NORWICH UNIVERSITY

Algae Fuel The Future of Biofuel and Energy Production

Andrew Pieroni

2/16/2015

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Table of Contents

1.0 Introduction .......................................................................................................................... 4

2.0 Growing Microalgae .............................................................................................................. 5

2.1 Types of Algae .................................................................................................................... 5

2.2 Production Inputs .............................................................................................................. 6

2.2.1 Carbon Dioxide ....................................................................................................... 6

2.2.2 Water ..................................................................................................................... 6

2.2.3 Sunlight .................................................................................................................. 7

2.2.4 Nitrogen and Phosphorus ...................................................................................... 7

2.2.5 Ideal Geographic Locations .................................................................................... 7

3.0 Production Processes ............................................................................................................ 8

3.1 Cultivation Processes ......................................................................................................... 8

3.1.1 Open Pond Systems ............................................................................................... 9

3.1.2 Closed Photo Bioreactor ...................................................................................... 11

3.1.3 Hybrid Systems .................................................................................................... 12

3.2 Harvesting Processes ....................................................................................................... 13

3.2.1 Flocculation .......................................................................................................... 13

3.2.2 Micro-Screening ................................................................................................... 14

3.2.3 Centrifugation ...................................................................................................... 14

3.3 Refining Processes ........................................................................................................... 14

3.3.1 Drying Biomass .................................................................................................... 14

3.3.2 Lipid Extraction and Transesterification .............................................................. 14

4.0 Financial Impacts ................................................................................................................ 15

4.1 Process Inputs-Optimization ............................................................................................ 19

4.1.1 Land Utilization .................................................................................................... 19

4.1.2 Water Usage ........................................................................................................ 20

4.1.3 Carbon Dioxide Demand ...................................................................................... 21

4.1.4 Nutrient Usage ..................................................................................................... 22

4.2 Distribution and Utilization .............................................................................................. 23

4.3 Public/Private Partnerships ............................................................................................. 23

5.0 Comparison of Microalgae Biodiesel to Other Fuel Sources .............................................. 23

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5.1 Microalgae Biodiesel vs. Petroleum Products ................................................................. 23

5.2 Microalgae Biodiesel vs. Natural Gas ............................................................................... 25

5.3 Microalgae Biodiesel vs. Other Biofuel Sources .............................................................. 26

5.4 Environmental Benefits of Microalgae Biodiesel ............................................................. 27

6.0 Conclusion ........................................................................................................................... 27

Tables Table 2.1: Chemical Composition (%dry matter basis) of Selected Microalgae

Table 3.1: Advantages and Limitations of Microalgae Biodiesel Production Processes

Table 4.1: Unit Process Cost Contribution

Table 4.2: Stationary CO2 sources in the United States

Table 5.1: Biofuel Source Yield Comparison

Figures Figure 3.1: Microalgae Biodiesel Production Process Flow Diagram

Figure 4.1: Projected Costs of Future Microalgae

Figure 4.2: Life Cycle Analysis of Microalgae Biodiesel Production

Figure 4.3: Production Unit Process Cost Allocation

Figure 4.4: Unit Process Cost Sensitivities

Figure 5.1: History of Crude Oil Prices

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Abstract With the growing concern of fossil fuels and their effect on global climate change, as well as the volatile markets of fossil fuels, there has been an increased demand for a new environmentally friendly source of energy. Many believe that biofuels will have a greater impact on our energy demands to establish sustainable fuel sources and energy independence. First generation biofuels, which are produced from crop seeds, create pressure on agricultural markets by taking up valuable resources necessary for crops and reducing the available supply of crops, therefore, increasing the cost on consumers. There have been recent advancements in the production of biodiesel from microalgae, a second generation biofuel.

Microalgae biodiesel is a more environmentally-friendly, mass-produced product that can meet the performance of petroleum products, provides similar economic benefits as natural gas production, generates higher biodiesel yields than other biofuel sources, and does not compete with food crops for required nutrients. Microalgae biodiesel will be the environmentally friendly source of energy that enables energy independence in the U.S.

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1.0 Introduction Many in the United States (U.S.) and around the world are looking for a more sustainable and financially stable source of energy to meet global energy demands. On December 19th, 2007, the Energy Independence and Security Act of 2007 (EISA) was signed by President George W. Bush. The primary functions of EISA are to:

• Move the U.S. toward greater energy independence and security; • Increase the production of clean renewable fuels; • Protect consumers; • Increase the efficiency of products, buildings, and vehicles; • Promote research on and deploy greenhouse gas capture and storage options; • Improve the energy performance of the Federal Government Many believe that biofuels will have a greater impact on our energy demands to establish sustainable fuel sources and energy independence. Biofuels are generated from biomass or bio waste whose energy is obtained through a process of biological carbon fixation, a process which converts inorganic carbon, such as carbon dioxide (CO2), into organic compounds. Unlike fossil fuels, biofuels either sequester or fix CO2 from the atmosphere through photosynthesis. However, many of the first generation biofuels, which are produced from crop seeds, create pressure on agricultural markets by taking up valuable resources necessary for crops and reducing the available supply of crops. As a result, the increased cost is passed onto the consumer.

There have been recent advancements in the production of biodiesel from microalgae, a second generation biofuel. The first attempt to produce microalgae lipids took place in Germany during and after WWII (Lundquist, Woertz, Quinn, & Benemann, 2010). Research found that many green algae species, when limited with nitrogen, accumulated oil within their cells, accounting for up to 70% of dry weight. Microalgae oil production was revived by the US Department of Energy (DOE), when they initiated the Aquatic Species Program (ASP) in 1980 with the goal of developing cost effective microalgae biofuels production (Lundquist, Woertz, Quinn, & Benemann, 2010). The vision of the ASP was:

“A vast arrays of algae ponds covering acres of land analogous to traditional farming. Such large farms would be located adjacent to power plants. The bubbling of flue gas from a power plant into these ponds provides a system for recycling of waste CO2 from the burning of fossil fuels” (Sheehan, Dunahay, Benemann, & Roessler, 1998)

The research of the ASP found that microalgae were able to produce large amounts of oils that could become competitive with fossil fuels, have a higher oil yield than other biofuel sources, and do not compete with food crops for resources (Singh, Nigam, & Murphy, 2010).

