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Algal Biofuels Can Make a 

Difference

Renewable Energy Roundtable

Philip T. Pienkos

March 27, 2012

NREL/PR-7A40-54590
2

What is Lignocellulosic Biomass?

38-50%

5-13%

23-32%

15-25%

Lignin

Other Cellulose

(Glucose sugar)

Hemicellulose

(Pentose sugars)

(“Young clean coal”)

Softwoods

Grasses

Hardwoods

Crop residues

MSW

(Extractives, ash, etc.)
3

Primary Conversion Routes

Transformation 

through

Intermediates

(sugars)

Biochemical

Conversion

Thermochemical 

Conversion

Gasification 

(reduction to CO, H2) 

and Pyrolysis

Initial focus on ethanol and 

mixed alcohols. Now 

attention turning to 

advanced hydroccarbon

biofuels

Photo by David Parsons, NREL/PIX 06809
4

Terrestrial Biomass Is Not Enough

• Potential sustainable 

biomass production: 

1.3B tons per year

o Ag wastes

o Municipal solid wastes

o Forestry wastes

o Energy Crops

• Convert to 130B gallons 

ethanol = 87B GGE

Source: http://www1.eere.energy.gov/biomass/pdfs/final_billionton_vision_report2.pdf
5

U.S. Transportation Fuel Demand

2010 2035

Gasoline 126 116

Diesel 43 64

Jet fuel 23 27

Source: http://www1.eere.energy.gov/biomass/pdfs/final_billionton_vision_report2.pdf

Products in a Barrel of Crude (gal)

Gasoline* (Finished Motor Gasoline – E10) 

(cars & trucks)

Diesel (on-road, rail)

Aviation (jet fuel)

23 bgy

126 bgy

43 bgy

* Peaked in 2004 at 136 bgy
6

U.S. Transportation Fuel Demand

2010 2035

Gasoline 126 116

Diesel 43 64

Jet fuel 23 27

Source: http://www1.eere.energy.gov/biomass/pdfs/final_billionton_vision_report2.pdf

Products in a Barrel of Crude (gal)

Gasoline* (Finished Motor Gasoline – E10) 

(cars & trucks)

Diesel (on-road, rail)

Aviation (jet fuel)

23 bgy

126 bgy

43 bgy

* Peaked in 2004 at 136 bgy

One billion tons is not enough.

Ethanol only addresses the gasoline 

fraction.
7

Multiple Paths to Energy Security

• Domestic coal and natural 

gas reserves can be 

converted to liquid fuels

• Supplement biomass to 

provide path to energy 

security

• Environmental impact

o Greenhouse gas emissions

o Water usage and 

contamination

o Land usage

Photo by David Parsons, NREL/PIX 06734

Photo by David Parsons, NREL/PIX 05048
8

What Can Algae Contribute?

• Wigmosta et al. evaluated available 

US lands appropriate for algal 

cultivation

o 166,000 square miles

o 57B gallons oil per year

• Based on conservative productivity 

estimates

o 600 gallons/acre/year

o Mascarelli (2009): 1400 

gallons/acre/year

o Weyer et al. (2010): 3800-5500 

gallons/acre year

• Job creation

o Total workers: 37,498 

o Acres per worker: 144

o Typical farm acres per worker: 

100-200

Wigmosta, M. S., A. M. Coleman, R. J. Skaggs, M. H. Huesemann, and L. J. Lane 

(2011), National microalgae biofuel production potential and resource demand, 

Water Resour. Res., 47, W00H04, doi:10.1029/2010WR009966. 

Figure courtesy Mark Wigmosta, PNNL
9

How Algal Biofuels Figure Into Renewable Fuel Standards

5 billion 

gallons 

could 

come 

from 

algae
10

Why Fuels from Algae?

• Algae can produce more lipids per 

acre than terrestrial plants --

potentially 10x - 100x 

• Can use marginal, non-arable land

• Can use saline/brackish water

• No competition with food, feed, or 

fiber

• Can utilize large waste CO2

resources 

• Potential to displace significant 

amount of U.S. diesel and jet fuel 

usage

• An algal biorefinery could produce 

oils, protein, and carbohydrates 

and a variety of other products

Photo by Dennis Schroeder, NREL/PIX 18070

Photo by Warren Gretz, NREL/PIX 01723
11

Input/Output

• Wigmosta et al. evaluated 

available US lands 

appropriate for algal 

cultivation

o 166,000 square miles

o 57B gallons oil per year

o Human Resources

– Total workers: 37,498 

– Acres per worker: 144

– Typical farm acres per worker: 

100-200

o Evaporative losses of 8 x 

1,013 gallons water per year

o 1,400 gallon water per gallon 

fuel

Wigmosta, M. S., A. M. Coleman, R. J. Skaggs, M. H. Huesemann, and L. J. Lane 

(2011), National microalgae biofuel production potential and resource demand, 

Water Resour. Res., 47, W00H04, doi:10.1029/2010WR009966. 

