Biomass Fuel Quality Enhancement and Respiratory Quotient (RQ) for Ranking Fossil and Biomass Fuels Based on CO2 Emissions - Novel Combustion Concepts for Sustainable Energy Development - page 50

3 Results and Discussion

3.1 Fuel Preparation and Properties

Biomass fuels used for the current study, mesquite and juniper, were harvested from
the rangelands in north central Texas near Vernon. Both mesquite and juniper are
scattered over a large area which is estimated to be 200,000 ha. It should be noted
that the species is not concentrated throughout the entire area but dispersed with a
spacing of around 1 km. After the fuel is harvested using a chainsaw, a chipper is
used to reduce the particle size from trunk and branches. It also includes the bark. It
was observed that, when a freshly harvested biomass (moisture content around
45 %) was sent into the chipper for reducing the particle size, the chips produced
after the chipping process had a lower moisture percentage of between 10 and 20 %.
This might be because of the drying of the wood chips within the chipper using the
heat produced as a result of the chipping process. Vermeer wood chippers were
used for processing the biomass. Further details on the preparation of the samples
are available elsewhere (Chen 2012 ). Properties of mesquite and juniper obtained
from the commercial testing labs are shown in Table 1 .

Table 1 Ultimate and
Proximate analyses of
mesquite and juniper

Raw biomass
Mesquite Juniper

Moisture (ar) 15.53 5.85

Volatile matter (ar) 66.09 77.99

Fixed carbon (ar) 16.71 14.25

Ash (ar) 1.67 1.91

Carbon (ar) 43.60 49.27

Oxygen (ar) 33.57 37.00

Hydrogen (ar) 4.98 5.68

Nitrogen (ar) 0.62 0.28

Sulfur (ar) 0.03 0.01

Dry ash-free basis
VM (daf) 79.8 84.6

FC (daf) 20.2 15.4

HHV (kJ/kg) 16,666 18,987

HHV dry (kJ/kg) 19,730 20,167

HHV DAF (kJ/kg) 20,128 20,584

VM HHV DAF (kJ/kg) 16,923 18,351

HHV Boie,DAF (kJ/kg) 21,059 21,509

HHV (kJ/kg st O 2 ) 13,652 13,632