Doris Hamill October 14, 2013 Doris Hamill October 14, 2013

Mass (Biochar) Carbon sequestration Agricultural productivity Suppression of soil emissions Water retention & filtration Energy (Biofuels) Biogas for heating Biofuels for transportation Charcoal for high temperature (e.g. cooking) Biomass Conversion 2

Dominic Woolf, James E. Amonette, F. Alayne Street-Perrott, Johannes Lehmann, Stephen Joseph; Sustainable biochar to mitigate global climate change; NATURE COMMUNICATIONS | 1:56 | DOI: /ncomms1053 | “The main aim of this study is to provide an estimate of the theoretical upper limit, under current conditions, to the climate-change mitigation potential of biochar when implemented in a sustainable manner.” Dominic Woolf, Johannes Lehmann, Elizabeth M. Fisher, and Largus T. Angenent; Biofuels from pyrolysis in perspective: trade-offs between energy yields and soil-carbon benefits “The aim of this study is to review the potential pathways for co-production of transport fuels with biochar and to model how process parameters affect the yields of biochar and fuel.” “The aim of this study is to review the potential pathways for co-production of transport fuels with biochar and to model how process parameters affect the yields of biochar and fuel.” 3

Use waste biomass – Agricultural (grains, sugar cane, manure residues) – Forestry (harvested wood residue, mill waste, diseased stock) – Biomass crops on marginal lands: not agricultural, not wild Modern conversion technology – Minimize black carbon particulates and potent greenhouse gas emissions: CH 4, N 2 O – Capture all usable energy: heat, hydrocarbons Local / regional focus – Sources, production, use – Local market forces 4

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Assuming current carbon-intensity of the energy supply Climate change mitigation potential 7

 –  Soil saturation period Biochar Combustion 8

Baseline carbon intensity mix  100 year cumulative mitigation potential from maximizing biochar production vs. biomass combustion High C-intense energy (e.g. coal) favors biomass combustion. “… climate-change mitigation … impact of biochar is about one-fourth larger, on an average, than that obtained if the same biomass were combusted for energy.” 9

Increase in mitigation of biochar relative to bioenergy; calibrated using scant literature from both field and greenhouse studies. Severity of soil fertility constraints C-intensity of offset energy (kg C GJ -1 ) natural gas baseline mix oilcoal Carbon intensity of energy being offset 10

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Biochar Enthalpy (GJ/Mg Dry Mass) Pyrolysis Temperature (  C) Note: biochar yield is also a function of the lignin mass fraction of the feedstock. not commercially viable thermal cracking gasification T range Optimal for energy products 75-80% thermal efficiency <5% production of biochar 13

Biochar carbon yield MG carbon / MG dry mass Biofuels energy yield GJ/Mg dry mass biochar and all energy products gasification point (700  C) biochar and syn gas biochar and liquid fuels 14

$110 Mg -1 C to $440 Mg -1 C “…minimum biochar price of $110 Mg -1 C to $440 Mg -1 C … before increasing biochar production could increase revenue ” $320 Mg -1 C “… minimum biochar price of $320 Mg -1 C would be required before slow pyrolysis FT- biofuel and biochar co-production would increase revenues relative to fast pyrolysis without biochar ” $580 Mg -1 C “… utilizing fast pyrolysis biochar as a soil amendment would only become economic at a biochar price of $580 Mg -1 C.” 15 liquid fuels gaseous fuels

Sustainable use of biomass for biochar has more environmental benefits than for biofuels – Exceptions when regional soil quality is high and/or biofuels offsetting regional use of coal Conversion of biomass into biofuels is more profitable than into biochar – Except when / where fuel price is low – Depends on market price for biochar Widespread use of biochar for environmental remediation inhibited by market forces 16