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2.0 Growing Microalgae The products of photosynthesis from microalgae are oxygen, in the form of O2, and organic matter as either carbohydrates or lipids (U.S. Department of Energy, 2010). Lipids are the precursor for biodiesel. The accumulation of lipids begin when microalgae consume nutrients (generally nitrogen) (Singh, Nigam, & Murphy, 2010). An excess of carbon is still integrated within the cells due to the limited supply of nutrients, and is converted into lipids in the form of Triaglycerol (TAG). These TAG molecules provide no structural support for the microalgae cell, but rather act as a source of storage for carbon and energy. The TAG is finally transesterified into biodiesel (see Section 3.3.2) (Singh, Nigam, & Murphy, 2010). Microalgae can complete an entire growth cycle every few days (Lundquist, Woertz, Quinn, & Benemann, 2010).

2.1 Types of Algae There are various types of algae and microalgae, including seaweeds (acroalage), phytoplankton (microalgae), dinoflagellets, green algae (chlorophyceae), golden algae (chryosophyceae) and diatoms (bacillariophyceae). Research has shown that microalgae cells have higher yields than algae cells, and has been the focus of more recent advancements (Schenk, et al., 2008). These cells can range from small single-celled to multicellular organisms, which thrive in brackish fresh and marine water conditions. The three major components of microalgae biomass are protein, carbohydrates and oils (Lundquist, Woertz, Quinn, & Benemann, 2010). However, microalgae biomass has a wide variety of chemical composition (refer to Table 2.1). (Singh, Nigam, & Murphy, 2010)

Table 2.2 -Chemical Composition (%dry matter basis) of Selected Microalgae (Singh, Nigam, & Murphy, 2010)

PROTEIN CARBOHYDRATES LIPIDS NUCLEIC ACID

FRESHWATER ALGAE SPECIES SCENEDESMUS OBLIQUUS 50-56 10-17 12-14 3-6

SCENEDESMUS QUADRICAUDA 47 - 1.9 - SCENEDESMUS DIMORPHUS 8-18 21-52 16-40 -

CHLAMYDOMONAS RHEINHARDII 45 17 21 - CHLORELLA VULGARIS 51-58 12-17 14-22 4-5

CHLORELLA PYRENOIDOSA 57 26 2 - SPIROGURA SP. 6-20 33-64 11-21 -

EUGLENA GRACILIS 39-61 14-18 14-20 - SPIRULINA PLATENSIS 46-63 8-14 4-9 2-5 SPIRULINA MAXIMA 60-71 13-16 6-7 3-4.5

ANABAENA CYLINDRICAL 43-56 25-30 4-7 - MARINE ALGAL SPECIES DUNALIELLA BIOCULATA 49 4 8 -

DUNALIELLA SALINA 57 32 6 - PRYMNESIUM PARVUM 28-45 25-33 22-38 1-2

TETRASELMIS MACULATE 52 15 3 - PORPHYRIDIUM CRUENTUM 28-39 40-57 9-14 -

SYNECHOCCUS SP. 63 15 11 5

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Several investigations have led to the conclusion that microalgae are capable of producing more lipids (biodiesel) in stressed conditions compared to normal conditions (Johnson & Sprague, 1987). Microalgae composition is primarily for energy conversion; their simplistic construction allows them to adapt and thrive in various environmental conditions. Under unfavorable conditions, microalgae may alter their lipid biosynthetic processes to form and accumulate neutral lipids. These lipids generally take the form of TAG at 20-50% dry cell weight, which correlate directly to potential biodiesel yield. (Singh, Nigam, & Murphy, 2010)

2.2 Production Inputs 2.2.1 Carbon Dioxide Since microalgae is approximately 45% carbon, it is an essential input in the microalgae biodiesel production process (Singh, Nigam, & Murphy, 2010). The supply of carbon generally comes in the form of Carbon Dioxide (CO2) during cultivation to help conduct photosynthesis. During cultivation, CO2 must be continuously fed to the microorganisms during daylight hours. Estimates say that approximately 1.8 tons of CO2 is required to produce 1 ton of algal biomass (Wijffels & Barbosa, 2010).

Flue gas of industrial plants could be viable sources of C02 if properly directed to a production facility. However, concerns of excess levels of NOX and SOX potentially inhibiting the cultivation of microalgae would need to be addressed (Schenk, et al., 2008). CO2 could also be recycled from the facility. Anaerobic digestion of spent biomass produces biogas, mostly methane (CH4), that could be combusted to generate CO2 and recycled to the cultivation process (Benemann, 2009). Refer to Section 4.1.4.

2.2.2 Water Estimates say that 1.5 liters of water are required to produce approximately one liter of microalgae based biodiesel, based on the production system (refer to Section 3.1). Freshwater, salt water, effluent municipal wastewater and agricultural runoff water, and brackish water could be viable sources of water.

In open pond systems, extra fresh water needs to be added to account for evaporation. If closed systems are used and are cooled with salt water buffer, freshwater usage can be reduced substantially. Production systems in large water bodies (oceans, lakes, etc.) could be used for cultivation, provided they have adequate protection from wind (Wijffels & Barbosa, 2010).

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The National Renewable Energy Laboratory (NREL) have identified that the high oil producing microalgae species prefer brackish water (Schenk, et al., 2008). The benefit of using brackish water is that it is non potable and not suitable for agricultural uses, reducing competition with other industries. The concern with the use of seawater is that it can contain high levels of heavy metals, trace metals and other toxic compounds. Pretreatment of the salt water may be necessary to reduce these compounds to optimal levels. Also, specific strains of microalgae which have shown the ability to overcome the introduction of these metals and harmful compounds would likely be required (Schenk, et al., 2008). Effluent municipal wastewater and agricultural runoff water would also likely need to be pretreated prior to introduction into the cultivation process to ensure optimum water quality.

