 13% fibers, 5% minerals, and other minor viscosity, cetane number, etc) of camelina-based biodiesel are constituents such as glucosinolates and vitamins. The concen- similar to those of biodiesel prepared from soybean oil, thus tration of glucosinolates in dry camelina seeds ranges from 13 indicating its acceptability for use as biodiesel [5]. Additionally, to 36 lmol/g. When ingested in sufficient quantity, glucosino- fatty acid ethyl esters have been prepared from camelina oil and lates cause deleterious effects in animals such as reduced palat- along with methyl esters were evaluated as blend components ability as well as decreased growth and production. Conse- in petrodiesel (a15 ppm S). As was the case with the neat esters, quently, camelina meal cannot exceed 10 wt% of the total food camelina-based biodiesel blends in petrodiesel exhibited fuel ration given to feedlot beef cattle and broiler chickens in the properties comparable to the corresponding soybean-based United States. However, even a 10% ceiling represents signifi- blends [5]. Commercially, Green Earth Fuels, LLC in partnership cant market potential where large numbers of animals are with Sustainable Oils, LLC and INEOS in partnership with Great

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Figure 1. Life cycle diagram for production of alternative diesel fuels from camelina.

Plains Oil & Exploration, LLC are among the industrial produ- cers of fatty acid methyl esters from camelina oil.

Renewable diesel fuels from lipids Renewable diesel is defined by the U.S. Internal Revenue Code (IRC) as a fuel produced from biological materials by thermal depolymerization that meets the fuel specification require- Figure 2. Simplified scheme for industrial biodiesel production from feedstocks with low FFA and water content. Depicted are ments of ASTM D975 (petroleum diesel fuel) or ASTM D396 two CSTR reactors in sequence with glycerol removal in (home heating oil). The industrial reaction by which lipids are between. Methanol recovered after distillation can be recycled. converted to renewable diesel is referred to as hydrodeoxygena- CSTR = continuously stirred tank reactor; FFA = free fatty acids; tion (hydrotreatment) and normally involves elevated pressure FAME = fatty acid methyl esters. (40–150 atm) and temperature (350–4508C) in the presence of a heterogeneous catalyst and hydrogen to achieve sufficient con- Table 3. Comparison of biodiesel to renewable diesel with petrodiesel as version (Figure 3). All or a fraction of the linear alkanes (paraf- a reference fins) resulting from hydrotreatment can be isomerized in a sec- Renewable Diesel Biodiesel ond stage to improve cold flow properties, although isomerized hydrocarbons have significantly lower cetane numbers than Chemical Structure Hydrocarbons FAME Catalyst Heterogeneous Homogeneous their linear counterparts [4]. Renewable diesel is composed of Requirements H2, Pressure, Heat Methanol, Heat C15–C18 paraffins with a boiling range (260–3208C) within that Feedstock FFA problematic? No Yes of traditional petrodiesel (200–3508C). Byproducts? Propane Glycerol Positive energy balance? No Yes The chemical composition and fuel properties of renewable Renewable feedstock? Yes Yes diesel are different from biodiesel and in many cases are closer Biodegradable fuel? No Yes to that of petrodiesel (see Table 3). While the renewability aspect Relative to petrodiesel: of renewable diesel is retained versus biodiesel, advantages such Density Similar Higher as biodegradability, positive energy balance, excellent lubricity, Viscosity Similar Higher and high flash point are sacrificed. However, disadvantages such Sulfur content Lower Lower as poor oxidative stability, cold flow properties, and energy den- Flash point Similar Higher Lubricity Similar Better sity as well as elevated NOx exhaust emissions versus petrodiesel Cetane number Highera Higher are eliminated if renewable diesel is prepared instead of biodie- NOx exhaust emissions Similar Higher b sel. Furthermore, renewable diesel can be produced using exist- Cold flow properties Similar Lower Oxidative stability Similar Lower ing petroleum oil refinery capacity and is compatible with the Energy density Similar Lower current diesel fuel distribution infrastructure [4]. a Linear paraffins. b Isomerized (branched) paraffins. Camelina oil as feedstock for renewable jet fuel Production of renewable jet fuels from vegetable oils initially fuels have freezing points no higher than –408C (–478C for JP8). requires hydrodeoxygenation similar to renewable diesel fuel Selective catalytic cracking of the paraffins to shorter-chain (Figure 3). However, isomerization to branched paraffins to hydrocarbons (C7–C18) is also performed, as jet fuels have a some- improve cold flow properties is critically important in the case of what lower boiling range than diesel fuel. With existing catalyst jet fuel, as linear paraffins freeze at the temperatures encoun- and reactor technologies, selective catalytic cracking and isomer- tered at the operational altitudes of most commercial aircraft. ization can be accomplished in a single stage. Lastly, aromatics Consequently, ASTM D1655 requires that aviation turbine (jet) can be introduced either by blending renewable hydrocarbons

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Life cycle analysis of camelina-derived renewable biofuels and land use change

