DOI: 10.5061/dryad.69p8cz9d0
title: Code and data in support of: Uncertainty in determining carbon dioxide removal potential of biochar

description: A quantitative and systematic assessment of uncertainty in life-cycle
 assessment is critical to informing sustainable development of carbon
 dioxide removal (CDR) technologies. Biochar is the most commonly sold form
 of CDR to date, and it can be used in applications ranging from concrete
 to agricultural soil amendments. Previous analyses of biochar rely on
 modeled or estimated life-cycle data and suggest a cradle-to-gate range of
 0.20–1.3 kg CO2 net removal per kg of biomass feedstock, driven by
 differences in energy consumption, pyrolysis temperature, and feedstock
 sourcing. Herein, we quantify the distribution of CDR possible for biochar
 production with a compositional life-cycle inventory model paired with
 scenario-aware Monte Carlo simulation in a “best practice” (incorporating
 lower transportation distances, high pyrolysis temperatures, high energy
 efficiency, recapture of energy for drying and pyrolysis energy
 requirements, and co-generation of heat and electricity) and “poor
 practice” (higher transportation distances, lower pyrolysis temperatures,
 low energy efficiency, natural gas for energy requirements, and no energy
 recovery) scenarios. In the best-practice scenario, cradle-to-gate CDR
 (which is representative of the upper limit of removal across the entire
 life cycle) is highly certain, with a median removal of 1.4 kg of CO2e /
 kg biomass and results in net removal across the entire distribution. In
 contrast, the poor-practice scenario results in median net emissions of
 0.090 kg CO2e / kg biomass. Whether this scenario emits (66% likelihood)
 or removes (34% likelihood) carbon dioxide is highly uncertain. The
 emission intensity of energy inputs to the pyrolysis process and whether
 the bio-oil co-product is used as a chemical feedstock or combusted are
 critical factors impacting the net carbon dioxide emissions of biochar
 production, together responsible for 98% of the difference between the
 best- and poor-practice scenarios.
description: # Uncertainty in determining carbon dioxide removal potential of biochar
 README for Biochar Uncertainty Sceniaro Aware Monte Carlo Simulation code
 **Accompanies publication:** Kane, Seth, et al. "Uncertainty in
 determining carbon dioxide removal potential of biochar."
 Environmental Research Letters (2024). doi: 10.1088/1748-9326/ad99e9
 Prepared by: Seth Kane and Ahmad Bin Thaneya **Prepared on:** 10.4.2024
 **Last edited on:** 08.01.2025 **Last edited by:** Seth Kane **Last ran
 in:** MATLAB R 2024a (Vers. 24.1.0.2628055), Python Vers. 3.12.8, and
 Microsoft Excel Vers. 16.91 **Contents:** **Visual_framework.pdf:** ```
 Flow diagram describing the location of input data to each model,
 interconnection of models contained herein, and description and location
 of results in the below-described file structure. ``` **Folder: Predictive
 pyrolysis model uncertainty code** ``` Contains the MATLAB code that
 determines model error distributions from the residuals of the validation
 dataset. See README contained in this folder for additional details. ```
 **Folder: Scenario-Aware Monte Carlo Simulation code** ``` Contains the
 Python code that performs Scenario-Aware Monte Carlo simulation. See
 README contained in this folder for additonal details. ``` **Folder: Scen.
 1 Inputs and results** ``` Contains: ``` ``` Model run results
 (‘all_stats_Scen1.csv’ for complete results, presented as individual
 values of the variables listed in the first row that make up the
 distribution of results and ‘summary_stats_Scen1.csv’ for only final
 greenhouse gas emission values presented as individual model run results
 that combined make up the results distributions) including variables in
 'all_stats_Scen1.csv', in order of columns: ``` ``` Col. B:
 Biochar yield (kg biochar / kg biomass) ``` ``` Col. C: Biochar ash
 content (kg ash / kg biochar) ``` ``` Col. D: Biochar carbon content (kg C
 / kg biochar) ``` ``` Col. E: Biochar hydrogen content (kg H / kg biochar)
 ``` ``` Col. F: Biochar oxygen content (kg O / kg biochar) ``` ``` Col. G:
 Biochar bound carbon (kg CO2e / kg biomass) ``` ``` Col. H: Syngas final
 yield (kg syngas / kg biomass) ``` ``` Col. I: Syngas CO2 content (kg CO2
 / kg syngas) ``` ``` Col. J: Syngas CO content (kg CO / kg syngas) ``` ```
 Col. K: Syngas CH4 content (kg CH4 / kg syngas) ``` ``` Col. L: Syngas H2
 content (kg H2 / kg syngas) ``` ``` Col. M: Syngas higher molecular weight
