Improving Carbon Sequestration of Biochar through Biomass Chemical Modification

Transcription

1 Improving Carbon Sequestration of Biochar through Biomass Chemical Modification Wei Zheng Ling Zhao Nancy Holm Illinois SustainableTechnology Center, University of Illinois, Champaign, IL 2014 Midwest Biochar Conference August 8, 2014 Champaign, IL

2 Global Climate Change & Global Warming Climate change is primarily resulted from: Natural causes such as changes in Earth's orbit, changes in solar activity, or volcanic eruptions. Human activities

3 Climate Change & Global Warming Recent studies indicate that human activities are very likely to explain most observed global warming, especially warming since the mid-20th century. Global warming is believed that it is caused from the large emissions of greenhouse gases, primarily from CO 2. Climate change will change our life on Earth and will affect all living beings on Earth.

4 Proofs for Climate Change & Global Warming Too much rain too fast: Champaign got roughly 4 to 6 inches of rain in few short hours. This is the worst rainfall on record for the city since 1993

5 Proofs for Climate Change & Global Warming global average temperature increases with increasing atmospheric CO 2 concentrations Global atmospheric concentration of CO 2 (since industrial revolution)

6 Carbon Sequestration Geological CO 2 Storage vs Biochar Do we need go so deep?

7 What is Different Between Biochar and Other Carbons? Biochar is a carbon-enriched and porous material produced from a variety of biomass. Biochar is similar in its appearance to charcoal, char, activated carbon, and other black carbon materials. The difference of biochar and carbon-rich materials: Biochar is produced with the intent to deliberately apply to soil to: Sequester carbon Improve soil quality

8 How Biochar Sequester Atmospheric Carbon? Because biochar is very recalcitrant to microbial decomposition and mineralization, it may persist in soil for millennia. The natural carbon cycle is neutral. If we use pyrolysis to produce biochar from waste biomass, we can lock up 50% biomass carbon into biochar. Considering biochar removes circulating CO 2 from the atmosphere and stores it into soils for a long term, the net process is carbon negative. Therefore, biochar production from waste biomass and its application into soils has a great potential to alleviate global warming.

9 Carbon Footprint Analysis Schematics for biomass or biochar remaining after charring and decomposition in soil. (A) C remaining from biomass decomposition after 100 years from IPCC; C remaining after charring or pyrolysis; bio-char C remaining after decomposition. (B) range of biomass C remaining after decomposition of crop residues and estimation of bio-char. From: Lehmann et al in Mitigation and Adaptation Strategies for Global Change

10 Idea for Improving Carbon Retention in Biomass Pyrolysis Six P-rich chemicals or passivator-like materials were chosen as chemical additives in this study: triple superphosphate (TSP), phosphate rock tailing (PRT), bonemeal (BM), clay, H 3 PO 4, and H 3 BO 3.

11 Effect of Chemical Additives on Carbon Retention 80 Biochars from sawdust Remanent C after pyrolysis (%) sawdust BC saw BC saw -TSP BC saw -PRT BC saw -Clay BC saw -BM BC saw -H 3 PO 4 BC saw -H 3 BO 3

12 Effect of Chemical Additives on Carbon Retention 80 Biochars from switchgrass Remanent C after pyrolysis (%) switchgrass -TSP -PRT -Clay -BM -H 3 PO 4 -H 3 BO 3

13 Triple Superphosphate (TSP) Triple superphosphate (TSP) is P-containing fertilizer. Also, it is an environmentally friendly and low-cost chemical additive. Thus, TSP was chosen as a preferred additive for the following studies. TSP is produced from phosphate rock.

14 Effect of Pyrolysis Systems on Carbon Retention 80 Carbon Retention (%) Linear pyrolysis (S) 40 Gradient pyrolysis BC saw -F BC saw -S BC saw -TSP-F BC saw -TSP-S -F -S -TSP-F -TSP-S (F)

15 Interaction Mechanism between TSP and Biomass During Pyrolysis Intensity (a.u.) P 2p Unmodified biochar ev ev C-O-PO ev ev TSP modified biochar Binding energy (ev) XPS spectra of P 2p X-ray photoelectron spectroscopy (XPS) The appearance of the peak at ~135.0 ev in TSP modified biochar is attributed to the formation of the C-O-PO 3 chemical bond.

16 Interaction Mechanism between TSP and Biomass During Pyrolysis C-P X-ray diffractometer (XRD) TSP-BC PRT-BC H 3 BO 4 -BC H 3 PO 3 -BC BC A new peak at 2θ o =26.6 which corresponds to the C-P chemical bond was observed in all P-chemical modified biochars

17 Stability of Remaining Carbon Schematics for biomass or biochar remaining after charring and decomposition in soil. (A) C remaining from biomass decomposition after 100 years from IPCC; C remaining after charring or pyrolysis; bio-char C remaining after decomposition. (B) range of biomass C remaining after decomposition of crop residues and estimation of bio-char. From: Lehmann et al in Mitigation and Adaptation Strategies for Global Change

18 Assess Biochar Thermochemical Stability by TGA 100 Weight loss (%) TSP-F -TSP-S Biochars from switchgrass -S -F Temperature ( o C) TGA in N 2 The biochar TGA analysis under N 2 reflects its thermal stability Weight loss (%) Temperature ( o C) TSP TGA in N 2 The results show that the different mass loss between TSP-modified and unmodified biochars derives from this chemical additive loss, suggesting that sequestered carbon in TSP-modified and unmodified biochars have similar thermal stabilities.

