roadmap algae biofuel

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2 Executive Summary
3 "We must invest in a clean energy economy that will lead to new jobs, new
4 businesses and reduce our dependence on foreign oil," said President Obama.
5 "The steps I am announcing today help bring us closer to that goal. If we are to be
6 a leader in the 21st century global economy, then we must lead the world in clean
7 energy technology. Through American ingenuity and determination, we can and
8 will succeed."
9 President Barack Obama
10 "Developing the next generation of biofuels is key to our effort to end our
11 dependence on foreign oil and address the climate crisis -- while creating millions
12 of new jobs that can't be outsourced," Secretary of Energy Steven Chu said. "With
13 American investment and ingenuity -- and resources grown right here at home -- we
14 can lead the way toward a new green energy economy."
15 Secretary of Energy Steven Chu
16
17 Speaking at the May 5th, 2009 White House ceremony announcing $800M in new
18 biofuel research activities
19
20
21 The 2007 Energy Independence and Security Act (EISA) was enacted in response
22 to concerns about global energy security and supply. The Act contains provisions
23 designed to increase the availability of renewable energy that decreases greenhouse gas
24 (GHG) emissions while at the same time also establishing an aggressive Renewable Fuels
25 Standard (RFS). This new fuels standard mandates the production of 36 billion gallons of
26 renewable fuels by 2022 of which at least 21 billion gallons must be advanced biofuels
27 (i.e., non-corn ethanol). While cellulosic ethanol is expected to play a large role in
28 meeting the EISA goals, a number of next generation biofuels, particularly those with
29 higher-energy density than ethanol, show significant promise in helping to achieve the 21
30 billion gallon goal. Of these candidates, biofuels derived from algae, particularly
31 microalgae, have the potential to help the U.S. meet the new RFS while at the same time
32 moving the nation ever closer to energy independence.
33
34 To accelerate the deployment of biofuels created from algae, President Obama and
35 Secretary of Energy Steven Chu announced on May 5 th, 2009 the investment of $800M
36 new research on biofuels in the American Recovery and Renewal Act (ARRA). This
37 announcement included funds for the Department of Energy Biomass Program to invest
38 in the research, development, and deployment of commercial algal biofuel processes.
39
40 Microalgae are unicellular, photosynthetic microorganisms that are abundant in
41 fresh water, brackish water, and marine environments everywhere on earth. These
42 microscopic plant-like organisms are capable of utilizing CO 2 and sunlight to generate
43 the complex biomolecules necessary for their survival. A class of biomolecules
44 synthesized by many species is the neutral lipids, or triacylglycerols (TAGs). Under
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4. 45 certain conditions, some microalgae can accumulate significant amounts of lipids (more
46 than 50% of their cell dry weight).
47
48 There are several aspects of algal biofuel
49 production that have combined to capture the
50 interest of researchers and entrepreneurs around
51 the world. These include: 1) High per-acre
52 productivity compared to typical terrestrial oil-
53 seed crops, 2) Non-food based feedstock
54 resources, 3) Use of otherwise non-productive,
55 non-arable land, 4) Utilization of a wide variety
56 of water sources (fresh, brackish, saline, and
57 wastewater), and 5) Production of both biofuels
58 and valuable co-products. More than 20 years
59 ago, the Department of Energy-supported
60 Aquatic Species Program (ASP), which
61 represents the most comprehensive research effort to date on fuels from algae, illustrated
62 the potential of this feedstock to be converted into liquid transportation energy. Much has
63 changed since the end of the ASP. With rising petroleum prices and concerns about
64 energy independence, security, and climate change, the quest to use of microalgal
65 feedstocks for biofuels production has again been gaining momentum over the past few
66 years. While the basic concept of using algae as an alternative and renewable source of
67 biomass feedstock for biofuels has been explored over the past several decades, a
68 scalable, sustainable and commercially viable system has yet to emerge.
69
70 The National Algal Biofuels Technology Roadmap Workshop, held December 9-10,
71 2008, was convened by the Department of Energy‘s Office of Biomass Program in the
72 Office of Energy Efficiency and Renewable Energy (EERE). This two day event
73 successfully brought together more than 200 scientists, engineers, research managers,
74 industry representatives, lawyers, financiers and regulators. The workshop participants
75 broadly represented stakeholders from different areas of industry, academia, the
76 National laboratory system as well as governmental and non-governmental agencies
77 and organizations. The primary purpose of the workshop was to discuss and identify the
78 critical barriers currently preventing the economical production of algal biofuels at a
79 commercial scale. The input to the roadmap document was structured around the
80 Workshop‘s break-out sessions which were specifically created to address the various
81 process operations that must be tackled in developing a viable algal biofuels industry.
82 The workshop addressed the following topics/technical barriers:
83  Algal Biology
84  Feedstock Cultivation
85  Harvest and Dewatering
86  Extraction and Fractionation of Microalgae
87  Algal Biofuel Conversion Technologies
88  Co–Products
89  Distribution and Utilization of Algal Based-Fuels
90  Resources and Siting
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5. 91  Corresponding Standards, Regulation and Policy
92  Systems and Techno-Economic Analysis of Algal Biofuel Deployment
93  Public-Private Partnerships
94
95 This document represents the output from the workshop and is intended to provide a
96 comprehensive roadmap report that summarizes the state of algae-to-fuels technology and
97 documents the techno-economic challenges that likely must be met before algal biofuel
98 can be produced commercially. This document also seeks to explain the economic and
99 environmental impacts of using algal biomass for the production of liquid transportation
100 fuels Based on the outcome of the workshop, the technical barriers identified involve
101 several scientific and engineering issues which together represent a significant challenge
102 to the development of biofuels from microalgae. Taking these barriers into consideration,
103 this roadmap also serves to make research and funding recommendations that will begin
104 to lay the groundwork for overcoming the technical barriers that currently prevent the
105 production of economically viable algal-based biofuels.
106
107 Viewpoints expressed during the DOE workshop and road mapping effort was that
108 many years of both basic and applied R&D will likely be needed to overcome the current
109 technical barriers before algal-based fuels can be produced sustainably and economically
110 enough to be cost-competitive with petroleum-based fuels. Since both research and
111 engineering improvements are absolutely critical components to implementing any
112 commercial-scale, algal-based fuel production facility, it is also clear that a
113 multidisciplinary research approach will be necessary to accelerate progress over the
114 short term (0-5 years). For example, the ability to quickly test and implement new and
115 innovative technologies in an integrated process setting will be a key component to the
116 success of any such effort. Such an approach will ultimately serve as the engine that not
117 only drives fundamental research and technology development but also demonstration
118 and commercialization. Based on the work that needs to be accomplished, the proposed
119 R&D activities will also require long-term coordinated support from relevant government
120 agencies and national laboratories, private sector, academia, and the participation from
121 virtually all interested stakeholders. Lastly, there is a need for a significant investment in
122 our colleges and universities, as well as field experts, to train the professional work force
123 that will be needed for developing the necessary infrastructure as well as the operation
124 and maintenance of a robust and domestic algal biofuels industry.