Figure courtesy Mark Wigmosta, PNNL
12

Bio-based Products from Algae

TAGs

HC Fuels

Fatty Acids TAGs

Algae Cyanobacteria Photosynthetic 

Bacteria

Commodity 

Chemicals 

(Ethylene)

Specialty 

Chemicals 

(Carotenoids)

Image 

Removed 

for 

Publication

Image 

Removed for 

Publication

Image 

Removed for 

Publication

Photo by Dartmouth Electron Microscope 

Facility, Dartmouth College, NREL/PIX 19459

Photo by Toshi Otsuki, NREL/PIX 08332

Image 

Removed 

for 

Publication
13

Comparing Potential Oil Yields

Crop

Oil Yield 

Gallons/acre

Corn 18

Cotton 35

Soybean 48

Mustard seed 61

Sunflower 102

Rapeseed/Canola 127

Jatropha 202

Oil palm 635

Algae (Wigmosta et al.) 600

Algae (Mascarelli) 1,400

Algae (Weyer et al.) 3,800-5,500

Photos by Oak Ridge National Lab, John De La 

Rosa, Warren Gretz, NREL/PIX 19965, 01768, 

03016, 04078 
14

Land Usage: A Matter of Scale

Photos by Warren Gretz, Dennis Schroeder, 

Bob Allan, NREL/PIX 03246, 10512, 19549 
15

Land Usage: A Matter of Scale

Corn 

144,000 

square 

miles

Energy 

crops 

86,000 

square 

miles

Photos by Warren Gretz, Dennis Schroeder, 

Bob Allan, NREL/PIX 03246, 10512, 19549 

Algae 

166,000 

square 

miles
16

What Is the Definition of Marginal Land?

Southwest Desert

Image Removed for 

Publication

Image Removed for 

Publication

Image Removed for 

Publication

Image Removed for 

Publication

Southeast Coast

Untilled Farmland

Freeport, TX

Ft. Myers, FL

Photos by Warren Gretz, NREL/PIX 08026 
17

Land Usage: Competition

Image 

Removed for 

Publication

Image Removed 

for Publication
18

Design Configuration

Green = algae cell density

Lipid 

Extraction

Phase 

Separation

Solvent 

Distillation

Upgrading 

(hydrotreater)

Anaerobic 

Digestion

Algae 

Growth 

CO2

Makeup nutrients

Recycle nutrients/ water

Makeup solvent Solvent recycle

Spent algae

+ water

Sludge

Biogas 

for 

energy Flue gas from turbine

Hydrogen

Offgas

Naphtha 

Diesel

Raw

oil

Power

Flocculent

Recycle water Blowdown

Makeup water

Settling DAF Centrifuge

0.05% (OP)

0.4% (PBR)

1% 10% 20%

Steam turbine

combined cycle

10%

5%

Red = harvesting/extraction losses

10%
19

Results: Baseline Costs

$523

Direct Installed Capital, $MM (PBR)

PBR System

CO2 Delivery

Harvesting

Extraction

Digestion

Power Generation

Inoculum System

Hydrotreating

OSBL Equipment

Land Costs

$114

Total = $243MM

Total = $637MM

Baselines show high costs of today’s 

currently available technologies, 

opportunities for cost reduction

$9.28 

$17.52 

$10.66 

$19.89 

$0

$5

$10

$15

$20

$25

OP

(TAG)

PBR

(TAG)

OP

(Diesel)

PBR

(Diesel)

Product selling price ($/gal)

TAG/Diesel Selling Prices (OP vs PBR)

Operating ($/gal of product) Capital ($/gal of product)

$67

$12

$46 $18

$12

$13

$24

$9

$21

$22

Direct Installed Capital, $MM (Ponds)

Ponds

CO2 Delivery

Harvesting

Extraction

Digestion

Power Generation

Inoculum System

Hydrotreating

OSBL Equipment

Land Costs
20

Sensitivity: Ponds

-$6 -$4 -$2 $0 $2 $4 $6 $8

Evaporation rate (0.15 : 0.3 : 0.6 cm/day)

Water source (underground : utility purchase)

Water recycle (100% : 95% : 80%)

CO2 price ($0 : $36 : $70/ton)

Inoculum costs (50% : base : 150%)

Extraction costs (50% : base : 150%)

Nutrient recycle (100% : base : 0%)

Harvesting costs (50% : base : 150%)

Pond liner (none : add liner)

Operating factor (365 : 330 : 250 days/yr)