19 Assess Biochar Thermochemical Stability by TGA Weight loss (%) Biochars from switchgrass TGA in Air -S -TSP-S -TSP-F -F Compared to biochars produced from biomass only, TSP-modified biochars need much higher temperatures for decomposition, suggesting the TSPaddition could increase biochar oxidation stability Temperature ( o C) The biochar TGA analysis under air reflects its oxidation stability

20 Biological Mineralization of TSP-Modified Biochar in Soil mg CO 2 -C g -1 (Soil + Biochar) Soil Soil+ -F Soil+ -S Soil+ -TSP-F Soil+ -TSP-S Biochars from switchgrass Time (d)

21 Carbon Footprint Analysis of Biochar The cumulative amounts of CO 2 that evolved during the incubation period from biochar amended soils were calculated according to a double exponential model: CO 2 C = C 1 1 e k 1t + C 2 (1 e k 2t ) Where CO 2 -C is the cumulative C emitted as CO 2 while C 1 and C 2 are the sizes of the stable and labile C compartments, respectively. k 1 and k 2 are corresponding CO 2 emission rates while t is time.

22 Carbon Footprint Analysis of Biochar Initial C in biomass 100% Input into soil directly Final C after several years 0-10% Pyrolysis TSP-modified biochar Input into soil 60~65% 100% 50% 40-45% Energy input Energy output 40~45% Pyrolysis Input into soil 100% Chemical 100% 70% 60-65% treatment Energy input Energy <10% output

23 P Leaching from TSP-Modified Biochars Biomass Biochar Leached P (mg) per g solid Sawdust BC saw -F biochars BC saw -S BC saw -TSP-F 4.45 BC saw -TSP-S 7.07 Switchgrass -F biochars -S TSP-F TSP-S 6.18 TSP 101

24 TSP-Modified Biochar for a Slow Release Fertilizer?? ISTC Slow Release Fertilizer

25 Summary Wei Zheng Ling Zhao Nancy Holm Illinois SustainableTechnology Center, University of Illinois, Champaign, IL 2014 Midwest Biochar Conference August 8, 2014 Champaign, IL

26 Climate Change & Global Warming Climate change are primarily resulted from: Natural causes such as changes in Earth's orbit, changes in solar activity, or volcanic eruptions. Human activities

27 Facts for Climate Change & Global Warming It is believed global warming is caused from the large emissions of greenhouse gases, primarily from CO 2

28 Carbon Sequestration Geological CO 2 Storage vs Biochar Do we need go so deep?

29 Improve Carbon Retention of Biochar During Biomass Pyrolysis Six P-rich chemicals or passivator-like materials were chosen as chemical additives in this study: triple superphosphate (TSP), phosphate rock tailing (PRT), bonemeal (BM), clay, H 3 PO 4, and H 3 BO 3.

30 Effect of Chemical Additives on Carbon Retention 80 Biochars from switchgrass Remanent C after pyrolysis (%) switchgrass -TSP -PRT -Clay -BM -H 3 PO 4 -H 3 BO 3

31 Interaction Mechanism between TSP and Biomass During Pyrolysis C-P X-ray diffractometer (XRD) TSP-BC PRT-BC H 3 BO 4 -BC H 3 PO 3 -BC During pyrolysis, TSP-P and biomass-c may bond together through C-O-PO 3 and C-P groups so that more carbon remains in biochars BC

32 Assess Biochar Thermochemical Stability by TGA TSP-S Weight loss (%) Biochars from switchgrass TGA in Air -TSP-F S -F Temperature ( o C) The TGA analysis showed that TSP-modified biochars are thermo-chemically stable.

33 Biological Mineralization of Biochar in Soil mg CO 2 -C g -1 (Soil + Biochar) Soil Soil+ -F Soil+ -S Soil+ -TSP-F Soil+ -TSP-S Biochars from switchgrass Time (d) When TSP-modified biochars applied to soils, they are very recalcitrant to microbial decomposition and mineralization

34 Carbon Footprint Analysis of Biochar Initial C in biomass 100% Input into soil directly Final C after several years 0-10% Pyrolysis TSP-modified biochar Input into soil 60~65% 100% 50% 40-45% Energy input Energy output 40~45% Pyrolysis Input into soil 100% Chemical 100% 70% 60-65% treatment Energy input Energy <10% output

35 TSP-Modified Biochar for a Slow Release Fertilizer?? ISTC Slow Release Fertilizer

36 Acknowledgments Dr. Sharma, B.K. John Scott Dr. Li, X. Wiles, K. Murali, D. Manandhar, J Dr. Rajagopanlan, K. Dr. Zou, Y. Dr. Marlin, J. Joe Pickowitz Ed Zaborski Luber, E. This study is being supported by Russell and Helen Dilworth Memorial Fund