125
126
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6. 127
128 Contents
129 Executive Summary ......................................................................................................................... iii
130 Contents .......................................................................................................................................... iv
131 1. Introduction ............................................................................................................................ 1
132 About the Roadmap ................................................................................................................. 1
133 America’s Energy Challenges .................................................................................................. 2
134 The Algae-to-Biofuels Opportunity........................................................................................... 5
135 Microalgae as a Feedstock for Fuel Production ................................................................. 5
136 The Potential of Microalgal Oils .......................................................................................... 6
137 Integrating With Biorefinery Concept .................................................................................. 8
138 Investments So Far in Algal Biofuels Development................................................................. 8
139 Early Work to 1996 ............................................................................................................. 8
140 Research from 1996 to Present ....................................................................................... 11
141 Going Forward ....................................................................................................................... 13
142 Roadmapping a Strategy for Algal Biofuels Development & Deployment ....................... 13
143 Need for a Sizeable, Strategically Structured and Sustained Investment ........................ 13
144 2. Algal Biology ........................................................................................................................ 15
145 Algae: Basic Biological Concepts ..................................................................................... 15
146 Algal Classification ........................................................................................................... 16
147 Photosynthesis/CO2 Fixation ............................................................................................ 17
148 Strain Isolation, Selection, and/or Screening ......................................................................... 17
149 Isolation and Characterization of Naturally Occurring Algae Species/Strains ................. 18
150 Role of Algal Culture Collections ...................................................................................... 20
151 References ....................................................................................................................... 21
152 Cell Biology: Physiology and Biochemistry ............................................................................ 21
153 Photosynthesis ................................................................................................................. 22
154 Metabolic Carbon Fluxes and Partitioning ........................................................................ 22
155 Metabolic Link between Starch and Lipid Metabolism ..................................................... 23
156 Lipid Synthesis and Regulation ........................................................................................ 24
157 References ....................................................................................................................... 27
158 Biohydrogen: Direct Biophotolysis and Oxygen Sensitivity of the Hydrogen-Evolving
159 Enzymes ................................................................................................................................ 29
160 Fermentative Hydrogen Production (Indirect Biophotolysis) ............................................ 31
161 References ....................................................................................................................... 32
162 Genomics and Systems Biology ............................................................................................ 33
163 Development of Algal Model Systems .............................................................................. 33
164 Sequencing and Annotation of Algal Genomes................................................................ 37
165 Establishment of an Integrated Systems Biology and Bioinformatics Framework to
166 Develop a Fundamental Understanding of Carbon Partitioning in Algae ......................... 39
167 Development & Adaptation of Genetic Tools and Deployment of Synthetic Biology
168 Systems for Metabolic Engineering of Model Algal Organisms ....................................... 40
169 References ....................................................................................................................... 44
170 3. Algal Cultivation ................................................................................................................... 48
171 Introduction ............................................................................................................................ 48
172 Advantages of Algae as a Biofuel Crop ............................................................................ 48
173 Algal Bioreactor Designs .................................................................................................. 48
174 Addressing Feedstock Productivity .................................................................................. 49
175 Scale-Up Barriers .................................................................................................................. 49
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7. 176 References............................................................................................................................. 57
177 4. Downstream Processing: Harvesting and Dewatering ........................................................ 59
178 Introduction ............................................................................................................................ 59
179 Processing Technologies ....................................................................................................... 59
180 Flocculation and Sedimentation ....................................................................................... 59
181 Flocculation and Dissolved Air Flotation .......................................................................... 60
182 Filtration ............................................................................................................................ 60
183 Centrifugation ................................................................................................................... 61
184 Other Techniques ............................................................................................................. 61
185 Drying ............................................................................................................................... 61
186 Systems Engineering ............................................................................................................. 61
187 5. Extraction and Fractionation of Microalgae ......................................................................... 64
188 Introduction ............................................................................................................................ 64
189 Current Practices for Lipid Extraction/Fractionation .............................................................. 64
190 Nontraditional Extraction Approaches .............................................................................. 70
191 Challenges ............................................................................................................................. 71
192 Presence of Water Associated with the Biomass ............................................................. 71
193 Energy Consumption and Water Recycle ........................................................................ 71
194 Goals ...................................................................................................................................... 72
195 Missing Science Needed to Support the Development of New Extraction and Fractionation
196 Technologies.......................................................................................................................... 73
197 Algal Cell Wall Composition ............................................................................................. 73
198 Lipid Genesis, Chemistry, and Structure .......................................................................... 73
199 Development of Multitasking Extraction Processes ......................................................... 73
200 Conclusion ............................................................................................................................. 74
201 References............................................................................................................................. 74
202 6. Algal Biofuel Conversion Technologies ............................................................................... 77
203 Introduction (Producing “Fit for Purpose” Algal Biofuels) ...................................................... 77
204 Direct Production of Biofuels from Algae ............................................................................... 78
205 Alcohols ............................................................................................................................ 78
206 Alkanes ............................................................................................................................. 79
207 Hydrogen .......................................................................................................................... 80
208 Processing of Whole Algae .................................................................................................... 81
209 Pyrolysis ........................................................................................................................... 81
210 Gasification ....................................................................................................................... 83
211 Anaerobic Digestion of Whole Algae ................................................................................ 84
212 Conversion of Algal Extracts .................................................................................................. 84
213 Transesterification ............................................................................................................ 85
214 Biochemical Catalysis ....................................................................................................... 86
215 Chemical Catalysis ........................................................................................................... 87
216 Supercritical Processing ................................................................................................... 88
217 Processing of Algal Remnants after Extraction ..................................................................... 90
218 References............................................................................................................................. 91
219 7. Co-products ......................................................................................................................... 95
220 Introduction ............................................................................................................................ 95
221 Commercial Products from Microalgae ................................................................................. 96
222 Potential Options for the Recovery of Co-products ............................................................... 99
223 Crosscutting Areas / Interfaces............................................................................................ 105
224 References........................................................................................................................... 107
225 8. Distribution and Utilization ................................................................................................. 110
226 Distribution ........................................................................................................................... 110
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8. 227 Utilization ............................................................................................................................. 111
228 Algal Blendstocks to Replace Middle-Distillate Petroleum Products.............................. 112
229 Algal Blendstocks for Alcohol and Gasoline-Range Petroleum Products ...................... 112
230 Research Needs .................................................................................................................. 113
231 References........................................................................................................................... 113
232 9. Resources and Siting ......................................................................................................... 114
233 Introduction .......................................................................................................................... 114
234 Resources Overview ............................................................................................................ 115
235 Climate............................................................................................................................ 115
236 Water .............................................................................................................................. 117
237 Carbon Dioxide ............................................................................................................... 120
238 Land ................................................................................................................................ 121
239 Integration with Water Treatment Facilities, Power Utilities, Other Industries .................... 123
240 Water Treatment Applications ........................................................................................ 123
241 Algae Production Techniques for Water Treatment Plants ............................................ 125
242 Summary of Potential Benefits of Algae Production with Wastewater Treatment ......... 127
243 Co-location of Algal Cultivation Facilities with CO2-Emitting Industries .............................. 128
244 Advantages of Co-location of Algae Production with Stationary Industrial CO 2 Sources131
245 Barriers to Co-location of Algae Production with Stationary Industrial CO 2 Sources ..... 131
246 Recommended Areas for Research and Policy Evaluations ............................................... 132
247 Conclusions and Recommendations ................................................................................... 133
248 Section 9 Appendix – Additional Figures ............................................................................. 135
249 10. Corresponding Standards, Regulation, and Policy ............................................................ 144
250 Introduction .......................................................................................................................... 144
251 Rationale for Standards and Regulations Development ................................................ 144
252 Status of Standards and Regulations Relating to the Algal Biofuels Industry ................ 145
253 Standards and Regulations Issues ................................................................................. 145
254 Developing Standards ......................................................................................................... 146
255 Areas in Which Standards Are Needed .......................................................................... 146
256 Status of Algal Biofuels Industry Standards ................................................................... 147
257 Timeline for Completing Actions ..................................................................................... 148
258 Building a Regulatory Structure ........................................................................................... 149
259 The Case for Regulation ................................................................................................. 149
260 Status of Algal Biofuels Industry Regulation .................................................................. 150
261 Timeline for Completing Actions ..................................................................................... 151
262 Policy Framework for Algal Biofuels .................................................................................... 152
263 Policy Objectives ............................................................................................................ 152
264 Policy Options ................................................................................................................. 154
265 11. Systems and Techno-Economic Analysis of Algal Biofuel Deployment ............................ 157
266 Introduction .......................................................................................................................... 157
267 Workshop Results and Discussion ...................................................................................... 158
268 Systems Analysis ................................................................................................................. 161
269 Algae Production Cost Uncertainties – Illustrative Example ............................................... 164
270 Algae Techno-Economic analyses: System Dynamics modeling ........................................ 168
271 Recommended Priorities and R&D Effort ............................................................................ 169
272 References........................................................................................................................... 171
273 12. Public-Private Partnerships ............................................................................................... 175
274 Introduction .......................................................................................................................... 175
275 Building Successful Public-Private Partnerships ................................................................. 176
276 The Benefits of Algal Biofuels Public-Private Partnerships ................................................. 177
277 Partnership Environment in the Algal Biofuels Industry ...................................................... 178
278 Challenges for Algal Biofuels Public-Private Partnerships to Address ................................ 178
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9. 279 Algal Biology ................................................................................................................... 179
280 Algal Cultivation and Processing .................................................................................... 181
281 Conversion to Fuels “Fit for Use”, Distribution & Utilization ........................................... 181
282 Resources & Siting, Regulations & Policy, and Systems Analysis & Techno-Economic
283 Modeling ......................................................................................................................... 181
284 Various Roles Anticipated by Stakeholders ......................................................................... 182
285 Government .................................................................................................................... 182
286 Individual Companies within the Private Sector ............................................................. 183
287 Emerging Trade Organizations....................................................................................... 184
288 Academia ........................................................................................................................ 184
289 Partnership Models .............................................................................................................. 184
290 Models for Openness ..................................................................................................... 185
291 Models for Technology Commercialization .................................................................... 185
292 Models for Industry Growth ............................................................................................ 186
293 Models for Shared Investment........................................................................................ 186
294 Recommendations and Timeline ......................................................................................... 186
295 Appendix: ..................................................................................................................................... 190
296 Scenarios Illustrating Preliminary Consequence Assessment: ........................................... 190
297 Basis for Order-of-Magnitude Projections of CO2 Utilization with Algae Production ...... 195
298 References........................................................................................................................... 203
299
300
302
301
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10. 303
304 1. Introduction
305 About the Roadmap
306 The framework for National Algal Biofuels Technology Roadmap was constructed at the
307 Algal Biofuels Technology Roadmap Workshop, held on December 9 and 10, 2008 at the
308 University of Maryland College Park. The Workshop was organized by the U.S.
309 Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy‘s
310 Biomass Program to discuss and identify the critical barriers currently preventing the
311 development of a domestic, commercial-scale algal biofuels industry.