2.2.3 Sunlight Large scale cultivation will need to rely on natural sunlight as the main source of light energy (Wijffels & Barbosa, 2010). Research has shown that during summertime or when working at lower elevations, sunlight intensities can be high and can often oversaturate the photosynthetic cycle. Steps need to be taken to increase photosynthetic efficiencies during intense sunlight while reducing the light energy intensity at the reactor surface. This can be accomplished by stacking the reactor units vertically. (Wijffels & Barbosa, 2010)

2.2.4 Nitrogen and Phosphorus Nitrogen and phosphorus are the main nutrients required for microalgae biodiesel production; the biomass of microalgae consists of approximately 7% nitrogen and 1% phosphorus (Wijffels & Barbosa, 2010). Research has shown that all nutrients required for microalgae biodiesel production can be provided by effluent municipal wastewater; allowing microalgae farms to potentially gain income for partially treating public wastewater (Bandala, Chen, & Lee, 2012). Surface run off from agricultural areas could also be used to provide the necessary nutrients to microalgae.

The concern with both effluent municipal wastewater and agricultural runoff is that it could contain high levels of heavy metals, trace metals and other toxic compounds. Again, pretreatment of the water may be necessary, and specific strains of microalgae would likely be required (Schenk, et al., 2008).

2.2.5 Ideal Geographic Locations Microalgae naturally grow in many climates. However, microalgae perform best in more temperate areas, such as the desert environments in the southwestern

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U.S. Currently, the agricultural industry in the southwestern U.S. is confined to cattle and limited production of irrigated crops. The microalgae varieties identified as high oil producers by the National Renewable Energy Laboratory (NREL) prefer brackish water. Brackish water, which is not used for human consumption or agricultural production, is in plentiful supply in the southwestern U.S., making the area ideal for microalgae cultivation. (Schenk, et al., 2008).

3.0 Production Processes Optimizing biofuel production processes is required in order to improve the economics of microalgae based biodiesel. Figure 3.1 lists the unit process for microalgae biodiesel production. These processes include cultivation (algae growth), harvesting (settling, DAF, Centrifuge), and refining (Lipid Extraction, Phase Separation and Upgrading).

Figure 3.1: Microalgae Biodiesel Production Process Flow Diagram (Davis, et al., 2012)

3.1 Cultivation Processes The open pond system is the most basic process for cultivated microalgae. Closed bioreactor systems have been proven to be more efficient at biomass production, but have dramatic increases in energy costs compared to open pond systems. Hybrid systems are becoming more popular to meet the growth efficiency of the closed bioreactors, while meeting the cost efficiency of open pond systems. Once generated, the microalgae must go through different processes in order to achieve the energy output required of microalgae based biodiesel.

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Table 3.1 Advantages and Limitations of Microalgae Biodiesel Production Processes (Singh, Nigam, & Murphy, 2010)

PRODUCTION SYSTEM ADVANTAGES DISADVANTAGES

OPEN POND

• Cost Effective • Low Maintenance • Utilizes non-agricultural land • Low Energy/Utilities • Adequate for Mass Cultivation

• Poor Biomass Productivity • Large land area required • Adequate for only a few algae strains • Poor mixing, light and CO2 capture • Open to atmosphere-easy to contaminate • Difficulties growing algae cultures for long

periods

CLOSED BIOREACTOR (TUBULAR)

• Large illumination surface area • Suitable for outdoor cultures • Cost Effective • Good biomass productivities

• Degree of wall growth • Fouling • Large Land Area Required • Gradients along the tubes of:

o pH o O2 o CO2

CLOSED BIOREACTOR (FLAT PLATE)

• High biomass productivities • Easy sterilization • Low oxygen build up • Readily tempered • Good Light path • Cost Effective • Low Maintenance • Good for immobilization of algae • Large illumination surface area • Suitable for outdoor cultures

• Scale-up requires many compartments/support materials

• Difficult temperature control • Small degree of hydrodynamic stress • Some degree of wall growth

CLOSED BIOREACTOR (COLUMN)

• Compact • High mass transfer • Low energy • Good mixing with low shear stress • Easy sterilization • High potential for scale-up • Readily tempered • Good for immobilization of Algae • Reduced photo inhibition and photo

oxidation

• Small illumination area • Not Cost Effectivce • Shear stress • Technical construction • Decrease of illumination surface area during

scale-up

HYBRID SYSTEM

• Relatively cost effective • High biomass productivity • Continuously supply fresh inoculum into

low nutrient conditions to encourage production and prevent dominance of invasive species

• For large scale operations in series reactors/ponds needed to prevent a shock load

• As the size of the reactors increase, complexity should be reduced to maintain cost efficiency

• Adequate for only a few algae strains

3.1.1 Open Pond Systems An open pond system can either be an open tank or natural pond (Singh, Nigam, & Murphy, 2010). The microalgae are cultivated in suspension, and are introduced to fertilizers and nutrients in the growth medium. CO2 is introduced via gas exchange with natural contact of the pond surface and the atmosphere.

Open pond systems can be built, operated, and maintained efficiently with respect to economics. A broad range of materials can be used to construct the

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ponds since transparency of the walls is not a required specification of the open pond system. The only major input into the open pond system is the power required to drive the paddlewheels in raceway ponds, which are needed to direct the flow of water and create turbulence to ensure adequate sunlight distribution. Maintenance of open ponds systems mainly consists of skimming biofilm that builds up on the surface. Ponds built in wastewater systems are generally designed to use gravity to power the mixture and flow of the water. Algal ponds can also be used in connection with wastewater treatment plants, and can be built using site specific constraints with retaining walls or floor trenches that form the basis of the pond (Schenk, et al., 2008).

The major disadvantages to open pond systems are that they are in fact “open” to the atmosphere, and are susceptible to environmental conditions. Evaporation occurs at rates similar to land crops. Unwanted microorganisms or other species can contaminate the ponds which can severely inhibit biodiesel yields.

