This document discusses microalgae biodiesel as a sustainable source of biofuel. It describes how microalgae can be grown using carbon dioxide, water, sunlight and nutrients to produce lipids that can be extracted and processed into biodiesel. The document compares microalgae biodiesel production to petroleum, natural gas and other biofuels. It finds that microalgae biodiesel yields higher volumes than other biofuel sources, does not compete with food crops for resources, and can sequester carbon dioxide from power plant emissions. The conclusion is that microalgae biodiesel production offers an environmentally friendly domestic source of energy.

1. NORWICH UNIVERSITY
Algae Fuel
The Future of Biofuel and Energy Production
Andrew Pieroni
2/16/2015

2. 1
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

3. 2
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

4. 3
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.

5. 4
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).

6. 5
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

7. 6
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).

8. 7
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

9. 8
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.

10. 9
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

11. 10
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)

12. 11
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

13. 12
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

14. 13
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).

15. 14
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

16. 15
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

17. 16
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.

18. 17
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

19. 18
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.

20. 19
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

21. 20
(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).

22. 21
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
CEMENTPLANTS 86.3 112
ELECTRICITY GENERATION 2,702.5 3,002
ETHANOLPLANTS 41.3 163
FERTILIZER 7.0 13
INDUSTRIAL 141.9 665
OTHER 3.6 53
PETROLEUMANDNATURAL
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.

23. 22
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

24. 23
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

25. 24
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)

26. 25
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

27. 26
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

28. 27
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

29. 28
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.

30. 29
References
Anderson, V., Broberg, S., & Hackl, R. (2011). Integrated Algae Cultivation for Biofuels Production in
Industrial Clusters. EnergiSystem.
Bandala, E. R., Chen, B., & Lee, K. T. (2012, May). Technoeconomic Assessment on Innovative Biofuel
Technologies: The Case of Microalgae. Retrieved from International Scholoarly Research
Network-Renewable Energy.
Benemann, J. R. (2009). Microalgal Biofuels: A Brief Introduction. John Benemann.
Bracmort, K. (2013). Algae's Potential as a Transportation Biofuel. Congressiona Research Service.
Casey, T. (2014, October 1). $25 Million Algae Biofuel Blitz Planned by Energy Departmen. Retrieved
from Clean Technica: http://cleantechnica.com/2014/10/01/25-million-algae-biofuel-blitz-
planned-energy-department/
Christiansen, K. L. (2011). Cost Structures and Life Cycke Impacts of Algal Biomass and Biofuel
Production. Iowa State University.
Davis, R., Fishman, D., Frank, E. D., Wigmosta, M. S., Aden, A., Coleman, A. M., . . . Wang, M. Q. (2012).
Renewable Diesel From Algal Lipis: An Integrated Baseline for Cost, Emissions, and Resource
Potential from a Harmonized Model. U.S. Department of Energy.
Friedman, N. (2015). Oil Prices Fall to Fresh Lows. The Wall Street Journal.

31. 30
Goldenberg, S. (2010, February 13). Algae to Solve the Pentagon's Jet Fuel Problem. Retrieved from The
Guardian: http://www.theguardian.com/environment/2010/feb/13/algae-solve-pentagon-fuel-
problem
Grace Communication Foundation. (2015). Natural Gas Fracking Introduction. Retrieved from Grace
Communication Foundation: http://www.gracelinks.org/191/natural-gas-fracking-introduction
Johnson, D. A., & Sprague, S. (1987). FY 1987 Aquaitc Species Program. Golden, Colorado: Solar Energy
Research Institute.
Li, Y., & Wan, C. (2011). Algae for Biofuels. The Ohio State University.
Lundquist, T. J., Woertz, I. C., Quinn, N. W., & Benemann, J. R. (2010). A Realistic Technology and
Engineering Assessment of Algae Biofuel Production. Berkeley, California: Univeristy of
California- Energy Biosciences Institute.
Marks, J. (2013, September 20). Algae Biofuel Emits at Least 50% Less Carbon than Petroleum Fuels.
Retrieved from Inhabit.com: http://inhabitat.com/algae-biofuel-emits-more-than-half-the-
carbon-emissions-of-petroleum/
National Biodiesel Board. (2014). Biodiesel Myths Busted. Retrieved from biodiesel.org:
http://www.biodiesel.org/docs/default-source/ffs-basics/biodiesel-myths-vs-
facts.pdf?sfvrsn=14
Natural Resource Defense Council. (2014). Unchecked Fracking Threatens Health, Water Supply.
Retrieved from Natural Resource Defense Council: http://www.nrdc.org/energy/gasdrilling/
Pienkos, P. T., & Darzins, A. (2008). The Promise and Challenges of Microalgal-derived biofuels. Wiley
InterScience.
Rapier, R. (2012, May 7). Current and Projected Costs for Biofuels from Algae and Pyrolysis. Retrieved
from Energy Trends Insider: http://www.energytrendsinsider.com/2012/05/07/current-and-
projected-costs-for-biofuels-from-algae-and-pyrolysis/
Reed, V. (2012, September 25). Biomass Program. Retrieved from U.S. Department of Envery: Energy
Efficiency & Renewable Energy:
http://energy.gov/sites/prod/files/2014/03/f14/obp_overview_algae_summit.pdf
Richardson, J. W., Outlaw, J. L., & Allison, M. (2010). The Economics of Micro Algae. Retrieved from
AgBioForum.
Ro, S. (2014, December 19). Annotated History of Oil Prices since 1961. Retrieved from Business Insider:
http://www.businessinsider.com/annotated-history-crude-oil-prices-since-1861-2014-12

32. 31
Schenk, P. M., Thomas-Hall, S. R., Stephens, E., Marx, U. C., Mussgnug, J. H., Posten, C., . . . Hankamer, B.
(2008, March 4). Second Generation Biofuel: High Efficiency Microalgae for Biodiesel
Production. Bioenergy Resources.
Sheehan, J., Dunahay, T., Benemann, J., & Roessler, P. (1998). A Look Back at the U.S. Department of
Energy's Aquatic Species Program-Biodiesel from Algae. Golden, Colorado: national renewable
Energy Laboratory.
Sherin, J., & Norman, E. (2013). Is Algae Fuel a Viable Alternative to Petroleum. University of California-
San Diego: School of Management.
Singh, A., Nigam, P. S., & Murphy, J. D. (2010, June 9). Mechanism and Challenges in Commercialisation
of Algal Biofuels. Bioresource Technology.
Soladiesel. (2014). Retrieved from Solazyme: http://solazyme.com/solutions/fuel/?lang=en
U.S. Department of Energy. (2010). National Algal Biofuels Technology Roadmap. Energy Efficiency &
Renewable Enery-Biomass Program, U.S. Department of Energy. U.S. Department of Energy.
U.S. Energy Information Administration. (2015, February 11). Retrieved from U.S. Energy of Information
Administration : http://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=RWTC&f=M
Weissman, J. C., Tillet, D. M., & Goebel, R. P. (1989). Design and Operation of an Outdoor Microalgae
Test Facility. Golden, Colorado: Solar Energy Researcj Institute.
Wijffels, R. H., & Barbosa, M. J. (2010, August 13). An Outlook on Microalgal Biofuels. Science Magazine,
pp. 796-799.