312 Microalgae offer great promise to contribute a significant (=< 100%) portion of the
313 renewable fuels that will be required to meet the U.S. biofuel production target of 36
314 billion gallons by 2022, as mandated in the Energy Independence and Security Act of
315 2007 under the Renewable Fuels Standard. In the longer term, biofuels derived from
316 algae represent an opportunity to dramatically impact the U.S. energy supply for
317 transportation fuels. The cultivation of algae at a commercial scale could provide
318 sufficient fuel feedstock to meet the transportation fuels needs of the entire United States,
319 while being completely compatible with the existing transportation fuel infrastructure
320 (refining, distribution, and utilization). Further, algal biofuels could prove sustainable for
321 generations – they consume CO2 as a nutrient, have a much higher yield potential than
322 other terrestrial biomass feedstocks, and can be grown with non-fresh water sources
323 without needing to use high-value arable land. However, despite their huge potential, the
324 state of technology for producing algal biofuels is regarded by many in the field to be in
325 its infancy. There is a general consensus that a considerable amount of research,
326 development, and demonstration (RD&D) needs to be carried out to provide the
327 fundamental understanding and scale-up technologies required before algal-based fuels
328 can be produced sustainably and economically enough to be cost-competitive with
329 petroleum-based fuels. For this reason, a major objective of the Workshop was to help
330 define the activities that will be needed to resolve the challenges associated with
331 commercial-scale algal biofuel production and lay the framework for an algal biofuels
332 technology roadmap.
333 The Algal Biofuels Technology Roadmap Workshop brought together the
334 interdisciplinary expertise needed to fully discuss the promise and challenges of a
335 commercial algal biofuels industry. The Workshop and the reporting process were
336 designed to be as inclusive and transparent as possible. More than 200 participants were
337 invited to attend the Workshop and broadly represented stakeholders from different areas
338 of industry, academia, the United States national laboratory system, as well as
339 governmental and non-governmental agencies and organizations. Over the course of the
340 two days, the Workshop produced a very stimulating look at the growing algal biofuels
341 industry and the opportunity to explore the science and engineering challenges that must
342 be overcome to realize the sustainable production of algal biofuels at commercial scale.
343 The Workshop participants drew on their experience and expertise during a series of
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11. 344 technical discussions spanning all aspects of enabling a sustainable commercial algal
345 biofuels industry. In these discussions throughout the Workshop, there was an underlying
346 overwhelming consensus for the continued development of algal biofuels; participants
347 agreed upon the need for DOE to coordinate with other federal agencies to support
348 fundamental and applied research, infrastructure development, technology deployment,
349 and information management at a national level, as well as to engage in the development
350 of supportive policy, regulation, and standards for the emerging algal biofuels industry.
351 These outcomes from the Workshop provided key inputs to the development of this Algal
352 Biofuels Technology Roadmap.
353 The Workshop participants were provided with several valuable existing resource
354 materials pertinent to algal biofuels in advance of the Workshop so as to ensure a uniform
355 level of awareness of these materials. These materials included seminal literature
356 references, general reviews and reports and are available at no cost to the general public
357 for download and review by visiting the DOE Algae Biofuels Technology Roadmap Web
358 site at http://www.orau.gov/algae2008/resources.htm. The available resources also
359 contained materials sorted by topics of the Workshop‘s break-out sessions.
360 Developed from the discussions held at the Workshop, this roadmap presents information
361 from a scientific, economic, and policy perspective that can support and guide R&D
362 investment in algal biofuels. While addressing the potential economic and environmental
363 benefits of using algal biomass for the production of liquid transportation fuels, the
364 roadmap describes the current status of algae R&D. In doing so, it lays the groundwork
365 for identifying the technical barriers that likely need to be overcome for algal biomass to
366 be used in the production of economically viable biofuels.
367
368 The roadmap is structured around the Workshop‘s break-out sessions—they were
369 specifically created to address the various aspects that must to be tackled in developing a
370 viable algal biofuels industry:
 Systems and Techno-Economic  Algal Biology
Analysis
 Algal Cultivation  Processing (Harvesting and Dewatering)
 Extraction/Fractionation  Conversion to Fuels
 Co-products  Distribution & Utilization
 Resources and Siting  Standards, Regulation, and Policy
371
372 America’s Energy Challenges
373 As petroleum supplies diminish in the world, the United States becomes increasingly
374 dependent upon foreign sources of crude oil. The United States currently imports
375 approximately two-thirds of its petroleum and more than 60% of this petroleum is used
376 for transportation fuels. The rising energy demand in many rapidly developing countries
377 around the world is beginning to create intense competition for the world‘s dwindling
378 petroleum reserves. Furthermore, the combustion of petroleum-based fuels has created
379 serious concerns over global warming effects due to greenhouse gas (GHG) emissions.
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12. 380 In response to these global energy concerns and in an effort to move the U.S. toward
381 greater energy independence and security, President George Bush signed into law the
382 Energy Independence and Security Act of 2007 (EISA), which contains new standards
383 for vehicle fuel economy, as well as provisions that promote the use of renewable fuels,
384 energy efficiency, and new energy technology research and development. The new
385 energy legislation is designed to reduce the U.S. dependence on foreign oil by increasing
386 the production of domestic alternative fuels and establishing a very aggressive
387 Renewable Fuels Standard (RFS) (Table 1).
388 Table 1: EISA requirements under RFS
Renewable Fuels Mandated Production by Volume
Corn Starch-Based Ethanol 15 billion gallons by 2015
Biodiesel 500 million gallons starting in 2009 and peaking
at 1 billion gallons by 2012
Cellulosic Ethanol 100 million gallons in 2010, growing to 16 billion
gallons by 2022
Other Advanced Biofuels 5 billion gallons by 2022
(other than corn-based ethanol such as that produced
from wood chips, agricultural waste or dedicated energy
crops)
389
390 While cellulosic ethanol is expected to play a large role in meeting the EISA goals, it is
391 unlikely that the supply of cellulosic ethanol will meet the EISA requirement of 100
392 million gallons by 2012 since most small-scale demonstration plants are not scheduled to
393 begin production until the 2010-2011 timeframe.
394
395 Advanced biofuels also face significant challenges in meeting their targets set by EISA.
396 As required by EISA, advanced biofuels must produce GHG emissions across their
397 lifecycle that are at least 50% less than GHG emissions produced by petroleum-based
398 transportation fuels. Moreover, the development of biofuels from oil crops and waste
399 cooking oil/fats cannot realistically meet the demand for liquid transportation fuels
400 because conventional oil yields per hectare from oil crops would require unrealistic
401 acreages of land in excess of the total land area of the United States (Tyson et al., 2004).
402 Further, more than 90% of the vegetable oil produced in the U.S. is used in the food
403 products market, thereby severely limiting its use as a biofuel feedstock. Therein lies one
404 of the main drivers in the development of microalgal diesel fuels—microalgae promises
405 much higher productivities per unit area given its higher photosynthetic efficiency when
406 compared to conventional crops. Table 2 contains data which demonstrates that potential
407 oil yields from algae are also significantly higher than the yields of oilseed crops. Under
408 the current yield scenarios, the potential oil yields from certain algae are projected to be
409 at least 60 times higher than from soybeans per acre of land on an annual basis—
410 approximately 15 times more productive than jatropha and approximately 5 times that of
411 oil palm (Rodolfi et al., 2009). With these features of higher growth rates and increased
412 oil yields, algae have the potential to replace a significant amount of the current U.S.
413 diesel fuel usage while using only a fraction of the land equivalent what would be
414 required from terrestrial crops.