Photo 3.1-Open ponds at SunEco Energy pilot plant in Chino, California (http://suneco.inkrefuge.com)

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Photo 3.2- Raceway pond (http://large.stanford.edu/publications/coal/references/hsu/)

3.1.2 Closed Photo Bioreactor Closed Photo Bioreactors (PBRs) are generally considered to be the reactor of choice for microalgae biodiesel production due to their higher yield outputs (Singh, Nigam, & Murphy, 2010). In a closed PBR, microalgae are cultivated in suspension while closed off from the elements. Artificial heat and light are used in some applications (Singh, Nigam, & Murphy, 2010). Most closed bioreactors are designed as either tubular, plate, or bubble column reactors. (Schenk, et al., 2008)

Microalgae have low photosynthetic efficiencies when oversaturated with light energy. Therefore, closed PBRs must be designed to improve light distribution over a large surface area to not oversaturate any microalgae culture with excess light energy. This is usually achieved by arranging the tubular reactors in “fence-like” construction, or stacked vertically. These stacks are generally oriented in a north-south direction to prevent oversaturation of light energy to the surface and to dilute light energy in the horizontal and vertical directions. Optimizing the light dilution requires the bioreactor surface area to be significantly larger than the used footprint of the reactor system; research shows surface area to volume ratios of 400m2/m3 provide increased biomass concentrations. (Schenk, et al., 2008)

External dirt and microalgae accumulate in each PBR that over time prevent the introduction of light (Singh, Nigam, & Murphy, 2010). Closed PBRs must be mixed at all times to prevent sedimentation of cells and properly distribute

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required inputs (refer Section 2.2) throughout the microalgae. Mixing also contributes to light energy dilution by enabling all cultures to receive equivalent levels of light energy at the surfaces of the reactors (Schenk, et al., 2008).

Closed PBRs can support up to five times higher productivity of microalgae biomass and have smaller operational footprints on yield basis than open ponds. However, closed PBRs use large amounts of water, energy, and chemicals to produce the increased yield (Schenk, et al., 2008). Closed PBRs are being designed to minimize costs when possible: transparent pipes to allow continuous natural light; gravity powered feed of growth medium; bubbling CO2 to maximize capture, etc. (Singh, Nigam, & Murphy, 2010).

Photo 3- Closed Photobioreactors (http://www.renewablegreenenergypower.com/algae-biodiesel/)

3.1.3 Hybrid Systems Open ponds are efficient and cost effective, but run the risk of contamination. Closed bioreactors produce high biomass yields, but are up to ten times more expensive than open pond systems to construct and operate (Schenk, et al., 2008). Hybrid systems include the use of both the open pond and closed bioreactor systems. Desired strains are first cultivated in closed bioreactors, which allows for effective protection of the cultivated microalgae from contamination (Singh, Nigam, & Murphy, 2010). Once enough of the strains are cultivated, they are then inoculated into open pond systems. Inevitably, unwanted species will breakthrough and dominate the open system; the time to breakthrough depends on the environmental conditions and the physical

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characteristics of the unwanted species. The pond then must be flushed to reduce contamination and clean the pond. (Schenk, et al., 2008)

For large scale operations, it is likely that a series of reactors and ponds will be needed in order to prevent a shock load to the cultivated strain. As the size of the reactors increase, complexity (nutrient and input loads, mixing, etc.) should be reduced to improve cost efficiency. In order to maximize an in-series reactor operation, an algal specie that is fast growing in the early inoculum stages and productive in the late open pond stage, will need to be continuously supplied into the open ponds at low nutrient conditions (Schenk, et al., 2008). This introduction will encourage continuous production of microalgae biodiesel while preventing the dominance of invasive species.

3.2 Harvesting Processes Due to large water content in microalgae, the harvesting methods must be improved to be more cost effective and energy-efficient to improve the economics of microalgae biodiesel production. In general practice, the goal is to achieve 2-7 % of suspended microalgae in a dry matter basis. Deciding which harvesting method to use depends on the size and other properties of the specific strain harvested (Singh, Nigam, & Murphy, 2010). In some cases, pretreatment may also be required to improve the biomass yield. Current algal aquaculture use flocculation, micro-screening and centrifugation (Schenk, et al., 2008). Flocculation is mostly applied to harvesting from open pond systems, while micro-screening and centrifugation are mostly applied to closed PBRs (Singh, Nigam, & Murphy, 2010).

3.2.1 Flocculation Flocculation is the aggregation and sedimentation of the biomass in thickener or clarifiers, similar to wastewater treatment standards (Singh, Nigam, & Murphy, 2010). When a strain has poor natural sedimentation standards, flocculants (inorganic or organic compounds) are added to the water to allow microalgae to increase particle size and to increase sedimentation. Inorganic compounds (alum, ferric chloride) are too expensive for large scale operations. Organic cationic polymers are preferred because much less is required, and can be used during other downstream processes (Schenk, et al., 2008). Although the capital and operating costs of flocculation are relatively low, the efficiency of the mass removal, especially in shallow depth ponds, is low (Singh, Nigam, & Murphy, 2010).

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3.2.2 Micro-Screening Micro-screening, or filtration, is popular at a laboratory scale. But in order to work in a large scale cultivation, larger microalgae strains would be necessary to improve the screening effectiveness (Schenk, et al., 2008). The screening process can range from simple screening of the cultivated microalgae, to complex pressure filtration systems (Singh, Nigam, & Murphy, 2010).

3.2.3 Centrifugation Centrifugation is determined by Stoke’s Law, in which the sedimentation velocity is directly related to the cell density and cell radius (Schenk, et al., 2008). The overall principal of centrifugation is to accelerate the sedimentation process (Singh, Nigam, & Murphy, 2010). Commercial grade centrifuges can operate with either rotating walls or with fixed walls. These centrifuges create 10,000 g forces to separate out the dense solids (microalgae) from the liquids (water).

