by dr ku syahidah ku ismail adapted from cheng, j. (2010) biomass to renewable energy processes

Chapter 1:BIOMASS RESOURCES &

CHARACTERISTICS OF BIOFUELSBy

Dr Ku Syahidah Ku IsmailAdapted from Cheng, J. (2010) Biomass to

Renewable Energy Processes

Biomass Energy Technology

Renewable Energy vs Fossil Fuel Energy

Fossil fuel reserves are limited and will be depleted.

Burning fossil fuels causes environmental concerns eg. GHG emmission.

Energy from biomass releases CO2, but the CO2 is utilized for biosynthesis during the growth of biomass.

Carbon cycle

Types of Biomass Resources

Corn Sugarcane

Napier grassLignocellulosic waste Algae

Sugar CropsIncludes sugarcane, sugar beets, sweet

sorghum, apples, grapes etc.Molasses – residual syrup remaining from

crystallization of sugar from sugarcane and sugarbeets, is also a common feedstock

Pulp and papermill sludges contain 40-50 wt% glucose

These sugars can be directly fermented by yeast Saccharomyces cerevisiae .

SugarcaneBrazil is the largest producer (514 million

tons in 2007)India is the second largest producer, followed

by China.It has stalks bunched in stools of 5-50 stalksCan be grown in regular rotation with other

crops.Requires tropical or subtropical climate.Time to maturity is between 8-24 months.Strong sunlight and plentiful water is needed

to meet the considerable growth potential.

Sugar BeetA biennial root vegetableHigh content of sucrose in its root.Grown in temperate climatesAverage sugar (sucrose) content is around

17% of total raw biomass.World’s largest sugar beet producer: France,

USA and Russia

Sweet SorghumUsed in the production of sugar, syrup, fuel

and roofing applications.Thrive under drier and warmer conditions.Largely produced in Asia, followed by North

America.The juice contains 56% sucrose, 30% glucose,

14% fructose.

Starch and Inulin CropsCorn, potatoes, cassava etc. Starch is a glucose polymer with 2 main

components: amylose and amylopectinInulin, like starch, is a storage carbohydrate,

but its basic unit is fructose rather than glucose

Inulin is commonly found in tuber crops such as dahlia and Jerusalem artichoke.

CornTypically planted in the spring when warm

temperatures are condusive for growth.Soil moisture is another key factor that

determines the adaptability of corn to an area.

Predominant component of corn is starch, 64-78% of the total mass on a dry basis.

Other carbohydrates include cellulose fiber, pentosans, sucrose and monomeric sugars such as glucose, fructose and raffinose.

WheatChina – largest producer, followed by IndiaContains 77% starch content (dry basis)

Agricultural ResiduesIt refers to either crop residues or processing

residues.Corn stover – remains in a field after

harvesting corn, includes stalks (50%), leaves (22%), cobs (15%) and husks (13%).

Wheat straw Rice straw

Herbaceous BiomassSwitchgrass MiscanthusCoastal Bermuda Grass

Oil SeedsSoybeanRapeseed (Canola)SunflowerOil PalmWaste Edible Oil

Biofuel CharacteristicsBiofuel – a solid, gaseous or liquid fuel

produced from biomassEthanol, butanol, diesel etc.1st generation biofuel – food based material 2nd generation biofuel – cellulosic materials3rd generation biofuel - algae

Comparison of Transportation FuelsFossil Fuel - derived

Biorenewable Resource - Derived

Fuel Type Gasoline No 2 Diesel Fuel

Methanol Ethanol Methyl ester (from soybean)

Specific gravity @ 16C

0.72 – 0.78

0.85 0.796 0.794 0.886

Kinematic viscosity @ 20C (m/s)

0.8 x 10-6

2.5 x 10-

6

0.75 x 10-6

151 x 10-6

3.9 x 10-6

Boiling point (C) 30-225 210-235 65 78 339

Flash point (C) -43 52 11 13 188

Autoignition temp (C)

370 254 464 423 -

Octane no. (research)

91-100 - 109 109 -

Octane no. (motor) 82-92 - 89 90 -

Cetane no. < 15 37-56 < 15 < 15 55

Heat of vaporization (kJ/kg)

380 375 1185 920

Lower heating value (MJ/kg)

43.5 45 20.1 27 37Source: Brown, R.C. (2003) Biorenewable Resources

Bioethanol Global Demand

Cellulosic Biofuel Projection