Page 40 - Materials Chemistry, Second Edition

26 E. I. Wiloso and R. Heijungs

requiring inputs and producing outputs. The creation of fossil fuels is a sponta-
neous process without human intervention. The forestry is, thus, an activity that
should be included in the flow diagram of an LCA study, whereas the process of
fossil fuel formation should not (Guinée et al. 2009). Wegener Sleeswijk et al.
(1996), in their report on the application of LCA to agricultural products, propose
to not include biogenic carbon dioxide in the analysis if the entire life cycle is
being analyzed. If the study is based on cradle-to-gate analysis, carbon seques-
tration must either be included, or it must be explicitly stated that this fixation is
being excluded from the study. If this is not done, there is a danger that if other
researchers use the results of the study, they will include, say, the emission of CO 2
during combustion of biodiesel fuel, while fixation of CO 2 was omitted in the
cradle-to-gate analysis.
There is currently no consensus regarding how to treat biogenic carbon at the
policy level. The Intergovernmental Panel on Climate Change (IPCC) currently
considers biomass to be carbon neutral, suggested by the adoption of a stock-
change method rather than an input–output flow approach in carbon accounting
(Levasseur et al. 2012a). In this case, if biogenic carbon is released later in the life
cycle, CO 2 emissions are not accounted for to avoid double counting. As discussed
in Johnson (2009), a life cycle-based method such as the British specification PAS
2050 (BSI 2011) suggests the same approach as IPCC, not considering biogenic
carbon uptakes and emissions, while the International Reference Life Cycle Data
System ILCD (EC-JRC-IES 2010) recommends the opposite. Similar to PAS
2050, EU Directive (2009) also excludes the capture of CO 2 in the cultivation of
biomass and emissions from biofuel use from the calculation of GHG emissions by
setting their values equal to zero. The rationale behind these differences is the
argument that the combustion or decay of woody biomass is simply part of the
global cycle of biogenic carbon, and over a long period of time, it does not
increase the amount of carbon in circulation due to compensation by photosyn-
thetic processes. Meanwhile, in the conventional LCA practices, all flows
including carbon uptake and emissions should be accounted for in the inventory
stage without considering the time scale. To deal with this time frame issue,
Levasseur et al. (2012a) proposed to treat biogenic carbon as temporary storage
with dynamic LCA. The argument behind this approach is that the concentration of
CO 2 in the atmosphere is temporarily reduced and some radiative forcing is
avoided. This is favorable in the short term as it also allows ‘buying time,’ while
technology develops in the field of GHG emission reduction and mitigation (Le-
vasseur et al. 2012b).

3.4 Treatment of Multi-Functional Processes

Various forms of bioenergy products are ideally derived from feedstocks produced
with much lower life cycle GHG emissions than traditional fossil fuels and with
little or no competition with food production. According to Tilman et al. (2009),