The role of biochar in achieving Carbon Neutral

The role of biochar in achieving Carbon Neutral bioenergy systems Koldo Saez de Bikuña Salinas 1, Andreas Ibrom 1, Michael Z. Hauschild 2 1 -Center for Ecosystems and Environmental Sustainability, Technical University of Denmark 2 -Division for Quantitative Sustainability Assessment, Technical University of Denmark

INTRODUCTION • Before 2008, the world was green and everything seemed bio-beautiful… …until Searchinger & Fargione came… i. LUC occurs whenever displacement of previous crops results in their production being moved to other areas elsewhere in the form of agricultural expansion – cannot be measured: need modeling the i. LUC nightmare!!! 2 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

INTRODUCTION • Marginal lands: the bypass solution to i. LUC? Def. : Lands at the margin of economic viability DK: Extensive grassland • Land abandonment in EU & US: cornerstone of the Land Use paradox – Socio-economic phenomena affecting developed countries. – Coexists with tropical deforestation in developing countries!! I che t’s ape r! 3 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

INTRODUCTION (Hatna et al. 2011) ~250. 000 ha “marginal” Fallow, ext. pastures, set aside 10% of total 4100 ha willow 4 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

RESEARCH QUESTION To what extent can we offset with biochar, or avoid with marginal lands, i. LUC emissions from energy cropping? GOAL To illustrate through biochar the influence of the land type and other modeling assumptions in the GWP of a gasification bioenergy system, including direct & indirect effects. ü Case-study: LCA of a willow + gasification (biochar as soil amendment) Marginal vs. Arable land 5 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

SCOPE Technology: low-tar, 2 -stage gasification + IC gas engine (decentralized cogen) Highly efficient! ~90% Time horizon: 20 and 100 years Place: Denmark FU: use of 1 ha land (Cherubini et al. ) Life cycle approach: consequential Life cycle perspective: individualist (20 y) and hierarchic (100 y) Transition phase: willow as temporary crop. 6 DK fossil free after 2050: willow as permanent crop DTU Chemical Engineering, Technical University of Denmark 4% ISIE Guildford 25/09/2020

SYSTEM DESCRIPTION Field operations (capital goods, diesel, lubricating oil) Herbicide PLOUGHING, HARROWING, ROLLING NPK fertilizer Willow cuttings WEED PLANTING CONTROL SEED BED PREPARATION COPPICING ESTABLISHMENT FERTILIZING HARVESTING & CHIPPING FERTILIZING & HARVESTING (six 3 -year rotations) TRANSPORT & STORAGE GASIFICATION FINALIZATION Ash & char residues ∆SOC & i. LUC emissions to air, soil, surface water, groundwater ly Most y ar prim ! data 7 Non primary emission data (air): N 2 O, NOX, NH 3 Non primary emission data (water): NO 3 - , P DTU Chemical Engineering, Technical University of Denmark HEAT & POWER ISIE Guildford 25/09/2020

KEY ASSUMPTIONS • Substituted energy (consequential) in decentralized cogen (H&P): – Transition phase: Natural Gas (gas turbine) – Post-2050 grid: Biogas plant • Reference Land (land use type): – Arable usual land management – Marginal Extensive pastureland • i. LUC arable: worst-case, economic model (Kløverpris Ph. D 2008) – All i. LUC burden allocated to the willow plantation – No intensification effects considered. • i. LUC marginal: deterministic (Tonini et al. 2015, unpublished) – Grass substitution based on equivalent nutritive value from marginal cattle feed: soymeal (proteins) and maize grain mix (energy) – Intensification effects and emissions from production included. 8 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

RESULTS: arable, 20 yrs DK in transition Temporary crop (high i. LUC!) Reference LU: Low C-stocks 36, 6% of harvested biomass as biochar to be Carbon Neutral!! approx. 2 Mg C ha-1 year-1 of biochar sequestration needed (40 in total) ~ 27% of SOC!!! 9 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

RESULTS: marginal, 20 yrs DK in transition Temporary crop Reference LU: Medium C-stocks 4% of harvested biomass as biochar… make it Carbon Negative!! approx. 120 kg C ha-1 year-1 or 17 t CO 2 -eq ha-1 sequestered ~ 8% of SOC 10 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

RESULTS: arable, 100 yrs Post-2050 DK: 100% RE Permanent crop (low i. LUC!) Reference LU: Low C-stocks 4% of harvested biomass as biochar… make it Carbon Negative!! 213 kg C ha-1 year-1 or a total 145 t CO 2 -eq ha-1 sequestered ~ 14% of SOC 11 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

Post-2050 DK: 100% RE RESULTS: marginal, 100 yrs Permanent crop Reference LU: Medium C-stocks 23, 8% of harvested biomass as biochar to be Carbon Neutral!! approx. 700 kg C ha-1 year-1 of biochar sequestration needed … 47% of SOC!!! 12 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

SENSITIVITY & UNCERTAINTY ANALYSIS (work in progress) • Substituted energy (consequential): decentral CHP – Transition phase: Coal more C-negative – Post-2050 grid substitution: If Renewable: small crediting (Biogas plants) If Fossil Fuel: crediting more C-negative • Reference Land: – Arable marginal/abandoned – i. LUC + C-stocks – Marginal natural reserve - i. LUC, + C-stocks • i. LUC: – New approaches (much lower figures) even more C-negative!! • Yield: – Marginal: already low figure (6 t DM ha-1 year-1 ) – Arable: 8, 5 t DM ha-1 year-1 higher Biochar % required 13 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

TAKE HOME MESSAGES • Willow + gasification + biochar amendment is a potential carbon negative energy system (Carbon Neutral at worst). • i. LUC can be hardly avoided: marginal lands still in use!!! • i. LUC offsetting with biochar cannot compensate for other impacts, especially irreversible biodiversity losses. 20 y 100 y MARGINAL ARABLE 4% C-Negative 36, 5% C-Neutral (120 kg C ha-1 yr-1) (2 Mg C ha-1 yr-1) 23, 8% C-Neutral 4% C-Negative (700 kg C ha-1 yr-1) (213 kg C ha-1) • Key assumptions are crucial for results (epistemic uncertainties): – Reference Land: set by land type – Dynamic energy grid baseline – Assumptions behind and method choice for i. LUC modeling. – Time allocation criteria (permanent vs. temporary energy crop) 14 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

Thank you all for your attention!! … questions? ksde@kt. dtu. dk 15 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020

Annex: stability of Viking’s biochar 16 DTU Chemical Engineering, Technical University of Denmark ISIE Guildford 25/09/2020