Bài giảng - Biofuels

• Coal, Oil, Natural Gas Biofuel: Any fuel that derives from biomass – recently living organisms or their metabolic byproducts • Biodiesel, Butanol, Ethanol, Hydrogen... Why Biofuels?

BIOFUELS

Fossil Fuel: a hydrocarbon fuel, such as petroleum,

derived from living matter of a previous geologic time.

• Coal, Oil, Natural Gas

Biofuel: Any fuel that derives from biomass – recently

living organisms or their metabolic byproducts

• Biodiesel, Butanol, Ethanol, Hydrogen

Why Biofuels?

 Reduce dependency on fossil-fuels

 Reduce GHG emissions (reduce impact on health, environment)

 Improve energy security

 Contribute to rural development through domestic production

BIODIESEL

What is Biodiesel

Mono-alkyl esters of fatty acids (i.e methyl or ethyl

esters) which are produced by transesterification of triglyceride

Biodiesel Production

• Biodiesel Blend: mixture of biodiesel and petroleum diesel

• BXX = volume XX% biodiesel

• Most common blends are B5, B20

• Physical properties very similar to

conventional diesel

• Must meet the quality requirements of ASTM D6751

Sources of Lipids for Biodiesel Production

 Animals

 Plants

 Oleaginous microorganisms

 Algae

What are Algae?

 Algae

 Most live in water

 Photosynthetic

Capture light energy

Convert inorganic to organic matter

 Nonvascular

 Use lipids and oils to help float in water

 Range from small, single-celled species

to complex multicellular species, such

as the giant kelps

Why Algae?

 Photosynthetic organisms are capable of efficiently using solar energy and CO2 to create biomass

 Algae, like terrestrial plants, produce

storage lipids in the form of triglycerides.

 Capable of utilizing high nutrients in waste water streams

 Incredible growth rates (much faster than plants)

Why Algae?

 As the use of biofuels expands globally,

traditional food crops such as corn and soy

beans are increasingly being used as feedstocks for the most popular liquid biofuels, ethanol and

biodiesel, rather than as foods

This raises price competition between fuels and food commodities- not a sustainable practice

 Algae can be grown on non-arable land, where food crops simply cannot grow

 Micro Algae 1850 [based on actual biomass yields]

 Micro Algae 5000-15000 [theoretical laboratory yield]

Cultivating Algae for Liquid Fuel Production (http://oakhavenpc.org/cultivating_algae.htm); 2005

Fig1 Procedure of algal biodiesel

production

Disadvantages : expensive, difficult to scale up, energy intensive

Open vs closed Algal production system

The use of a fuel containing Chlorella

vulgaris in a diesel engine

 Some microalgae such as Chlorella vulgaris are

unicellular (5–10 μm) and has a high lipid

content, which is suitable for combining in an emulsion fuel An emulsion consisting of

transesterified rapeseed oil, a surfactant and a

slurry of C vulgaris was used as a fuel in an

unmodified single cylinder diesel engine

 The fuel consumption and emissions of this

fuel was determined and although the carbon

monoxide levels were higher the Nox emission

was lower than that of diesel.

Fig 2 The formation of an emulsion of biodiesel and algae: (1)

biodiesel with surfactant (0.5% Triton X-100); (2) biodiesel with 20% algal slurry; (3) biodiesel with surfactant with 20% algal slurry The

components were mixed vigorously and the photograph taken after 24 h.

WANT TO PROPOSE SOME NEW

MICROBE FOR BIODISEL

PRODUCTION? READ THE PROVIDED ARTICLE TO FIND OUT HOW.

Ethanol Production

Ethanol Production

Glycolytic Pathway for

Ethanol Production by

Saccharomyces cerevisiae

CO2 is commonly captured and purified with a

scrubber so it can be marketed to the food processing industry for use in carbonated beverages and flash-

freezing applications.

Dried distillers grain (DDG) is commonly used as a

high-protein ingredient in cattle, swine, poultry, and fish diets

Acetone-Butanol-Ethanol

(ABE) Production

4 carbon alcohol C4 H10 O: 4 isomeric

How butanol is produced?

1 Biological synthesis (ABE

How butanol is produced from starch?

Starch Starch hydrolysis Glucose

Butyric and acetic

ABE recovery by Gas stripping

 Gas stripping was initiated from about the 36 h

by recycling oxygen free N2 gas through the

system.

 The ABE vapors was cooled in a condenser

which has been previously fluxed with oxygen

free N2

 The stripped ABE was collected into the

solvents collector (125 mL flask).

Co-culturing an amylase producing Bacillus with a

Clostridum for ABE production

oTo increase substrate utilization

oTo reduce cost of product (no requirement in substrate pretreatment and addition of reducing agent)

Clostridium butylicum TISTR 1032

Bacillus subtilis WD 161

Fermentation condition design

Anaerobic Pretreatment

Without anaerobic pretreatment

Stirred at 120 rpm during fermentation process

Hydrogen Production

(i) biomass production by photosynthesis, (ii)

biomass concentration, (iii) aerobic dark fermentation yielding

4 mol hydrogen/mol glucose in the algae cell, along with

2 mol of acetates, and (iv) conversion of 2 mol of acetates

into hydrogen

Clostridium acetobutylicum