Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 27
2
Overview of
Algal Biofuel Supply Chain
A
ssessing the sustainability of algal biofuels requires an understanding of the indi
vidual components that make up potential supply chains. This chapter focuses
on the basic processes of algal biofuel production from the biology and traits of
the organisms, to methods for cultivation, and to processing into liquid fuels. It discusses
algal strains and the attributes of those strains critical for biofuel production, the photo
auto trophic methods for algae cultivation through open-pond and closed photobioreactor
systems, the processes for collection and dewatering if necessary, and the processing of
algal lipid, biomass, or secreted products into fuels. It provides the basic descriptions of the
supply chain components used in later chapters and summarizes some critical process
improve ments that could enhance the overall sustainability of algal biofuels.
2.1 ALGAL FEEDSTOCKS
The organisms considered as potential feedstock for algal biofuel production belong to
a vast and diverse assemblage of aquatic organisms that carry out oxygen-evolving pho-
tosynthesis and lack the stems, roots, leaves, and embryos of plants (Leliaert et al., 2011).
The category includes eukaryotic species that are related to the plant lineage and can be
further categorized as macroalgae that are large structured species (for example, kelps) or
microalgae that are microscopic species (for example, Nannochloropsis spp.). In the context
of biofuel, the term "microalgae" also includes cyanobacteria, a diverse prokaryotic lineage
whose ancestor gave rise to the plant chloroplast (Keeling, 2010). More than 40,000 species
of microalgae have been described, and they collectively cover a comprehensive spectrum
of habitats and tolerances of ranges of pH, salinity, and temperature (Van den Hoek et al.,
1995; Falkowski and Raven, 1997; Paerl, 2000). McKenzie (2011) estimated that prokaryotic
and eukaryotic microalgae are responsible for more than 40 percent of net primary produc-
tivity on Earth. Algae can be a more appealing biofuel feedstock than land plants because
of their faster biomass doubling cycle, their more accessible forms of stored carbon than
27
OCR for page 28
28 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
the lignocelluloses used for cellulosic biofuels, and their ability to thrive on water sources
and on land sites that are unsuitable for terrestrial farming.
Microalgae contain diverse pigments and metabolites that are desirable as nutritional
supplements and colorants. Examples of such products include astaxanthin, an antioxidant
derived from the alga Haematococcus, and a high-protein powder derived from cyanobac-
terial species of Spirulina (Arthrospira) (Gershwin, 2008; Guedes et al., 2011). Commercial-
scale algal ponds that grow these and other microalgae have operated for more than a
decade (Del Campo et al., 2007). However, the scale of deployment for algae cultivation for
fuel is expected to be much larger than the scale of algae cultivation for nutraceuticals or
other specialty products currently available in the market.
Generating biofuels from algae requires exploiting and expanding the demonstrated
commercial-scale growth of algal biomass, and harvesting the relatively accessible carbon
stored therein. Carbon is stored within algal cells in various forms, and these molecules
can be accessed by different technologies. Both eukaryotic and prokaryotic algal cells are
rich sources of polar lipids that are associated with membranes; in some cases, the photo-
synthetic thylakoid membranes are extensive. Carbon is such a crucial element for algae
that it is typical for them to store surplus carbon when cellular division is restricted by
some factor other than carbon availability--this situation is termed unbalanced growth. In
many eukaryotic microalgae, photosynthetic carbon fixation continues under unbalanced
conditions. Under extended periods of environmental stress, the excess fixed carbon is
stored in the form of neutral lipids called triacylglycerols (TAGs). TAGs are hydrocarbon
chains terminated in a carboxylic acid group. The three carboxyl groups are bound to
glycerol through an ester linkage. Biofuels containing hydrocarbon chains longer than six
carbons are particularly valued because of their high heats of combustion, volatility, and
compatibility with existing engines. As discussed later in this chapter, extracted TAGs can
be converted to biodiesel using a number of technologies, including transesterification and
hydrotreating. Even algal species that do not store large amounts of TAGs can be converted
to biofuels through various chemical conversion technologies. For example, species that
store polysaccharides can be fermented to yield ethanol, and other biomass processing
technologies, such as gasification, pyrolysis, and hydrothermal liquefaction, have shown
great utility for the conversion of whole biomass into biofuels.
The incipient algal biofuel industry is emerging and evolving from its early founda-
tions in algae cultivation for fish feedstuff and for human nutraceuticals. Early technology
development of processing algae to fuels emphasized the conversion of neutral lipids
(TAGs) to biodiesel. Choices of algal feedstocks have been expanding to address the goals
of fuel production rather than nutritional content and to exploit new technologies for pro-
cessing biomass that extend beyond those that focus on TAGs. Ideal attributes for algal
feedstock for fuels include rapid and dense growth; efficient use of nutrients, light, and
carbon dioxide (CO2) under a range of temperatures; resistance to pests and predators; ac-
cumulation of desirable macromolecules that can be processed into fuels; ease of harvest;
and the absence of undesirable by-products.
Commercial and research interest in the United States has focused on microalgae,
and these species are emphasized in this report. Microalgae have been reported to reach
short-term maximum productivities of 50-60 g dry weight per square meter (m2) per day in
CO2-enriched open ponds in Hawaii and California (Sheehan et al., 1998). These and other
data on productivity from laboratory-scale experiments have promoted the reputation of
microalgae as prime candidates for providing cheap biomass feedstocks for food, feedstuff,
or energy. Some authors have extrapolated values of maximal biomass productivity and
combined them with maximal oil content to predict oil yields of 100 tonnes per hectare
OCR for page 29
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 29
(ha) per year. Such reports have spurred investment in intensive research on algal biofuel
production. However, such high productivity projections have yet to be obtained in large-
scale, long-term experiments. Serious barriers remain for reproducing optimal growth and
productivity conditions at a commercial scale. They include maintaining the stability of the
culture and delivering the required nutrients and other resources in an efficient manner at
such scales. Current yields from large-scale operations range from 40-60 tonnes dry weight
of algal biomass production per ha per year, and conservative projections anticipate up to
100 tonnes dry weight of biomass, or 30 tonnes of biodiesel per ha per year in subtropical
or tropical, sunny climates (Scott et al., 2010). Estimated yields from a variety of cultivation
systems are discussed later in the chapter.
2.1.1 Strain Diversity
The choice of strains for biomass production depends on the desired product and
technology to be used for fuel production, the source, and the type of cultivation facility
(open versus closed). Initial efforts using outdoor ponds focused on production of biodiesel
by the transesterification of TAGs to produce fatty-acid methyl esters (FAME).1 Therefore,
strains that accumulate TAGs were selected. Five groups of microalgae were classified
as high priority for biofuel production by the U.S. Aquatic Species Program (Sheehan et
al., 1998): diatoms (Bacillariophyceae), green algae (Chlorophyceae), golden-brown algae
(Chrysophyceae), prymnesiophytes or haptophytes (including Prymnesiophyceae), and
eustigmatophytes (Eustigmatophyceae). Many strains and genera of eukaryotic microalgae
are potential high-oil producers for large-scale culture (Sheehan et al., 1998; Rodolfi et al.,
2009). These include species of Tetraselmis, Dunaliella, Chlorococcum, Scenedesmus, and Chlo-
rella, and particularly Neochloris oleoabundans and Botryococcus braunii from Chlorophyta;
the genera of Amphora, Amphiprora, Cylindrotheca, and Navicula, and the species of Nitzschia
dissipata, Phaeodactylum tricornutum, and Chaetoceros muelleri from Bacillariophyta; the spe-
cies of Nannochloropsis ocalata and N. salina from Eustigmatophyceae; and the genera of
Isochrysis and Pavlova from Haptophyta.
Improvements of technologies that convert total biomass to yield drop-in fuels--such
as those being pursued by companies such as Inventure (Inventure, 2012), Xtrudx (Xtrudx
Technologies, 2012), and Solvent Rescue Limited (Solvent Rescue Limited, 2012) and aca-
demic institutions such as Old Dominion University (Hatcher, 2011)--are changing the
scope of organisms that are being considered for biofuel production. All categories of algae
are rich in polar lipids that can be recovered by such processes, and they have cellulose or
other polysaccharide cell walls composed of sugars. Cyanobacteria store excess carbon as
glycogen rather than TAGs, and cyanobacteria and macroalgae accumulate quantities of
other complex polysaccharides. These and other macromolecules are all potential carbon
sources for producing drop-in fuels if appropriate processing technologies are available. In
addition, algal carbohydrate potentially can be a feedstock for fermentative fuel production
processes that are based on heterotrophic organisms, such as those used by LS9, Inc. (LS9
Inc., 2011) and Solazyme (Solazyme, 2012). Cyanobacteria are used directly for ethanol pro-
duction by Algenol (Chance et al., 2011a; Algenol Biofuels, 2012). As of 2012, a number of
marine macroalgal species are being considered for biofuel production in India. An example
1As Chapter 3 discusses, algal triacylglycerols are reacted with methanol to form fatty-acid methyl esters
(FAME). Due to its higher viscosity compared to conventional liquid transportation fuels, FAME cannot be used
as a drop-in fuel, but can be blended with conventional diesel.
OCR for page 30
30 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
is the red algal species Kappaphycus alvarezii, a species cultivated for its high carrageenan2
content (Russell, 1983; Rodgers and Cox, 1999; Woo et al., 2000). Species of Spirulina have
properties suitable for aquaculture, and they are grown at relatively large scales for sale as
a nutritional supplement (Earthrise Nutritional, 2009a). Still, the spectrum of cyanobacteria
that could be suitable for fuel production is largely unexplored. P rokaryotic algal species
provide additional diversity in light harvesting, tolerance of growth habitat and pH, and
facility of genetic modification.3 Moreover, some cyanobacterial species are diazotrophs;
that is, they are able to fix atmospheric nitrogen (N). Although no current commercial
operations rely on a nitrogen-fixing strain, several filamentous strains that have good light-
harvesting properties and for which genetic methods are well developed are diazotrophic
(Heidorn et al., 2011; Ruffing, 2011). The use of these strains as a biofuel feedstock or as a ni-
trogen provider for non-fixing strains (to reduce nutrient input) has received little attention.
Clear differences exist in carbon storage forms (important as fuel feedstock), dominant
pigments (important for solar energy capture), and accessory pigments such as carotenoids
(which can be valuable commercial products) among different algal divisions (Table 2-1).
Furthermore, their pigmentation and composition are affected by growth conditions and
environmental stress.