Growth rate (50 : 25 : 12.5 g/m2/day)

Lipid content (50 : 25 : 12.5%)

Change to TAG price ($/gal)

Open Pond Sensitivities

More “bang for the buck”

targeting lipids vs growth rate

(Realistically, difficult to 

maximize both simultaneously)
21

Projecting future costs

Growth rate 25 g/m2/d 25 g/m2/d 30 g/m2/d 30 g/m2/d 1.25 g/L/d 1.25 g/L/d 1.5 g/L/d 1.5 g/L/d

Lipid content 25% 40% 50% 50% 25% 40% 50% 50%

Harvesting cost Base Cut by 50% Cut by 50% Cut by 50% Base Cut by 50% Cut by 50% Cut by 50%

Extraction cost Base Base Cut by 50% Cut by 50% Base Base Cut by 50% Cut by 50%

Spent biomass 

utilization

AD AD AD Sell @ 

$500/ton

AD AD AD Sell @ 

$500/ton

$9.28

$5.45

$3.99

$2.27

$17.52

$11.19

$7.74

$6.10

$0

$2

$4

$6

$8

$10

$12

$14

$16

$18

$20

OP

(base)

OP

(target 1)

OP

(target 2)

OP

(high-value

coproduct)

PBR

(base)

PBR

(target 1)

PBR

(target 2)

PBR

(high-value

coproduct)

Product selling price ($/gal)

Capital ($/gal of lipid) Operating ($/gal of lipid)
22

Establishing cost targets (MYPP)

$0

$2

$4

$6

$8

$10

$12

2012 2014 2016 2018 2020 2022 2022* 2022**

Product selling price ($/gal)

Open Pond Learning Curve

Operating ($/gal of lipid)

Capital ($/gal of lipid)

Raw oil price (total)

Diesel price (total)

*Cut extraction costs by 50%

**Cut extraction costs by 50% and

 sell spent biomass @ $500/ton

Cut harvesting cost 50%

Growth rate 

[g/m2/day]

25 20 20 25 30 30 30 30

Lipid content

[dry wt%]

25% 35% 40% 40% 40% 50% 50% 50%
23

Comparison to Biochemical Ethanol Cost Curve

$0.00

$1.00

$2.00

$3.00

$4.00

$5.00

$6.00

$7.00

$8.00

$9.00

$10.00

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Minimum Ethanol Selling Price (2007$ per gallon) 

Conversion Feedstock

$3.85 

$3.64 $3.57 

$3.18 

$2.77 

$2.62

$2.15 

$4.27 

$5.33 

$6.90 

$9.16 
24

Multiple Biomechanical Conversion Strategies and Routes of 

Algal Feedstocks Into Bio Fuels

Ethanol and butanol from 

extracted algal biomass could add 

an additional 24 B GGE. Total 

contribution of algal biomass 

could be as high as 90 B GGE.
25

Algal Biofuels Can Reshape the Food vs. Fuel Debate

• Algal biomass used as food 

supplement since pre-columbian

times

• Extracted biomass could provide 

approximately 180M tons protein per 

year

o Aquaculture

o Animal feed

o Pet food

o Human food

• Indirect land usage very different for 

algae compared to terrestrial crops

• Possible competition for fertilizer 

inputs especially potassium

o Recycle option for some processes

o Capture nutrients from wastewater or 

natural blooms

Photos by Roger Taylor NREL/PIX 07491 
26

Algae and Carbon Capture

• Algal biomass sufficient to produce 57B gallons 

oil per year would require approximately 1B 

tons CO2

• This is equivalent to output from 350 500 MW 

coal-fired power plants or 70% of US capacity

• A 500 MW power plant would require 

approximately 200 square miles of algae ponds 

to capture CO2

• Capture occurs only in daylight hours

• Transportation/distribution will add to capital 

costs

• CO2 pipelines carry fossil CO2

o Collected, transported and re-injected for enhanced 

oil recover

o Use for algae cultivation will add to greenhouse 

gases 

• Concentrated forms of CO2 (cement kilns, 

fermentation offgas, anaerobic digester) better 

scaled and more economical for transport

• Air capture CO2 could be game changer
27

Conclusions

• Even by conservative calculations, algal biomass could 

surpass terrestrial biomass for contribution to liquid fuel 

replacements

• Land requirement would be significant (~5% of 

conterminous US area)

o Competition for other uses

o Indirect land use mitigated by complexity of shift from 

agriculture to algae culture

o brine disposal could greatly reduce reliance on freshwater

• Algae could mitigate significant CO2 emissions, but it will be 

difficult to balance local supplies and demand

• Algae could add to global food supply rather than take away

o Issues of scale and quality must be considered