3.3 Refining Processes

3.3.1 Drying Biomass In order to extract the lipids to produce oil, the harvested microalgae biomass must be dried (Singh, Nigam, & Murphy, 2010). Several technologies can be used to conduct the drying process, including spray drying, rotating drum drying, and flash drying. Research shows that biomass with wetted microalgae concentrations of 15-25% needs to be dried/processed to a 90% concentration. Estimates say that 70% of the energy required for the overall production of microalgae biodiesel is accounted for in the drying process: evaporating 1kg of water will always require at least 800kcal of energy (Singh, Nigam, & Murphy, 2010).

3.3.2 Lipid Extraction and Transesterification Lipid Extraction:

Lipid extraction is the process of relieving the lipids from the microalgae cell in order to utilize it. Lipid extraction can be achieved through several methods, including solvent extraction, osmotic shock, ultrasonic extraction, and critical point CO2 extraction. The solvent most utilized for extraction is hexane, either used alone or in combination with oil expeller or press. The oil dissolves in

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cyclohexane when extracted from the microalgae pulp. The oil is then separated from the cyclohexane by distillation. This two stage process accounts for more than 95% of the oil present in the microalgae. (Singh, Nigam, & Murphy, 2010)

Osmotic shock is the sudden reduction in osmotic pressure, which causes cells to rupture and release cellular components, including oil. Certain microalgae species which lack cell walls are more suitable for this extraction process (Singh, Nigam, & Murphy, 2010). Ultrasonic extraction is when ultrasonic waves create cavitation bubbles in a solvent. The bubbles then collapse near the cell walls. This causes the cell walls to break and release the oil into the solvent. Critical point CO2 extraction is the most chemically efficient process; however the higher energy costs make it unsuitable for large scale biodiesel production.

Transesterification:

Transesterification, which is the chemical reaction required to produce Biodiesel, is the addition of three molecules of alcohol to one molecule of natural oil, or lipids performed at a high pH (Schenk, et al., 2008). The result is fatty acid alkylester and glycerol as by-products (Singh, Nigam, & Murphy, 2010).

Transesterification is sensitive to the presence of water, which can negatively impact the yield and quality of the biodiesel. Saponification reactions occur when in the presence of water. Unsaturated fatty acids may also cause similar problems because they can induce cross linking of fatty acid chains, creating tar formation in the biomass.

4.0 Financial Impacts For years, the DOE has been conducting research and analysis in identifying efficiencies, needs, and the directions for research and development for algal oil feedstock production to establish cost analyses (i.e. algal productivity, capital depreciation costs, operating costs, co-product credits, etc.) (U.S. Department of Energy, 2010). While most citable sources are fairly dated, they present a wide variability in approach to final costs (from per gallon of algal oil to per kg of “raw” biomass). Cost estimates of algal production vary greatly due to differences in assumptions regarding technology costs, productivity, improvements, and possible legal obligations (i.e. carbon credits) (Christiansen, 2011). Furthermore, existing analyses have ignored the potential of capital growth and under performance of early generation production facilities, which impact the early unit cost of algal biofuels, potentially affecting investment decisions. However, research and analysis has concluded that with a combination of improved

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biological productivity and fully integrated production systems, the cost of microalgae biodiesel can be reduced to approximately $100 per barrel to be competitive with petroleum products (Christiansen, 2011). The DOE also believes that as production increases, the cost per gallon of biodiesel will decrease (refer to Table 4.1).

Figure 4.1: Projected Costs of Future Microalgae Biodiesel (Reed, 2012) http://energy.gov/sites/prod/files/2014/03/f14/obp_overview_algae_summit.pdf

In order for biodiesel to become more suitable in meeting global energy demands, economic feasibility for industrial production must be achieved. There are costs associated with the inputs described in Section 2.2, the cultivation processes in Section 3.1, the harvesting processes in Section 3.2 and the refining processes in Section 3.3. Before focusing efforts for process optimization can begin, one must first understand the associated costs with each unit process.

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Figure 4.2: Life Cycle Analysis of Microalgae Biodiesel Production (Reed, 2012)

Table 4.1 depicts the total cost allocation for each process step and the associated unit-level capital cost translated to a common functional unit (Davis, et al., 2012). Figure 4.3 also presents the allocated cost of each unit process compared to the entire production process (Reed, 2012). Based on Table 4.1 and Figure 4.3, the ponds for cultivation generate the greatest single cost burden after considering all capital expenses (inoculum system, cultivation ponds, and land cost) and operating expenses (nutrient costs, power costs, labor, and maintenance). The centrifuge process represents the lowest cost burden for capital expenses; however, it represents the highest operation costs for the harvesting and dewatering processes.

Table 4.1: Unit Process Cost Contribution (Davis, et al., 2012)

PROCESS AREA UNIT OPERATION $/GAL CONTRIBUTION CAPEX COSTS (DIRECT INSTALLED COSTS PER

FUNCTIONAL UNIT) BIOMASS PRODUCTION Ponds(inoculation, cultivation,

land cost) $6.70 $22,000/acre pond

Liners $5.43 $20,000/acre pond Infrastructure (CO2/water delivery, minor equipment $1.50 $5,700/acre pond

HARVESTING AND DEWATERING

Primary Settling $1.52 $134,100/MGD to primary harvesting

DAF $1.05 $5,000/ MGD to primary harvesting

Centrifuge $0.17 $16,000MGD to primary harvesting

EXTRACTION AND FRACTIONATION

Cell Disruption $0.51 $25,200/(dry ton/day) algae to extraction

Extraction/Separation $0.36 $7,500/(dry ton/day) algae to extraction

SPENT BIOMASS UTILIZATION AD + CHP System $0.56 $42,300/(dry ton/day) algae to extraction

CONVERSION Hydrotreating $0.83 $190/(gal/day) oil

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Figure 4.3: Production Unit Process Cost Allocation (Reed, 2012)

Figure 4.4 shows the cost sensitivity and potential variability of several of the unit processes. Increased efficiency reduces the production costs, while decreased efficiency increases the cost (Davis, et al., 2012). The extraction efficiency process shows the highest cost sensitivity and variability. When the extraction efficiency is increased to 100%, the diesel price decreases by $2.80/gal; when decreased to 60%, the cost increases by $8.30/gal. The extraction efficiency sensitivity is due to the high cost of ponds and liners, whose expense in growing algal biomass goes to waste if the lipids are not recovered. This is not due to the extraction cost itself, which is listed independently on Figure 4.4. Other costs associated with biodiesel production may have greater capital and operational costs, however are not included on Table 4.4 due to the limited cost sensitivity and variability.

