Does Biochar Deliver Carbon- Negative Energy?

Transcription

1 Does Biochar Deliver Carbon- Negative Energy? Johannes Lehmann Department of Crop and Soil Sciences Cornell University

2 Terra Preta de Indio normal soil J. Major, 23 normal soil Terra Preta Terra Preta 5 to 8, years BP (Central Amazon, Brazil)

3 The Discovery of Terra Preta

4 What is biochar? Complete chemical change during heating in absence of air (pyrolysis) Knicker, 27, Biogeochem 85, Schmidt and Noak, 2, Global Biogeochem Cycles 14,

5 Natural Occurrence

6 Natural Biochar Abundance in Soils 35 3 Number of soils (% of all tested soils) Average 2% (n=452) NSA Lead Profiles QLD Transect DWN Transect Major Australian Cities Katherine Daly Waters 34Gt SOC (-1m) (Grace et al., 26, Carbon Balance and Management 1,14) Black Carbon (% of total organic C) NSA (N=58) DWN (N=28) QLD (N=114) 2% 7Gt.1Gt CE /yr fossil fuel (Department of Climate Care, 28) Lehmann et al, 28, Nature Geoscience 1,

7 Biochar Abundance in World Soils Krull et al, 28, in: Nova Sci Publ (World Soils Archive of ISRIC)

8 Biochar System Core Principles Lehmann, 27, Frontiers in Ecology and the Environment 7,

9 Biochar System Core Principles 75% mass loss 4-55% carbon BIOMASS Pyrolysis 5% carbon loss 75-9% carbon BIOCHAR Lehmann, 29, Springer

10 Biochar System Core Principles Cellulose, Lignin etc. Amorphous Carbon Turbostratic Carbon H H OH OH H OH O O H H H H OH H OH OH O OH H OH n H 2 O HO O O OH OH CH 2 O O OH OH OH CO, CO 2, CH 4 volatile organics O OH O OH O OH O HO HO O + CH 3 HO O OH O HO OH OH CH + O O OH Relative Proportion O/C H/C Temperature ~2 C ~4 C ~6 C Pyrolysis Intensity Lehmann et al., 21, forthcoming

11 Biochar Stability and Stabilization Mechanisms

12 Biochar Stability and Stabilization Chemical stability + particulate nature (a) (b) 1 μm (c) (d) Total Carbon Black Carbon Lehmann et al, 29, in: Earthscan Publ Lehmann et al, 28, Nature Geoscience 1,

13 Biochar Stability and Stabilization Biochar Saturation (Six et al, 22, Plant and Soil 241: ) C in Soil Ordinary organic matter (plant residues, manures, compost) C Input

14 Biochar Stability C mineralization [mg CO 2 -C g -1 C] Mean residence time of 435 yrs at 1 C MAT HAT ACU DS Open = Adjacent soil Filled = Anthrosol LSD=.5 BC-poor soils BC-rich soils (Terra Preta Central Amazon Defined period of BC accumulation) Days Liang et al., 28, Geochimica et Cosmochimica Acta 72, (N=3; BC age ranges from 8 to 7, years)

15 Biochar Stability (a) ME Non-BC Soils (b) NY Biochar from hardwood in storage areas for historical pig iron production (13 years old) MRT of 1335 yrs at 1 C MAT Carbon Dioxide Evolution (mg CO 2 -C/gC) (c) PA (e) TN (g) AL BC Soils BC-containing soil Adjacent soil (d) OH (f) GA Days Cheng et al., 28, Journal of Geophysical Research, 113, G227

16 Biochar Stability 4 Inceptisols (Northern Territory, Australia) 13 and 15 profiles 27 C MAT, 887 mm MAP Grass vegetation under varying assumptions of burning severity and BC formation Model run to equilibrium (for BC MRT to 1m) Soil carbon (Mg ha -1.3m -1 ) MRT of 13 and 26 yrs ( ) at 28 C MAT modelled No BC formation BC formation but no BC disappearance BC formation with fitted BC disappearance measured BC non- BC Time Lehmann et al, 28, Nature Geoscience 1,

17 Biochar Stability MRT of 2 years Incubation period (days) (ryegrass biochar, n=4) Kuzyakov et al., 29, Soil Biol. Biochem 41,

