Composition of biomass feedstocks is highly variable. High throughput and accurate characterization of biomass feedstocks is a necessity for any biomass-to-biofuels conversion program as it enables evaluation of conversion yields and process economics.

1. Sep 2014
Composition analysis of biomass
for biofuels
Introduction
• Composition of biomass feedstocks is highly variable.
• High throughput and accurate characterization of biomass
feedstocks is a necessity for any biomass-to-biofuels conversion
program as it enables evaluation of conversion yields and process
economics
• Biomass mainly consists of cellulose, hemicellulose, lignin and ash.
Biomass carbohydrate content is of prime importance because it is
directly proportional to ethanol yield.
• Fibretherm uses filtration method to determine crude fibre,
neutral detergent fibre (NDF) and acid detergent fibre (ADF). It
optimizes the digestion of the samples and speeds up the washing
and filtration processes. Hence, more number of samples can be
handled in a relatively short time.
• Calorific value (CV) is the amount of heat produced by the
complete combustion of a material and is expressed in Kcal/Kg.
Higher the calorific value of the biomass the better is it’s suitability
for power generation.
Methodology
• Moisture (%): 1 g of dry biomass sample is taken and moisture
percentage is calculated using moisture balance.
• NDF (%): 1 g of moisture free sample is taken and placed in a
fibrebag along with the spacer with NDF solution in fibretherm.
NDF treated sample is washed, dried overnight and weights taken.
• ADF (%): The dried sample is run with ADF solution. ADF treated
sample is washed, dried overnight and weights taken.
• Acid detergent lignin (ADL) (%): The dried samples are transferred
to Gooch crucibles and treated with 72% H2
SO4
for 3 hours. The
crucibles are washed, dried overnight and weights taken.
• Ash (%): The crucibles are placed in muffle furnace at 500°C for 4
hours and weights taken after cooling.
• CV (Kcal/Kg): Sample is weighed and placed in a heavy duty
stainless steel cylinder referred as “Bomb” which is sealed with
oxygen and the sample is ignited electrically. The complete
oxidation of the compound releases heat and is measured through
the temperature rise of the water by a sensor, which is used to
calculate calorific value.
Formulae
• NDF = ((Dry weight of sample after treatment- Ash) / Initial weight
of the sample) * 100
• ADF = ((Dry weight of sample after treatment- Ash) / Initial weight
of the sample) * 100
• ADL = ((Dry weight of sample after 72% H2
SO4
treatment- Ash) /
Initial weight of the sample) * 100
• Hemicellulose = ((NDF – ADF) / weight of sample) *100
• Cellulose = ((ADF – ADL) / weight of sample)*100
• Silica = ((weight of crucible after ignition - weight of empty
crucible)/ weight of sample)*100
• CV = TxW-(CVT+CVW)/M
• Where T: rise in temperature (°C); W: water equivalent (Cal/°C);
CVT: CV of thread; CVw : CV of ignition wire; M: mass of sample (g)
Results
• Composition analysis of different types of sorghum
Conclusions
• The range of cellulose, hemicellulose and lignin among sorghum types is high.
• High calorific value feedstocks are preferable for bio-power projects.
Fibretherm apparatus Digital Bomb Calorimeter
For further information please contact: Dr P. Srinivasa Rao, Senior Scientist, Research Program –
Dryland Cereals. Email: p.srinivasarao@cgiar.org
This work is being
undertaken
as part of the
Cellulose
Hemicellulose
Lignin
Ash
Moisture
ICSV 93046
ICSV 25333
Kansas Collier - bmr 6
SSG 59-3 CO 19
RTx 430 - bmr 12
ICSSH 71
ICSSH 28
DBT