415
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13. a
416 Table 2: Comparison of oil yields from biomass feedstocks
Crop Oil Yield (Gallons/Acre/Yr)
Soybean 48
Camelina 62
Sunflower 102
Jatropha 202
Oil palm 635
b
Algae 1,000-4,000
a
417 Adapted from Chisti (2007)
418 b
Estimated yields, this report
419
420 Although a number of other proposed advanced biofuels show significant potential in
421 helping to achieve the 21 billion gallon EISA mandate, biofuels derived from algal
422 biomass feedstocks show considerable promise as a potential major contributor to the
423 displacement of petroleum-based fuels. There are several aspects of algal biofuel
424 production that have combined to capture the interest of researchers and entrepreneurs
425 around the world:
426  Unlike other oil crops, algae grow rapidly and many
Advantages of Algal Biomass
427 are exceedingly rich in lipid oil (oil levels of 20% to
428 50% are quite common).  High per-acre productivity
429  Using algae to produce feedstocks for biofuels  Non-food resource
430 production will not compromise the production of  Use of otherwise non-
431 food and other products derived from terrestrial productive, non-arable land
432 crops.  Utilization of a wide variety of
433  The cultivation of algae does not entail land conflict water sources
434 for doing agriculture for food production.  Reduced GHG release into
435  The water used to grow algae can include waste the atmosphere
436 water and non-potable saline water that cannot be  Production of biofuels and co-
437 used by conventional agriculture or for domestic products
438 use.
439  Algae have a tremendous technical potential for recycling CO2-rich flue gases
440 from coal burning power plants as well as from natural gas recovery operations.
441  An algal biorefinery could potentially integrate several different conversion
442 technologies to produce biofuels including biodiesel, green diesel, green gasoline,
443 aviation fuel, ethanol, and methane as well as valuable co-products including oils,
444 protein, and carbohydrates.
445
446 While the basic concept of using algae as an alternative and renewable source of biomass
447 feedstock for biofuels has been explored in the past, a scalable, commercially viable
448 system has not emerged. Past research investments have been intermittent and short-term
449 thus insufficient to enable the development of an algae-based biofuels technology. Given
450 recent and dramatic advances in relevant fields, in particular biology, and the fact that
451 realizing the strategic potential of this feedstock will require critical engineering
452 innovations and science breakthroughs, from understanding algal mass culture to
453 downstream processing, a more substantial and sustained investment is paramount. This
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14. 454 investment much include a significant R&D effort focused on answering fundamental
455 biological questions related to algal physiology to support the engineering and scale-up
456 effort..
457 The Algae-to-Biofuels Opportunity
458 Microalgae as a Feedstock for Fuel Production
459 In terms of chemical properties, the most important difference between fossil fuels and
460 those derived from biomass feedstocks is that petroleum, natural gas, and coal are made
461 of hydrocarbons—compounds composed entirely of carbon and hydrogen. In contrast,
462 commercially available biomass-derived fuels (ethanol and biodiesel) contain oxygen (in
463 addition to carbon and hydrogen), yielding different physical and chemical properties of
464 the fuel and thus different combustion characteristics. As a result, the biomass-derived
465 oxygenates have a reduced heating value compared to hydrocarbons. Oxygenates, which
466 are in a partially oxidized state, release less energy upon combustion (complete
467 oxidation) than do hydrocarbons, which are in a completely reduced state.
468
469 Table 3 compares the typical lower heating value (LHV) of several fuels in use today.
470 Ethanol, for example, is more highly oxidized than a hydrocarbon since it contains
471 oxygen (CH3CH2OH) and liberates significantly less energy on combustion than do
472 petroleum-based components. Butanol (CH3(CH2)3OH), on the other hand, has two
473 additional carbon atoms, which makes it a higher energy density fuel. Alcohols are,
474 nevertheless, beneficial fuel alternatives because the presence of oxygen allows these
475 molecules to burn cleaner and more efficiently. Biodiesel, a renewable fuel currently
476 produced commercially from vegetable oils (soy, canola, and sunflower), has
477 significantly higher volumetric energy densities due to the presence of long chain fatty
478 acids that contain carbon, hydrogen, and oxygen (e.g., CH3(CH2)14COOH). The presence
479 of oxygen in these fatty acid methyl esters has the added benefit of acting as an
480 oxygenate and enhances engine performance in much the same fashion as the alcohols.
481 Petroleum-derived diesel, which is comprised of approximately 75% saturated
482 hydrocarbons (alkanes) and 25% aromatic hydrocarbons, has the highest energy density
483 of all the fuels listed because the components in diesel contain only carbon and hydrogen
484 substituents (no oxygen).
485 Table 3: Lower Heating Value (LHV)* of Various Liquid Transportation Fuels
Fuels LHV (Btu/Gallon)
Ethanol 76,000
Butanol 99,840
Gasoline 115,000
Biodiesel (B100) 117,000
Petroleum Diesel 128,500
*
486 The lower heating value or LHV of a fuel is the energy that can be recovered when the water of
487 combustion is released as a vapor.
488 Source: DOE, Hydrogen Analysis Resource Center
489
490 Feinberg (1984) has discussed the issue comparison between the composition of various
491 algal species with fuel chemical requirements. For this reason, only a brief
5

15. 492 characterization of the microalgae feedstock (as produced at the culture facility and fed to
493 the fuel production facility) is presented here to establish the basis for determining
494 appropriate process requirements for converting microalgal constituents into fuels.
495
496 Research conducted over the last 50 years has demonstrated that microalgae produce a
497 diverse array of chemical intermediates and hydrocarbons and, therefore, offer promise as
498 a potential substitute for products currently derived from petroleum or natural gas. Three
499 major components can be extracted from microalgal biomass: lipids (including
500 triglycerides and fatty acids), carbohydrates, and proteins. Bioconversion products
501 include alcohols, methane, hydrogen, and organic acids, and catalytic conversion
502 products include paraffins, olefins, and aromatics.
503
504 While each of the three main biochemical fractions of microalgae can be converted into
505 fuels, lipids have the highest energy content and potential. The lipids of some species are
506 composed of hydrocarbon molecules, similar to those found in petroleum feedstocks,
507 while those of other species resemble vegetable oils (corn, soybean, canola, and others)
508 that can be converted to a synthetic diesel fuel. Lipids are not the only potential biofuels
509 feedstock from algae. Carbohydrates can be converted into ethanol by fermentation.
510 Alternatively, all three components present in biomass can be converted into methane gas
511 by an anaerobic digestion process or into syngas or pyrolysis oil by thermochemical
512 conversion. Microalgae would thus be attractive feedstocks for fuel production if their
513 productivity can be effectively exploited.
514
515 Although this report will briefly consider all the potential conversion processes to
516 produce fuel from microalgal feedstocks, it will focus on the high-energy lipids. Many
517 species have the ability to accumulate large quantities of these compounds, especially
518 when cultivated under nutritive stress (Milner, 1976). Most lipids in algal cells are found
519 in the membrane that surrounds the cell and cellular organelles. However, some strains
520 produce a significant amount of storage lipids when grown under nutrient-limiting
521 conditions. Oil levels of 20-50% are quite common (Chisti, 2007). The idea of generating
522 biodiesel from the microalgal storage lipids was the main focus of DOE‘s Aquatic
523 Species Program from 1978 to 1996 (Sheehan et al., 1998).
524
525 The Potential of Microalgal Oils
526 Numerous algal strains have been shown to produce more than 50% of their biomass (on
527 a dry cell weight basis) as lipid with much of this present in the form of triacylglycerols
528 (TAGs) (Hu et al., 2008). (It should be noted however, that like many aspects of algal
529 biofuels research, the methodology generally used for algal lipid analysis - largely based
530 on solvent extraction and gravimetric analysis - has yet to be standardized and thus the
531 values published in the literature should be regarded, at best, as only an estimation of the
532 lipid content.) Further, some algae accumulate high levels of lipids when cultivated under
533 stress (e.g. limitations of certain nutrients) or in response to changes in culture conditions.
534 For this reason, algal cellular lipid content can vary both in quantity and quality.
535 Importantly, from a production point of view, accumulation of lipid produced under
536 stress conditions is generally at the expense of significantly reduced biomass yields.
537 Algae-derived oils contain fatty acid and triglyceride compounds, which like their
6

16. 538 terrestrial seed oil counterparts, can be converted into biodiesel (via transesterification to
539 yield fatty acid methyl esters) (Fukuda et al., 2001), and green diesel, green jet fuel, and
540 green gasoline (produced by a combination of hydroprocessing and catalytic cracking to
541 yield alkanes of various carbon chain lengths) (Kalnes et al., 2007).
542 Given that scalable algal biofuels are not yet attainable, applying a modest estimate of the
543 potential productivity of oil from algae at 1,200 gallons/acre/year on the area of land
544 equivalent to that used to produce the 2007 U.S. soybean crop (67 million acres) yields a
545 figure greater than 100% of the petroleum diesel consumed annually in the U.S. Had the
546 oil from the entire 2007 soybean crop been converted to biodiesel, on the other hand, it
547 would have provided only 2.8 billion gallons of fuel. (Source: Soy Stats™, American
548 Soybean Association). This amount of biodiesel would displace just 6% of the
549 approximately 44 billion gallons of petroleum on-road diesel used annually in the U.S.