Emphasizing individual strains that are intended for monoculture discounts potential
advantages that could be associated with mixed cultures. A recent study showed increased
lipid production in algal cultures as a function of species diversity in mixed cultures under
nutrient-limiting growth conditions (Stockenreiter et al., 2012). However, this effect has
been demonstrated only at the laboratory scale or in low-density natural algal populations,
and requires confirmation for extended periods of time and at relevant volumes. More-
over, lipid production of mixed algal culture could be different under the nutrient-replete
conditions of ponds designed for maximal growth. Mixed cultures might facilitate cross-
protection, diversity of products through product conversion, flocculation and harvesting
improvements, and efficient use of light in the water column (Stomp et al., 2007). However,
mixed cultures increase the heterogeneity of the potential product, which could affect the
quality of yield and the ability to optimize the diverse characteristics of the mixture for a
single product. The potential to enhance the supply chain of algal biofuel through growth
of mixed cultures merits additional research to determine the effects on desirable product
yield and biomass accumulation (see section Cultivation in this chapter). Because data are
not available for large-scale, mixed-species systems, this report introduces the concept of
mixed culture systems but focuses primarily on monoculture systems.
Among the biggest challenges for strain selection is the difficulty of translating desir-
able strain properties from the laboratory to the field. A desirable strain would have robust
growth in open ponds under natural weather and cultivation conditions, and would retain
attributes that are selected and measured in the controlled conditions of the laboratory.
However, the ability to grow well and compete when exposed to environmental conditions
is difficult to predict. Few strains are already proven to be robust in outdoor mass cultiva-
tion, and years of investment in time and process went into their commercial development.
2A gelatinous substance extracted from red algae and widely used as a stabilizing or thickening agent in indus-
trial, pharmaceutical, and food products.
3Within the text of this report, the committee will distinguish whether it is discussing "genetic modification" or
"genetic engineering" specifically. The committee considers genetic modification to be a general term and includes
in its definition any organism whose genetic material has been altered through an array of approaches, including
traditional cross breeding, mutagenesis, and genetic engineering. Genetic engineering is a modern technique that
enables the introduction of a foreign gene or genes into the genome of an organism through recombinant DNA
methods in an attempt to introduce a new trait into that organism.
OCR for page 31
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 31
TABLE 2-1 Characteristics of Photoautotrophic Algaea
Dominant
Photosynthetic Accessory Pigments Principal Energy
Division Pigment(s) (Carotenoids) Storage Compound % Proteinb % Lipidb
Cyanoprokaryota Phycobilins, Zeaxanthin, beta-carotene, Glycogen, other 10-70 1-20
(blue-green algae) Chlorophyll a myxoxanthin, echinenone, polysaccharides,
canthaxanthin polyhydroxyalka-
noates,
Bacillariophyceae Chlorophyll a, Fucoxanthin, Lipid 5-35 5-55
Chlorophyll c beta-carotene,
diadinoxanthin,
diatoxanthin
Haptophyceae Chlorophyll a, Beta-carotene Chrysolaminaran 5-30 5-55
Chlorophyll c
Chlorophyceae Chlorophyll a, Lutein, Starch 5-30 5->50
Chlorophyll b beta-carotene,
violaxanthin, neoxanthin
Haptophyceae Chlorophyll a, Fucoxanthin Starch 5-35 5-50
Chlorophyll c
Raphidophyceae Chlorophyll a Diatoxanthin Lipid 5-35 5-55
Rhodophyceae Phycobilins, Starch 5-15 5-15
Chlorophyll a
Phaeophyceae Chlorophyll a Fucoxanthin Starch 5-15 5-15
Chrysophyta Chlorophyll Beta-carotene, fucoxanthin Lipids (oil) Leucosin 20-30 30-40
a and c
Eustigmatophyta Chlorophyll a vialaxanthin, beta-carotene Lipids (oil) 10-30 40-65
a Table shows wide ranges in the percentage of lipids and proteins, reflecting that these and other parameters are
dramatically affected by growth conditions.
b Percentages are given as a percent of dry weight.
Successful mass cultivation of new strains likewise will require intensive work to com-
mercialize, whether those strains are native, genetically modified, or bred for improved
attributes.
2.1.2 Desirable Strain Properties
Regardless of the technology or strain, the goal is to maximize the quantity of a final
product per unit time, area, or water volume. Further, the desire is to maximize the product
output per unit input of energy, nutrients, and other resources. Biomass and lipid accumu-
lation per unit time are two measures of productivity (see Rodolfi et al., 2009 for example).
Many other criteria are important for selecting algal strains for commercial biofuel produc-
tion, including variables that alter cost in the supply chain that are important for economic
viability (for example, AQUAFUEL, 2009). Ideally, the criteria for strain selection are mea-
surable. Among important selection criteria are:
· Photosynthetic efficiency. The most objective measure to compare productivity
of algae with land crops is photosynthetic efficiency. Photosynthetic efficiency is
defined as the percent of available light (energy) that is converted into biomass
energy. However, this definition might not be the most relevant for a given supply
chain, depending on how the biomass will be processed and what the final prod-
ucts and coproducts will be (Box 2-1).
OCR for page 32
32 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
BOX 2-1
Relevance of Photosynthetic Efficiency to Biofuel Production
The amount of biofuel produced per unit of land area is a key parameter in the evaluation of any biofuel
production process. Photosynthetic efficiency, a measure of how efficiently light energy is converted to
chemical energy, is one of the key determinants of overall biomass yield. The measure relevant to biofuel
production is the amount of energy contained in biomass expressed as a ratio of the solar energy sup-
plied (Blankenship et al., 2011). The calculation is performed for a typical area integrated over a year or
a growing season. When done this way, values of up to 3 percent have been reported for microalgae
(Wijffels and Barbosa, 2010). Some authors choose to calculate photosynthetic efficiency based on only
the percentage of photosynthetically active radiation (PAR) present (Ort et al., 2011), or even only the PAR
absorbed (Janssen et al., 2001). These calculations lead to considerably higher values and lead to some
confusion around the potential for biofuel production from algae.
Further complicating this particular discussion is determination of the heat of combustion, or the heat-
ing value,a to be used. For measures of total photosynthetic efficiency, the heat of combustion is generally
taken to be the higher heating value of the dried biomass (Jenkins et al., 1998).
The critical feature for this discussion is not the exact efficiency, but rather that the value is far below
what should be theoretically possible (Robertson et al., 2011). Indeed, many have lamented that photo-
synthesis uses one of the "slowest metabolic enzymes in the contemporary biosphere" (Parikh et al., 2006;
p.113). Considerable improvement in photosynthesis might be realized by any number of techniques of
modern biology. Improvements in photosynthesis would lead directly to more prolific production of bio-
fuels, which would consequently reduce the land, water, nutrient, and energy inputs required. Improve-
ments to photosynthesis would directly improve the sustainability of algal biofuels.
a "The higher heating value (also known as gross calorific value or gross energy) of a fuel is defined as the amount of heat
released by a specified quantity (initially at 25°C) once it is combusted and the products have returned to a temperature
of 25°C, which takes into account the latent heat of vaporization of water in the combustion products. The lower heat-
ing value (also known as net calorific value) of a fuel is defined as the amount of heat released by combusting a specified
quantity (initially at 25°C) and returning the temperature of the combustion products to 150°C, which assumes the latent
heat of vaporization of water in the reaction products is not recovered" (DOE-EERE, 2012a).
· Quantity of final products. This category includes the total amount of biomass, its
composition, and the products to be refined, extracted, or excreted from the biomass:
· Total caloric value of the biomass (for combustion or a total biomass processing
technology).
· Percent lipids and lipid composition (for biodiesel).
· Percent starch and carbohydrate composition (for subsequent fermentation
and to identify higher value by-products such as agar).
· Percent protein and protein composition (soluble and insoluble protein for
food and feedstuff).
· Total secretion of desirable products.4
· Presence of high-value coproducts.
4Some companies, such as Joule and Algenol, have taken a dramatically different approach, relying not on ac-
cumulation of biomass, but on the secretion of desirable products from stable algal cultures (Robertson, D.E., S.A.
Jacobson, F. Morgan, D. Berry, G.M. Church, and N.B. Afeyan. 2011. A new dawn for industrial photosynthesis.
Photosynthesis Research 107(3):269-277). In this paradigm that uses photobioreactors, the criteria for strain selec-
tion are different from those used for open ponds. Planktonic unicellular species that would be difficult to protect
from grazers and to harvest from ponds, are desirable within bioreactors. Well-developed genetic model organ-
isms that are amenable to genetic engineering (such as Synechocystis sp. strain PCC 6803, Synechococcus sp. strain
PCC 7002, and Synechococcus elongatus PCC 7942; and the unicellular green alga Chlamydomonas reinhartii) can be
used in the controlled environment of photobioreactors.
OCR for page 33
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 33
· Nutrient and other resource requirements. These include the quantity of nutri-
ents, such as CO2, nitrogen, and phosphorus; the type and quality of the water
supply; and siting requirements. Strains could be selected because of their nutrient-
use efficiency. Strains also might be selected because of their ability to flourish in
brackish or wastewater, which would reduce the demand on freshwater supplies,
and in the climatic conditions of a particular site.
· Robustness. This term describes the overall stability of the crop, which depends on
resistance to extremes of climate and environmental variables (for example, com-
petitors, pathogens and predators, salinity and dissolved solutes, temperature, and
pH). Tolerances to these variables vary widely within the diverse spectrum of mi-
croalgae. The ability to thrive in water with various salts, metals, and other solutes
could become increasingly important as competition for freshwater use among dif-
ferent sectors increases. Resistance to high pH allows growth in alkaline conditions
that favor a monoculture crop over sensitive predators and pathogens. Filamen-
tous species or species with large cell size tend to be more resistant to grazers than
unicellular species with small cell size (Tillmann, 2004). Tolerance to a broad range
of temperatures could be important if the algae are cultivated in regions with high
daily or seasonal fluctuation in temperature. To maintain year-round production,
it might be desirable to rotate strains that have different temperature tolerance pro-
files. The wide spectrum of sites that are under consideration for production ponds
will require organisms with different light, water quality, and climatic tolerances.
Robustness might be assessed by scoring the strain success under a wide range of
potentially relevant conditions such as in Evens and Niedz (2011).
· Harvestability. Harvesting cost and energy consumption can vary dramatically
among different algal strains (Uduman et al., 2010). Contributing factors include
the sedimentation rate and the capability for induced bioflocculation5 or auto-floc-
culation. Filamentous strains that can be seined, species with positive buoyancy,
or species that settle out of the water column quickly once agitation ceases might
not require centrifugation, and they can be harvested easily. Growing mat-forming
algae or algal films could facilitate harvesting (Tang et al., 1997), but to the commit-
tee's knowledge, such approaches have not been scaled up. Strategies that rely on
harvesting secreted products rather than biomass simplify the harvesting step, but
such strategies require photobioreactors for algae cultivation to prevent contami-
nation by microorganisms that would consume the product.
· Processability and extractability. This parameter includes factors that influence
the ease of extracting algal oil or processing algal biomass to fuels, for example,
cell volume, thickness and toughness of the cell wall, the presence of tough fibers
(for example, cellulose and silica) or cell walls, and the moisture content (Brennan
and Owende, 2010). A measure for processability and extractability could be the
energy input per gram of dry weight necessary for fractionation and full recovery
of all biomass components.
