LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 2A: LAND USE 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
higher than for field lettuce systems. Figure 4 shows the combined impacts for the scenarios 1 and 2, illustrating
that scenario 1, greenfield housing with displaced lettuce production, has a GWP approximately 74 t
ha -1 higher than for scenario 2.
4. Discussion
Within the agricultural system at both farm and market levels, comparisons can be made both intra-region
and inter-region. The larger commercial field farm, LF4, although producing with better economies of scale,
exhibited only a marginally smaller GWP at farm level than local Sydney field farms, highlighting that
smaller farms can compare favourably with respect to environmental impacts (see Figure 3). For lettuce at
the Sydney market, supply chain activities (including road transport) impacted GWP most negatively for the
interstate farm, effectively reversing the order of the GWP impacts for the three field farms, resulting in LF4
having the higher GWP impact for lettuce at the Sydney market. The benefit of this method is that both field
and supply chain impacts have been assessed, with proximity to market having a positive impact on emissions
abatement. Emissions for LF3 were relatively high as a result of infrastructure requirements and electricity
demand, which in NSW is predominantly coal fired. Farm level data has illustrated that hydroponic
systems are not necessarily more environmentally friendly, however, if an alternate electricity mix were
available for which emissions could be significantly reduced, the hydroponic farm would see the most dramatic
benefits.
Avoiding the use of ‘average’ data obtained a more realistic analysis of environmental impacts. Preliminary
results are indicating dramatic reductions in global warming potential when farm-level data is used
compared to Australian average estimates. For example, results from this project are orders of magnitude less
than average estimates calculated for horticultural sectors, where farm gross margin data was used to make
GWP claims (O'Halloran et al., 2008). Confidence in the values reported in this project was assured by comparison
to contemporary lettuce LCAs (Marton et al., 2010; Milà i Canals et al., 2008). Even with truncation
errors of up to 87% reported as part of process LCA (Crawford 2011), the benefits of using local data over
use of averages are dramatic.
Collecting data for urban systems presented a greater challenge than collection from farms. Building LCA
literature was oriented to individual buildings or building components, with a lack of literature providing
detailed bills of quantities for the housing styles to be modelled or data on housing systems. Land preparation,
demolition, waste, infrastructure installation and revised bills of quantities will be included in a subsequent
phase of the project in order to improve authenticity and reduce uncertainty in the greenfield and infill
models. Although inter-farm differences in GWP of up to 25 percent were observed for field lettuce, GWP
impacts within the agricultural production systems proved less significant compared to the larger impacts of
the urban systems (Figure 3). With the urban system dominating impacts, the interstate farm LF4 would need
to demonstrate significant improvements in environmental impacts to trade-off against greenfield expansion,
which as shown in scenario 1, was not observed. This indicates that the region where lettuce is produced is
less relevant to overall GWP impacts than the urban housing model implemented. The focus becomes less on
how best to produce lettuce and more on how housing systems can be leveraged to support emissions abatement.
A further challenge within the method included the need to use European derived Ecoinvent data in SimaPro
due to absence of representative Australian processes. The electricity mix in European processes using
nuclear energy may give more conservative impacts than using energy from the dominantly coal fired
mix in Australia. Future work will include further data collection from regional locations, improving the
urban modelling and analysing the consequences of urbanising Sydney’s horticultural lands in a resource
constrained and climatically uncertain future. Applying time limits to future scenarios, by which time marginal
suppliers and technologies may have changed, is a further challenge for management.
5. Conclusion
The benefit of CLCA at the urban-agricultural intersection has been to provide a new perspective on periurban
land-use change. Scenarios for producing lettuce versus producing housing were evaluated for GWP.
Preliminary analysis for the two scenarios modelled has illustrated that, although differences were observed
within the agricultural system, it is the urban housing system dominating GWP impacts. Policy focus on
urban housing systems for greenhouse gas abatement in the regional context is recommended.
6. References
ABS 2010. Value of Agricultural Commodities Produced, Australia, 2008-09, 'Table 1 VACP - All Commodities - National, Australia',
data cube: excel spreadsheet, cat. no. 7503.0, (Data Cube All commodities, by Australia, State and Statistical Division).
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