550 Further, as a figure of merit (see Appendix), algae require approximately 2 kg of CO2 for
551 every kg biomass generated, therefore, this technology has the potential to recycle CO2
552 emissions from power plants and other fixed sources of CO2.
553
554 Improvements in either area productivity (gm/m2/day) or lipid content (gm/dry cell
555 weight) would significantly reduce the land area needed ultimately to produce this
556 quantity of biofuel. The algal residue that remains after removal of the lipid component
557 (i.e., largely carbohydrate and protein) could be used for the generation of energy
558 (biopower), more liquid fuels through fermentation (ethanol, biobutanol, etc.), or gaseous
559 (methane) fuels through anaerobic digestion, or serve as a feedstock for the generation of
560 higher-value co-products. In the future, an algal-based biorefinery could potentially
561 integrate several different conversion technologies to produce many biofuels as well as
562 valuable co-products including oils, protein, and carbohydrates.
563
564 With concerns about petroleum supplies and costs as energy demands grow worldwide,
565 energy independence, security, and global warming, the potential use of microalgal
566 feedstocks for biofuels production, specifically lipids derived from them, has gained
567 significant momentum over the past few years. It has been reported that the use of
568 vegetable oil and fat-based feedstocks, which are widely used in world food markets,
569 cannot realistically satisfy the ever-increasing demand for transportation fuels, nor are
570 they likely to displace any significant portion of the U.S. petroleum fuel usage (Tyson et
571 al., 2004). Algal oils do, however, have that potential because their oil yield/acre can be 5
572 to 60 times higher than that of terrestrial oil crops (see Table 2).
573
574 In addition to the production of energy-rich lipids, algae can also be regarded as an
575 alternative source of carbohydrates. For example, some algae and cyanobacteria can
576 accumulate large quantities of storage polysaccharides as a product of photosynthesis.
577 These include starch, glycogen, and chrysolaminarin, three different polymers of glucose.
578 Additionally, the main structural elements of algal cell walls have been shown to be
579 composed of polysaccharides such as cellulose, mannans, xylans, and sulfated glycans.
580 Algal-derived polysaccharides can be hydrolyzed (chemically or enzymatically) into
581 sugars that can be fermented to ethanol.
582
7

17. 583 Integrating With Biorefinery Concept
584 While the conversion of solar energy into renewable liquid fuels and other products from
585 algal lipid feedstocks is technically feasible (Chisti, 2007), currently such biofuels cannot
586 be produced economically enough to be cost-competitive with fossil fuels. A significant
587 basic science and applied engineering R&D effort is required before the vision and
588 potential of algae for biofuels can be fully realized. It is, however, conceivable that in the
589 not too distant future, algae farms could become an integral part of a biorefinery concept
590 that incorporates other advanced technologies to produce a variety of biofuels such as
591 cellulosic ethanol, biodiesel, renewable ―green‖ diesel, gasoline, jet fuel, and a wide
592 range of co-products. This biorefinery could be integrated, at least initially, with a fossil
593 fuel-based power plant. The CO2 generated by this plant and from an integrated ethanol
594 plant would serve as a rich source of nutrients for the growth of algae, as well as serve to
595 mitigate the release of CO2 by recycling it.
596 After extraction of the algal oils, the residue could be used as a starting feedstock to drive
597 ethanol production (through the use of algal-derived sugars) or fed back into the power
598 plant to be burned as a fuel source. To round out the biorefinery, a biodiesel plant or
599 petroleum refinery (or both) would convert the algal lipids into the most cost-effective
600 fuel depending on the economic situation. Ultimately, substantial R&D is needed to
601 develop an algae-to-biofuels production system that can become an integrated component
602 in a biorefinery that operates at high efficiency with minimal inputs at a low cost.
603
604 For these and other reasons, algae hold tremendous potential for the long-term biofuels
605 strategy for transportation energy within the United States. Corn ethanol, though it poses
606 longer-term sustainability challenges, can be used in the near term since the needed
607 technologies and biomass production are readily available and it can help establish and
608 exercise an ethanol-based biofuels economy. In the near to mid-term, cellulosic biofuels,
609 starting with ethanol, present tremendous potential for replacing up to 30% of the U.S.
610 gasoline usage, and cellulosic ethanol follows naturally from starch ethanol. Moving
611 further out, other advanced biofuels from cellulosic biomass may provide reduced
612 distribution costs and higher energy densities. Finally, in still longer term (perhaps 10
613 years), biofuels from algae present an opportunity at the greatest scale and with very
614 attractive sustainability characteristics.
615
616 Investments So Far in Algal Biofuels Development
617 Early Work to 1996
618 Proposals to use algae as a means of producing energy date back to the late 1950s when
619 Meier (1955) and Oswald and Golueke (1960) suggested the utilization of the
620 carbohydrate fraction of algal cells for the production of methane gas via anaerobic
621 digestion. Not until the energy price surges of the 1970s did the possibility of using algae
622 as a fuel source receive renewed attention. A detailed engineering analysis by Benemann
623 et al., (1978) indicated that algal systems could produce methane gas at prices
624 competitive with projected costs for fossil fuels. The discovery that many species of
625 microalgae can produce large amounts of lipid as cellular oil droplets under certain
8

18. 626 growth conditions dates back to the 1940s. Various reports during the 1950s and 1960s
627 indicated that starvation for key nutrients, such as nitrogen or silicon, could lead to this
628 phenomenon. The concept of utilizing these lipid stores as a source of energy only gained
629 serious attention during the oil embargo of the early 1970s, ultimately becoming the
630 major push of DOE‘s Aquatic Species Program.
631
632 The Aquatic Species Program represents the most comprehensive research effort to date
633 on fuels from algae. The program lasted from 1978 until 1996 and supported research
634 primarily at DOE‘s NREL (formerly the Solar Energy Research Institute). The Aquatic
635 Species Program also funded research at many academic institutions through
636 subcontracts. Approximately $25 million (Sheehan, 1998) was invested during the 18-
637 year program. During the early years, the emphasis was on using algae to produce
638 hydrogen, but the focus changed to liquid fuels (biodiesel) in the early 1980s. Advances
639 were made through algal strain isolation and characterization, studies of algal physiology
640 and biochemistry, genetic engineering, process development, and demonstration-scale
641 algal mass culture. Techno-economic analyses and resource assessments were also
642 important aspects of the program. In 1998, a comprehensive overview of the project was
643 completed (Sheehan et al., 1998). Some of the highlights are described briefly below.
644
645 The Aquatic Species Program researchers collected more than 3,000 strains of microalgae
646 over a seven-year period from various sites in the Western, Northwestern, and
647 Southeastern U.S. representing a diversity of aquatic environments and water types.
648 Many of the strains were isolated from shallow, inland saline habitats that typically
649 undergo substantial swings in temperature and salinity. The isolates were screened for
650 their tolerance to variations in salinity, pH, and temperature, and also for their ability to
651 produce neutral lipids. The collection was narrowed to the 300 most promising strains,
652 primarily green algae (Chlorophyceae) and diatoms (Bacillariophyceae).
653
654 After promising microalgae were identified, further studies examined the ability of many
655 strains to induce lipid accumulation under conditions of nutrient stress. Although nutrient
656 deficiency actually reduces the overall rate of oil production in a culture (because of the
657 concomitant decrease in the cell growth rate), studying this response led to valuable
658 insights into the mechanisms of lipid biosynthesis. Under inducing conditions, some
659 species in the collection were shown to accumulate as much as 60% of their dry weight in
660 the form of lipid, primarily TAGs. Cyclotella cryptica, a diatom that is a attractive lipid
661 producer, was the focus of many of the biochemical studies. In this species, growth under
662 conditions of insufficient silicon (a component of the cell wall) is a trigger for increased
663 oil production. A key enzyme is acetyl-CoA carboxylase (ACCase), which catalyzes the
664 first step in the biosynthesis of fatty acids used for TAG synthesis. ACCase activity was
665 found to increase under the nutrient stress conditions (Roessler, 1988), suggesting that it
666 may play a role as a ―spigot‖ controlling lipid synthesis, and thus the enzyme was
667 extensively characterized (Roessler, 1990). Additional studies focused on storage
668 carbohydrate production, as biosynthesis of these compounds competes for fixed carbon
669 units that might otherwise be used for lipid formation. Enzymes involved in the
670 biosynthesis of the storage carbohydrate chrysolaminarin in C. cryptica were
9

19. 671 characterized (Roessler, 1987 and 1988) with the hope of eventually turning down the
672 flow of carbon through these pathways.
