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7/29/2019 microalgae to biodiesel

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Prof. Roberto Rana

University of Foggia

Faculty of Economics

University of Foggia - Faculty ofEconomicsErasmus Intensive Programme EPROBIO


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Why to use algae to produce biofuels?

Over this last decades the frequent oil crises

and environmental impact of fossil fuels, hasdived many industrialized countries tocarrying out research to discover analternative sources of fuels able to ensure a

new energy sources supply that reduceemissions of CO2, nitrogen monoxides andsulphur into the atmosphere.

So, has been introduced biofuels mainlyderived from sugar cane, corn, as bio-

ethanol or biodiesel, obtained fromrapeseed, soybean, etc. However someresearchers believe that bio-energy will notbe able to satisfy future world fuels

requirements, since intense energy crop


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Why to use algae to produce biofuels? Algae are the fastest growing

microorganisms (some unicellular algaedouble their weight in 12-24 hours, whilecells are able to separate in less than 4hours),

Algae are most abundant biomassproducers in earths biosphere. Some algaehave a high yield (biomass production) (50-70 t/hectares per year).

Most algae are unicellular and thereforecontain a very high amount of starches orlipids (up to 50% dw).

Compared to plants, algae require less

space to grow, have more tolerant


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RHODOPHYTA

Chondrus crispus

Gelidium spp

PHAEOPHYTA

Fucus spp

Laminaria spp

Ascophyllum nodosum

CLOROPHYTAUlva lactuca

MACROALGAE

Classification of Algae

Worldwide are described 30 000 species of microalgae (< 10% of estimated).The classes (29) are distinguished by the structure of flagellate cells (e.g.,

scales, angle of flagellar insertion, microtubular roots, and striated roots), thenuclear division process (mitosis), the cytoplasmic division process

(cytokinesis), and the cell covering.

Spirulina spp flos-aquae

Diatomee

(Bacillariophyta)

MICROALGAE

Cianoficae Clorophycophyta

Green algae

Chrysophycophyta

(golden algae)

Dinophyta

(dinpflagellates)

Neochlorisoleoabundans,

Scenedesmus

dimorphus,

Botryococcus brunii


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Macroalgae or seaweeds

The worlds mostsuccessful seaweedcultivation industriesare in Asia. Howeverthis continent is reallow in technology

Japan is one ofthe big producer

and consumer ofseaweeds in the

world.

Cultivating seaweed in

Portugal, England andIreland is traditional.People use fertilizer for

their seaweed.

China is thebiggest producer

and consumer ofseaweed

The shallow coral

lagoons off the

coast of EastAfrica andZanzibar are

host to multipleseaweed farms.

Seaweeds cultivation are old. Seaweed has

been part of the Chinese diet for over 2000years and probably much longer. The macro-algae have a high biomass yield from 7-30t/hectares.


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Macroalgae growing systems

There are many

technologies tocultivate seaweed.For instancetraditionalseaweed farminguses lines, ropes,nets or rafts,floating suspendedin the sea.

Young seaweed orpart of seaweed

are attacked to thesubstrate and thanare left to grow for6 to 8 weeks,depending on the

species andlocation.

Generally seaweeds species grow

very fast and can be croppedwithin a few months.


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A new cultivationsystems of seaweed

Because most ofmacro algae live onthe sea bed isdifficult to cultivate

in offshoreinstallations andhave highproduction. These

technology, indeed,are subjected to theaction of waves andtides. To resolve

these problemsA concave mirror placed in the sea

surface converges the radiation at depths

where macroalgae grow


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Paths of the various energy products fromseaweedSyngas is the name given to a

gas mixture that contains

varying amounts of carbon

monoxide and hydrogen. Thegas is obtained by a process

that occurs at high

temperature and in absence of

oxygen


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MICROALGAE

The microalgae areunicellular

organisms, in generalphotosynthetic, with

a few microns size(


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MICROALGAEMicroalgae generally have a protein,

carbohydrates and fats content vary widelydepending on the species. For instance

the average amount of lipid ranges from 1-

40% dry weight. Fats composition and

quantity depend on the environmental

factors of the algae broth (temperature,

salinity, light intensity, etc.). So, when algal

cells grow in situations of nutrientdeficiency (such as nitrogen, silicon, etc.)

or in a broth rich in sodium chloride, can

increase fats content more than 70%.