· Added value of coproducts. The algal biomass could be used to produce coprod-
ucts that have an intrinsic added value, such as carotenoids, phycobilins, docosa-
hexaenoic acid, or eicosapentaenoic acid (Pal et al., 2011). Coproducts can offset
some of the costs of the biofuel product. A specification of the compounds and their
expected added value per gram of dry biomass needs to be indicated. However,
the market value of coproducts could decrease under an excessive-supply and low-
demand condition.
5Bioflocculation is the clumping together of microorganisms through biological interactions.
OCR for page 34
34 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
· Local origin of strains. Using locally selected strains could ease management and
improve sustainability (RSB, 2011). Some governments have sought to restrict the
importation of nonnative species, for example, the 81st Texas Legislature House
Bill 3391 (2009). However, the cosmopolitan nature and wind-borne movements
of algae make it unlikely that legislation can reasonably define species as native or
nonnative. Regardless of legislation, local strains might have unique adaptations to
the local climate, water, and possible parasites that imported or laboratory-grown
strains might not have.
· Non-toxic. The selection of non-toxic algal strains will increase social acceptability
and reduce the potential impacts related to occupational exposures and accidental
releases.
2.1.3 Strain Development and Engineering
Modern agriculture has advanced primarily on the development of improved germ-
plasm, and algae cultivation will likely advance using similar approaches. As with tradi-
tional agriculture, advances in breeding, mutagenesis, and genetic engineering are likely
to play roles in algal germplasm enhancement. Domestication of algae potentially could
change their phenotype dramatically because the desired characteristics for production are
different from those that have evolved in the selective pressures of the wild and because hy-
pereutrophic aquaculture conditions will support genotypes that would not be fit in natural
environments. Breeding and engineering will enable the stacking of desirable traits within a
single species or mixture of species. The definition of desirable traits, product type desired,
choice of production organism, and specification of growth and harvesting methods will
influence the needs for further development on a case-by-case basis.
The understanding of genetics, physiology, and metabolism at present is uneven across
the spectrum of genera and species of algae that might have desirable features for algal
biofuel production. Major hurdles include the need to develop genetic technologies for
new species that have not been domesticated previously and that have desirable char-
acteristics for large-scale cultivation. The application of genomic approaches could ac-
celerate the analysis of new strains by addressing changes in gene expression for a given
organism under various conditions and identifying conserved and nonconserved genes
among organisms. Those approaches facilitate the identification of candidate genes that
might be relevant for particular pathways of interest (Flaherty et al., 2011; Karpowicz et
al., 2011; Lopez et al., 2011; Weckwerth, 2011). Cryogenic storage methods, such as those
used at the Culture Collection of Algae at the University of Texas (UTEX, 2012), also may
prove important to maintaining germplasm stocks and to replenishing pond inocula with
a desired genotype after genetic drift of the crop population. Cultured algae, particularly
cultures held for more than 10 years in selective media, have been shown to have reduced
growth and production of unexpected secondary metabolites (Martins et al., 2004). A factor
that might be overlooked in efforts to genetically engineer metabolic pathways in algae is
that both eukaryotic and prokaryotic strains possess circadian clocks that time the peaks
of daily rhythmic changes in physiological and metabolic functions (Suzuki, 2001; Ditty et
al., 2003; Matsuo and Ishiura, 2010; O-Neill et al., 2011). The mechanisms and the physi-
ological and metabolic consequences of circadian rhythms are insufficiently understood in
these organisms.
At present, few eukaryotic algal species are readily amenable to breeding or genetic
engineering. Published transformation methods are well developed for Chlamydomonas
reinhardtii and Phaeodactylum tricornutum. Solazyme appears to rely on genetically engineered
OCR for page 35
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 35
Chlorella species for heterotrophic fermentation of algal oils. About 30 strains of eukaryotic
microalgae have been transformed using biolistic bombardment, vigorous mixing with
glass beads, electroporation, or deoxyribonucleic acid (DNA) transfer from Agrobacterium
tumefaciens. Strains that have been transformed include representatives of green, red, and
brown algae; diatoms; euglenoids; and dinoflagellates (Radakovits et al., 2010). However,
in many cases the reported transformation is only transient (Radakovits et al., 2010), and
these reports have not led to routine adoption and application for most of those strains.
Nevertheless, the transformations demonstrate that developing genetic systems for diverse
species is possible with focused effort.
Targeted gene inactivation by homologous recombination has been a long-standing
challenge for manipulation of Chlamydomonas and other algal nuclear genes. However,
Kilian et al. (2011) made progress in this area when they reported successful knockouts of
Nannochloropsis sp. nuclear genes encoding nitrate reductase and nitrite reductase. Various
genes have been suppressed successfully in Chlamydomonas by interfering ribonucleic acid
(RNAs) (Cerutti et al., 2011). High-throughput methods to introduce interfering RNAs
could provide an effective way for gene inactivation in diverse strains that do not exhibit
homologous recombination of transgenic DNA. Another challenge for nuclear modification
is that gene expression is often silenced when heterologous genes are inserted randomly
into the Chlamydomonas reinhardtii nuclear genome (Fuhrmann et al., 1999). Manipulation
of the chloroplast genome is facile in C. reinhardtii, but not in other algae (Radakovits et
al., 2010). A report of stable chloroplast transformation in Porphyridium suggests that chlo-
roplast transformation via homologous recombination might be a universally applicable
approach (Lapidot et al., 2002). Waaland et al. (2004) reviewed macroalgal species as candi-
dates for genomic research and concluded that the red alga Porphyra yezoensis exhibits nu-
merous attributes conducive to further analyses. Extensive biochemical and physiological
research has been conducted on the macroalgae because of their use in the food industry.
Because there is extensive variation in the extent and type of genetic malleability among
different algal species, technologies would have to be developed on a case-by-case basis
for individual new algal types whose physiological and metabolic properties suggest their
potential as production strains. Moreover, it will be highly desirable to develop methods
that can be used to more rapidly develop a genetic system de novo in new strains or species
as they are discovered.
Genetic manipulation is more straightforward among cyanobacteria than eukaryotic
algae because prokaryotes are amenable to techniques of bacterial genetics (Figure 2-1);
some species are naturally transformable and take up exogenous DNA without specific
intervention (Heidorn, 2011; Ruffing, 2011). Figure 2-2 shows some of the biochemical
pathways in cyanobacteria that can be engineered to produce different desired products.
Methods for gene inactivation via homologous recombination and the stable expression of
transgenes, from plasmids or integrated into the chromosome, are well established in at
least a dozen diverse species (Ducat et al., 2011; Ruffing, 2011). However, the developed
model organisms have been maintained in the laboratory for several decades and are not
likely to be suitable for growth under outdoor cultivation conditions. The Spirulina species
that grow robustly outdoors have proven recalcitrant to manipulation. Despite some re-
ports of transgenic Spirulina (Toyomizu et al., 2001; Kawata et al., 2004), many laboratories
have failed to achieve stable transformation of the organism. This failure is likely, at least in
part, due to a host of restriction endonucleases that specifically cleave foreign DNA (Zhao
et al., 2006). Steps that protect plasmids by methylation while they are in an Escherichia coli
host and before they are introduced to the cyanobacterium by conjugation have facilitated
genetic technologies for the nitrogen-fixing filamentous strains Anabaena (Nostoc) sp. PCC
OCR for page 36
36 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
nucleoid
photosynthetic thylakoid membranes
carboxysome
FIGURE 2-1 Overview of cyanobacterial organization.
NOTE: The cartoon diagram in the middle shows the longitudinal section of a representative cyanobacterium
(modeled after Synechococcus elongatus). The major features are indicated on the cartoon diagram above and the
electron micrograph below.
SOURCE: Adapted from Ducat et al. (2011). Micrograph image courtesy of and reprinted with permission from
Lou Sherman, Purdue University.
7120, Anabaena sp. ATCC 29413, and Nostoc punctiforme ATTC 29133 (Elhai et al., 1997).
Similar approaches are likely to work for other strains that initially resist transformation.
A filamentous cyanobacterium isolated from an outdoor pond that has robust growth
properties similar to Spirulina species has been found to be easily manipulated by conjugal
introduction of transgenes and transposons (Taton et al., 2012). This finding suggests that
diverse cyanobacterial model strains that are more relevant for biofuel development than
current laboratory strains could be readily developed.
Genetic engineering holds the promise of transplanting completely novel pathways
from heterologous sources and making products of tailored composition (Figures 2-1 and
2-2; Ruffing, 2011). Some demonstrations from genetically engineered cyanobacteria in-
clude the production of 1-butanol, isobutyraldehyde, N-alkanes, free fatty acids, and sugars
from transformable species of Synechococcus (PCC 7002 and 7942), Thermosynechococcus (BP-
1), and Synechocystis (PCC 6803) (Atsumi et al., 2009; Niederholtmeyer et al., 2010; Lan and
Liao, 2011). Transgenic strains could play an important role in biofuel production, and some
companies are making major investments in these technologies (for example, the Exxon
Mobil alliance with Synthetic Genomics, Inc.; Marler, 2011; Roessler, 2011) even though
OCR for page 37
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 37
FIGURE 2-2 Schematic representation of engineered biochemical pathways in cyanobacteria.
NOTE: Core metabolism of photosynthetic processes is shown in black text. Branch points used to pro-
duce various desired compounds are highlighted in colored boxes. Abbreviations: 3-PGA, 3-phosphoglyc-
erate; FNR, ferredoxin NADP+ reductase.
SOURCE: Adapted from Ducat et al. (2011).
strains have not been used in outdoor systems. The use of engineered strains in outdoor cul-
tivation will be regulated according to the type of genetic modifications applied. The U.S.
Environmental Protection Agency (EPA) under the Toxic Substances Control Act (TSCA)
recognizes microorganisms that carry sequences from another genus as new organisms
that require regulatory permitting (EPA, 2011). Under TSCA, organisms that are modified
by technologies based solely on rearranging and reinserting endogenous genetic material
into strains of interest are not categorized as genetically modified. Thus, self-cloned spe-
cies can be used in open ponds without special oversight. Growing genetically modified
algae in photobioreactors will follow the same regulatory standards that are common in
the fermentation and biotechnology industries.
Irrespective of the algal strain cultivated and its end use, some areas of improvement
in strain and cultivation are generally desirable. These include:
· Modulation of carbon allocation.
· Increases in culture density.
· Net increase in photosynthetic efficiency.
· Algal crop protection.
· Other enhancements.
2.1.3.1 Modulation of Carbon Allocation
The basic strategies to adapt microalgae to increased oil production for processing to
diesel were summarized by Radakovits et al. (2010). A major target of genetic engineering
OCR for page 66
66 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
BOX 2-2
Research and Development for Enhancing Algal Biofuel Production
Research and development directed at domestication of algae for biofuel production is vitally important.
