Depending if the plant’s primary objective is to
generate electricity or to generate heat, the electrical
efficiency (
η
e
) of a biomass-fired CHP plant can vary
between 20 and 30% [20-21]. In this study, the electrical
efficiency is established at 25%. As for the thermal
efficiency (
η
th
), modern CHP plants can convert between
55 and 70% of their energy input to heat [20]. For this
study, the thermal efficiency is established at 60%.
Finally, the total or overall efficiency of a biomass-
fired CHP plant is given by the following equation:
η
tot =
η
e +
η
th
(4)
where
η
tot
is the total efficiency,
η
e
is the electrical
efficiency and
η
th
is the thermal efficiency. Therefore, in
this study, the total efficiency of the dedicated biomass-
fired CHP plant is established at 85%.
E. Application: Province of New Brunswick, Canada
As an application of the methodology proposed, the
large scale assessment of biomass, along with the
technical power potential of this biomass for the
commercial cogeneration of heat and power in industrial-
sized combined heat and power plants, is applied to the
province of New Brunswick (NB), Canada. The province
of New Brunswick, one of the smallest of the Canadian
provinces, both in size (71,450 km
2
) and population
(748,319 inhabitants), is part of the Maritime Provinces
on the eastern coast of Canada. The province’s primary
economic activities are, in urban areas, those of service-
based sectors such as health care, government services,
education, retail, finance, and insurance sectors. On the
other hand, the natural resource sectors, such as forestry,
mining, farming and fishing dominate the primary
economic activities in the province’s rural areas.
In New Brunswick, forests cover nearly 85% of the
landscape, with roughly 60,000 km
2
being productive
forest [22]. Because of this important forest resource, the
large scale biomass assessment methodology presented in
this study is applied to the province’s forest biomass
resource. In such, 17 potential CHP locations have been
identified within the study area, along with their
corresponding procurement areas, as shown in Fig 1.
In regards to the supply of biomass, forest inventory
data, AAC data, forest biomass equations and forest
biomass expansion factors (stem wood to residual forest
biomass or bark ratios) are used to estimate the total
amounts of forest biomass available annually in the
province of New Brunswick. More specifically, the
forest biomass assessment of the merchantable stem-
wood is based on AAC data while the residual forest
biomass and bark categories are estimated using data
based on forest biomass allometric equations. When
forest biomass data are not available, averages of stem
wood to residual forest biomass or bark ratios are used.
Because there are different types of land ownership
(federal, provincial, private, and industrial) in the study
area and each have their own distinctions and
particularities as how their forested lands are managed, as
well as the type of data available, a combination of
Fig. 1. Potential CHP locations and corresponding procurement areas in
the study area.
different methods is used to estimate the total available
supply of forest biomass for the entire province. These
annual potential harvests of forest biomass are then
allotted to the procurement area of each potential CHP
plants [18].
For the conversion of forest biomass to energy,
estimations of softwood and hardwood effective heating
values for all biomass components (softwood and
hardwood species), based on an average moisture content
of 50%, are taken from the FPInnovations FPJoule model
[23] and are presented in Table I. These heating values
represents what is commonly referred to as the effective
heating value (EHV) because they take into account the
amount of energy that is consumed during the
vaporization of water in the biomass [20].
TABLE
I
F
OREST BIOMASS EFFECTIVE HEATING VALUES
(
GREEN BIOMASS
)
Biomass components
Softwood
(MJ/kg)
Hardwood
(MJ/kg)
Merchantable wood
10.2
9.99
Residual biomass
10.3
9.99
Bark
10.3
9.81
R
ESULTS
Table II shows the results from the large scale
assessment of the forest biomass in the province of New
Brunswick, Canada. From Table II, it can be seen that
the total annual potential harvest of forest biomass is
approximately 15.5 Mt green weight (GT) at harvest for
the area of interest. Approximately 58% of the potential
harvest comes from softwood biomass (8.9 Mt GT),
while hardwood biomass accounts for the remaining 42%
(6.6 Mt GT).
For its part, Table III presents the total annual potential
electric and thermal energy for all procurement areas.
2013 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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