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Figure 4.4: Unit Process Cost Sensitivities (Davis, et al., 2012)

4.1 Process Inputs-Optimization The inputs required for the biodiesel production process need to be optimized to improve the economics of microalgae biodiesel production. Optimization of each input includes land utilization, water usage, and facilitating for both CO2 nutrient demand.

4.1.1 Land Utilization For large scale production, large areas of land for both open pond systems and closed PBRs are required. Estimates say that to produce 10 million gallons of oil feedstock annually, a range of 800 to 2,600 acres of microalgae cultivation surface area is required (U.S. Department of Energy, 2010).

The availability of land is influenced by various factors: physical, social, economic, legal/political, etc. (U.S. Department of Energy, 2010). Physical characteristics, including topography and soil, could affect both the availability and the price of land.

As mentioned in Section 2.2.5, ideal locations for microalgae biodiesel production are considered to be in the arid deserts of the southwest U.S. (Schenk, et al., 2008). However, a vast amount of land in the western U.S. is government owned: national parks, national forests, etc. (U.S. Department of Energy, 2010). Public and private ownership of the desired land could have various legal obstacles that will need to be navigated in order to be utilized

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(environmental impacts, non-competition agreements, profit sharing, public support, etc.).

4.1.2 Water Usage A major proponent to the development of microalgae biodiesel is the potential to use water not otherwise required for agriculture or potable purposes. However, water demand will have significant impacts on the economic feasibility of microalgae biodiesel; mismanagement could easily lead to the loss of public support. (U.S. Department of Energy, 2010)

As the cultivation systems increase, so do the water demands. In an example established by Goebel, Tillet and Weissman, a hypothetical 1 hectare (ha), 20 cm deep open pond would require 530,000 gallons to fill. In an arid desert, evaporation could exceed 0.5 cm per day; in a 1 ha pond that equates to a loss of 13,000 gallons of water per day (Weissman, Tillet, & Goebel, 1989). Therefore, water conservation will need to be at the forefront in developing sustainable and economically effective production facilities.

A potential solution to water conservation can be found in the design and layout of the facility. (U.S. Department of Energy, 2010). The production facility should be designed to maximize gravity power when possible. Recycling water should be considered; however, the amount of water that can be recycled depends on the algal strain, water, process, and location. Some algal cultures can double their biomass on a daily basis during cultivation, which in turn means half of the culture volume must be processed on a daily basis, potentially up to 260,000 gallons per day in the example established by Goebel, Tillet and Weissman (U.S. Department of Energy, 2010). Therefore, recycling water may prove to be economically beneficial. However, increased energy would be required to return the large volume of water back into the system, which would inevitably increase operation costs.

Analysis and/or treatment of water entering and exiting the facility, as well as water being returned to the process, would be necessary. The quality of the returned water would need to be verified to ensure it is adequate for cultivation purposes. Incoming water (surface water, groundwater, wastewater, or seawater) may require certain levels of decontamination, disinfection, or other remediation prior to use, depending on the entering quality (U.S. Department of Energy, 2010).

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4.1.3 Carbon Dioxide Demand Efficient microalgae cultivation will require CO2 at levels not attainable through natural diffusion from the atmosphere. Therefore, a steady supply will be required for a production facility. Flue gas from industrial facilities could be a viable option for CO2 supply, and could prove to be mutually beneficial to the industrial facilities for repurposing their emissions rather than releasing to the atmosphere post air scrubbing. These sources, represented in Table 4.4, are stationary in their location, and are generally represented by power generation or geographically locked industries, providing potentially long-term sources of adequate supply of CO2.

Table 4.2: Stationary CO2 sources in the United States (U.S. Department of Energy, 2010)

CATEGORY CO2 EMISSIONS (MILLION METRIC TON/YEAR) NUMBER OF SOURCES

AG PROCESSING 6.3 140 CEMENT PLANTS 86.3

112

ELECTRICITY GENERATION 2,702.5

3,002 ETHANOL PLANTS 41.3

163

FERTILIZER 7.0

13 INDUSTRIAL 141.9

665

OTHER 3.6

53

PETROLEUM AND NATURAL

GAS PROCESSING

90.2

475

REFINERIES/CHEMICAL 196.9

173

TOTAL 3,276.1 4,796

However, it must be noted that microalgae production will not effectively sequester CO2 emissions, but rather capture and repurpose the emissions maintaining a certain level instead of increasing emissions. Also, the CO2 generated flue gas can only be effectively utilized in the cultivation process during active sunlight hours for photosynthesis to occur. CO2 emissions during non-active sunlight hours will still need to be off-gased. The flue gas would likely require pretreatment to remove any likely toxins and heavy metals prior to introduction into the cultivation process. (U.S. Department of Energy, 2010)

As mentioned in Section 2.2.1, CO2 could also be recycled from the facility. Anaerobic digestion of spent biomass produces biogas, mostly methane (CH4), that could be combusted to generate CO2 and recycled to the cultivation process (Benemann, 2009). This supply of CO2 will likely be cleaner than the supply from flu gas, and would be ready to direct introduction to the cultivation process.

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4.1.4 Nutrient Usage Supply, availability and cost of nutrients (Nitrogen, Phosphorus, Potassium, etc.) required for microalgae growth will also play a role in economic feasibility for mass production of microalgae biodiesel. Taking into account up to 50% nutrient recycle, nitrogen, phosphorous, and iron additions represent a significant operating cost, accounting for 6-8 cents per gallon of algal fuel in 1987 U.S. dollars (U.S. Department of Energy, 2010) (Benemann, 2009).