18 Biochar Quality, Biochar Stability A (corn-35-bc) B (corn-6-bc) Carbon loss rate (% year -1 ) a b 35 C 6 C b b 5 nm 5 nm Corn-BC Oak-BC (1 year, 3 C, in sand culture, N=8) Nguyen and Lehmann, 29, Organic Geochemistry 4, Nguyen et al., 21, Environmental Science and Technology 44,

19 Biochar Decomposition Abiotic degradation Biochar production and application to soil Biotic decomposition of labile biochar fraction Biotic decomposition of stable biochar fraction Erosion Leaching/eluviation Bio-/pedoturbation Recalcitrance Protection by aggregation Interactions with mineral and organic matter Stability Mechanisms Decay/Transport Mechanisms Time Lehmann et al., 29, in: Earthscan Publ

20 Biochar Decomposition 1 Carbon remaining (% of initial) years 5 years 1 years 5 years 1 years MRT Time (years) Lehmann et al., 29, in: Earthscan Publ

21 Global Potential for Emission Reductions and Carbon Sequestration Annual Application and Mineralization (fraction per year) Application Years 1 1, Annual Application and Net Sequestration (fraction per year) MRT Proportion of labile C (MRT of 2 yrs) 5 Application Years 5 1 1, Half of total adoption within 3 years and 9% within 5 years Lehmann et al, 21, in: Imperial College Press, forthcoming

22 Biochar Effects on non-co 2 Greenhouse Gases

23 Effects of Biochar on Nitrous Oxide N 2 O: Up to 73% reduction Alfisol Vertisol Bhupanderpal-Singh et al., 21, JEQ published online

24 Biochar Soil Improvement

25 Biochar Soil Improvement Cation Exchange Capacity (mmol c kg -1 ) DS ACU LG HAT Other Anthrosols (Sombroek et al., 1993) Biochar-rich Anthrosols soils r 2 =.784 CEC=8.6C Organic Carbon (mg g -1 ) Biochar-poor soils Adjacent Soils r 2 =.99 CEC=2.81C+9.1 Liang et al., 26, Soil Sci. Soc. Am. J. 7:

26 Biochar Product Carbon recovery (% of initial C) ph Carbon recovery Optimum Temperature ( C) Lehmann, 27, Frontiers in Ecology and the Environment 7, Surface area CEC ph CEC (mmol c kg -1 ) Surface area (m 2 g -1 ) Biochar from black locust (N=3)

27 Biochar Oxidation New-BC HF Negative charge Positive charge <2 >7 5 New-BC GW Point of zero net charge (PZNC) 13-year-old Biochar (from pig iron production) in comparison to biochar made with traditional kilns Cheng, Lehmann, Engelhard, 28, Geochim Cosmochim Acta, 72, Surface charge (mmole kg C -1 ) BC-HA BC7 NY ph BC3 QC CT >2 <3

28 Nutrient Retention Nutrient amount (kg ha -1 ) 6 Crop uptake Ca Leaching by saturated flow 4 Leaching by unsaturated flow B a B a K A b A b A Mg b a NO 3 + NH 4 * A A B a b 2 Improved nutrient uptake and crop yield Biochar applied once Total over 2 years Colombia (n=3) Biochar application rate (t ha -1 ) Biochar application rate (t ha -1 ) Major, PhD thesis

29 Temporal Variation in Yield Response Maize grain yield (t*ha -1 ) Control No biochar 8 t * ha -1 a 2 t * ha -1 a ab a b a a a b a b c t/ha biochar Applied once in 23 Colombian Llanos (N=3) 2t/ha biochar Year Major et al., 21, Plant and Soil, published online

30 Soil Fertility Benefits Dependent on Soil Properties 12 1 Biochar Sawdust Manure Tithonia LSD.5 Maize grain yield (t ha -1 ) Biochar applied each season Kenya (n=3) Time since conversion (years) Kimetu et al., 28, Ecosystems 11:

31 Soil Biology Ogawa

32 Biochar System Core Principle Mitigation of Climate Change Waste Management Energy Production Soil Improvement Social, Financial Benefits Lehmann and Joseph, 29, Earthscan

33 Biochar System Lehmann, 27, Nature 447:

34 Systems Analysis: Energy Balance Energy balance (MJ/MJ), Slow pyrolysis Switchgrass Forage corn Corn stover (crop residue) Wheat straw Biochar to energy Biochar to soil Gaunt and Lehmann, 28, Environmental Science and Technology 42:

