ADDIS ABABA UNIVERSITY
COLLEGE OF NATURAL SCIENCES
CENTER FOR ENVIRONMENTAL SCIENCE
Title: Biofuel production from microalgae: Challenges and
opportunities
Course advisor: Prof. H.S. Patil
By Dejene Tsegaye
January 2015
Contents
1.Introduction
2.General overview biofuel from Microalgae
3.Steps in producing micro algae biofuel
4.Experience of developing country
5.Conclusion
Introduction
Concerns about shortage of fossil fuels, increasing
crude oil price, energy security and accelerated global
warming have led to growing worldwide interests in
renewable energy sources such as biofuels.
An increasing number of developed and rapidly
developing nations perceive biofuels as a key to
reducing reliance on foreign oil, lowering emissions of
greenhouse gases (GHG), mainly carbon dioxide
(CO2) and methane (CH4), and meeting rural
development goals.
Sustainability is a key principle in natural resource
management, and it involves operational efficiency,
minimization of environmental impact and socio-
economic considerations; all of which are
interdependent.
It has become increasingly obvious that continued
reliance on fossil fuel energy resources is
unsustainable, owing to both depleting world reserves
and the green house gas emissions associated with their
use.
Therefore, research initiatives now a days are aimed at
developing alternative renewable and potentially
carbon neutral solid, liquid and gaseous biofuels as
alternative energy resources.
Biofuels
Primary Secondary
Firewood, wood
chips, pellets,
1st generation 2nd generation 3rd generation
animal waste, Bioethanol obtained from Biodiesel from
Bioethanol and biodiesel
forest and crop edible crops starch (wheat, microalgae
produced from conventional
residues, and barley, corn, potato) or Bioethanol from
technologies but based on
filling gas sugars (from sugarcane, microalgae and
novel starch, oil and sugar
sugar beet, etc.) seaweeds
crops such as Jatropha,
cassava, lignocellulosic
Biodiesel from, oil crops
materials (e.g. straw, wood,
(rapeseed, soybeans,
and grass)
sunflower, palm, coconut,
used cooking oil, animal
fats, etc.) Non-edible
but compute
wz edible
crops for land
and water
Microalgae covers all unicellular and simple multi-cellular
microorganisms, including both prokaryotic microalgae, i.e.
cyanobacteria (Chloroxybacteria), and eukaryotic microalgae, e.g.
green algae (Chlorophyta), red algae (Rhodophyta) and diatoms
(Bacillariophyta).
Autotrophic, use sunlight
Heterotrophic; does not use sun light
It has been estimated that about 200,000-800,000 species exist of
which about 35,000 species are known.
Composition of microalgae (dry basis): protein (12–35%); lipid
(7.2–23%); carbohydrate (4.6–23%).
Historical milestones of biofuel production from micro-algae
Production of Chlorella species in Japan: 1960.
Spirulina harvesting facility in Mexico and
Thailand in 1970 and 1977 respectively.
46 large scale factories in Asia by 1980
producing about 1 ton/month of microalgae.
Spirulina production by 2000 stands at
remarkable figure of about 3000 tpa (USA,
China, Thailand being major producers).
comparison of oil yield for various oilseed
crops
Source: Bennenmen,2008
A wide range of fuel products
Biodies
el
Ethanol
Microalgae
Methan
e
Hydrogen
Uniqueness of microalgae biofuels
Important characteristics of Algae
High % of total biomass is oil
Maintains a high % of oil even
under stress
Compatible with the wide area
climate Adaptability
Grown under conditions which are
Higher oil unsuitable for conventional crop
yield production (marine water, wastewater,
open ponds)
Microalgae
fuels Algae remove massive amounts of CO2 from the
air. Algae farms are glutton eaters of CO2 gas
providing a means for recycling waste carbon
dioxide from fossil fuel combustion.
Range of
WWT & CO2
products
capture
Steps in producing biofuel from algae
Cultivation of Microalgae type
Harvesting
Extraction of Oil from Microalgae
Trans-esterification, fermentation, AD/etc
Biofuel
Cultivation of Algae
Microalgae cultivation is the first step of the whole
microalgae bioenergy production process.
Algae have the potential to produce considerably greater
amounts of biomass and lipids per hectare than terrestrial
biomass, and can be cultivated on marginal lands, so do
not compete with food or other crops.
Algae can be cultivated photo-synthetically using sunlight
for energy and CO2 as a carbon source.
Proposed commercial algal biofuels
production facilities engage both closed
(tubes; photo bioreactors) and open (ponds)
cultivation systems (Demirbas, 2010).
Closed Photo-bioreactor (PBR)
A Photo-bioreactor is a controlled system that adds in some
type of light source. The term photo-bioreactor is more
commonly used to define a closed system.
A pond covered with a greenhouse could also be considered an
unsophisticated form of photo-bioreactor
Hence, photo-bioreactor is closed system which provides a
controlled environment and enables high productivity of algae.
This shows all growth requirements (carbon dioxide, water and light)
for algae are introduced into the system and controlled according to
the desires.
