Consequences of the cultivation of energy crops for the global nitrogen cycle

Transcription

1 Hans van Grinsven, Lex Bouwman, Bas Eickhout, Edward Smeets, Gert-Jan van den Born, Mark van Oorschot, Jean-Paul Hettelingh, Jan Ros, Hans Eerens, Henk Westhoek Consequences of the cultivation of energy crops for the global nitrogen cycle work in progress

2 EU Policy targets renewables are ambitious primary energy use in Mtoe Renewables* 97 (5,8%) 210 (12%) (20%) - bioenergy - biofuel transport 69 (4,1%) (0,5%) 149 (8,3%) (5,75%) (13%) (10%) Which bioenergy? - Electricity - Heat - Transport * no import Van Grinsven Energy crops and global N cycle 2

3 Biomass potential by source (EU22) Potential share of energy crops in 2020 is 40% Van Grinsven Energy crops and global N cycle 3

4 Global and regional impacts are complex GHG land use economy nitrogen biodiversity balance CO2 N2O C-seq by N marginal cropland nature energy food security taxes protection fertilizer area runoff N-dep NH3 eutrophic NOx Deposition Criteria for sustainability? Van Grinsven Energy crops and global N cycle 4

5 Scenarios and models for N-impact analysis Two OECD Environment Outlook scenarios Global Cooperation for Environmental Policy (GC) Baseline Model: IMAGE 2.4 (Bouwman et al.) (Integrated Model for the Assessment of the Global Environment) spatially explicit land use and emission calculations See Bouwman et al. (2006) Integrated modelling of global environmental change. An overview of IMAGE 2.4) available from: noverviewofimage2.4.html Van Grinsven Energy crops and global N cycle 5

6 Storylines OECD scenarios Baseline Global Cooperation General Agriculture Climate policy Energy crops No new policies Minor Global cooperation on environment, land degradation, food security Liberalisation of production & trade (50% reduction 2030) Carbon tax OECD -2012, BRIC-2020, ROW st and 2 nd generation on abandoned & marginal soils Van Grinsven Energy crops and global N cycle 6

7 Biodiversity loss not driven by nitrogen Source: MNP-UNEP_WCMC 2006 GTAP-IMAGE-GLOBIO - model Van Grinsven Energy crops and global N cycle 7

8 Land use by energy crops 7000 Energy crops Cropland 6000 Grassland GC-scenario Baseline 14% of cropland Mha Mha Source: IMAGE 2.4 Van Grinsven Energy crops and global N cycle 8

9 Global yields of energy crops GC scenario First Second generation Pg Pg Southeast Asia Eastern Asia Eastern Asia Southern Asia Southern Asia West Asia West Asia Subsaharan Africa Subsaharan Africa North Africa and middle East North Latin America Africa and middle East Latin Industrialized America Industrialized : relative share 1 st & 2 nd : 70% 30% 2050: relative share 1 st & 2 nd : 30% 70% Van Grinsven Energy crops and global N cycle 9

10 Regions of energy crops in GC scenario Energy crops 268 Mha in 2050 (14% of cropland area) 1 st generation Latin America, Subsahar Africa SE Asia 2 nd generation also industrialised, N. America Van Grinsven Energy crops and global N cycle 10

11 Global implications GC for N-fertilizer use GC collaboration to reduce land degradation, to increase crop production and food security N-efficiency food crops Industrialized +20% +5% Countries with N-depletion: -20 to -200% -50% China, India +20% +10% Energy crops 1 st generation: kg/ha 2 nd generation: kg/ha (willow, switch grass, poplar) Van Grinsven Energy crops and global N cycle 11

12 Impacts for global use of nitrogen fertilizer N in Tg/yr Baseline +5% No net increase of Energy crops 2nd generation fertilizer use between Energy crops 1st generation baseline and GC Cropland % N-fertiliser of energy Grassland crop ~ % land use N in Tg/yr GC +13% Energy crops 2nd generation Energy crops 1st generation Cropland? No net effect of energy crops if constricted to marginal cropland 40 Grassland Source: IMAGE (Bouwman et al., 2006) Van Grinsven Energy crops and global N cycle 12

13 Impacts on nitrous oxide and ammonia kg N 2 O-N ha yr > 4.5 GC-2050 Contribution in 2050 of energy crops in GC scenario: +0.7 Tg N2O-N yr-1 (7.5%) Relatively low due to low application rates and poor soil conditions +2.2 Tg NH3-N yr-1 (4.6%) N2O model Bouwman et al. (2002) Glob. Biogeoch. Cycl. 16(4) doi: /2001gb Van 16(2) Grinsven Energy crops and global N cycle NH3 model Bouwman et al. (2002) Glob. Biogeoch. Cycl. doi:doi: /2000gb

14 Impacts on NOx - for EU Bioenergy as share of conventional reference LCA emissions by 2030 [% - deviation to reference] 125% 100% 75% 50% 25% 0% -25% -50% -75% -100% GHG emissions - CO2-eq. 100% exploit. - least cost 100% exploit. - least cost (b) PRIMES LCEP (2004) b=baseline (2005) Air GHG emissions SO2 NOx Particulate matter NOx increase 50%! combustion effect N-content in fuel effect application denox Van Grinsven Energy crops and global N cycle 14

15 Impact N2O on GHG balance for energy crops Energy crop Use Region GHG reduction Maize Gasoline North America 17 Maize Gasoline EU25 11 Sugar cane Gasoline South Africa 78 Sugar cane Gasoline South America 88 Sugar cane Gasoline South Asia 76 Sugar cane Gasoline Oceania 66 Rapeseed Diesel North America 18 Rapeseed Diesel EU25 30 Palm fruit Diesel South America 56 Palm fruit Diesel Africa 39 Palm fruit Diesel South East Asia 59 Source: Smeets, Bouwman and Stehfest, in prep. Robust GHG savers N 2 O crucial for GHG balance Van Grinsven Energy crops and global N cycle 15

16 Conclusions global nitrogen cycle Large amounts of N (and also P) fertilizers are needed for future production of 1 st and 2 nd generation energy crops on marginal soils In GC scenario 13% of N fertilizer use in 2050 Associated N 2 O emission is 7.5% and NH 3 4.6% N 2 O emissions remove the GWP saving effect of some crops (a.o. maize-gasoline and rapeseed-diesel) Additional NOx from production and use of biofuels is substantial and needs more attention Need more integrated approach to translate various N-impacts to global biodiversity impacts N-deposition, N-runoff; terrestrial and aquatic Biodiversity impact of climate Van Grinsven Energy crops and global N cycle 16

17 Conclusions sustainability of energy crops Regional and global impacts and trade-offs of energy crops are multiple and complex nitrogen is only one aspect, probably not the most important Sound criteria for sustainability are demanded but do we go for Complex: full blast LCA and CBA Simple: land-water-food-(biodiversity) > energy Intermediate: relative GWP potential versus eutrophication potential (Miller et al., 2007) Van Grinsven Energy crops and global N cycle 17