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ANU Energy Change Institute energy.anu.edu.au
Bioenergy from photosynthetic algae and cyanobacteria.
Associate Professor Michael Djordjevic
Research School of Biology
http://biology.anu.edu.au/michael_djordjevic/
ANU Energy Change Institute energy.anu.edu.au
Multitude of Global Research and Development Initiatives
Determine the suitability and feasibility of using aquatic photosynthetic
microorganisms as a source of renewable bioenergy.
ANU Energy Change Institute energy.anu.edu.au
100 billion tons of carbon per year
Satellite Sensed Photosynthesis
ANU Energy Change Institute energy.anu.edu.au
Satellite Sensed Photosynthesis
About half occurs in oceans: phytoplankton
ANU Energy Change Institute energy.anu.edu.au
Satellite Sensed Photosynthesis
About half occurs in oceans: phytoplankton • cyanobacteria • algae
Energy from microalgae?
L
S
• Diverse range of energy-rich compound compounds e.g. • Lipid (L) and lipid-like (eg hydrocarbon) (Lipid readily converted to ‘drop in’ fuel) • Starch (S) (Starch converted to ethanol)
• Can grow, under ideal conditions, faster than terrestrial plants and all the biomass contains the energy rich compounds (unlike plants). Also no lignin. • Also contain other compounds of interest with medicinal or food-related applications • Energy-rich compounds vary (negligible to 20-30% of dry weight) • Energy cost in growing and extracting internal lipid and hydrocarbon-like molecules • Can they be harnessed in an industrial setting and can these strain be improved?
Chlamydomonas
L
L
S
L
L
L
L
L
L
L L
S
Chlamydomonas
L
L
S
S
S
S
S
S
S S S
S
S S S
S
S
S
S
S
S
Improving Energy from microalgae?
•Biosolar group. Can microalgae be improved?
• Dr. Djordjevic (Algae), Gabriel James (Ph.D) • Dr. Hiller (Thermophilic cyanobacteria), Duncan Fitzpatrick (Ph.D) • Dr. Price (Cyanobacteria), • Dr. Hocart (Mass spectrometry facility).
L
S
Chlamydomonas
L
L
S
S
S
S
S
S
S S S
S
S S S
S
S
S
S
S
S L
L
L
L
L
L
L
ANU Energy Change Institute energy.anu.edu.au
0
10
20
30
40
50
60
70
cc-124 cc-125 I7 BAF-J5
Tota
l Fat
ty A
cid
(%) D
ry C
ell W
eigh
t
N+
N-
600 - 700% increase in lipid content
L
Further yield increases can be achieved by optimising growth temperature: ~ 70% of dry weight
Can microalgae be improved: metabolic engineering
L
S
Chlamydomonas
L
L
S
S
S
S
S
S
S S S
S
S S S
S
S
S
S
S
S L L
L L L
L L L
James et al 2011 James et al 2012
ANU Energy Change Institute energy.anu.edu.au
Cyanobacteria
• Cyanobacteria: highly productive photosynthetic bacteria (=25% global photosynthesis)
• fast growth rates, high biomass yields and accumulate glycogen, poly-Beta hydroxybuterates but moderate and diverse lipid (~10-20% dry weight)
•Have efficient CO2 uptake/concentrating mechanism
• allows inorganic carbon uptake • some strains fix atmospheric nitrogen • largely ANU research
Plasma membrane (inner) Thylakoid
membrane
Carboxysome
Restricted CO2 leakage
Outer membrane
Rubisco 1B
CA
PGA
ccmKLMN, ccmORbcLS(1B), CcaA HCO3
-
CO2
CO2
NADPH
HCO3-HCO3
-
NADPH
HCO3-
HCO3-CO2
NDH-13
NDH-14
BicA
SbtA Na+
HCO3-HCO3
-
Na+
HCO3-
ATPBCT1
β- Carboxysomes
Ci transporters
HCO3-
Freshwater β-Cyanobacteria
ANU Energy Change Institute energy.anu.edu.au
• Can the metabolic engineering success from algae be translated to cyanobacteria?
• So far: NO.
• Does not lead to a great increase in lipid production inside cells.
Cyanobacteria: Engineering Biofuel Production by Gene manipulation
ANU Energy Change Institute energy.anu.edu.au
• Entire metabolic pathways can and have been introduced into cyanobacteria
• Genes can be easily knocked out and added
• Can biofuel feedstock production be increased by gene manipulation?