673
674 Metabolic engineering, which involves the modification of an organism at the genetic
675 level to achieve changes in cellular metabolism, has proven successful for enhanced
676 production of many compounds in industrial strains. Importantly, the genomics
677 revolution has accelerated progress in metabolic engineering for many organisms. For
678 this reason, metabolic engineering of microalgae has become increasingly accessible and
679 could theoretically result in strains that produce more oil or produce it under different
680 conditions (e.g., obviating the need for nutrient stress). Research during the latter years of
681 the Aquatic Species Program focused on the metabolic engineering of green algae and
682 diatoms that involved the development of basic genetic tools as well as actual pathway
683 modifications.
684
685 The first successful transformation of microalgae with potential for biodiesel production
686 was achieved in 1994 with the diatoms C. cryptica and Navicula saprophila (Dunahay et
687 al., 1995). A second major accomplishment was the isolation and characterization of the
688 gene from C. cryptica encoding the ACCase enzyme (Roessler and Ohlrogge, 1993), the
689 first example of an ACCase gene from a photosynthetic organism. A key gene involved
690 in carbohydrate biosynthesis was also isolated (US patent 5,928,932; Jarvis and Roessler,
691 1999).
692
693 Initial attempts at metabolic engineering using these tools were successful in altering the
694 genes‘ expression levels, but no effect was seen on lipid production in these preliminary
695 experiments (Sheehan et al., 1998). Termination of the Aquatic Species Program in 1996
696 prevented further development of these potentially promising paths to commercially
697 viable strains for oil production.
698
699 During the course of the Aquatic Species Program research, it became clear that novel
700 solutions would be needed not only for biological productivity, but also for various
701 problematic process steps. Cost-effective methods of harvesting and dewatering algal
702 biomass and lipid extraction, purification, and conversion to fuel are critical to successful
703 commercialization of the technology. Harvesting is the process of collecting small
704 microalgal cells from the dilute suspension of a growing culture—a process step that is
705 highly energy and capital intensive. Among various techniques, harvesting via
706 flocculation was deemed particularly encouraging (Sheehan et al., 1998). Extraction of
707 oil droplets from the cells and purification of the oil are also cost-intensive steps. The
708 Aquatic Species Program focused on solvent systems, but failed to fully address the
709 scale, cost, and environmental issues associated with such methods. Conversion of algal
710 oils to ethyl- or methyl-esters (biodiesel) was successfully demonstrated in the Aquatic
711 Species Program and shown to be one of the less challenging aspects of the technology.
712 In addition, other biofuel process options (e.g., conversion of lipids to gasoline) were
713 evaluated (Milne et al., 1990), but no further fuel characterization, scale-up, or engine
714 testing was carried out.
715
10

20. 716 Under Aquatic Species Program subcontracts, demonstration-scale outdoor microalgal
717 cultivation was conducted in California, Hawaii, and New Mexico (Sheehan et al., 1998).
718 Of particular note was the Outdoor Test Facility (OTF) in Roswell, N.M., operated by
719 Microbial Products, Inc. (Weissman et al., 1989). This facility utilized two 1,000 m2
720 outdoor, shallow (10-20 cm deep), paddlewheel-mixed raceway ponds, plus several
721 smaller ponds for inocula production. The raceway design was based on the ―high rate
722 pond‖ system developed at UC Berkeley. The systems were successful in that long-term,
723 stable production of algal biomass was demonstrated, and the efficiency of CO 2
724 utilization (bubbled through the algae culture) was shown to be more than 90% with
725 careful pH control. Low nighttime and winter temperatures limited productivity in the
726 Roswell area, but overall biomass productivity averaged around 10 g/m2/day with
727 occasional periods approaching 50 g/m2/day. One serious problem encountered was that
728 the desired starting strain was often outgrown by faster reproducing, but lower oil
729 producing, strains from the wild.
730
731 Several resource assessments were conducted under the Aquatic Species Program.
732 Studies focused on suitable land, saline water, and CO2 resources (power plants)
733 primarily in desert regions of the Southwest United States. Sufficient resources were
734 identified for the production of many billions of gallons of fuel, suggesting that the
735 technology could have the potential to have a significant impact on U.S. petroleum
736 consumption. However, the costs of these resources can vary widely depending upon
737 such factors as land leveling requirements, depth of aquifers, distance from CO2 point
738 sources, and other issues. Detailed techno-economic analyses underlined the necessity for
739 very low-cost culture systems such as unlined open ponds. In addition, biological
740 productivity was shown to have the single largest influence on fuel cost. Different cost
741 analyses led to differing conclusions on fuel cost, but even with optimistic assumptions
742 about CO2 credits and productivity improvements, estimated costs for unextracted algal
743 oil were determined to range from $59-$186/barrel (Sheehan et al., 1998). It was
744 concluded that algal biofuels would never be cost competitive with petroleum, which was
745 trading at less than $20/barrel in 1995. DOE estimated at that time that the cost of
746 petroleum would remain relatively flat over the next 20 years. (Although, as we now
747 know, the energy landscape has changed dramatically in the intervening 14 years.)
748 Overall, the Aquatic Species Program was successful in demonstrating the feasibility of
749 algal culture as a source of oil and resulted in important advances in the technology.
750 However, it also became clear that significant barriers would need to be overcome in
751 order to achieve an economically feasible process. In particular, the work highlighted the
752 need to understand and optimize the biological mechanisms of algal lipid accumulation
753 and to find creative, cost-effective solutions for the culture and process engineering
754 challenges. Detailed results from the Aquatic Species Program research investment are
755 available to the public in more than 100 electronic documents on the NREL Web site at
756 www.nrel.gov/publications .
757
758 Research from 1996 to Present
759 Since the end of DOE‘s Aquatic Species Program in 1996, federal funding for algal
760 research in general has been limited and intermittent. Federal funding is split between
11

21. 761 DOE and the Department of Defense (DoD). Recent initiatives such as a major DARPA
762 (Defense Advanced Research Projects Agency) solicitation Air Force Office of Scientific
763 Research (AFOSR) algal bio-jet program and several DOE Small Business Innovative
764 Research (SBIR) request for proposals suggest that funding levels are beginning to
765 increase. State funding programs and research support from private industry also make up
766 a significant proportion of research funding. An ever-increasing level of research focus
767 on algal biofuels has taken place at a number of U.S. national labs, including NREL,
768 Sandia National Laboratories, National Energy Technology Laboratory, Los Alamos
769 National Laboratory, and Pacific Northwest National Laboratory. Private investment in
770 biofuels, in general, and algal biofuels, in particular, has been increasing at a dramatic
771 pace over the last few years.
772
773 Not only in algae, investment in the clean fuels sector in general has been booming, with
774 a major increase in cleantech capital investment during the past five years. Since 1999,
775 investment in cleantech has increased almost five fold. The venture firms are looking at
776 biomass, solar, and wind technologies, and in some instances, are investing in the
777 construction of actual facilities for the production of fuels and electricity (Krauss, 2007).
778 In the first three quarters of calendar year 2007, 168 deals were signed with a combined
779 value of $2.6 billion (Gongloff, 2007). The total investment in cleantech in 2006 was
780 between $1.8 billion, and $2.3 billion, depending on the study (Gongloff, 2007; Krauss,
781 2007). The Wall Street Journal (2007) reported that 180 deals with a total value of $1.8
782 billion were completed in 2006, an average value of $10 million per deal. In early 2007,
783 the average deal value was $15 million, illustrating the increasing magnitude of
784 investments that venture firms are completing.
785
786 With the increase in interest worldwide amongst the investment community in clean
787 technologies, microalgae production has also received interest from the private sector.
788 Energy companies, both large and small, are investing in demonstration plants, feedstock
789 development, and process improvement. Many of these companies became interested in
790 algae during the rapid rise in cleantech investment from 2004 to 2006 and as algae‘s
791 advantages, such as its growth on traditionally underutilized land, production of high
792 energy lipids, and high yield per land area, became more widely known. When tied with
793 energy security and energy independence, the opportunity for algae-to-biofuels is
794 significant, and the investment community is responding.
795
796 The investment community‘s focus is not always on utilization of the lipids. Some
797 companies have identified niches based on the production of ethanol from algal biomass.
798 Commercial entities are exploring all aspects of the algae-to-fuels process, including
799 technologies based both on lipid conversion and the conversion of other algae
800 components. Algae have been used to produce high value, small quantity products for
801 decades, and new companies are looking to expand algae‘s impact.
802
803 In summary, the >150 algal biofuels companies in existence today worldwide are
804 attempting to help make the algae-to-fuels concept a reality. Further, large existing
805 companies with either market interest derived from their current business revenues (e.g.