A recent life-cycle analysis (LCA) study concluded that the life cycle greenhouse gas emissions, cumulative energy demand, and fossil energy demand of camelina-derived biodiesel and renewable diesel and jet fuels was significantly lower than for the corresponding petroleum derived fuels [6]. The study was based on camelina grown in Montana (USA) by Sustainable Oils, LLC and processed by Targeted Growth, Inc. into renewable jet and diesel fuels in Seattle using UOP, LLC hydrotreatment tech- nology. Specifically, life cycle greenhouse gas emissions for renewable diesel and jet fuels produced from camelina oil are 80% and 75% lower relative to their petroleum counterparts. Camelina-derived biodiesel exhibited a life-cycle greenhouse gas savings compared to petrodiesel of 78.5%. A significant outcome of these findings is that camelina-derived biodiesel as well as renewable diesel and jet fuels qualify as advanced biofuels according to the Renewable Fuels Standard (RFS2) created by the U.S. Energy Independence and Security Act of 2007 and adminis- tered by the U.S. Environmental Protection Agency. Lastly, culti- Figure 3. Simplified scheme for industrial production of renew- vation of camelina as an energy crop in a rotational cycle with able diesel and jet fuels from camelina oil; HDO = hydrodeoxy- genation; ISO = isomerization; SCC = selective catalytic crack- wheat that displaces fallow weeds on otherwise unused land sug- ing; RCA = ring-closing aromatization. Renewable diesel = mix- gests minimal land use change impacts, since no food produc- ture of C15–C18 branched and linear alkanes; Renewable jet tion is displaced by camelina under such a scenario. fuel = mixture of branched aromatics and C7–C9 branched alkanes. Conclusion with petroleum jet fuel or by conversion of a portion of the bio- Camelina shows excellent promise as a significant source of based paraffins into branched aromatics by ring-closing aromati- “drop-in” alternatives to traditional petroleum-derived diesel zation (Figure 3). Because aromatization would add a third stage and jet fuels. Fuel properties of renewable liquid fuels prepared to the production of renewable jet fuel, blending with petroleum from camelina oil compare favorably with their corresponding jet fuel obviously represents a more viable option from economic fossil-derived counterparts. In particular, significantly lower and process standpoints. For comparison, typical petroleum- life-cycle greenhouse gas emissions versus petroleum fuels qua- derived jet fuel boils in the 150–2908C range and consists of lify camelina-derived renewable fuels as advanced biofuels hydrocarbons such as paraffins and cycloalkanes (naphthenes) in under RFS2. Future agronomic advancements will improve the the C9–C16 range along with no more than 25% by volume (ASTM already impressive yield of camelina oil along with its resistance D1655) aromatics (e.g., alkylbenzenes or alkylnapthalenes). to disease, weeds and pests. Further improvements in hydro- Several commercial ventures have produced or are currently treatment technology will increase the yield and efficiency as working toward production of camelina-derived renewable jet well as optimize the composition of hydrocarbons prepared fuel, including Accelergy Corp., Altair, Inc., Biojet Corp. and Sus- from lipids such as camelina oil. tainable Oils, LLC. Additionally, Altair, Inc. is also working toward production of renewable diesel fuel. The U.S. Air Force (USAF) has successfully test flown an F/A-18 Super Hornet fighter References jet as well as an A-10 Thunderbolt II fighter jet on a blend of camelina-derived renewable jet and standard JP-8 jet fuel. The [1] Hill, J. et al. Proc. Natl. Acad. Sci. 2006, 103, 11206–11210. USAF has a goal to acquire half of its domestic aviation fuel from [2] Tilman, D. et al. Science 2009, 325, 270–271. alternative fuels by 2016. Additionally, commercial entities [3] Moser, B.R. In vitro Cell. Dev. Biol.-Plant 2009, 45, 229–266. such as KLM Royal Dutch and Japan Airlines have performed suc- [4] Huber, G.W. et al. Chem. Rev. 2006, 106, 4044–4098. cessful test flights with camelina jet-JP8 blends. In the case of the [5] Moser, B.R., Vaughn, S.F. Bioresour. Technol. 2010, 101, Japan Airlines test flight, the bio-derived jet fuel component was 646–653. obtained from three feedstocks: camelina (84%), Jatropha (15%) [6] Shonnard, D.R. et al. Environ. Prog. Sustainable Energy and algal (1%) oils. Additionally, Great Plains Oil & Exploration, 2010, 29, 382–392. LLC and the Energy & Environmental Research Center at the Uni- versity of North Dakota have entered into an agreement to pro- [7] Leonard, E.C. Inform 1998, 9, 830–838. duce combinations of jet fuel, diesel, gasoline and propane from [8] Moser, B.R., Vaughn, S.F. Bioresour. Technol. 2010, 101, camelina. Lastly, 14 airlines have signed a memorandum of 646–653. understanding (MOU) with Altair, Inc. to purchase up to 750 mil- [9] Zuhr, J., and Matthaus, B. Ind. Crops Prod. 2002, 15, 155– lion gallons of renewable jet fuel and diesel derived from came- 162. lina at Seattle-Tacoma International Airport (Washington, USA). [10] Frohlich, A. and Rice, B. Ind. Crops Prod. 2005, 21, 25–31.

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