• Possible R and D solution : manipulate cyanobacteria to secrete fatty acids
Synechococcus PCC7942 carboxysome genes
K1 L M N O L S
ccm genes Rubisco genes
M35
Cyanobacteria: Amenable to Genetic Manipulation
L
L
L
L
L
L
L
ANU Energy Change Institute energy.anu.edu.au
Global Research Initiatives to maximise production of High Energy Products from Algae
Can algae and cyanobacterial strains be utilised in commercial processes to amass enough biomass so that the quantity of the high energy products can generate a sustainable bioenergy source?
a) Higher yield of high energy feedstock per cell b) High biomass per unit time c) Minimise infrastructure costs d) Lower input costs e) Lower extraction/conversion cost
ANU Energy Change Institute energy.anu.edu.au
• Numerous Australian and International R & D initiatives to engineer/optimise or generate elite strains or to produce alternative fuels
• Australian Higher Ed : (Brisbane [UQ], Nth. Qld, Melbourne, Adelaide [SARDI, University of Adelaide], Perth [Murdoch], Canberra [ANU], Hobart [CSIRO])
• Maximising biomass is critical and well as production per cell • some local “super stains” have been identified (SARDI).
• Best conditions in pilot plants:
• produces 20-25 g useful organic weight of algae per m2 per day has been reported relying primarily on photosynthesis to make energy to drive growth • but not scaled up to massive industrial production
Initiatives to produce algae for biofuels
ANU Energy Change Institute energy.anu.edu.au
Initiatives to produce algae for biofuels and specialised oils
Solazyme Sapphire Energy: “Green Crude Farm”
Algae.tec Clean algae biofuel project
Considerations:
• Nutrient requirements • Water requirement/movement • Extraction cost • Purification/conversion costs • Requirements for land
Absolute best case scenario with current technology:
• $84/bbl • (13-64 ha /MW = 50-20 g per m2 day) • ~ 50,000 L ha per year
Vision for outdoor scale up
Assumptions: CO2 capture from coal fired power station, non arable cheap land, continuous production, waste-water utilisation, possibility for co-products, recycling of nutrients in residual biomass, control of evaporation.
• Stephens et al. Nature Biotech. 28: 126-128, 2010. • Lundquist et al. A realistic technology and engineering assessment of Algal Biofuel production. Energy . Bioscience Institute, University of California Berkeley Oct 2010
600-39,000 sq km estimated
ANU Energy Change Institute energy.anu.edu.au
Alternative Assessment “National Research Council (NRC) of the U.S. National Academies says that large-scale production of biofuels from algae is untenable with existing technology, ...would require the use of too much water, energy, and fertilizer”.....
...scaling up to 39 billion litres using current technology... “would require an unsustainable level of inputs” ....
“Growers would also have to add between 6 million and 15 million metric tons of nitrogen and between 1 million and 2 million metric tons of phosphorus to produce 39 billion liters of algal biofuels” ......(44% and 107% of the total use of nitrogen in the United States, and between 20% and 51% of the nation's phosphorus use for agriculture).
..but the NRC did “not consider any one of these sustainability concerns a definitive barrier to sustainable development of algal biofuels”. (e.g. Nutrient/ water recycling)
(R. Service. “Large-Scale Algae Biofuels Currently Unsustainable, New Report Concludes”. Science. 24th October, 2012).
ANU Energy Change Institute energy.anu.edu.au
• Photosynthetic microorganism are attractive systems to produce high energy storage molecules
• Algae: are capable of storing significant amount of cellular mass as lipid
• Algae: grow slowly and require significant input of nitrogen to support growth but under optimal conditions could provide a source of biofuel
• Cyanobacteria: grow much more vigorously
• Cyanobacteria: Tend to store energy as carbohydrate rather than lipid and lipid-like molecules
• Cyanobacteria: Are genetically tractable.
• A possible future initiative: Manipulate photosynthetic microorganisms to secrete fatty acids or other lipids/hydrocarbons/sugars. This may overcome some of the barriers to effective scale up.
• Nutrient /water/energy issues required for scale up need addressing.
Perspectives
Hydrogen from micro algae?
No hydrogen fuel infrastructure
ANU Energy Change Institute energy.anu.edu.au
Plasma membrane (inner) Thylakoid
membrane
Carboxysome
Restricted CO2 leakage
Outer membrane
Rubisco 1B
CA
PGA
ccmKLMN, ccmORbcLS(1B), CcaA HCO3
-
CO2
CO2
NADPH
HCO3-HCO3
-
NADPH
HCO3-
HCO3-CO2
NDH-13
NDH-14
BicA
SbtA Na+
HCO3-HCO3
-
Na+
HCO3-
ATPBCT1
β- Carboxysomes
Ci transporters
HCO3-
Freshwater β-Cyanobacteria
0.5 µM
carboxysomes
thylakoids
Carboxysome ~ 150 nm dia.
Cyanobacterial CO2 concentrating mechanism or CCM (largely ANU research)