This effort will require improving the functional understanding of the biology, physiology, and ecology of
microalgae. This upstream research and development will help inform and guide downstream engineer-
ing methods and designs for cultivation and processing systems that will enhance the entire algal biofuel
production chain. Thus, concerted, complementary efforts in algal domestication and biofuel production
will include:
·Development of strategies to improve carbon fixation rates and yields of algal crops at commercial
production-level scale.
·Development of algal strains or multi-species assemblages that achieve high productivity and high
volumetric concentrations over a wide range of environmental conditions (including variations in
temperature and light levels) and are as easily harvested and processed as possible.
·Evaluation and development of improved crop protection methods.
·Design and development of robust, low-cost, long-lasting production systems for algal strains
or multi-species assemblages that demand minimal regulations and control of environmental
parameters.
·Development of strains that excrete oil or other fuel precursors, especially immiscible products.
·Development of improved harvest technologies that reduce energy required during collecting and
processing.
·Design and development of integrated biological and engineering production strategies that obvi-
ate algae harvesting, drying, and oil-extraction processes.
·Design and development of integrated biological and engineering production strategies that con-
tinually reuse the algae, water, and nutrients.
·Design and development of systems that can process whole biomass into fuels.
SUMMARY FINDING FROM THIS CHAPTER
Algal strain development is needed to enhance traits that contribute to increasing fuel
production per unit resource use, reducing the environmental effects per unit fuel pro-
duced, and enhancing economic viability. Improvements in biomass or product (lipid,
alcohol, or hydrocarbons) yield, culture density, nutrient uptake, ease of harvest, and
photosynthetic efficiency are some of the improvements that would improve sustain-
ability of algal biofuels.
REFERENCES
81st Texas Legislature House Bill 3391, Bill introduced by the Texas House of Representatives relating to the con-
tinuation and functions of the Parks and Wildlife Department; changing the elements of an offense. § Chapter
952. (Regular Session, June 19, 2009).
Acién Fernández, F.G., J.M. Fernández Sevilla, J.A. Sánchez Pérez, E. Molina Grima, and Y. Chisti. 2001. Airlift-
driven external-loop tubular photobioreactors for outdoor production of microalgae: Assessment of design
and performance. Chemical Engineering Science 56(8):2721-2732.
Algae Energy. 2012a. Open cultivation system for growing algae. Available online at http://algae-energy.co.uk/
biofuel_production/cultivation/. Accessed May 15, 2012.
------. 2012b. Photobioreactors. Available online at http://algae-energy.co.uk/biofuel_production/pbrs/. Ac-
cessed May 15, 2012.
OCR for page 67
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 67
Algenol Biofuels. 2012. Homepage. Available online at http://algenol.com/. Accessed June 16, 2012.
Algomed. 2012. Microalgae cultivated in a 500 km long system of glass tubes--A German innovation. Available
online at http://www.algomed.de/index.php?lang=eng&op=algenfarm_anlage. Accessed May 15, 2012.
Amyris. 2012. Homepage. Available online at http://www.amyris.com/. Accessed June 17, 2012.
Andrianov, V., N. Borisjuk, N. Pogrebnyak, A. Brinker, J. Dixon, S. Spitsin, J. Flynn, P. Matyszczuk, K. Andryszak,
M. Laurelli, M. Golovkin, and H. Koprowski. 2009. Tobacco as a production platform for biofuel: Overex-
pression of Arabidopsis DGAT and LEC2 genes increases accumulation and shifts the composition of lipids
in green biomass. Plant Biotechnology Journal 8:1-11.
Anex, R.P., A. Aden, F.K. Kazi, J. Fortman, R.M. Swanson, M.M. Wright, J.A. Satrio, R.C. Brown, D.E. Daugaard,
A. Platon, G. Kothandaraman, D.D. Hsu, and A. Dutta. 2010. Techno-economic comparison of biomass-to-
transportation fuels via pyrolysis, gasification, and biochemical pathways. Fuel 89(Supplement 1):S29-S35.
AQUAFUEL. 2009. Deliverable 1.4 Report on biology and biotechnology of algae with indication of criteria for
strain selection. Available online at http://www.aquafuels.eu/attachments/079_D%201.4%20Biology%20
Biotechnology.pdf. Accessed September 14, 2012.
Aravanis, A. 2011. Near-Term Commercialization of Algal Biofuel. Presentation to the NRC Committee on the
Sustainable Development of Algal Biofuels on June 13.
Atsumi, S., W. Higashide, and J.C. Liao. 2009. Direct photosynthetic recycling of carbon dioxide to isobutyralde-
hyde. Nature Biotechnology 27(12):1177-1180.
Baptist, G., D. Meritt, and D. Webster. 1993. Growing Microalgae to Feed Bivalve Larvae. North Dartmouth: Uni-
versity of Massachusetts, Dartmouth.
Baud, S., S. Wuilleme, B. Dubreucq, A. de Almeida, C. Vuagnat, L. Lepiniec, M. Miquel, and C. Rochat. 2007. Func-
tion of plastidial pyruvate kinases in seeds of Arabidopsis thaliana. Plant Journal 52(3):405-419.
Becker, E.W. 1994. Microalgae: Biotechnology and Microbiology. Cambridge, UK: Cambridge University Press.
Benemann, J.R. 1986. Microalgae Biotechnology: Products, Processes, and Opportunities. Washington, DC: OMEC
International Inc.
------. 1989. The future of microalgal biotechnology. In Algal and Cyanobacterial Biotechnology, edited by
Cresswell R.C., N. Shah, and T.A. Rees. Harlow, England: Longman Scientific and Technical.
------. 2008. Opportunities and challenges in algae biofuel production. Available online at http://www.fao.org/
uploads/media/algae_positionpaper.pdf. Accessed October 21, 2011.
------. 2011. Promise and Challenges in Sustainable Development of Algal Biofuels: Questions and Answers.
Presentation to the NRC Committee on Sustainable Development of Algal Biofuels on July 5.
Bessler, H., V.M. Temperton, C. Roscher, N. Buchmann, B. Schmid, E.D. Schulze, W.W. Weisser, and C. Engels.
2009. Aboveground overyielding in grassland mixtures is associated with reduced biomass partitioning to
belowground organs. Ecology 90(6):1520-1530.
Bhave, R., T. Kuritz, L. Powell, and D. Adcock. 2012. Membrane-based energy efficient dewatering of microalgae
in biofuels production and recovery of value added coproducts. Environmental Science and Technology
46(10):5599-5606.
Blankenship, R.E., D.M. Tiede, J. Barber, G.W. Brudvig, G. Fleming, M. Ghirardi, M.R. Gunner, W. Junge, D.M.
Kramer, A. Melis, T.A. Moore, C.C. Moser, D.G. Nocera, A.J. Nozik, D.R. Ort, W.W. Parson, R.C. Prince, and
R.T. Sayre. 2011. Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for
improvement. Science 332(6031):805-809.
Borowitzka, M.A. 1992. Algal biotechnology products and processes--matching science and economics. Journal
of Applied Phycology 4(3):267-279.
------. 1999. Commercial production of microalgae: ponds, tanks, tubes and fermenters. Journal of Biotechnology
70(1-3):313-321.
Brennan, L., and P. Owende. 2010. Biofuels from microalgae--A review of technologies for production, process-
ing, and extractions of biofuels and coproducts. Renewable and Sustainable Energy Reviews 14(2):557-577.
Brown, R.M., D.A. Larson, and H.C. Bold. 1964. Airborne algae--Their abundance and heterogeneity. Science
143(360):583-585.
Butamax Advanced Biofuels, LLC. 2012. Homepage. Available online at http://www.butamax.com/. Accessed
June 17, 2012.
California Polytechnic State University. 2012. Tubular Photobioreactor. Available online at http://brae.calpoly.
edu/CEAE/biofuels.html. Accessed May 15, 2012.
Camacho Rubio, F., F.G. Acién Fernández, J.A. Sánchez Pérez, F. García Camacho, and E. Molina Grima. 1999.
Prediction of dissolved oxygen and carbon dioxide concentration profiles in tubular photobioreactors for
microalgal culture. Biotechnology and Bioengineering 62(1):71-86.
OCR for page 68
68 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
Carlozzi, P. 2003. Dilution of solar radiation through "culture" lamination in photobioreactor rows facing south-
north: A way to improve the efficiency of light utilization by cyanobacteria (Arthrospira platensis). Biotechnol-
ogy and Bioengineering 81(3):305-315.
Carpenter, S.R., and J.F. Kitchell. 1988. Consumer control of lake productivity. Bioscience 38(11):764-769.
Cernac, A., and C. Benning. 2004. WRINKLED1 encodes an AP2/EREB domain protein involved in the control of
storage compound biosynthesis in Arabidopsis. Plant Journal 40(4):575-585.
Cerutti, H., X.R. Ma, J. Msanne, and T. Repas. 2011. RNA-mediated silencing in algae: Biological roles and tools
for analysis of gene function. Eukaryotic Cell 10(9):1164-1172.
Chance, R.R., B. McCool, and J. Coleman. 2011a. Questionnaire reply from Algenol Biofuels Inc. Received by the
NRC Committee on Sustainable Development of Algal Biofuels on July 7.
Chance, R.R., B. McCool, and J.D. Coleman. 2011b. A Cyanobacteria-Based Photosynthetic Process for the Pro-
duction of Ethanol. Presentation to the NRC Committee on Sustainable Development of Algal Biofuels on
June 13.
Chase, J.M. 2003. Community assembly: when should history matter? Oecologia 136(4):489-498.
Chen, M., and R.E. Blankenship. 2011. Expanding the solar spectrum used by photosynthesis. Trends in Plant
Science 16(8):427-431.
Chen, P., M. Min, Y.-F. Chen, L. Wang, Y. Li, Q. Chen, C. Wang, Y. Wan, X. Wang, Y. Cheng, S. Deng, K. Hennessy,
X. Lin, Y. Liu, Y. Wang, B. Martinez, and R. Ruan. 2009. Review of the biological and engineering aspects of
algae to fuels approach. International Journal of Agricultural and Biological Engineering 2(4):1-30.
Cheng-Wu, Z., O. Zmora, R. Kopel, and A. Richmond. 2001. An industrial-size flat plate glass reactor for mass
production of Nannochloropsis sp. (Eustigmatophyceae). Aquaculture 195(1-2):35-49.
Clarens, A.F. 2011. Life cycle assessment of algae-to-energy technologies. Presentation to the NRC Committee on
Sustainable Development of Algal Biofuels on June 13.
Clarens, A.F., E.P. Resurreccion, M.A. White, and L.M. Colosi. 2010. Environmental life cycle comparison of algae
to other bioenergy feedstocks. Environmental Science and Technology 44(5):1813-1819.
Clemente, T.E., and E.B. Cahoon. 2009. Soybean oil: Genetic approaches for modification of functionality and total
content. Plant Physiology 151(3):1030-1040.
Cloud, B. 2011a. Questionnaire reply from Phyco Biosciences Inc. Received by the NRC Committee on Sustainable
Development of Algal Biofuels on September 27.