806 energy) or with know-how and technology potentially relevant to algal biofuels are
12

22. 807 beginning to show interest in algae as well. What‘s not known, of course, is which
808 entities will undertake the major funding investments needed to realize sustainable,
809 saleable algal biofuels.
810 Going Forward
811 Roadmapping a Strategy for Algal Biofuels Development & Deployment
812 The current state of knowledge regarding the economics of producing algal biofuels are
813 woefully inadequate to motivate targeted investment on a focused set of specific
814 challenges. Furthermore, because no algal biofuels production beyond the research scale
815 has ever occurred, detailed life cycle analysis (LCA) of algal biofuels production has not
816 been possible. For this reason, investment in algal biofuels research and development is
817 needed to identify and reduce risk. This supports private investments aimed at producing
818 algal biofuels at a commercial scale. In contrast, development of cellulosic biofuels
819 benefits from direct agricultural and process engineering lineage to the long-standing
820 agricultural enterprise of growing corn (a grass) for food (and recently, for conversion to
821 starch ethanol). There is no parallel agricultural enterprise equivalent for cultivating algae
822 at a similar scale. In short, the science of algae cultivation (algaculture), agronomy-for-
823 algae, if you will, does not exist. It is thus clear that a significant basic science and
824 applied engineering R&D effort including a rigorous techno-economic and LCA will be
825 required to fully realize the vision and potential of algae. The techno-economic analysis
826 can track the status of each contributing technology as per established benchmarks and
827 help identify opportunities for cost reduction. Additionally, the pervasive
828 interdependency of various processes and infrastructure in developing a cost-competitive
829 algae-to-biofuels supply chain necessitates systems analysis to ensure these entities work
830 together as an efficient system.
831 Thus a combination of systems, techno-economic, and life cycle analyses are critically
832 needed to gain greater understanding for informed decision making so that investments
833 can be targeted and optimized to greater positive effect. See section 11, Systems and
834 Techno-Economic Analyses of Algal Biofuel Deployment (page 157) for detailed
835 discussion and specifics.
836
837 Need for a Sizeable, Strategically Structured and Sustained Investment
838 In the years following the termination of the Aquatic Species Program, a small but
839 growing body of work has been reported in peer-reviewed journals dealing with topics
840 ranging from photobioreactor design to lipid metabolism, genetic manipulation, and
841 genomic analysis. The total body of work in the past years is relatively small, reflecting a
842 fairly low level of research funding. There is a large gap between the current reality of
843 commercial microalgae production technology and the goal of producing a microalgae
844 biomass with high oil content suitable for conversion to biofuels at a large scale.
845
846 One of the major unanimous conclusions of the Workshop was that a great deal of
847 RD&D is still necessary to make the algae-to-fuels process a reality and to engage the
848 private sector more aggressively, the associated level of risk must be reduced. The
849 Workshop participants agreed that the obvious first step toward achieving sustainable,
13

23. 850 scalable biofuels from algae is long-term and sustained investment in research and
851 development, whether at DOE national laboratories, universities, and/or in the private
852 sector. Ultimately, a sizable and strategically structured investment to tackle the RD&D
853 challenges of algal biofuels is needed to advance the knowledge and experience of the
854 nation‘s research community, which can then support the commercialization activities led
855 by venture-backed entrepreneurs, as well as existing business and technology leaders.
856
857 In addition, the Workshop participants identified the need for significant investment in
858 our colleges and universities to train the professional work force for the new bioeconomy,
859 including scalable algal biofuels. Over the past few years, U.S. academic laboratories
860 interested in various aspects of algae-to-biofuels research have largely experienced
861 inadequate levels of funding. Since the end of the DOE-sponsored Aquatic Species
862 Program in 1996, there has been no significant or sustained mechanism for funding
863 academic work in the development of algae-based biofuels (excluding biohydrogen from
864 algae). More specifically, what‘s needed in algal biology is a new generation of applied
865 biologists and engineers to design, build, and maintain large-scale systems to cultivate,
866 harvest, and process algal biomass at scale. University graduate research in modern
867 molecular biology needs funding to produce molecular biologists with skills in systems
868 biology (e.g., genomics, proteomics, and metabolomics) as applied to algal biology to
869 carry out the fundamental biology R&D to support this effort.
870
871 Further, the existing funding landscape is fractured, with most of the funding spread
872 across a variety of federal agencies (DoD, DOE, Environmental Protection Agency), state
873 governments, private industry, congressionally directed research, and internal
874 institutional funds. The disconnect between the various small funding efforts and the
875 absence of a centralized effort in this area has been a large source of frustration for the
876 academic research community. The Workshop participants felt that funding agencies with
877 varying missions need to work together to enable the development of partnerships that
878 span not only basic and applied research arenas, but the various disciplines needed to
879 tackle the diverse challenges algal biofuels present. A single federal agency coordinating
880 studies in the field or making investments strategic enough can acquire a long-term
881 leadership role and help tie in all the efforts across the nation toward the development of
882 algal biofuels.
883
884 See section 12, Public-Private Partnerships for continued discussion and
885 recommendations.
886
14

24. 887
888 2. Algal Biology
889 Algae: Basic Biological Concepts
890 The term ―algae‖ refers to a large group of simple plant-like photosynthetic organisms.
891 Algae are typically subdivided into two major categories based on their relative size.
892 Microalgae are defined as microscopic photosynthetic, free-living organisms that thrive
893 in diverse ecological aquatic habitats such as freshwater, brackish (<3.5% salt), marine
894 (3.5% salt), and hypersaline (>3.5% salt) environments within a wide range of
895 temperature and pH (Falkowski and Raven 1997). Unicellular microalgae are easily
896 distinguished from their larger counterparts, the macroalgae or ―seaweeds,‖ which have
897 cells organized into structures resembling leaves, stems, and roots of higher plants.
898 Microalgae can be subdivided into two broad categories: the prokaryotic cyanobacteria
899 and the true eukaryotic algae. Cyanobacteria, often referred to as the blue-green algae,
900 have been included traditionally as ―algae,‖ but these organisms are clearly
901 photosynthetic ―prokaryotes‖—bacterial organisms that lack a defined nucleus. Because
902 cyanobacteria do not typically produce much lipid (Hu et al. 2008), they are not a focus
903 for this discussion. Nonetheless, as we will demonstrate below, there are reasons to
904 consider cyanobacteria for certain aspects of research relevant for biofuel production.
905
906 Microscopic algae were among the first life forms to appear on our planet (Falkowski et
907 al., 2004). They are responsible for fixing massive amounts of CO2 while producing and
908 sustaining the atmospheric oxygen that supports the majority of life on Earth (Falkowski
909 and Raven, 1997). Microalgae play a significant role in global productivity capacity, with
910 some strains capable of doubling their cell numbers several times per day. By some
911 estimates, microalgae, though making up only 0.2% of global photosynthetic biomass,
912 have been found to account for approximately 50% of the global organic carbon fixation
913 (Field et al., 1998) and contribute approximately 40% to 50% of the oxygen in the
914 atmosphere.
915
916 The biochemical mechanism of photosynthesis in microalgae is similar to that found in
917 all plants. However, unlike their terrestrial counterparts, microalgae are particularly
918 efficient converters of solar energy due to their simple structure. Free of the need to
919 generate support and reproductive structures, and with a ready supply of water and
920 nutrients, the microalgal cell can devote the majority of the energy it traps into biomass
921 growth. Under the limitations of current technology, algae can convert up to 15% of the
922 photosynthetically available solar irradiation (PAR), or roughly 6% of the total incident
923 radiation, into new cell mass (Benemann et al., 1978). In contrast, terrestrial crops
924 generally have lower photosynthetic conversion efficiencies. For example, the
925 photosynthetic efficiencies for sugar cane, the most productive terrestrial crop, are no
926 better than 3.5% to 4% (Odum 1971). But it is not only photosynthetic efficiency that
927 makes algae attractive candidates for biofuel production, but also because, unlike
928 terrestrial plants which produce specialized oil bearing seeds, every algal cell can be a
929 lipid factory, greatly increasing the amount of oil that can be produced per acre. As a
930 result, microalgae are a relevant target for scientific studies for biomass energy
15

25. 931 production, biofuels production, and utilizing the excessive amounts of CO2 currently
932 being released into the atmosphere through the heavy reliance on fossil fuels.
933
934 Algal Classification
935 The biodiversity of microalgae is enormous with tens of thousands of species being
936 described and as many as 10 million extant (Metting, 1996). Microalgae have been
937 isolated from diverse ecosystems such as freshwater, brackish, marine, hyper-saline,
938 snow, and even hot springs, which require special adaptations in metabolism for survival.
