Environmental Engineering Reference
In-Depth Information
taBle 8.2
comparison of Biodiesel and hrd energy requirements and GhG emissions
Petroleum
diesel
sBo
Biodiesel
rso
Biodiesel
tallow
Biodiesel
tallow
Gd
sBo Gd
rso Gd
FED, MJ/MJ
1.25
0.41
0.34
0.41
0.37
0.24
0.11
CED, MJ/MJ
1.27
1.53
1.42
1.88
1.82
1.26
1.14
GHG gCO
2
-eq/MJ
85
48
40
46
41
17
6
SBO, soybean oil; RSO, rapeseed oil; GD, HRD from UOP/ENI ecofining process.
Three renewable feedstocks are considered in Table 8.2: soybean oil, rapeseed oil, and tallow.
It can be seen that plant-derived fuels exhibit a higher CED and lower FED when compared with
petroleum diesel. The higher CED is due to the additional energy required to cultivate, harvest, and
transport the feedstock. Because carbon dioxide (CO
2
) generated in the combustion of biomass-
derived fuel is considered carbon neutral, their FED and GHG emissions are significantly lower than
petroleum diesel for all of the biofuels. For tallow, a waste material derived from meat production,
the CED is lower than that for petroleum diesel. As a waste, this feedstock is free of the upstream
energy burdens assigned to the primary meat product.
It is important to note that land-use change (LUC) effects are not included in the GHG emissions
shown in Table 8.2. Although LUC GHG impacts can be negative or positive, depending on the prior
condition of the land, controversial indirect land-use change (ILUC) impacts often consider a worst-
case scenario in which food crop conversion to energy crop production leads to rainforest destruction.
Long-term concerns associated with diverting food crops to fuel production or carbon-rich forests to
cultivated land has shifted the commercial focus away from first-generation feedstocks like soybean
and rapeseed oil and toward next-generation (inedible) oils such as jatropha and camelina, which
can be intercropped, grown on marginal land, or grown as a rotation crop (Shonnard et al. 2009).
Ultimately, algae could become the major source of TAG-rich feedstock for biofuel production.
8.2.3 c
urrEnt
S
tatE
oil;
c
ommErcialization
The production of biodiesel is widespread, with most of the existing production capacity located in
Europe, mainly Germany and France. In 2007, total world biodiesel production was approximately
5-6 million tons, with 4.9 million tons processed in Europe (of which 2.7 million tons was
from Germany) and most of the rest from the United States (NBB 2008). For comparison, total
world production of vegetable oil for all purposes in 2005-2006 was approximately 110 million
tons, with approximately 34 million tons each of palm oil and soybean oil (FEDIOL 2008). A
significant increase in the production of biodiesel is expected over the next few years in South
America. Table 8.3 provides an estimate of existing and future biodiesel capacity in countries
with large production rates (Thurmond 2008).
There are numerous biodiesel technology providers, and the required process scheme is strongly
dependent upon feedstock properties. Special pretreatment or acid-catalyzed esterification is
required for feeds (such as tallow) containing significant amounts of FFAs.
Although not as widespread, hydroprocessing for the production of renewable transportation
fuels is also a commercial technology practiced in existing petroleum refineries. Several commercial
facilities for HRD production are in operation or in latter stages of design and construction. These
include the NExBTL process (Neste Oy), Synfining process (Syntroleum), and Co-processing
(Petrobras and ConocoPhillips) as well as the UOP/ENI Ecofining and UOP Renewable Jet Fuel
process. Table 8.4 provides a partial summary of feedstocks, plant locations, production capacity,
and approximate startup date. Over 800 million gallons/year (~3 million tons) of production capacity
is expected to be on stream before 2012.
