438 PP

1. Biodiesel from
Microalgae
Jessica Ketchum
Karris Roland

2. Introduction
 The depletion of fossil fuels and escalation of CO2
concentration in the atmosphere has shifted the global
interest to renewable fuels.
 Microalgae-derived biodiesel is a clean, sustainable
energy source due to high biomass productivity, rapid
lipid accumulation, and ability to survive in harsh
environments.
 Algae biodiesel does not include sulfur and diminishes
the release of particulate matter, CO, hydrocarbons,
and SOx.

3. Biodiesel Processing From
Microalgae

4. Extraction- “Whole
Lotta-Watta”
Problem
 Harvesting, dewatering and drying have been the
main barriers of algal oil production.
 “Algal cells are generally too small for traditional
means of filtration, centrifuging, or solvent
extraction.
 Average harvesting concentration (0.1-1%)

5. Attempts to Eliminate Dewatering
 Forcing Water and Algae to separate from each other
 “Milking” algal cell
 Getting Algae to concentrate
 Must have a solution to this problem:
 1 technology/60 days (May 2011-Biofuels Digest)
 National Algae Association-”Algae Growing,
Harvesting, Extraction Technologies”

6. New Technology!!
 1. Enzymatic Hydrolosis –AER
 2. PEF (Electric Pulse)-Diversified Technology
(0.1$/gal vs. 1.75$)
 3. Amphphillic Solvents -Aurora Algae (US patent
7,868,195)
 4. Solid-Liquid Separation-AlgaeVenture Systems
(0.007$/gal vs. 3.19$)
 5. Single Step and Live Extraction-OriginOil
 -Algal cell can heal itself after lysed, for
continuous process

7. We Choose Live Extraction
 Apply suitable electric field to Algal culture
 Volume will depict voltage necessary
 ---Should be around 20V, way less than PEF (10-30
kV/cm)
 Electric Field caused algal cells to release a portion of
their algal oil without rupturing

8. Viable on Commercial Scale??
 Cellana-Developer of algae-based feedstocks for
biofuels, animal feed, and Omega-3 nutritional oils.
 Announced multi-year off-take for commercial
production (Venture w/Neste Oil)
 Neste Oil-Worlds leading supplier of renewable
biodiesel
 Venture to produce commercial scale amounts of
Cellana’s ReNew™ Fuel

9. Sapphire Energy
 Sapphire Energy located in Columbus, NM. In 2011,
began construction of Crude Farm

10. Anaerobic Digestion Of Algae
Sludge
 Used to produce methane from remaining
algae feedstock
 Anaerobic microbes digest large molecular
weight carbon compounds into methane
 Reduces handled waste, and recovers
unused energy in residual algae feeds
 Most common algae species were:
 Scenedesmus spp.
 Chlorella spp.
 Operated in CSTR with 20 day residence
time1,2
 Terminal methanogenesis is carried out by
specialized group of anaerobic archaea.2
 Use of algae for energy (methane
production has been investigated since
OPEC oil crisis of 1973

11. Methane Production
 Methane production mainly influenced by
loading rate and C/N ratio of feed
 High loading rates of algae volatile solids
(VS), excess algae can inhibit the digestion
 Low C/N ratios, cause increased
production of ammonia. Inhibits microbe
digestion rate
 Algae biomass: C/N ratio 6/1
 Optimal C/N range 20/1 – 30/13
 Typical feed rate for one-stage CSTR: 1.6
[kg VS/(m3 * day)]

12. Transesterification
- Transesterification is the reaction of a fat or oil with alcohol to form
esters and glycerol.
- The triglyceride is a complex molecule that plants and animals use for
storing food energy; simply it is fat.

13. Transesterification Continued
 Transesterification is a multiple stage reaction, where
triglycerides are converted to diglycerides, then
diglycerides are converted to monoglycerides, and
monoglycerides are then converted to esters (biodiesel)
and glycerol (by-product).
 For the transesterification reaction oil or fat and a short
chain alcohol are used as reagents in the presence of a
catalyst.
 Alcohols that can be used are methanol (most preferred
due to its low cost, polar structure, and being the shortest
alcohol chain), ethanol, propanol, butanol.
 The catalysts can be acid (sulfuric acid, hydrochloric acid),
basic (NaOH, KOH) or enzymes. Commercially alkali-catalyzed
transesterification is most often utilized since it
is faster than acid-catalyzed transesterification.

14. Transesterification Continued
Parameters influencing the transesterification
reaction rate:
 Reaction temperature
 Type and amount of catalyst
 Mixing intensity
 Quality (purity, free fatty acid composition)
 Starting materials
Water content

15. Centrifugation
Centrifugation separates suspended solids from a liquid
solution
 The biodiesel droplets are separated from the glycerol
 A disk centrifuge is a system of rapidly rotating
concentric inverted cones placed close together to
minimize the time to capture dense particles or liquids
while allowing forced flow to continuously add feed
and discharge liquids.

16. Centrifugation Continued
 How a disk centrifuge works:
 Operates in continuous mode
 Feed enters on the axis of
rotation and forced to bottom
of rotating bowl
 Lighter fluid flows up and out
of the centrifuge
 A nozzle either ejects dense
particles or allows build up on
outer wall of the bowl

17. Centrifugation Continued
 Energy intensive and inefficient harvesting have been major
drawbacks in the algae industry
 Generally flow rates are > 1 L/min with a high capture rate of
90% and cost about $4.52/L
 Increasing the flow rate to > 1 L/min has lower capture rates,
but can be offset by larger volumes of culture water, with high
culture density and lipid content, processed by the centrifuges
and cost $0.864/L
 A recent study showed at a rate of 18 L/min by centrifugation
lowered the energy consumption by 82% when only 28.5% of
algal was harvested.

18. References
 Attached in Paper