------. 2011b. Questionnaire reply from Phyco BioSciences Inc. Received by the NRC Committee on Sustainable
Development of Algal Biofuels on July 25.
Courchesne, N.M.D., A. Parisien, B. Wang, and C.Q. Lan. 2009. Enhancement of lipid production using biochemi-
cal, genetic and transcription factor engineering approaches. Journal of Biotechnology 141(1-2):31-41.
Crown Iron Works. 2008. MultiPure degumming/neutralizing system. Available online at http://www.crown-
iron.com/userimages/DegNeuN1.pdf. Accessed June 16, 2012.
Cuello, J., and J. Ley. 2011. ACCORDION Photobioreactor for Algae Production of Biofuels and Biochemicals.
Presentation to the Conference EPA's GHG Emissions Standards for Power Plants and Oil Refineries on
February 2.
Cyanotech. 2012. Hawaiian Spirulina Pacifica® Available online at http://www.cyanotech.com/spirulina.html.
Accessed April 5, 2012.
Davis, R., A. Aden, and P.T. Pienkos. 2011. Techno-economic analysis of autotrophic microalgae for fuel produc-
tion. Applied Energy 88(10):3524-3531.
Del Campo, J.A., M. Garcia-Gonzalez, and M.G. Guerrero. 2007. Outdoor cultivation of microalgae for carotenoid
production: Current state and perspectives. Applied Microbiology and Biotechnology 74(6):1163-1174.
Dillon, H. 2011. Presentation in the session "Broadening the Bionergy Horizon." In DOE Biomass Summit: Replace
the Whole Barrel, Supply the Whole Market, July 26, 2012, National Harbor, MD.
Ditty, J.L., S.B. Williams, and S.S. Golden. 2003. A cyanobacterial circadian timing mechanism. Annual Review of
Genetics 37:513-543.
DOE-EERE (U.S. Department of Energy, Energy Efficiency and Renewable Energy). 2012a. Lower and higher heat-
ing values of fuels. Available online at http://hydrogen.pnl.gov/cocoon/morf/hydrogen/site_ specific/
fuel_heating_calculator?canprint=false. Accessed June 18, 2012.
------. 2012b. Drop-in biofuels. Available online at http://www.afdc.energy.gov/fuels/emerging_dropin_
biofuels.html. Accessed August 21, 2012.
DOE (U.S. Department of Energy). 2010. National Algal Biofuels Technology Roadmap. Washington, D.C.: U.S.
Department of Energy, Energy Efficiency and Renewable Energy.
Ducat, D.C., J.C. Way, and P.A. Silver. 2011. Engineering cyanobacteria to generate high-value products. Trends
in Biotechnology 29(2):95-103.
OCR for page 69
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 69
Duerr, E.O., A. Molnar, and V. Sato. 1998. Cultured microalgae as aquaculture feeds. Journal of Marine Biotechnol-
ogy 6(2):65-70.
Durand-Chastel, H. 1980. Production and use of Spirulina in Mexico. Pp. 51-64 in Algae Biomass. Amsterdam, The
Netherlands: Elsvier/North-Holland Biomedical Press.
Earthrise Nutritional, LLC. 2009a. Earthrise. Available online at http://www.earthrise.com/. Accessed February
9, 2012.
------. 2009b. About Earthrise: Our farm. Available online at http://earthrise.com/farm.html. Accessed August
26, 2012.
Edwards, M. 2010. Phyco Biosciences super trough growing algae. Available online at http://www.algaeindus-
trymagazine.com/abundance-food/. Accessed May 15, 2012.
Ehimen, E.A., Z.F. Sun, and C.G. Carrington. 2010. Variables affecting the in situ transesterification of microalgae
lipids. Fuel 89(3):677-684.
Ehira, S., and M. Ohmori. 2011. NrrA, a nitrogen-regulated response regulator protein, controls glycogen catabo-
lism in the nitrogen-fixing cyanobacterium Anabaena sp strain PCC 7120. Journal of Biological Chemistry
286(44):38109-38114.
Elhai, J., A. Vepritskiy, A.M. MuroPastor, E. Flores, and C.P. Wolk. 1997. Reduction of conjugal transfer efficiency
by three restriction activities of Anabaena sp. strain PCC 7120. Journal of Bacteriology 179(6):1998-2005.
Enay, S. 2011. Hawaii's Natural Energy Laboratory fuels innovation. Available online at http://www.hawaiibusiness.
com/Hawaii-Business/November-2011/Hawaiis-Natural-Energy-Laboratory-fuels-innovation/. Accessed
August 26, 2012.
EPA (U.S. Environmental Protection Agency). 2011. Microbial products of biotechnology: Final regulations under
the Toxic Substances Control Act summary (fact sheet). Available online at http://www.epa.gov/biotech_
rule/pubs/fs-001.htm. Accessed March 2, 2012.
Evens, T.J., and R.P. Niedz. 2011. Mapping the fundamental niches of two freshwater microalgae, Chlorella vulgaris
(Trebouxiophyceae) and Peridinium cinctum (Dinophyceae), in 5-dimensional ion space. International Journal
of Ecology DOI:10.1155/2011/738035.
Falkowski, P.G., and J.A. Raven. 1997. Aquatic Photosynthesis. Malden, MA: Blackwell Science.
Flaherty, B.L., F. Van Nieuwerburgh, S.R. Head, and J.W. Golden. 2011. Directional RNA deep sequencing sheds
new light on the transcriptional response of Anabaena sp strain PCC 7120 to combined-nitrogen deprivation.
BMC Genomics 12:332.
Frank, E.D., J. Han, I. Palou-Rivera, A. Elgowainy, and M.Q. Wang. 2011. Life-Cycle Analysis of Algal Lipid Fuels
with the GREET Model. Oak Ridge: TN: U.S. Department of Energy.
Frisch, D., A.J. Green, and J. Figuerola. 2007. High dispersal capacity of a broad spectrum of aquatic invertebrates
via waterbirds. Aquatic Sciences 69(4):568-574.
Fuhrmann, M., W. Oertel, and P. Hegemann. 1999. A synthetic gene coding for the green fluorescent protein (GFP)
is a versatile reporter in Chlamydomonas reinhardtii. Plant Journal 19(3):353-361.
García-González, M., J. Moreno, J.P. Cañavate, V. Anguis, A. Prieto, C. Manzano, F.J. Florencio, and M.G. Guer-
rero. 2003. Conditions for open-air outdoor culture of Dunaliella salina in southern Spain. Journal of Applied
Phycology 15(2-3):177-184.
Garthwaite, J. 2012. Unlocking Seaweed's Next-Gen Crude: Sugar. Available online at http://green.blogs.nytimes.
com/2012/01/23/unlocking-seaweeds-next-gen-crude-sugar/. Accessed June 13, 2012.
Gershwin, M.E., and A.B. Belay. 2008. Spirulina in human nutrition and health. Boca Raton: CRC Press.
Gevo. 2012. Homepage. Available online at http://www.gevo.com/. Accessed June 17, 2012.
Giordano, M., J. Beardall, and J.A. Raven. 2005. CO2 concentrating mechanisms in algae: Mechanisms, environ-
mental modulation, and evolution. Annual Review of Plant Biology 56:99-131.
Graham, D.W., and V.H. Smith. 2004. Designed ecosystem services: Application of ecological principles in waste-
water treatment engineering. Frontiers in Ecology and the Environment 2(4):199-206.
Gross, E.M. 2003. Allelopathy of aquatic autotrophs. Critical Reviews in Plant Sciences 22(3-4):313-339.
Guedes, A.C., H.M. Amaro, and F.X. Malcata. 2011. Microalgae as sources of high added-value compounds--A
brief review of recent work. Biotechnology Progress 27(3):597-613.
Guihéneuf, F., S. Leu, A. Zarka, I. Khozin-Goldberg, I. Khalilov, and S. Boussiba. 2011. Cloning and molecular
characterization of a novel acyl-CoA:diacylglycerol acyltransferase 1-like gene (PtDGAT1) from the diatom
Phaeodactylum tricornutum. FEBS Journal 278(19):3651-3666.
Hall, C.A., B.E. Dale, and D. Pimentel. 2011. Seeking to understand the reasons for different energy return on
investment (EROI) estimates for biofuels. Sustainability 3(12):2413-2432.
Hall, D.O., F.G. Acién Fernández, E.C. Guerrero, K.K. Rao, and E.M. Grima. 2003. Outdoor helical tubular pho-
tobioreactors for microalgal production: Modeling of fluid-dynamics and mass transfer and assessment of
biomass productivity. Biotechnology and Bioengineering 82(1):62-73.
OCR for page 70
70 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
Hannon, M., J. Gimpel, M. Tran, B. Rasala, and S. Mayfield. 2010. Biofuels from algae: Challenges and potential.
Biofuels 1(5):763-784.
Harun, R., M.K. Danquah, and G.M. Forde. 2010. Microalgal biomass as a fermentation feedstock for bioethanol
production. Journal of Chemical Technology and Biotechnology 85(2):199-203.
Hatcher, P.G. 2011. The ODU algae to biodiesel project. Presentation to the NRC Committee on the Sustainable
Development of Algal Biofuels on August 24.
Heaven, S., J. Milledge, and Y. Zhang. 2011. Comments on "Anaerobic digestion of microalgae as a necessary step
to make microalgal biodiesel sustainable." Biotechnology Advances 29(1):164-167.
Heidorn, T., C. Daniel, H. Hsin-Ho, L. Pia, O. Paulo, S. Karin, and L. Peter. 2011. Synthetic biology in cyanobacteria:
Engineering and analyzing novel functions. Pp. 539-579 in Methods in Enzymology, C. Voigt, ed. Academic
Press.
Hoffmann, M.D., and S.I. Dodson. 2005. Land use, primary productivity, and lake area as descriptors of zooplank-
ton diversity. Ecology 86(1):255-261.
Huesemann, M.H., T.S. Hausmann, R. Bartha, M. Aksoy, J.C. Weissman, and J.R. Benemann. 2009. Biomass produc-
tivities in wild type and pigment mutant of Cyclotella sp (Diatom). Applied Biochemistry and Biotechnology
157(3):507-526.
Inventure, Inc. 2012. Homepage. Available online at http://inventurechem.com/home.html. Accessed June 16,
2012.
Iowa State University. 2011. Iowa State University scientists genetically increase algae biomass by more than 50
percent. Available online at http://www.news.iastate.edu/news/2011/nov/spaldingdario. Accessed June
17, 2012.
IP Monitor. 2009. Patent application no. 209333021--genetically engineered herbicide resistant algae. Available
online at http://www.ipmonitor.com.au/patents/case/2009333021. Accessed June 15, 2012.
Jako, C., A. Kumar, Y.D. Wei, J.T. Zou, D.L. Barton, E.M. Giblin, P.S. Covello, and D.C. Taylor. 2001. Seed-specific
over-expression of an Arabidopsis cDNA encoding a diacylglycerol acyltransferase enhances seed oil content
and seed weight. Plant Physiology 126(2):861-874.
