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

GROUP 2, SESSION A: CARBON OR WATER FOOTPRINTS, SOIL, BIODIVERSITY 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
55. Using LCA to inform policy for biochar in New Zealand
Ruy Anaya de la Rosa 1 , Sarah J. McLaren 1,2,* , Jim Jones 1 , Ralph Sims 1
1 Massey University, Palmerston North, New Zealand, 2 New Zealand Life Cycle Management Centre, New
Zealand, Corresponding author. E-mail: S.McLaren@massey.ac.nz
Biochar is carbonised biomass; the focus of this study is biochar obtained from sustainable sources and sequestered
in soils to sustainably enhance their agricultural and environmental value under present and future
management. Biochar has attracted international attention as a carbon sequestration strategy since it can take
hundreds or thousands of years to decompose. Moreover, biochar offers opportunities in the energy, soil
management, and end-of-life biomass (ELB) recycling sectors.
The quantity of ELB feedstocks in New Zealand that could potentially be used to produce biochar was assessed.
In a highly optimistic scenario in which 80% of the available ELB is sourced to make biochar, over 1
million tonnes of CO2 could potentially be sequestered every year. This translates to about 1.5% of NZ’s
total greenhouse gas emissions (based on 2009 data). Although this percentage is small, the relative contribution
of using biochar on net greenhouse gas emissions may be much more significant when considering
products in particular economic sectors from a life cycle perspective e.g., in determining the carbon footprint
of agricultural products.
Although a number of biochar systems have been evaluated from a life cycle perspective, only two studies
(Roberts et al. 2010; Hammond et al., 2010) and one life cycle inventory analysis (Kameyama et al., 2010)
seem to have followed LCA methodology – and they all focus on just one impact category (climate change).
Also, one LCA study of ethanol produced from a hectare of corn includes stover-derived biochar in the
analysis (Kauffman et al., 2011). Using an LCA approach, the methodological issues concern the goal, scope
and decision-context of the study; functional unit; multiple functions; system boundaries and allocation;
choice of impact categories; indirect consequences; and reference scenario with which the biochar system is
compared. At the forefront of these variables, it is not clear when and how to conduct attributional versus
consequential LCA, and so results can vary considerably.
Therefore, particularly when considering future policy options to encourage or discourage production and
use of biochar, it is important to carefully consider the different variables and their influence on the final
results of an LCA study of biochar. This paper presents the results of a life cycle study on three different
future management options for the woody ELB from apple orchards in the Hawke’s Bay region in NZ undertaken
with the goal of informing stakeholders and policy makers on the best use of biomass to mitigate climate
change. Three different scenarios are compared: i) reference scenario, in which the woody ELB is
mulched and left on orchard soils; ii) energy scenario, in which the ELB is used for energy generation; and
iii) biochar scenario, in which the ELB is used for biochar production and application into the same area. The
results show that the fuller trade-offs associated with alternative end uses of biomass need to be explored
using a more complete system expansion perspective and representation of alternatives.
References
Hammond, J., Shackley, S., Sohi, S., Brownsort, P., 2011. Prospective life cycle carbon abatement for pyrolysis
biochar systems in the UK. Energy Policy, 39, 2646-2655.
Kameyama, K., Shinogi, Y., Miyamoto, T., Agarie, K., 2010. Estimation of net carbon sequestration potential
with farmland application of bagasse charcoal: life cycle inventory analysis through a pilot sugarcane
bagasse carbonisation plant. Aust. J Soil Res.,48, 586-592.
Kauffman, N., Hayes, D., Brown, B., 2011. A life cycle assessment of advanced biofuel production from a
hectare of corn. Fuel, 90,3306-3314.
Roberts, K.G., Gloy, B.A., Joseph, S., Scott, N.R., & Lehmann, J., 2010. Life Cycle Assessment of biochar
systems: estimating the energetic, economic, and climate change potential. Environ. Sci. Tech., 44, 827-
833.
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