Sources of the nutrients then become the driving force behind the economics. Utilizing virgin or reagent grade nutrients would likely drive up the cost of microalgae biodiesel. Nutrients from industrial sources could be viable (U.S. Department of Energy, 2010). However, transporting the sources to a biodiesel production facility will likely raise the cost of production to unfeasible levels. Therefore, utilization of readily available resources need to be considered: direct input from industrial and municipal waste streams and the recycling of nutrients already introduced into the microalgae cultivation process.

Industrial Waste Streams:

Utilizing municipal, agricultural, or industrial waste streams (wastewater, flue gas, agriculture runoff, etc.) for nutrient supply is a viable option. Microalgae are used in some wastewater treatment facilities within the U.S. for their ability to generate oxygen for the bacterial breakdown of organic materials and to sequester nitrogen, phosphorous, and other constituents into biomass in efforts to conduct water clean-up (U.S. Department of Energy, 2010).

Nutrient Reuse:

Another popular option to reduce costs is to practice diligent recycle. The final algal oil product that is ready for distribution does not contain nitrogen, phosphorous, or iron, which generally end up in the waste biomass. That spent biomass is then utilized in various sources, such as animal feed. However, nutrient recycle could potentially prove to be more economically beneficial for microalgae biodiesel production than wholesale of spent biomass. For example, if the spent biomass is treated by anaerobic digestion, biogas is produced that is comprised of mostly methane (CH4) and CO2. The nutrients will then be

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concentrated in the digester sludge and can be reintroduced into the cultivation process for utilization (Benemann, 2009).

4.2 Distribution and Utilization The delivery of nutrients/supplies, fuel intermediates, and final products from a biodiesel production facility to the consumer will play a vital role in economic feasibility for mass production of microalgae biodiesel (U.S. Department of Energy, 2010). The distribution of biodiesel can be lowered in four ways:

• Minimizing transport distance between process units; • Maximizing the substrate energy-density and stability; • Maximizing compatibility with existing infrastructure (e.g. storage tanks, high

capacity delivery vehicles, pipelines, dispensing equipment, and end-use vehicles);

• Optimizing the scale of operations to the parameters stated above.

To be utilized, specifications by organizations such as ASTM International must be met to ensure that a fuel is fit for purpose. In addition, algal biofuels, like all transportation fuels, must meet EPA regulations on engine emissions (U.S. Department of Energy, 2010). Microalgae biodiesel already being developed commercially has been proven to meet these standards.

4.3 Public/Private Partnerships In order for biodiesel to become more suitable in meeting global energy demands, public and private partnerships will need to be created for true development. The development of these partnerships will help accelerate the development of microalgae biodiesel with shared knowledge of all the unit processes. These partnerships will also establish the market in terms of developed infrastructure (pipelines, fillings stations, etc.), and labor forces to operate the production and distribution (U.S. Department of Energy, 2010).

5.0 Comparison of Microalgae Biodiesel to Other Fuel Sources

5.1 Microalgae Biodiesel vs. Petroleum Products In 2011, both the Navy and Continental Airlines flew aircraft using biofuel made from algal oil mixed with standard jet fuel (Sherin & Norman, 2013). Biodiesel can be utilized

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in existing petroleum diesel engines in blends up to 20 percent (B20) with little impact on operating performance (National Biodiesel Board, 2014). B20 also provides similar fuel economy, horsepower, torque, and haulage rates as petroleum diesel fuel. Biodiesel also has superior lubricity, and it has the highest BTU content of any alternative fuel.

Studies have found that microalgae biodiesel can reduce CO2 emissions by 50-70% compared to petroleum-based fuels, and that microalgae biofuel is close to matching the Energy Return on Investment (EROI) of fossil fuels (Marks, 2013). In 2008, the DOE found that to completely replace petroleum in the United States with microalgae biodiesel, an area of approximately 30,000 square kilometers of land, nearly half the total area of South Carolina, would be required. Researchers at the Pacific Northwest National Laboratory recently concluded that potentially 14% of the land in the continental U.S. (equivalent to the combined area of Texas and New Mexico) could be utilized for microalgae biodiesel production (Marks, 2013). Since much of the southwest U.S. is either undeveloped or underutilized, there is certainly a potential land availability necessary for a transition from fossil fuels to domestically produced microalgae biodiesel.

Figure 5.1 History of Crude Oil Prices (Ro, 2014)

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As shown in Figure 5.1, historically the market price of crude oil has been highly volatile. Petroleum products can either be relatively cheap or fairly expensive (Sherin & Norman, 2013). As of January 12, 2015, crude oil costs less than $50 per barrel, dropping below $2 per gallon (Friedman, 2015). However, in 2008 the price of crude oil was nearly $134 dollars per barrel (U.S. Energy Information Administration, 2015). The global price of oil can be impacted by production levels and the cost of distribution, but can also be severely impacted by political events in the region (i.e. the Oil Embargo from 1973-74, the Iranian Revolution from 1978-79, the Arab Spring in 2011, etc.). Economies that rely on the consumption of petroleum products are subject to the volatility of the global crude oil market. The production and distribution of microalgae biodiesel will provide economic stability by reducing the reliance on foreign oil imports as well as the benefit of job creation enabled by the new market.

5.2 Microalgae Biodiesel vs. Natural Gas Domestically produced natural gas has provided a recent boom in the U.S. energy market, supplying cheap energy throughout the country, fueling nearly 40 percent of the country’s electricity generation, and is being considered for further utilization in the transportation sector (Grace Communication Foundation, 2015). This boom has been enabled by modern technology that combines a new form of horizontal drilling with hydraulic fracturing – more commonly known as fracking. Fracking occurs by injecting a high pressure combination of fluid compounds into open fissures in underground shale-rock formations, forcing natural gas to flow to the production well.