Janssen, M., P. Slenders, J. Tramper, L.R. Mur, and R.H. Wijffels. 2001. Photosynthetic efficiency of Dunaliella ter-
tiolecta under short light/dark cycles. Enzyme and Microbial Technology 29(4-5):298-305.
Jenkins, B.M., L.L. Baxter, T.R. Miles Jr., and T.R. Miles. 1998. Combustion properties of biomass. Fuel Processing
Technology 54(1-3):17-46.
Jenkins, D.G., and M.O. Underwood. 1998. Zooplankton may not disperse readily in wind, rain, or waterfowl.
Hydrobiologia 387:15-21.
Jiménez, C., B.R. Cossío, and F.X. Niell. 2003. Relationship between physicochemical variables and productivity in
open ponds for the production of Spirulina: A predictive model of algal yield. Aquaculture 221(1-4):331-345.
Jorquera, O., A. Kiperstok, E.A. Sales, M. Embiruçu, and M.L. Ghirardi. 2010. Comparative energy life-cycle
analyses of microalgal biomass production in open ponds and photobioreactors. Bioresource Technology
101(4):1406-1413.
Joule Unlimited. 2012. Frequently asked questions. Available online at http://www.jouleunlimited.com/faq.
Accessed March 9, 2012.
Jurgens, K., J. Pernthaler, S. Schalla, and R. Amann. 1999. Morphological and compositional changes in a plank-
tonic bacterial community in response to enhanced protozoan grazing. Applied and Environmental Micro-
biology 65(3):1241-1250.
Kalnes, T., T. Marker, and D.R. Shonnard. 2007. Green diesel: A second generation biofuel. International Journal
of Chemical Reactor Engineering 5(1): ISSN (Online) 1542-6580.
Kan, Y., and J. Pan. 2010. A one-shot solution to bacterial and fungal contamination in the green alga Chlamydomonas
reinhardtii culture by using an antibiotic cocktail. Journal of Phycology 46(6):1356-1358.
Kanazawa, Z., C. Fujita, T. Yuhara, and T. Sasa. 1958. Mass culture of unicellular algae using the open pond circula-
tion method. Journal of General and Applied Microbiology 4:135-139.
Karpowicz, S.J., S.E. Prochnik, A.R. Grossman, and S.S. Merchant. 2011. The GreenCut2 resource, a phyloge-
nomically derived inventory of proteins specific to the plant lineage. Journal of Biological Chemistry
286(24):21427-21439.
Kawaguchi, K. 1980. Microalgae production systems in Asia. Pp. 25-33 in Algae Biomass Production and Use, G.
Shelef and C.J. Soeder, eds. Amsterdam, The Netherlands: Elsevier/North Holland Biomedical Press.
Kawata, Y., S. Yano, H. Kojima, and M. Toyomizu. 2004. Transformation of Spirulina platensis strain C1 (Arthro-
spira sp PCC9438) with Tn5 transposase-transposon DNA-cation liposome complex. Marine Biotechnology
6(4):355-363.
Keeling, P.J. 2010. The endosymbiotic origin, diversification and fate of plastids. Philosophical Transactions of the
Royal Society B: Biological Sciences 365(1541):729-748.
OCR for page 71
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 71
Kennedy, C.A., K. Thurston, D. Gahl, T. Gordon, and S. Julian. 1995. The Biocoil Project--1994-95. Available online
at http://advbio.cascadeschools.org/94-95/biocoil.html. Accessed May 15, 2012.
Kilian, O., C.S.E. Benemann, K.K. Niyogi, and B. Vick. 2011. High-efficiency homologous recombination in the
oil-producing alga Nannochloropsis sp. Proceedings of the National Academy of Sciences of the United States
of America 108(52):21265-21269.
Laloknam, S., K. Tanaka, T. Buaboocha, R. Waditee, A. Incharoensakdi, T. Hibino, Y. Tanaka, and T. Takabe. 2006.
Halotolerant cyanobacterium Aphanothece halophytica contains a betaine transporter active at alkaline pH and
high salinity. Applied and Environmental Microbiology 72(9):6018-6026.
Lan, E.I., and J.C. Liao. 2011. Metabolic engineering of cyanobacteria for 1-butanol production from carbon diox-
ide. Metabolic Engineering 13(4):353-363.
Lapidot, M., D. Raveh, A. Sivan, S. Arad, and M. Shapira. 2002. Stable chloroplast transformation of the unicellular
red alga Porphyridium species. Plant Physiology 129(1):7-12.
Lardizabal, K., R. Effertz, C. Levering, J. Mai, M.C. Pedroso, T. Jury, E. Aasen, K. Gruys, and K. Bennett. 2008.
Expression of Umbelopsis ramanniana DGAT2A in seed increases oil in soybean. Plant Physiology 148(1):89-96.
Laws, E.A., D.G. Redalje, D.M. Karl, and M.S. Chalup. 1983. A theoretical and experimental examination of the
predictions of two recent models of phytoplankton growth. Journal of Theoretical Biology 105(3):469-491.
Laws, E.A., S. Taguchi, J. Hirata, and L. Pang. 1988. Optimization of microalgal production in a shallow outdoor
flume. Biotechnology and Bioengineering 32(2):140-147.
Leckey, C.A.C., and M.K. Hinders. 2012. Viscous effects in the acoustic manipulation of algae for biofuel produc-
tion. Journal of Applied Phycology 24(1):145-156.
Lee, Y.K. 2001. Microalgal mass culture systems and methods: Their limitation and potential. Journal of Applied
Phycology 13(4):307-315.
Leliaert, F., H. Verbruggen, and F.W. Zechman. 2011. Into the deep: New discoveries at the base of the green plant
phylogeny. BioEssays 33(9):683-692.
Li, Y., D. Han, M. Sommerfeld, and Q. Hu. 2011. Photosynthetic carbon partitioning and lipid production in the
oleaginous microalga Pseudochlorococcum sp. (Chlorophyceae) under nitrogen-limited conditions. Biore-
source Technology 102(1):123-129.
Liu, X., A.F. Clarens, and L.M. Colosi. 2012. Algae biodiesel has potential despite inconclusive results to date.
Bioresource Technology 104:803-806.
Lopez, D., D. Casero, S.J. Cokus, S.S. Merchant, and M. Pellegrini. 2011. Algal functional annotation tool: A web-
based analysis suite to functionally interpret large gene lists using integrated annotation and expression data.
BMC Bioinformatics 12:282.
López, M.C.G.M., E.D.R. Sánchez, J.L. Casas López, F.G.A. Fernández, J.M.F. Sevilla, J. Rivas, M.G. Guerrero, and
E.M. Grima. 2006. Comparative analysis of the outdoor culture of Haematococcus pluvialis in tubular and
bubble column photobioreactors. Journal of Biotechnology 123(3):329-342.
Lorenz, R. 2002. GRAS notification: "Spirulina" microalgae. Available online at http://www.accessdata.fda.gov/
scripts/fcn/gras_notices/grn_101.pdf. Accessed August 26, 2012
Los Alamos National Laboratory. 2011. LANL develops first genetically engineered "magnetic" algae. Los Alamos
News Center: News, Releases, Video, Publications. Available online at http://www.lanl.gov/news/stories/
magnetic_algae.html. Accessed February 8, 2012.
LS9 Inc. (Life Sciences Sustaining 9 Billion). 2011. Homepage. Available online at http://www.ls9.com/. Accessed
February 9, 2012.
Ma, J.Y., S.F. Wang, P.W. Wang, L.J. Ma, X.L. Chen, and R.F. Xu. 2006. Toxicity assessment of 40 herbicides to the
green alga Raphidocelis subcapitata. Ecotoxicology and Environmental Safety 63(3):456-462.
Ma, J.Y., L.G. Xu, S.F. Wang, R.Q. Zheng, S.H. Jin, S.Q. Huang, and Y.J. Huang. 2002. Toxicity of 40 herbicides to
the green alga Chlorella vulgaris. Ecotoxicology and Environmental Safety 51(2):128-132.
Mahan, K.M., O.W. Odom, and D.L. Herrin. 2005. Controlling fungal contamination in Chlamydomonas reinhardtii
cultures. Biotechniques 39(4):457-458.
Marker, T., M. Linck, and L. Felix. 2010. Integrated hydropyrolysis and hydroconversion (IH2) process for di-
rect production of gasoline and diesel fuel from biomass. Paper read at the BIOMASS 2010, March 30-31,
Arlington, VA.
Marker, T.L., L.G. Felix, M.B. Linck, and M.J. Roberts. 2012. Integrated hydropyrolysis and hydroconversion (IH2)
for the direct production of gasoline and diesel fuels or blending components from biomass, Part 1: Proof of
principle testing. Environmental Progress and Sustainable Energy 31(2):191-199.
Marler, D. 2011. An Assessment of the Environmental Performance of Algal Biofuels. Presentation to the NRC
Committee on Sustainable Development of Algal Biofuels on September 8.
Martins, C.A., D. Kulis, S. Franca, and D.M. Anderson. 2004. The loss of PSP toxin production in a formerly toxic
Alexandrium lusitanicum clone. Toxicon 43(2):195-205.
OCR for page 72
72 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
Matsuo, T., and M. Ishiura. 2010. New insights into the circadian clock in Chlamydomonas. International Review of
Cell and Molecular Biology 280(C):281-341.
McHugh, D.J. 2003. A guide to the seaweed industry. Rome, Italy: FAO.
McKenzie, F.T. 2011. Our changing planet: An introduction to earth system science and global environmental
change, 4th edition. Upper Saddle, NJ: Prentice-Hall.
Mercer, P., and R.E. Armenta. 2011. Developments in oil extraction from microalgae. European Journal of Lipid
Science and Technology 113(5):539-547.
Milledge, J.J. 2011. Commercial application of microalgae other than as biofuels: A brief review. Reviews in Envi-
ronmental Science and Biotechnology 10(1):31-41.
Moheimani, N.R., and M.A. Borowitzka. 2006. Limits to productivity of the alga Pleurochrysis carterae (haptophyta)
grown in outdoor raceway ponds. Biotechnology and Bioengineering 96(1):27-36.
Molina, E., J. Fernández, F.G. Acién, and Y. Chisti. 2001. Tubular photobioreactor design for algal cultures. Journal
of Biotechnology 92(2):113-131.
Moreno, J., M.A. Vargas, H. Rodríguez, J. Rivas, and M.G. Guerrero. 2003. Outdoor cultivation of a nitrogen-fixing
marine cyanobacterium, Anabaena sp. ATCC 33047. Biomolecular Engineering 20(4-6):191-197.
Mveda. 2011. Sapphire Energy photo. Available online at http://www.mveda.com/blog/2011/03/sapphire-
develops-research-center/. Accessed May 15, 2012.