939 Furthermore, microalgae inhabit soil and biofilms, and are even found in symbiotic
940 association with other organisms.
941
942 As a group, cyanobacteria hold important practical implications as transformers of solar
943 energy. They range from simple, tiny unicellular organisms to multicellular colonies,
944 from simple to branched filaments. The unicellular cyanobacterium Synechocystis sp.
945 PCC6803 was the first photosynthetic organism whose genome was completely
946 sequenced (Kaneko et al., 1996). It continues to be an extremely versatile and easy model
947 with which to study the genetic systems of photosynthetic organisms. Cyanobacteria are
948 not generally known to produce large quantities of lipids, though they have been shown
949 to produce storage carbon in the form of starch or glycogen. Cyanobacteria are,
950 nevertheless, important as potential production strains for a variety of chemical
951 intermediates and fuels. For example, a recent report describes the production and
952 secretion of sucrose by photosynthetic prokaryotes (US 20080124767). In addition,
953 cyanobacteria have been engineered to produce ethanol through a photosynthetic process
954 (Deng and Coleman, 1998).
955
956 Eukaryotic microalgae, on the other hand, are not a well-studied group from a
957 biotechnological point of view. Among the species that are believed to exist, only a few
958 thousand strains are kept in culture collections throughout the world, a few hundred are
959 being investigated for their chemical content and just a handful are cultivated on an
960 industrial scale (Chisti, 2007).
961
962 Algae can be further classified into at least 12 major divisions. Within those major
963 divisions, some common classes of algae include the green algae (Chlorophyceae),
964 diatoms (Bacillariophyceae), yellow-green algae (Xanthophyceae), golden algae
965 (Chrysophyceae), red algae (Rhodophyceae), brown algae (Phaeophyceae) and
966 picoplankton (Prasinophyceae and Eustigmatophyceae). Examples of each of these
967 classes are known to produce high levels of lipids; these include Chromonas danica,
968 Phaeodactylum tricornutum, Nitzschia palea, Monallantus salina, Nannochloropsis sp.,
969 and Isochrysis sp (Chisti, 2007). Several additional divisions and classes of unicellular
970 algae have been described and details of their structure and biology are available (van den
971 Hoek et al., 1995).
972
973 The commercial application of microalgal biotechnology began to develop in the middle
974 of the last century. Today there are numerous commercial applications involving
975 microalgae. Microalgal mass cultures have applications in the production of human
976 nutritional supplements and specialty animal feeds (Becker 2004) and play a crucial role
16

26. 977 in aquaculture and wastewater treatment. They are cultivated as a source of highly
978 valuable molecules such as polyunsaturated fatty acids (PUFAs) (Ward and Singh 2005)
979 and pigments such as β-carotene and astaxanthin (Pulz and Gross, 2004).
980
981 Photosynthesis/CO2 Fixation
982 Photosynthesis is a process whereby certain varieties of bacterial species, eukaryotic
983 algae, and higher plants convert the potential of light energy into chemical energy.
984 Carbon, in the form of CO2 is recycled directly from the atmosphere generating biomass
985 and oxygen in the process. In eukaryotic algae, photosynthesis takes place in specialized
986 organelles called chloroplasts. Cyanobacteria are prokaryotes and do not possess
987 chloroplasts or any other such organelles. In these organisms, photosynthesis takes place
988 inside a membrane-bound sac known as a thylakoid. Cyanobacteria are widely believed
989 to be the ancestor of the chloroplast, taken up by a protozoan billions of years ago and
990 evolving into an endosymbiont. Photosynthesis is generally performed in two separate
991 steps, known as the light and dark reactions. In the photosynthetic light reactions, photons
992 of light are absorbed directly by chlorophyll and a variety of other accessory pigments to
993 excite electrons to a higher energy state. In a series of reactions, the energy is converted
994 into ATP and NADPH splitting water in the process and releasing oxygen as a by-
995 product. In the light independent process (i.e., dark reaction), CO2 from the atmosphere is
996 converted (―fixed‖) into sugar using ATP and NADPH generated during the light
997 reaction.
998
999 There are generally two processes whereby algae fix CO2: the C3 and C4 pathways Most
1000 algae and plants use the C3 pathway in which CO2 is first incorporated into a 3-carbon
1001 compound known as 3-phosphoglycerate. The enzyme that catalyzes this reaction,
1002 ribulose-bisphosphate carboxylase (RuBisCo), is also the enzyme involved in the uptake
1003 of CO2. The three carbon compound generated during the process enters the Calvin cycle
1004 leading to sugar formation.
1005
1006 Marine diatoms are responsible for up to 20% of the global CO2 fixation. Marine diatoms
1007 use the alternative C4 pathway, and, as a result, generally have enhanced photosynthetic
1008 efficiencies over C3 pathway organisms (Kheshgi et al., 2000). These organisms
1009 concentrate CO2 around Rubisco, thereby diminishing photorespiration, and the
1010 concomitant loss of energy. It is thought that this characteristic is responsible for the
1011 ecological significance of diatoms (Reinfelder et al. 2000), though it is not clear if this
1012 will provide a real advantage for diatoms cultivated in the presence of sufficient CO2.
1013
1014 Strain Isolation, Selection, and/or Screening
1015 Currently, a number of microalgal strains are available from culture collections such as
1016 UTEX (The Culture Collection of Algae at the University of Texas at Austin, Texas),
1017 with about 3,000 strains, and CCMP (The Provasoli-Guillard National Center for Culture
1018 of Marine Phytoplankton at the Bigelow Laboratory for Ocean Sciences in West
1019 Boothbay Harbor, Maine), with more than 2,500 strains. However, because many of the
1020 strains in these collections have been cultivated now for several decades, these strains
1021 may have lost part of their original properties such as mating capabilities or versatility
17

27. 1022 regarding nutrient requirements (de la Jara et al, 2003). To obtain versatile and robust
1023 strains that can be used for mass culture in biofuels applications, it is, therefore, essential
1024 to consider the isolation of new, native strains directly from unique environments. For
1025 both direct breeding as well as for metabolic engineering approaches to improved
1026 biofuels production, it is vital to isolate a large variety of microalgae for assembly into a
1027 culture collection serving as a bioresource for further biofuels research.
1028
1029 The goals of isolation and screening efforts are to identify and maintain promising algal
1030 specimens for cultivation and strain development. However, because it is not yet known
1031 how algae will be cultivated on a mass scale, new strains should be isolated from a wide
1032 variety of environments to provide the largest range in metabolic versatility possible.
1033 Further, it is recommended that the isolated strains be screened to develop baseline data
1034 on the effects of regional environmental variability on cultivars.
1035
1036 Isolation and Characterization of Naturally Occurring Algae Species/Strains
1037 Algae occur in a variety of natural aqueous habitats ranging from freshwater, brackish
1038 waters, marine, and hyper-saline environments to soil as well as symbiotic associations
1039 with other organisms (Round, 1981). At this time most commercial microalgae
1040 production facilities use open raceway pond technologies (e.g., Earthrise and Cyanotech
1041 Corp) (Chisti, 2007) and rely on natural strain succession to maximize biomass
1042 production throughout the year. Therefore, sampling and isolation activities for new
1043 strains have to account for temporal succession of microalgae in natural habitats. Further,
1044 any large-scale sampling and isolation efforts should be coordinated to ensure broadest
1045 coverage of environments and to avoid duplication of efforts.
1046
1047 For isolation of new strains from natural habitats traditional cultivation techniques may
1048 be used including enrichment cultures (Andersen & Kawachi, 2005). However,
1049 traditional methods take weeks to months for isolation of unialgal strains. Also, as many
1050 colonies are obtained from single cells the strains are often already clonal cultures. For
1051 large-scale sampling and isolation efforts, high-throughput automated isolation
1052 techniques involving fluorescence activated cell sorting (FACS) have proven to be
1053 extremely useful (Sieraki et. al, 2005).
1054
1055 Natural Habitats: Marine, Freshwater, Brackish/Saline, Wastewater, And Extreme
1056 Environments
1057 In addition to sampling from a variety of ecosystems, it is proposed that sampling
1058 strategies not only account for spatial distribution but also for the temporal succession
1059 brought about by seasonal variations of algae in their habitats. In addition, within an
1060 aqueous habitat some algae are typically found either in the planktonic (free floating) or
1061 benthic (attached) environments. Planktonic algae may be used in suspended mass
1062 cultures whereas benthic algae may find application in biofilm based production
1063 facilities. Thus, it is recommended to include sampling of both planktonic and benthic
1064 algae within the context of this roadmap.
1065
1066
1067 Identification of Criteria for Screening
18