Biochar Properties & Production Techniques Zoe Wallage Low Carbon Innovation Centre University of East Anglia

Presentation Outline Introduction & Overview Biochar Production Techniques Biochar Properties & Uses UEA Case Study Summary of Findings UEA’s Biomass Gasification CHP Plant

Research Overview Atmospheric Carbon (CO2) Terrestrial Carbon (SOC) Aim: Review the potential for carbon sequestration via biochar & assess the impact this technology may have on regional productivity & sustainability Objectives: Evaluate the technologies available for biochar production Identify the parameters influential to biochar yield & quality Atmospheric Carbon (CO2) Terrestrial Carbon (SOC)

What is Biochar & Why is it Important? Introduction slide

Biochar Carbon Cycle Lehmann (2007) Nature 447: 143 - 144 Lehmann et al (2006) Mitigation & Adaptation Strategies for Global Change 11: 403 - 427

Thermal Conversion of Biomass Introduction slide Lehmann (2007) Frontiers in Ecology & the Environment 5: 381 - 387

Thermal Conversion of Biomass Overall an endothermic process: Energy is required to initiate the process At present the technologies can be split into two distinct categories: Charcoal production Bio oil or syn gas production However, there is potential to move towards a third: “Tri-generation” that makes use of the biochar, energy-rich co-products (bio oil, syn gas) & heat Bio Oil Biochar Syn Gas Heat without Air Biomass

Biochar Production Techniques CHP Gasification Slow Pyrolysis (retort) Slow pyrolysis (kiln) Temp & Duration Solid (Biochar) Liquid (Bio oil) Gas (Syn Gas) Slow Pyrolysis ~500C Days 35% 30% Fast Pyrolysis Seconds 12% 75% 13% Gasification >800C Hours 10% 5% 85% Thermal conversion of biomass is the temperature driven chemical decomposition with limited oxygen, and is sometimes referred to as pyrolysis. However, just as biomass can be drawn from a number of sources, biochar and its co-products can be produced through a number of thermochemical processes, including slow (carbonisation), intermediate, and fast pyrolysis, and gasification (Demirbas 2004c; Winsley 2007). All of these processes produce some form of char (Gaunt & Lehmann 2008). Thermal technologies can effectively process all forms of biomass, and whilst combustion and gasification of biomass have been commercially proven, pyrolysis is often thought to offer greater flexibility as it can generate varying yields of solid (char), and liquid and gaseous (energy) outputs (Warnken 2008). Fast Pyrolysis

BEST Energies: Biochar via Slow Pyrolysis Biochar Production Dynomotive: Bio oil via Fast Pyrolysis Eprida: Hydrogen & Char Fertiliser via Pyrolysis University of Hawaii: Flash Carboniser (Fast Pyrolysis) BEST Energies: Biochar via Slow Pyrolysis

Biochar Properties High carbon content (60 – 95% C) Resistant to biodegradation Significant adsorptive qualities (similar to activated carbon) Nutrients (& contaminants) essentially lock on to the structure Increases moisture holding capacity Enhances microbial biomass

Biochar Properties: Process Conditions Enhanced biochar yields from: Lower temperatures (<400C) Higher pressures Longer vapour residence time Slower heating rate Larger particle size

Biochar Properties: Process Conditions Temperature As temperature increases: Biochar yield decreases Fixed carbon increases Surface area increases Ash content increases Structural Development

Biochar Properties: Feedstock Materials The variable nature of the chemical constituents in the feedstock biomass influence the structure, properties & yield of biochar. Roundwood As may be expected, the variable nature of the chemical constituents in the feedstock biomass influences the structure, properties and yields of the resulting biochar and energy-rich co-products. For example, materials with high lignin concentrations have been found to generate higher biochar yields (Demirbas 2004c), whilst Nik-Azar et al (1997) demonstrated that the mineral content is also influential, with woody material impregnated with Na, K and Ca found to yield up to 15% more biochar than the original beech wood. In contrast, extractive compounds have been found to influence the gaseous emission profiles formed during pyrolysis, although they are not thought to substantially influence charcoal yield due to their low concentrations (Brown 2009). Woodchip Rice Husks

Biochar Properties: Feedstock Materials Poultry Litter Manure Biodegradable Waste Softwood Hardwood

UEA Case Study: Biomass Gasification CHP

UEA Case Study: Biomass Gasification CHP

Gasification Outputs Biochar

UEA Case Study 1.4 MWe 2.0 MWth 6, 719 t CO2 yr-1 (34%↓) 3% Biochar Yield 300 t char yr-1 195 t C yr-1 716 t CO2 yr-1 (4% ↓) Biochar ...& this particular system is optimised for energy production!

Summary of Findings Biochar is produced by the thermal decomposition of biomass using: Slow Pyrolysis Fast Pyrolysis Gasification Technology must be “closed-loop” with efficient product recovery Biochar yield & quality varies significantly with feedstock type & process conditions Biomass gasification CHP is currently viable & will produce modest quantities in the near-term Bio Oil Biochar Syn Gas Heat without Air Biomass

So, the future is in our hands… Blue text slide with white bullet points Thank you! Zoe.Wallage@uea.ac.uk 01603 591279