NanoVoltaix. 2012. Photo-Bioreactors. Available online at http://www.nanovoltaix.com/markets/algae.php.
Accessed May 15, 2012.
NBB (National Biodiesel Board). 2012. Plants listings. Available online at http://www.biodiesel.org/production/
plants/plants-listing. Accessed June 15, 2012.
Niederholtmeyer, H., B.T. Wolfstadter, D.F. Savage, P.A. Silver, and J.C. Way. 2010. Engineering cyanobacteria to
synthesize and export hydrophilic products. Applied and Environmental Microbiology 76(11):3462-3466.
O-Neill, J.S., G. Van Ooijen, L.E. Dixon, C. Troein, F. Corellou, F.Y. Bouget, A.B. Reddy, and A.J. Millar. 2011. Cir-
cadian rhythms persist without transcription in a eukaryote. Nature 469(7331):554-558.
Olaizola, M. 2000. Commercial production of astaxanthin from Haematococcus pluvialis using 25,000-liter outdoor
photobioreactors. Journal of Applied Phycology 12(3-5):499-506.
Olguín, E.J., S. Galicia, G. Mercado, and T. Pérez. 2003. Annual productivity of Spirulina (Arthrospira) and nutri-
ent removal in a pig wastewater recycling process under tropical conditions. Journal of Applied Phycology
15(2-3):249-257.
Ondrey, G. 2004. Biodiesel production using a heterogeneous catalyst. Chemical Engineering Journal, Chemantator
(October).
OneWater, Inc. 2012. OneWater. Available online at http://onewaterworks.com/. Accessed June 14, 2012.
Ono, E., and J.L. Cuello. 2004a. Design parameters of solar concentrating systems for CO2-mitigating algal pho-
tobioreactors. Energy 29(9-10):1651-1657.
------. 2004b. Feasibility assessment of open-pond microalgal CO2 mitigation technology with implemention of
the Kyoto Protocol: A case study for Japan. Environment Control in Biology 42(3):161-168.
------. 2006. Feasibility assessment of microalgal carbon dioxide sequestration technology with photobioreactor
and solar collector. Biosystems Engineering 95(4):597-606.
Ort, D.R., X. Zhu, and A. Melis. 2011. Optimizing antenna size to maximize photosynthetic efficiency. Plant Physi-
ology 155(1):79-85.
Osanai, T., Y. Kanesaki, T. Nakano, H. Takahashi, M. Asayama, M. Shirai, M. Kanehisa, I. Suzuki, N. Murata, and
K. Tanaka. 2005. Positive regulation of sugar catabolic pathways in the cyanobacterium Synechocystis sp PCC
6803 by the group 2 sigma factor sigE. Journal of Biological Chemistry 280(35):30653-30659.
Pal, D., I. Khozin-Goldberg, Z. Cohen, and S. Boussiba. 2011. The effect of light, salinity, and nitrogen availability
on lipid production by Nannochloropsis sp. Applied Microbiology and Biotechnology 90(4):1429-1441.
Parikh, M.R., D.N. Greene, K.K. Woods, and I. Matsumura. 2006. Directed evolution of Rubisco hypermorphs
through genetic selection in engineered E. coli. Protein Engineering Design and Selection 19(3):113-119.
Paerl, H.W. 2000. Marine plankton. Pp. 121-148 in The Ecology of Cyanobacteria: Their Diversity in Time and
Space, Whitton, B.A. and M. Potts, eds. Boston, M.A.: Kluwer Academic.
Pedroni, P.M., J. Davison, H. Beckert, P. Bergman, and J. Benemann. 2001. A proposal to establish an international
network on biofixation of CO2 and greenhouse gas abatement with microalgae. Available online at http://
www.netl.doe.gov/publications/proceedings/01/carbon_seq/p17.pdf. Accessed August 26, 2012.
Peled, E., S. Leu, A. Zarka, M. Weiss, U. Pick, I. Khozin-Goldberg, and S. Boussiba. 2011. Isolation of a novel oil
globule protein from the green alga Haematococcus pluvialis (chlorophyceae). Lipids 46(9):851-861.
Pew Center on Global Climate Change. 2011. Advanced biohydrocarbon fuels. Available online at http://www.
c2es.org/docUploads/AdvancedBiohydrocarbonFuels.pdf. Accessed August 21, 2012.
Phycal. 2011. Questionnaire reply from Phycal. Received by the NRC Committee on the Sustainable Development
of Algal Biofuels on July 6.
OCR for page 73
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 73
Polle, J.E.W., S.D. Kanakagiri, and A. Melis. 2003. tla1, a DNA insertional transformant of the green alga Chlamydo-
monas reinhardtii with a truncated light-harvesting chlorophyll antenna size. Planta 217(1):49-59.
Proterro. 2012. Homepage. Available online at http://proterro.com/. Accessed June 17, 2012.
Ptacnik, R., T. Andersen, P. Brettum, L. Lepisto, and E. Willen. 2010. Regional species pools control community
saturation in lake phytoplankton. Proceedings of the Royal Society B-Biological Sciences 277(1701):3755-3764.
Pushparaj, B., E. Pelosi, M.R. Tredici, E. Pinzani, and R. Materassi. 1997. An integrated culture system for outdoor
production of microalgae and cyanobacteria. Journal of Applied Phycology 9(2):113-119.
Radakovits, R., R.E. Jinkerson, A. Darzins, and M.C. Posewitz. 2010. Genetic engineering of algae for enhanced
biofuel production. Eukaryotic Cell 9(4):486-501.
Ramachandra, T.V., D.M. Mahapatra, B. Karthick, and R. Gordon. 2009. Milking diatoms for sustainable energy:
Biochemical engineering versus gasoline-secreting diatom solar panels. Industrial and Engineering Chem-
istry Research 48(19):8769-8788.
Raven, J.A. 2010. Inorganic carbon acquisition by eukaryotic algae: Four current questions. Photosynthesis Re-
search 106(1-2):123-134.
Reppas, N.B. 2012. Methods and compositions for the recombinant biosynthesis of N-Alkanes. Patent US8183027,
filed September 23, 2011, and issued May 22, 2012.
Reynolds, C.S. 1997. Vegetation processes in the pelagic: A model for ecosystem theory. Vol. 9, Excellence in Ecol-
ogy. Oldendorf, Germany: Ecology Institute.
Richmond, A., E. Lichtenberg, B. Stahl, and A. Vonshak. 1990. Quantitative assessment of the major limitations on
productivity of Spirulina platensis in open raceways. Journal of Applied Phycology 2(3):195-206.
Robertson, D.E., S.A. Jacobson, F. Morgan, D. Berry, G.M. Church, and N.B. Afeyan. 2011. A new dawn for indus-
trial photosynthesis. Photosynthesis Research 107(3):269-277.
Rodgers, S.K., and E.F. Cox. 1999. Rate of spread of introduced rhodophytes Kappaphycus alvarezii, Kappaphycus
striatum, and Gracilaria salicornia and their current distribution in Kane'ohe Bay, O'ahu, Hawai'i. Pacific Sci-
ence 53(3):232-241.
Rodolfi, L., G.C. Zittelli, N. Bassi, G. Padovani, N. Biondi, G. Bonini, and M.R. Tredici. 2009. Microalgae for oil:
Strain selection, induction of lipid synthesis and outdoor mass cultivation in a low-cost photobioreactor.
Biotechnology and Bioengineering 102(1):100-112.
Roesijadi, G., S.B. Jones, L.J. Snowden-Swan, and Y. Zhu. 2010. Macroalgae as a Biomass Feedstock: A Preliminary
Analysis. Richland, WA: Pacific Northwest National Laboratory.
Roessler, P. 2011. Algal Strain Selection and Development for Biofuel Production. Presentation to the NRC Com-
mittee on Sustainable Development of Algal Biofuels on September 8.
RSB (Roundtable on Sustainable Biofuels). 2011. Principles and criteria. Available online at http://rsb.epfl.ch/
page-24929.html. Accessed July 18, 2011.
Ruenwai, R., S. Cheevadhanarak, and K. Laoteng. 2009. Overexpression of acetyl-CoA carboxylase gene of Mucor
rouxii enhanced fatty acid content in Hansenula polymorpha. Molecular Biotechnology 42(3):327-332.
Ruffing, A.M. 2011. Engineered cyanobacteria: Teaching an old bug new tricks. Bioengineered Bugs 2(3):136-149.
Russell, D.J. 1983. Ecology of the imported red seaweed Eucheuma striatum Schmitz on Coconut Island, Oahu,
Hawaii. Pacific Science 37(2):87-107.
Scott, S.A., M.P. Davey, J.S. Dennis, I. Horst, C.J. Howe, D.J. Lea-Smith, and A.G. Smith. 2010. Biodiesel from algae:
Challenges and prospects. Current Opinion in Biotechnology 21(3):277-286.
Sharif, D.I., J. Gallon, C.J. Smith, and E. Dudley. 2008. Quorum sensing in cyanobacteria: N-octanoyl-homoserine
lactone release and response, by the epilithic colonial cyanobacterium Gloeothece PCC6909. ISME Journal
2(12):1171-1182.
Sheehan, J., T. Dunahay, J. Benemann, and P. Roessler. 1998. A Look Back at the U.S. Department of Energy's
Aquatic Species Program: Biodiesel from Algae. Golden, CO: National Renewable Energy Laboratory.
Shen, Y., W. Yuan, Z.J. Pei, Q. Wu, and E. Mao. 2009. Microalgae mass production methods. Transactions of the
ASABE 52(4):1275-1287.
Sierra, E., F.G. Acien, J.M. Fernandez, J.L. Garcia, C. Gonzalez, and E. Molina. 2008. Characterization of a flat plate
photobioreactor for the production of microalgae. Chemical Engineering Journal 138(1-3):136-147.
Smith, A.G., S.A. Scott, M.P. Davey, J.S. Dennis, I. Horst, C.J. Howe, and D.J. Lea-Smith. 2010a. Biodiesel from
algae: Challenges and prospects. Current Opinion in Biotechnology 21(3):277-286.
Smith, V.H., B.L. Foster, J.P. Grover, R.D. Holt, M.A. Leibold, and F. deNoyelles, Jr. 2005. Phytoplankton species
richness scales consistently from laboratory microcosms to the world's oceans. Proceedings of the National
Academy of Sciences of the United States of America (102):4393-4396.
Smith, V.H., B.S.M. Sturm, F.J. deNoyelles, and S.A. Billings. 2010b. The ecology of algal biodiesel production.
Trends in Ecology and Evolution 25:301-309.
Solazyme. 2012. Homepage. Available online at www.solazyme.com. Accessed February 9, 2012.
OCR for page 74
74 SUSTAINABLE DEVELOPMENT OF ALGAL BIOFUELS
Solix Biofuels. 2011. The LumianTM AGS4000: A high productivity algae growth system. Available online at http://
www.solixbiofuels.com/content/products/lumian-ags4000. Accessed February 9, 2012.