 product (C2p) content (kg C2p / kg syngas) ``` ``` Col. N: CO2 emissions
 from combustion of syngas (kg CO2 / kg biomass) ``` ``` Col. O: Bio-oil
 yield (kg bio-oil / kg biomass) ``` ``` Col. P: Bio-oil carbon content (kg
 C / kg bio-oil) ``` ``` Col. Q: Bio-oil hydrogen content (kg C / kg
 bio-oil) ``` ``` Col. R: Bio-oil oxygen content (kg C / kg bio-oil) ```
 ``` Col. S: Bio-oil bound carbon (kg CO2e / kg biomass) ``` ``` Col. T:
 CO2 emissions from combustion of bio-oil (kg CO2 / kg biomass) ``` ```
 Col. U: External (non-waste heat) energy used for biomass drying (MJ / kg
 biomass) ``` ``` Col. V: Higher heating value of bio-oil, if combusted (MJ
 / kg biomass) ``` ``` Col. W: Lower heating value of bio-oil, if combusted
 (MJ / kg biomass) ``` ``` Col. X: Pyrolysis energy requirement (negative
 is energy input) (MJ / kg biomass) ``` ``` Col. Y: Syngas higher heating
 value (MJ / kg biomass) ``` ``` Col. Z: Syngas lower heating value (MJ /
 kg biomass) ``` ``` Col. AA: Total process energy balance (MJ / kg
 biomass) ``` ``` Col. AB: CO2 emissions from energy inputs to system (kg
 CO2e / kg biomass) ``` ``` Col. AC: Total fossil CO2 emissions of process
 (kg CO2e / kg biomass) ``` ``` Col. AD: Total biogenic CO2 emissions of
 process (kg CO2e / kg biomass) ``` ``` Col. AE: Total bound carbon of
 process (kg CO2e / kg biomass) ``` ``` and of variables in
 ‘summary_stats_Scen1.csv’: ``` ``` Col. B: Upstream harvesting emissions
 allocated to waste biomass (kg CO2e/kg biomass) ``` ``` Col. C: Upstream
 transportation emissions (kg CO2e/kg biomass) ``` ``` Col. D: total fossil
 CO2 emissions (kg CO2e/kg biomass) ``` ``` Col. E: total biogenic CO2
 emissions (kg CO2e/kg biomass) ``` ``` Col. F: Total bound carbon of
 process (kg CO2e / kg biomass) ``` ``` Result distributions
 (‘Scen1_dist_stats.csv’) contains descriptive statistics (Minimum of
 distribution, 10th, 25th, 50th, 75th, and 90th percentile of distribution
 and maximum value) of the distribution results presented in
 'summary_stats_Scen1.csv'. All units are kg CO2e/kg biomass. ```
 ``` Model inputs (‘inputs_Scen1.csv’) for Scenario 1, containing
 distributions of inputs used to determine results, including: ``` ``` Col.
 C-F: Distributions of cellulose, hemicellulose, lignin, and ash in the
 original biomass in wt. component/dry wt. biomass ``` ``` Col. G: Moisture
 content of the biomass feedstock in wt. water/whole wt. biomass ``` ```
 Col. H: Pyrolysis temperature modeled in degree C. ``` ``` Col. I-L:
 Pyrolysis thermal efficiency, bio-oil combustion thermal efficiency, and
 syngas combustion thermal efficiency in MJ/MJ. ``` ``` Col. M-N: Wood loss
 efficiency (wt./wt.) and green wood mass requirement (kg) for sawmilling
 to assign upstream allocation of growth, harvesting, and transportation
 emissions to biochar product. ``` ``` See Bose, et al. Life-cycle
 greenhouse gas footprint of cross-laminated timber from mixed hardwood and
 softwood from fire-prone California forests, Under review at Environmental
 Science & Technology for details on determining wood loss efficiency
 and green wood mass requirement and the main text and Supplemental
 information of Kane, et al. "Uncertainty in determining carbon
 dioxide removal potential of biochar." Environmental Research Letters
 (2024). doi: 10.1088/1748-9326/ad99e9 for details on the determination of
 all other input parameters. ``` **Folder: Scen. 2 Inputs and results** ```
 Contains model run results distributions and model inputs for Scenario 2.
 See the above description for Scenario 1 inputs for a complete list of
 variables and files present in this folder. ``` **Folder: Alt. Scen. 1
 bio-oil combustion results** ``` Contains model run results distributions
 for the alternative Scenario 1 with bio-oil combustion, named with the
 same file convention as folder ‘Sceni. 1 Inputs and results’. Inputs for
 this model run are the same as contained in “Scen. 1 Inputs and results”
 ``` **Folder: Deterministic model runs** ``` Contains model input
 parameters and results for deterministic runs of Scenario 1
 (‘Model_Scen1.xlsx’) and Scenario 2 (‘Model_Scen2.xlsx’) of the predictive
 pyrolysis model. Full description of the model, as well as the original
 model spreadsheet used to perform the calculations, are reported in: ```
 ``` Seth Kane and Sabbie A. Miller. 2024. “Predicting Biochar Properties
 and Pyrolysis Life-Cycle Inventories with Compositional Modeling.”
 Bioresource Technology 399 (May): 130551.
 https://doi.org/10.1016/j.biortech.2024.130551. ```