35 Systems Analysis: Emission Balance Avoided Emissions (kg CO 2 /ha/yr), Slow pyrolysis Biochar to energy Biochar to soil Bioenergy crops ,551-18,595 Crop residues ,833 Gaunt and Lehmann, 28, Environmental Science and Technology 42:

36 Systems Analysis: Life Cycle Assessment System boundaries Fossil fuels production Pyrolysis facility Electricity production Heat exhaust T Biomass collection Shredding Drying Slow pyrolysis T Farm equipment, agrochemicals (a) T (-) T (-) Biochar Syngas heat product Construction Natural gas production Compost materials & combustion T Soil application T (-) Fertilizers Roberts et al, 21, Environmental Science and Technology 44,

37 Systems Analysis: Life Cycle Assessment (b) Greenhouse gases (kg CO 2 e t -1 dry feedstock) Late stover Early stover Switch grass A Switch grass B Yard waste emit. reduct. emit. reduct. emit. reduct. emit. reduct. emit. reduct. Net = Net = Net = Net = + 36 Net = LUC & field emiss. agrochems field ops other stable C avoid foss fuel gen. & comb. land-use seq. reduced soil N2O emiss. avoid compost Roberts et al, 21, Environmental Science and Technology 44,

38 Systems Analysis: Sensitivity Analysis Stover collection energy sensitivity Energy per tonne collected (MJ) (baseline) 833 Net energy (MJ) % change 1% % -2% Stover collection emissions sensitivity Emissions per tonne collected (kg (baseline) 76 CO 2 e) Net CO 2 e (kg) % change 12% % -2% Late Stover Slow pyrolysis (1-1t/hr) Roberts et al, 21, Environmental Science and Technology 44,

39 Systems Analysis: Sensitivity Analysis Char yield sensitivity Char yield input 12 wt % 28.8 wt % (baseline) 35 wt % Net CO 2 e (kg) % change -13% % 1% Stable C sensitivity Stable C content of biochar % 5% 8% (baseline) 9% Net CO 2 e (kg) % change -68% -26% % 9% Late Stover Slow pyrolysis (1-1t/hr) Roberts et al, 21, Environmental Science and Technology 44,

40 Systems Analysis: Sensitivity Analysis Syngas energy sensitivity 5% of Energy yield input baseline (baseline) 15% of baseline Net energy (MJ) % change -63% % 63% Net CO 2 e (kg) % change -19% % 19% Late Stover Slow pyrolysis (1-1t/hr) Roberts et al, 21, Environmental Science and Technology 44,

41 Costs - transportation 6 6 (b) Net GHG (kg CO 2 e t -1 dry stover) Net revenue Net energy Net GHG Net energy (MJ t -1 dry stover) Revenue ($ t -1 dry stover) Late stover, high C price Slow pyrolysis (1-1 tons/hr capacity) Distance (km) Roberts et al, 21, Environmental Science and Technology 44,

42 Co-Benefits: Waste Stream Management Case Study West-Virginia West Virginia Poultry Farm 99, chickens t/yr poultry litter Pyrolysis of 3 kg/hr dry litter (at 5 C) Off-sets 114,L propane gas US$66, /yr t/yr biochar

43 Biochar Cook Stoves Torres

44 Small-scale Bioenergy Traditional 3 Stone Stove Biochar Cook Stove Whitman and Lehmann, 29, Environmental Science and Policy 12,

45 Co-Benefits: Health Lower indoor pollution=lower respiratory + eye infections Torres

46 Costs Carbon Trading Aspects Relatively easy counting Proof of source possible Low risk of rapid evasion Paraguay

47 Biochar Benefits Systems Dimension Mitigation of Climate Change Waste Management Energy Production Soil Improvement Social, Financial Benefits

48 Biochar Benefits Systems Dimension Mitigation of Climate Change Waste Management Energy Production Soil Improvement Social, Financial Benefits

49 Biochar Benefits Systems Dimension Mitigation of Climate Change Waste Management Energy Production Soil Improvement Social, Financial Benefits

50 Biochar Benefits Systems Dimension Mitigation of Climate Change Waste Management Energy Production Soil Improvement Social, Financial Benefits

51 Biochar The Way Forward Not WHETHER, but WHERE