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

PARALLEL SESSION 3A: LAND USE CHANGE 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
ever, the different assumptions made regarding marginal energy and crop decreased or increased the magnitude
of the impacts or savings in all scenarios. In the case of mono-digestion, GW impacts were significantly
increased as compared to their levels in the co-digestion scenarios (increase between 112 and 150 t CO2-eq.
ha -1 ), reflecting the tremendous benefits obtained when avoiding storage and application of raw manure. The
sensitivity analysis also demonstrated that additional pelletisation and milling of the biomass in the co-firing
scenarios would decrease the GW performance of these scenarios to a level very close to direct biomass
combustion. The results of the MonteCarlo simulation for GW supported the ranking of the bioenergy scenarios
found with the baseline scenarios, demonstrating that despite of the significant uncertainties, the results
obtained were robust.
Table 1. Characterised results for the selected environmental impact categories
Crop Ryegrass Willow Miscanthus
BtE technologies a AD GA CO CF AD GA CO CF AD GA CO CF
Global Warming (kg CO2 eq/ha of perennial crop)
dLUC -167 -167 -167 -167 -249 -249 -249 -249 -211 -211 -211 -211
iLUC 309 309 309 309 309 309 309 309 309 309 309 309
Crop pre-treatment 118 118 118 118 46 28 28 28 42 24 24 27
Energy production 305 343 351 351 316 426 440 440 252 322 336 335
Energy substitution -408 -339 -416 -482 -448 -433 -521 -612 -355 -330 -432 -504
Use on land (digestate) 248 0 0 0 371 0 0 0 278 0 0 0
Raw manure management b
-155 0 0 0 -286 0 0 0 -222 0 0 0
Other 18 2 2 2 32 2 2 2 29 1 2 -1
Net c
268 266 197 131 91 83 9 -82 123 115 28 -45
Aquatic Eutrophication (N) (kg N/ha of perennial crop)
dLUC 434 434 434 434 -569 -569 -569 -569 -550 -550 -550 -550
iLUC 0 0 0 0 0 0 0 0 0 0 0 0
Crop pre-treatment 3 0 0 0 2 0,08 0,08 0,08 2 0,06 0,06 0,06
Energy production 59 43 41 41 63 52 34 34 50 41 54 43
Energy substitution -35 -29 -34 -41 -38 -36 -43 -52 -29 -28 -35 -43
Use on land (digestate) 2960 0 0 0 2840 0 0 0 2130 0 0 0
Raw manure management b
-1251 0 0 0 -2300 0 0 0 -1801 0 0 0
Other 40 4 3 4 38 0,9 0,9 1 28 0,9 1 0,5
Net c
2210 452 444 438 36,3 -552 -577 -586 -170 -536 -530 -550
Aquatic Eutrophication (P) (kg P/ha of perennial crop)
dLUC -10 -10 -10 -10 -2 -2 -2 -2 -3 -3 -3 -3
iLUC 0 0 0 0 0 0 0 0 0 0 0 0
Crop pre-treatment 0 0 0 0 0 0 0 0 0 0,07 0 0
Energy production 0,01 0,4 0,02 0,03 0,01 0,3 0,03 0,03 0,03 0,3 0,03 0,03
Energy substitution -0,2 -0,2 -0,3 -0,4 -0,2 -0,3 -0,4 -0,4 -0,2 -0,2 -0,3 -0,4
UOL (digestate) 98 0 0 0 99 0 0 0 115 0 0 0
Raw manure management b
11 0 0 0 5 0 0 0 8 0 0 0
Other -17 0,1 0,1 0,2 -17 0,1 0,1 0,1 -17 -4 -3 -3
Net c
82 -9 -10 -10 85 -2 -2 -2 103 -6 -7 -7
P as a ressource (kg P/ha of perennial crop)
dLUC -157 -157 -157 -157 48 48 48 48 0 0 0 0
iLUC 0 0 0 0 0 0 0 0 0 0 0 0
Crop pre-treatment 0 0 0 0 0 0 0 0 0 0 0 0
Energy production 0 0 0 0 0 0 0 0 0 0 0 0
Energy substitution 0 0 0 0 0 0 0 0 0 0 0 0
UOL (digestate) 0 0 0 0 0 0 0 0 0 0 0 0
Raw manure management b
560 0 0 0 550 0 0 0 556 0 0 0
Other -515 -1 0 0 -524 -1 -1 -1 -519 0 0 0
Net c
-112 -158 -158 -158 74 47 47 47 36 0 0 0
a
AD: Anaerobic digestion; GA: Gasification; CO: Combustion; CF: Co-firing.
b
Raw manure storage (avoided), application on land (avoided) and fertilisers (induced) because the raw manure is no longer a fertiliser.
c Eventual inconsistencies due to rounding.
4. Conclusion
Overall, co-firing of Miscanthus and willow were the options presenting the best environmental performances.
These performances can probably be increased in the future as yields for these crops undergo
further research and development, especially Miscanthus, a C4 crop. It should however be realised that a
main driver for future utilisation of biomass may be to balance electricity generation from fluctuating energy
sources, such as wind and solar power. Not all biomass combustion technologies may be suited for this, especially
when co-generation of heat is important, as such plants can have a fixed production ratio between
electricity and heat. Anaerobic co-digestion as well as gasification of biomass, on the other hand, may be
operated more flexible without similar constraints. Additionally, syngas or biogas offers the flexibility of
storage. On this basis, improving the environmental performance of these BtE conversion technologies
would be desirable. For anaerobic co-digestion, a solution may be to favour manure-based biogas together
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