Solvent Rescue Limited. 2012. Homepage. Available online at http://solventrescue.co.nz/. Accessed June 16,
2012.
Spirulinasource. 1999. Yaeyama farm in Southern Japan grows chlorella in circular ponds. New Ambadi farm in
India grows spirulina in raceway style ponds. Available online at http://www.spirulinasource.com/earth-
foodch6c.html. Accessed May 15, 2012.
Spolaore, P., C. Joannis-Cassan, E. Duran, and A. Isambert. 2006. Commercial applications of microalgae. Journal
of Bioscience and Bioengineering 101(2):87-96.
Stephens, E., I.L. Ross, J.H. Mussgnug, L.D. Wagner, M.A. Borowitzka, C. Posten, O. Kruse, and B. Hankamer. 2010.
Future prospects of microalgal biofuel production systems. Trends in Plant Science 15(10):554-564.
Stockenreiter, M., A.K. Grabe, H. Haupt, and H. Stibor. 2012. The effect of species diversity on lipid production by
micro-algal communities. Journal of Applied Phycology 24(1):45-54.
Stomp, M., J. Huisman, L.J. Stal, and H.C.P. Matthijs. 2007. Colorful niches of phototrophic microorganisms shaped
by vibrations of the water molecule. ISME Journal 1(4):271-282.
Sukenik, A., and G. Shelef. 1984. Algal autoflocculation--Verification and proposed mechanism. Biotechnology
and Bioengineering 26(2):142-147.
Suzuki, L., and C.H. Johnson. 2001. Algae know the time of day: Circadian and photoperiodic programs. Journal
of Phycology 37(6):933-942.
Tang, E.P.Y., W.F. Vincent, D. Proulx, P. Lessard, and J. de la Noue. 1997. Polar cyanobacteria versus green algae for
tertiary waste-water treatment in cool climates. Journal of Applied Phycology 9(4):371-381.
Taton, A., E. Lis, D.M. Adin, G. Dong, S. Cookson, S.A. Kay, S.S. Golden, and J.W. Golden. 2012. Gene transfer in
Leptolyngbya sp. Strain BL0902, a cyanobacterium suitable for production of biomass and bioproducts. Plos
One 7(1):e30901.
Teplitski, M., H. Chen, S. Rajamani, M. Gao, M. Merighi, R.T. Sayre, J.B. Robinson, B.G. Rolfe, and W.D. Bauer.
2004. Chlamydomonas reinhardtii secretes compounds that mimic bacterial signals and interfere with quorum
sensing regulation in bacteria. Plant Physiology 134(1):137-146.
Thelen, J.J., and J.B. Ohlrogge. 2002. Metabolic engineering of fatty acid biosynthesis in plants. Metabolic Engi-
neering 4:12-21.
Tillmann, U. 2004. Interactions between planktonic microalgae and protozoan grazers. Journal of Eukaryotic
Microbiology 51(2):156-168.
Toyomizu, M., K. Suzuki, Y. Kawata, H. Kojima, and Y. Akiba. 2001. Effective transformation of the cyanobacte-
rium Spirulina platensis using electroporation. Journal of Applied Phycology 13(3):209-214.
Trent, J. 2011. Offshore Membrane Enclosure for Growing Algae. Presentation to the NRC Committee on Sustain-
able Development of Algal Biofuels on September 8.
Tsukuda, O., T. Kawahara, and S. Miyachi. 1977. Mass culture of Chlorella in Asian countries. Pp. 363-365 in Biologi-
cal Solar Energy Conversion, A. Mitsui, S. Miyachi, A. San Pietro and S. Tamura, eds. New York: Academic
Press.
Turchetto-Zolet, A.C., F.S. Maraschin, G.L. de Morais, A. Cagliari, C.M.B. Andrade, M. Margis-Pinheiro, and R.
Margis. 2011. Evolutionary view of acyl-CoA diacylglycerol acyltransferase (DGAT), a key enzyme in neutral
lipid biosynthesis. BMC Evolutionary Biology 11:263.
Uduman, N., Y. Qi, M.K. Danquah, G.M. Forde, and A. Hoadley. 2010. Dewatering of microalgal cultures: A major
bottleneck to algae-based fuels. Journal of Renewable and Sustainable Energy 2(1): ISSN (Online) 1941-7012.
Ugwu, C.U., H. Aoyagi, and H. Uchiyama. 2007. Photobioreactors for mass cultivation of algae. Bioresource
Technology 99:4021-4028.
Ugwu, C.U., J.C. Ogbonna, and H. Tanaka. 2002. Improvement of mass transfer characteristics and productivi-
ties of inclined tubular photobioreactors by installation of internal static mixers. Applied Microbiology and
Biotechnology 58(5):600-607.
UTEX (The Culture Collection of Algae at the University of Texas at Austin). 2012. Cryopreservation of algae.
Available online at http://web.biosci.utexas.edu/utex/protocols.aspx. Accessed June 16, 2012.
Van den Hoek, C., D.G. Mann, and H.M. Jahns. 1995. Algae: An Introduction to Phycology. Cambridge, UK:
Cambridge University Press.
Vandamme, D., S.C.V. Pontes, K. Goiris, I. Foubert, L.J.J. Pinoy, and K. Muylaert. 2011. Evaluation of electro-
coagulation-flocculation for harvesting marine and freshwater microalgae. Biotechnology and Bioengineer-
ing 108(10):2320-2329.
Vasquez, V., and P. Heussler. 1985. Carbon dioxide balance in open air mass culture of algae. Archiv für Hydrobi-
ologie, Ergebnisse der Limnologie, Beiheft 20:95-113.
OCR for page 75
OVERVIEW OF ALGAL BIOFUEL SUPPLY CHAIN 75
Viswanathan, T., S. Mani, K.C. Das, S. Chinnasamy, and A. Bhatnagar. 2011. Drying characteristics of a microalgae
consortium developed for biofuels production. Transactions of the ASABE 54(6):2245-2252.
Vunjak-Novakovic, G., Y. Kim, X. Wu, I. Berzin, and J.C. Merchuk. 2005. Air-lift bioreactors for algal growth on
flue gas: Mathematical modeling and pilot-plant studies. Industrial and Engineering Chemistry Research
44(16):6154-6163.
Waaland, J.R., J.W. Stiller, and D.P. Cheney. 2004. Macroalgal candidates for genomics. Journal of Phycology
40(1):26-33.
Waditee, R., T. Hibino, T. Nakamura, A. Incharoensakdi, and T. Takabe. 2002. Overexpression of a Na+/H+ an-
tiporter confers salt tolerance on a freshwater cyanobacterium, making it capable of growth in sea water.
Proceedings of the National Academy of Sciences of the United States of America 99(6):4109-4114.
Wang, X., X. Liu, and G. Wang. 2011. Two-stage hydrolysis of invasive algal feedstock for ethanol fermentation.
Journal of Integrative Plant Biology 53(3):246-252.
Wang, Z.T., N. Ullrich, S. Joo, S. Waffenschmidt, and U. Goodenough. 2009. Algal lipid bodies: stress induction,
purification, and biochemical characterization in wild-type and starchless Chlamydomonas reinhardtii. Eu-
karyotic Cell 8(12):1856-1868.
Wargacki, A.J., E. Leonard, M.N. Win, D.D. Regitsky, C.N.S. Santos, P.B. Kim, S.R. Cooper, R.M. Raisner, A. Her-
man, A.B. Sivitz, A. Lakshmanaswamy, Y. Kashiyama, D. Baker, and Y. Yoshikuni. 2012. An engineered
microbial platform for direct biofuel production from brown macroalgae. Science 335:308-313.
Weckwerth, W. 2011. Green systems biology--From single genomes, proteomes and metabolomes to ecosystems
research and biotechnology. Journal of Proteomics 75(1):284-305.
Weis, J.J., D.S. Madrigal, and B.J. Cardinale. 2008. Effects of algal diversity on the production of biomass in homo-
geneous and heterogeneous nutrient environments: A microcosm experiment. Plos One 3(7):e2825.
Weissman, J.C., D.T. Tillett, and R.P. Goebel. 1989. Design and Operation of an Outdoor Microalgae Test Facility.
Golden, CO: Solar Energy Research Institute.
Wijffels, R.H., and M.J. Barbosa. 2010. An outlook on microalgal biofuels. Science 329(5993):796-799.
Williams, P.J.L.B., and L.M.L. Laurens. 2010. Microalgae as biodiesel and biomass feedstocks: Review and analysis
of the biochemistry, energetics and economics. Energy and Environmental Science 3(5):554-590.
Woo, M., C. Smith, and W. Smith. 2000. Ecological interactions and impacts of invasive Kappaphycus striatum in
Kane'ohe Bay, a tropical reef. Pp. 186-192 in Marine Bioinvasions, J. Pedersen, ed. Cambridge, MA: Massa-
chusetts Institute of Technology, Sea Grant College Program.
Wright, M.M., D.E. Daugaard, J.A. Satrio, and R.C. Brown. 2010. Techno-economic analysis of biomass fast pyroly-
sis to transportation fuels. Fuel 89:S11-S19.
Xtrudx Technologies, Inc. 2012. Homeage. Available online at http://www.xtrudx.com/about.html. Accessed
June 16, 2012.
Yue, L., and W. Chen. 2005. Isolation and determination of cultural characteristics of a new highly CO2 tolerant
fresh water microalgae. Energy Conversion and Management 46(11-12):1868-1876.
Zhao, F.Q., X.W. Zhang, C.W. Liang, J.Y. Wu, Q.Y. Bao, and S. Qin. 2006. Genome-wide analysis of restriction-
modification system in unicellular and filamentous cyanobacteria. Physiological Genomics 24(3):181-190.
Zheng, P., W.B. Allen, K. Roesler, M.E. Williams, S. Zhang, J. Li, K. Glassman, J. Ranch, D. Nubel, W. Solawetz, D.
Bhattramakki, V. Llaca, S. Deschamps, G.Y. Zhong, M.C. Tarczynski, and B. Shen. 2008. A phenylalanine in
DGAT is a key determinant of oil content and composition in maize. Nature Genetics 40(3):367-372.
Zimba, P.V., M.J. Sullivan, and H.E. Glover. 1990. Carbon fixation in cultured marine benthic diatoms. Journal of
Phycology 26(2):306-311.
Zmora, O., Richmond, A. 2003. Microalgae production for aquaculture. Pp. 365-379 in Handbook of Microalgal
Culture, Biotechnology and Applied Phycology. A. Richmond, ed. Boston, MA: Blackwell Publishing.
Zou, J.T., V. Katavic, E.M. Giblin, D.L. Barton, S.L. MacKenzie, W.A. Keller, X. Hu, and D.C. Taylor. 1997. Modifica-
tion of seed oil content and acyl composition in the brassicaceae by expression of a yeast sn-2 acyltransferase
gene. Plant Cell 9(6):909-923.
OCR for page 76