Millions of gallons of fracking fluid, which consist of water, sand and toxic chemicals, are used during the fracking process (Natural Resource Defense Council, 2014). Some of the fracking fluid remains in the shale-rock formations, potentially contaminating groundwater in the future. However, much of it is brought back to the surface as wastewater that consists of fracking chemicals. This waste water may potentially contain levels of naturally occurring radioactive materials and metals found in the surrounding subsurface. The wastewater is often pumped into holding ponds where it can leak and settle into surrounding groundwater and impact wildlife (Grace Communication Foundation, 2015).

Fracking for natural gas poses potential threats to water, air, land, and the health of communities (Natural Resource Defense Council, 2014). Groundwater contamination is a major concern for those who rely on drinking water wells near drilling operations (Grace Communication Foundation, 2015). Contamination of watersheds can pose threats to citizens hundreds of miles away that are reliant on watersheds contaminated

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from fracking operations. Studies have also shown toxic air pollution near fracking sites at dangerous levels; methane leaks profusely throughout the extraction, processing, and distribution of the gas (U.S. Energy Information Administration, 2015). Gas extraction reportedly can result in smog in rural areas at levels worse than downtown Los Angeles. Gas fracking and production has also been linked to increased risk of cancer, birth defects and seismic activity in neighboring areas.

Natural gas is domestically produced, and has provided an economic boom to the U.S. However, it has shown to have severe potential environmental impacts to the neighboring communities and environment, and should not be heavily relied upon as a sole energy source. Similarly, microalgae biodiesel will also be domestically produced and provide an economical boost from job creation enabled by the new market. However, microalgae biodiesel production does not inject contaminated water into the subsurface and is able to reuse the water already within the production process. Microalgae fix CO2 emissions from other industrial facilities and can repurpose the methane generated from the digested biomass.

5.3 Microalgae Biodiesel vs. Other Biofuel Sources It is believed that microalgae is either on par with, or better than, first generation biofuels and other second generation biofuel sources in terms of environmental and energy benefits (Marks, 2013). Oil-rich microalgae species are productive fuel crops, generating 10–100 times higher biomass and oil yield than other biofuel sources (refer to Table 5.1) (Bracmort, 2013). For example, microalgae with up to 50% lipid content, and a dry biomass productivity of 50 g/m²/day, can potentially produce 10,000 gallons oil/acre/year. By comparison, the next productive biofuel source is Palm Tree oil at 635 gallons/acre/year. Microalgae can be cultivated and harvested year round under different climatic conditions, but do not compete with food crops for arable land and potable water (Li & Wan, 2011).

Table 5.1: Biofuel Source Yield Comparison (Li & Wan, 2011)

CROP OIL YIELD

(GALLONS/ACRE/YR) Soybean 48

Camelina 62 Sunflower 102

Jatropha 202

Oil palm 635

Algae 10g/m²/day at 15% Triglycerides 1,200

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50g/m²/day at 50% Triglycerides 10,000

5.4 Environmental Benefits of Microalgae Biodiesel Microalgae biodiesel has many potential environmental benefits. Microalgae biodiesel production can limit its demand of fresh potable water by utilizing effluent municipal waste water, brackish water, saline water, or recycled water from within the cultivation and harvesting processes. Microalgae can provide fixing of CO₂ in the atmosphere, i.e., by conducting photosynthesis utilizing CO2 emitted from industrial facilities, or by utilizing CO2 regenerated from biogas produced by anaerobic digestion of the spent biomass. The biogas generated from the digested biomass can also be combusted to generate electricity that can help supply some of the energy demands of a production facility, a proven technology currently utilized in many wastewater facilities (Benemann, 2009).

Microalgae cultivation can provide treatment of wastewater by efficiently removing nutrients (i.e. nitrogen, phosphorous, etc.) and heavy metals (Li & Wan, 2011). Unlike the lipids in the microalgae cell, the nutrients required during the cultivation process are not part of the actual biodiesel makeup and are concentrated in the digested spent biomass. These nutrients can be recycled back into the cultivation process (Benemann, 2009).

Microalgae biomass can also be used for a variety of fuels and valuable co-products, including renewable hydrocarbons, alcohols, biogas, animal feed, fertilizers, industrial enzymes, and surfactants (U.S. Department of Energy, 2010).

6.0 Conclusion Microalgae biodiesel can potentially reduce CO2 emissions by 50-70% compared to petroleum-based fuels. B20 blends can be utilized in existing petroleum diesel engines with little to no alterations and can provide similar performance levels. Similar to natural gas production, microalgae biodiesel will also be domestically produced and provide an economical boost from job creation enabled by the new market. However, unlike natural gas production, microalgae biodiesel production does not create negative environmental impacts to the neighboring communities and environment.

Microalgae biodiesel is on track to outperform all first and other second generation biofuel sources. Currently, there are microalgae biodiesel products which meet the listed standards and have been optimized to be competitive in today’s energy market. Soladiesel BDR can be used with factory-standard diesel engines without modification and is fully compliant with the ASTM D 6751 specifications. Its emissions are able to outperform ultra-low sulfur diesel

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products, and demonstrates better cold temperature properties than other commercially available biodiesel.

Historically, the market price of crude oil has been highly volatile based on production levels, the cost of distribution, and by political events in the region. Economies that rely on the consumption of petroleum products are subject to the volatility of the global crude oil market. And with the consumption of petroleum products raising concerns over their impact on global climate change, there has been a demand in the U.S. for energy independence with cleaner and more sustainable energy sources. The U.S. DOE is promoting the use of microalgae biodiesel, and has a goal to bring the cost of microalgae biodiesel production down to nearly $100/barrel in order to compete with petroleum products.

Microalgae species can generate higher oil yield than other biofuel sources, can be cultivated and harvested under different climatic conditions, and do not compete with food crops for valuable resources. Microalgae biodiesel production can utilize waste water, produced water, brackish and saline water, recycled water and nutrients, and can generate CO2 and power to be reused from anaerobically digesting spent biomass.

In conclusion, microalgae biodiesel is the energy source of the future. When fully implemented, the production and distribution of microalgae biodiesel will provide an environmentally friendly and renewable source of energy, create economic stability by reducing the reliance on foreign oil imports, as well as through job creation enabled by the new industry.

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