Page 129 - Materials Chemistry, Second Edition

Life Cycle Assessment: Principles, Practice and Prospects
116

0.6 Wholesale Transport
Greenhouse emissions (kg CO 2 eq.) 0.4 sale of Transport Packaging to market
0.5

Corn chip production
0.3
Harvest,
crop
0.2
Growing
0.1
Sowing
0
$- $0.10 $0.20 $0.30 $0.40 $0.50 $0.60 $0.70
Costs in dollars

Figure 9.3 Cumulative greenhouse gas emissions and cost estimates for a 400 g packet of corn
chips (after Grant and Beer 2008).

pattern could be even more marked for other maize products where the post-farm activities
are less greenhouse intensive. For example, while in corn chip production 36% of greenhouse
gas emissions are attributable before the farm gate, for ethanol production from maize the
figure is 51%, and for starch production it is 58% (Fig. 9.3).
The study reveals important information for policy makers regarding on-farm emissions,
emissions beyond the farm gate, and the relationship between these two parts of the system of
corn chip production. On the farm, the pumping of water represents a significant energy use
and consequent greenhouse contribution, particularly if the water is being drawn from deep
bores – which may become a more prevalent practice with further water supply constraints.
The study suggests that pumping irrigation water from deep wells causes almost three times
more greenhouse gas emissions than irrigation using surface waters. Also, there appears to be
substantial potential to reduce emissions on-farm through stubble management, although soil
carbon and greenhouse gas emissions may also be influenced by other factors such as soil
tillage, fertiliser and crop rotation regimes (Follett 2001; West and Marland 2002; West and
Post 2002; Tilman et al. 2002; Duxbury 2005; Eckard 2006).
The substantial post-farm emissions indicate that there is also scope for exploring practical
mitigation options, particularly in relation to transport and packaging. Moreover, the clear
implication from the value chain results is that farming provides significant greenhouse gas
emissions but less value-added, and therefore limited ability to invest in, greenhouse reduction
innovations and practices. There would appear to be a prima facie case here for directing resources
towards these greenhouse-intensive but relatively cash-poor parts of the production chain.

9.6 Miles to market: the food miles debate
Fresh produce has been travelling further and further to market over recent decades. One
United Kingdom ((UK) study states that the amount of food moved by heavy goods vehicles
has risen by 23% since 1978, and the average distance for each trip has increased by over 50%

100804•Life Cycle Assessment 5pp.indd 116 17/02/09 12:46:22 PM