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

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

3. 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)

4. What is Biochar & Why is it Important?
Introduction slide

5. Biochar Carbon Cycle
Lehmann (2007) Nature 447:
Lehmann et al (2006) Mitigation & Adaptation Strategies for Global Change 11:

6. Thermal Conversion of Biomass
Introduction slide
Lehmann (2007) Frontiers in Ecology & the Environment 5:

7. 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

8. 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

9. 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

10. 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

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

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

13. 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

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

15. UEA Case Study: Biomass Gasification CHP

16. UEA Case Study: Biomass Gasification CHP

17. Gasification Outputs
Biochar

18. 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!

19. 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

20. So, the future is in our hands…
Blue text slide with white bullet points
Thank you!