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Microalgae

Biodiesel

Hydrogen

Bio-ethanol Biogas

Foodsuppleme

nts

Food

industry

Feed

industry

FinalChemicals

Commercial use of microalgae


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BIODIESEL FROM MICROALGAE

Microalgae, have the highest biomassproduction (50-70 t/ha) and oil content

(about 20-30 m3/ha) among all plants,

significantly higher than those of corn,soybeans, palm oil, etc..

According to some authors, the annual

yields are much higher, up to values

280t/ha.

Comparison between yield of most common

oleaginous crops and microalgae

Land surface

occupied by soy

productionnecessary to supply

USA diesel

consumptionLand surface

occupied by corn

production

necessary to supply

USA dieselconsumption

Land surface

occupied by algae

schemes necessary

to supply USAdiesel consumption

~ 250 billion liters of diesel is the nation presently consumes


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Although the idea of growing algae to obtain biofuels started to

the end of the 1940s, the first applied studies were

undertaken only twenty years later, when some American

researchers proposed to use these organisms to obtain biogas

by fermentation, to be burned in electric power plants.

During the first energy crisis (1973) the American Congress

set up the NREL (National Renewable Energy Laboratory),linked to the DOE (Department Of Energy). This laboratory

carried out a programme, call Aquatic Species Program

(ASP), to grow unicellular microalgae in a ponds connected to

electric power plants.

but thisprogramme wasstoped in 1996

because


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Initially DOE researchers was aimed at the possibility to

obtain biogas from the fermentation of microalgae and to

store CO2. The success of this experiment and the

discovery of large quantities of oil contained in

microalgae led researchers to use these organisms to

produce biodiesel.


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1Open ponds

2Photobioreactors


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Open cultivation systems

Open pond or racewaypondA raceway pond is a shallow

artificial pond used in the

cultivation of algae. The pond,

with a surface from 100-1000-

10000 m2

and a dept from 15-30cm, is divided by several baffles

forming one channel in the

shape of an oval, like an

automotive raceway circuit. From

above, many ponds look like a

maze (labyrinth). Each basin

contains a paddlewheel to make

the water flow continuously

around the circuit and prevents

the deposition of microalgae on

the bottom of the pond.


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Open pond or racewaypond

To cultivate microalgae requires an appropriate culture

medium (broth), consisting of an aqueous solution rich in

inorganic salts such as sodium chloride, potassium

carbonate, calcium chloride, potassium nitrate, calciumphosphate, etc.. and appropriate environmental conditions

(light, temperature, concentration of CO2, etc.).

Some installations are made by several pondswhere you can use a thermal power plantemissions (CO2, and oxides of nitrogen) and/or

sewage(wastewater with high concentration ofnitro en and hos horus to feed al ae.


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To prevent predation by other species, the salt

concentration of the broth is keep high


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In order to cultivate microalgae species thatprefer lower salt concentrations, achieving

a higher cell density and prevent the

contamination of culture medium, were

tested the photobioreactors.These facilities are closed systems in which

the algae are not direct contact with the

external environment and receive solar

radiation directly through the walls of

photobioreactor or from optical fibers or

solar collectors (concave mirrors).

Closed cultivation systems


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Closed cultivation systemsPlants may be placedPlants may be placed outdoorsoutdoors ororindoorsindoors (greenhouses).(greenhouses).

Plastic bagsPlastic bags

(outdoor or indoor)(outdoor or indoor)

PhotobioreactorsPhotobioreactors

are made in glass,are made in glass,

plastic or otherplastic or other

materialsmaterials


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Closed cultivation systems


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How the photobioreactor work:


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How tubular photobioreactor work:


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How flat panel photobioreactor work:

The flat panel photobioreactors are made in glass or Plexiglas and have

rectangular shape, vertically arranged, with a thickness about 1-5 cm. In thisvessels microalgae are harvested (recovered) at the top and kept in suspension

through an air flow introduced at the bottom generally by a special tube. This

system seems to offer high biomass yields, with the increased surface area

exposed to solar radiation that can improve the photosynthetic efficiency and

to increase biomass production (80g/L vs. 30-50/L).