PBRs facilitate better control of culture environment such as carbon
dioxide supply, water supply, optimal temperature, efficient exposure
to light, culture density, pH levels, gas supply rate, mixing regime, etc.
Photo bioreactors have not been engineered to the extent of other
bioreactors in commercial practice, and so there is certainly room for
cost reductions.
PBR
Advantages and dis Advantages of PBR
Advantages of Photo-bioreactors Disadvantages of Photo-bioreactors
Higher productivity
Capital cost is very high.
More uniform temperature.
Difficulty in sterilizing
Large surface-to-volume ratio.
Reduction in evaporation of growth
medium.
Open Ponds
Cultivation of algae in open ponds has been
extensively studied.
Open ponds can be categorized into natural waters
(lakes, lagoons, ponds) and artificial ponds or
containers.
The most commonly used systems include shallow big
ponds, tanks, circular ponds and raceway ponds.
The choice of Algae Production Technology?
Depends on
•Open raceway paddle wheel mixed ponds now used by 98%
commercial microalgae production (Dr.JasonPark,2009)
Major limitations in open ponds include
poor light utilization by the cells,
evaporative losses,
diffusion of CO2 to the atmosphere, and
requirement of large areas of land.
Furthermore, contamination by predators and other fast growing
heterotrophs have restricted the commercial production of algae
in open culture systems to only those organisms that can grow
under extreme conditions.
Also, due to inefficient stirring mechanisms in open cultivation
systems, their mass transfer rates are very poor resulting to low
biomass productivity
The biggest advantage of these open ponds is their simplicity,
resulting in low production costs and low operating costs and they are
easier to construct and operate than most closed systems.
The concept of sustainable development was defined in the Brundtland Commission of
the United Nations in 1987: “as a “development that meets the needs of the present
without compromising the ability of future generations to meet their own needs.”
(United Nations General Assembly, 1987). Succeeding this definition the following
requirements are need to be satisfied to obtain a sustainable algae production:
Microalgae production cannot endanger the food supply.
Microalgae production does not impact on biodiversity.
Microalgae production cannot destroy the self-cleaning capacity of local plants and
soil.
Green Gases emission balance should be ensured during the production process.
Maintaining and improving local water resources and prohibiting excessive
consumption of ground water and surface water resources
Maintaining and improving the air quality
Its production can promote local economic and social prosperity, increasing
Harvesting methods
There is no single best method for harvesting microalgae and
reducing their water content, as they contain a lot of water.
Most importantly, cost-effective and energy-efficient
harvesting methods are required to make the whole biofuels
production process economical.
Centrifugation and flocculation as two most commonly used
methods.
Currently, centrifugation is considered to be too cost- and
energy intensive for the primary harvesting of microalgae.
Extraction oil from microalgae
After harvesting, further concentration and oil extraction is required,
for which various processes are proposed, including cell breakage and
solvent extraction, possibly using a three phase centrifugation.
The residual biomass could be either sold as animal feed or, more
plausibly at present, converted to biogas, for use in on-site power
production, with the residual nutrients (and carbon) recycled back to
the growth ponds.
Developing countries experience
Most commercial microalgae operations are located in China, Taiwan
and India.
In 1997 there were around 110 commercial producers of microalgae in
the Asia Pacific region, with capacities ranging from 3 to 500 tons
/year.
Experiences in China, Taiwan, Thailand, Philippines, Indonesia,
Myanmar, Vietnam, South Korea, Mexico, Chile, Cuba, Chad, South
Africa (mainly for food, fertilizers, aquaculture, wastewater treatment)
No willingness to pay for ‘greener’ products!
Opportunities to adapt current production systems to bioenergy co‐
production
Opportunities
Growth
More than 100 companies are working on
algae fuels, especially in USA and UK
140
120
100
80
# of companies
60
40
20
0
2001 2002 2003 2004 2005 2006 2007 2008 2009
Investments
(in million dollar)
700
600
500
400
300
200
100
0
2006 2007 2008 2009
Challenges & Bottlenecks
Biological Economical
Technical
Picking up an algae
strain Maintenance of open pond cultivation
Cost of closed systems
Harvesting of microalgae
Limits to productivity of Microalgae
Physical factors such as light (quality and quantity),
temperature, nutrient, pH, O2 and CO2
Biotic factors including pathogens, predation and
competition by other algae, and
Operational factors such as: shear produced by
mixing, dilution rate, depth and harvest frequency
Conclusion
Imagine if we could
Grow a fuel without using land
Grow a fuel without polluting the atmosphere
Harvest a crop every day instead of yearly
Generate up to 300 times more biomass per acre
Grow Crops in both fresh and sea water, also in wastewater
(sewage)
Microalgae can be used in the wastewater treatment as the micro
organisms influencing the cleaning process
Developing countries should have to try it
Indicating micro-algae have many desirable attributes as renewable
energy sources and its can be a sustainable alternative as they are the
most efficient biological producer of oil on the plant
Thank you for
your Attention
You cannot solve the problem with the same kind of
thinking that created the problem (Albert Einstein)
Hence, ‘Grow clean’, not grow first clean up later!!
