Environmental Engineering Reference
In-Depth Information
Table 5 reports the prices of the products for the allocation based on economic values.
Table 5. List of prices of biorefinery products to be used in the
allocation procedure based on economic values.
Product
Unit
Price
Transportation (bioethanol)
a
$/kg
1.34
Transportation (MTHF)
a
$/kg
1.31
Furan resins
b
$/ton
3555
FUMA
c
$/ton
1278
Electricity
d
$/GJ
27.78
Heat
e
$/GJ
9.29
Biomethane
f
$/GJ
9.29
H
2
g
$/GJ
35.09
O
2
f
$/kg
8.93
a
Calculated on the basis of gasoline price in the US (1.06 $/L)
b
New chemical commodity, price in market not available. Estimate on the basis of the price of epoxy
resins
c
The price is referred to low grade fumaric acid
d
Average electricity price for households in the US
e
Price based on energy content of replaced natural gas
f
Average price natural gas for households in the US
g
Average estimated price of H
2
in future markets (Ducharme et al., 2005)
f
Average O
2
price for laboratories
The first impact category refers to all the GHG emissions released for feedstock production,
transport, conversion processes, provision of auxiliary materials and final use of the products.
These emissions are accounted for and converted to g CO
2
-eq. with equivalency factors. The
analysis considers three long lived GHGs released by human activities: CO
2
, CH
4
and N
2
O.
Their effect on global warming can be assessed by an index called Global Warming Potential
(GWP), which is a measure of how much a given mass of GHG contributes to global
warming relative to a reference gas (usually CO
2
) for which GWP is set to 1. For a 100-year
time horizon, GWPs of CO
2
, CH
4
and N
2
O are, respectively, 1, 25 and 298 g CO
2
-eq./g
emission
(IPCC, 2007). Using this index, one can calculate the equivalent CO
2
emission by multiplying
the emission of a GHG by its GWP.
Similarly, the cumulative primary energy demand accounts for all the life cycle stages,
from feedstock provision to final use of products. The primary energy demand is divided into
fossil, renewable and other energy demand. The same impact categories are evaluated for the
fossil reference system as well, with the intent to make comparisons and quantify savings.
In order to gain information concerning performances and conversion efficiencies of the
biorefinery system, the mass, energy, exergy and carbon efficiencies are carried out through
the whole biorefinery conversion chain. The C content of the different feedstock components
and final products are estimated and the C balance of the system calculated according to the
methodology depicted in (Cherubini and Jungmeier, 2008), while the exergy contents of the
molecules are derived from (Ayres et al., 1996).