O P d Ph t bi t


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Open Pond versus PhotobioreactorPARAMETER

SOPENPOND

NOTE PHOTO

BIOREACT

OR

NOTE

Land space fill High - Low -

Water loss Very high - Low -CO2 loss High Depends on the

depthness of the pondLow -

CO2 consume Medium - Medium -Concentration

of O2

Low O2 is released freely

from the surface oftanks

High O2 must be removed

due to inhibition ofphotosynt. problems

photo-oxidationTemperature Very variable Depends on the depth

of the pondsHigh Often requires a cooling

system accessories

Mixing algae Low It is carried out using a

paddlewheel

High Its occurs by pumping

in gas such as CO2Cleaning

equipmentNot required - Required It is required to clean

the walls of photob.because algae growthreduces the incoming

solar radiationContamination Very high Depends on the

chem./phys. charac. ofthe broth

Very low -


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Raceway Pond versus Photobioreactor

The comparison between raceway ponds and bioreactors

shows that the management of the former is difficult becausethe operational parameters such as temperature, salinity,

dissolved gases, etc., depend on environmental conditions. In

addition, productivity may be lower due to the phenomena of

contamination of parasites and competition with other aquaticplant species.

So, photobioreactors seem to be the most promising

technology, although currently the increased cost of production

of biomass and the complexity of managing prevent its

widespread use.


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A new technology process

HR BioPetroluem proposed a hybrid system thatprovides for the combined use of both technologies.

This new process use only photobioreactors to make apure culture of microorganisms, with high productivityand rate of nutrient intake. When the algae biomass

achieve high concentration than it is inoculated in openponds. To prevent contamination phenomena, algaebiomass are left in the tank for a day allowingsterilization during the follow night.

With the development of this hybrid productionsystem, HR BioPetroleum has achieved significant

Currently simple and inexpensive new facilities have been

proposed combining the two technologies allowing bothlower operating costs and increase biomass yields.

This system combines low costand the high productivity ofalgae ponds with the protectionof culture-closedphotobioreactors; allowscontamination-free

monocultures of the mostproductive algae to becultivated; minimizes capitalinvestment as a cost factor.


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Oil extraction

Flocculation

This phase can occur

spontaneously in a tank, but

can be speeded up by

raising the value of pH,

adding salts, lowering the

concentration of certain

nutrients or gases or byadding appropriate

flocculants.

Decantation/

Filtration

Centrifugation

Centrifugation is used to removemost of the water still present in

algal biomass. This is the most

expensive stage because of the

energy consumption (1000$/t)

and purchase cost.

Water

Open pond orOpen pond or

bioreactorsbioreactorsThe water removed, still rich in nutrients,

is sent again in the pond or bioreactors.

Filtration is carried out commonly onmembranes of modified cellulose. The

greatest advantage of this method as a

concentrating device is that it is able to

collect microalgae or cells of very low

density. However, concentration by

filtration is limited to small volumes andleads to the eventual clogging of the

filter by the packed cells when vacuum

is applied. This technology is used

when is not required an excessive

removal of water.


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Flocculation Decantation/

Filtration

Centrifugation

Water

Open pond orOpen pond or

bioreactorsbioreactorsThe water removed, yet rich in nutrients,

is sent in the pond or bioreactors.

Algaepaste

Extract

ion

OIL Cake

Animal feedAnimal feed

BiogasBiogasFinal ChemicalsFinal Chemicals

HeatHeatBIODIE

SEL

Trans-esterificationTrans-esterification

Oil extraction that mayoccur by simple coldpressing, with recovery70-75% of oil, or asuitable solvent(benzene, petroleumether, cyclohexane,etc.). immiscible inwater, with yields up to100%.

1g/L1g/L

50-100 g/L50-100 g/L

The cake nottreated usingcyclohexane, still

rich in preciouspolyunsaturated fatacids -3 and -6 , can be utilized asfeed because it is

rich also incarboh drates and

Oil extraction


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Though oil from microalgaemay be used as it is in dieselengine, in order to improve its

performance, it undergoes aprocess of trans-esterificationhaving it react with alcohol

(methanol).

OIL FROMMICROALGAE


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Biodiesel from microalgaeversusversus biodiesel standard

In general, biodiesel from microalgae has similarphysical-chemical characteristics and, in somecases, better than standard one, for example, afewer number of a Cold Filter Plugging Point and a

higher value of heating value.

Biodiesel from soyBiodiesel frommicroalgae

Cold filter plugging point (C)

Density(kg /L)

Viscosity

Acidity

Heating value


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Some economics aspectsUnit of

measurementsOpen Pond Pannell

Photobioreactor

Tuborar

Photobioreactor

Biomass production

T/y per hectare 20 60 40

Photosyntheticefficiency

% 1,5 5 3

Penetration of solarradiation in the

system

cm 20 3 3,4

Capital Costs /hect. 70 000 > 700 000 > 700 000

Energy consumption kWh/ha ~ 1.800 5.000-185.000 5.000-185.000

Production costs of

biomass

/kg (dw) 5.70 4.03 4.02

Major cost factor % Movement of paddle (15)

Input of air (24) Pumping (46)

The development of commercial-scale biodiesel from microalgae seems not yet economically feasible for both the low biomass

production and high cost. As you can see in table, photobioreactors have capital and operating costs much higher than open

pond because of more complex technology involved in this technology. However, higher yields in biomass would seem to offer

better development prospects to photobioreactors than open ponds.

At the present the cost of 1L of

biodiesel product withphotobioreactor is

< 3$/L (palm oil 0,6 $/L)< 3$/L (palm oil 0,6 $/L)

How can we reducethe price of biodiesel

from microalgae?


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Some economics aspects

Because 300 t/ha per year (dw) is considered the production of

microalgae biomass which would produce a real economic

benefit to the factory owner we are far from producing an

economic return in the production of biodiesel from algae

Actual yield in a best plant:15/m2 per day 50 t/hect. per year (dw)

oil ~ 20 t/ per year

Best yields a short-run:

30/m2 per day 100 t/hect. per year (dw)oil ~ 40 t/ per year

Best yields a long run:

50g/m2 per day 170 t/hect. per year (dw)


to produceGenetically Modified

Microalgae

to improve algae biomass productionto improve algae biomass production


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Open pond - algae cultivation

10%

90%

55%

45%

45%

90%

10%

75-78% lost

lost

lost

15% lost (mt= 1000t)

lost

/m2

S i t (GMO


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Some economics aspects (GMOmicroalgae)

light radiation is

not absorbed andrelease as heat

This phenomenon known as the light saturation effect is

particularly unfavorable to microalgae production systems.

In fact microrganisms live in the deep grow slightly because

of the sunlight intercepted by the algae placed on the

Because of the size of the chlorophyll pigment, 90% of

solar radiation absorb by the algal cell is lost as heat

In nature there is an mutant strain of alga (Chlamydomonas

reinhardtii) that has a short dimension of photosynthetic

pigments. This modification reduce the amount of light

absorbed by the algae leaving the radiation get in the deep.

Researchers now want to transfer this mutant

character to other species of microalgae

Wild types Mutant types

Wild types Mutant types

S i


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Some economics aspects

Because 300 t/ha per year (dw) is considered the production of

microalgae biomass which would produce a real economic

benefit to the factory owner we are far from producing an

economic return in the production of biodiesel from algae

Actual yield in a best plant:15/m2 per day 50 t/hect. per year (dw)


Best yields a short-run:

30/m2 per day 100 t/hect. per year (dw)oil ~ 40 t/ per year

Best yields a long run:

50g/m2 per day 170 t/hect. per year (dw)


to improve algae biomass productionto improve algae biomass production

How can we reducethe price of biodiesel

from microalgae?

to use by-productscame from oil

production(i.e. astaxantina)


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It should be noted, however, that the simplecomparison between the input and output energyshow that open ponds involve a higher "energyreturn than the photobioreactors.

*Include the energy consumption in the plant and the energy consumption to

produce the devices.

** Includes the energy obtainable from the production of algal biomass

I wonder how photobioreactorscan be considered the cheapest

technology if they consume 100times more energy than openponds?Energy is considered an important cost: it represent40% of the total costs


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The production of biodiesel from

microalgae is a valid alternative to the

traditional energy crops, because the use

of these microorganisms do not subtracts

valuable resources for food.

Future developments


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However, the low biomass yields and high

production costs prevent a large-scale

commercial development. In deed, as we

see above, 1 liter of oil from microalgae

costs about six times the palm oil.

Future developments


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So, some researchers believe that commercialdevelopment of biodiesel production from

microalgae requires many years before being

feasible. They think, in deed, that has not yetshown that intensive algal culture provide

more energy than that it consumes.

Future developments

This figure shows the energy invested over the

lifecycle versus the energy in the algae biomass


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Challenges for the future are:

1) genetic improvement of microalgae species (to

create an organism with a higher yield in biomass

and oil);2) to resolve technical issues (fouling,

contamination of the broth, control of operating

parameters, etc.);

3) economic valorization of by-products (final

chemical, biogas, animal feed, etc.)

Future developments

The achieve of these

targets will reduce capitaland management costs

and will allow the large-scale production ofbiodiesel from


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