The role of Biochar in Sequestering
Carbon
Dr Ondřej Mašek
ondrej.masek@ed.ac.uk
Dr. Saran Sohi and Dr. Simon Shackley
University of Edinburgh, UK Biochar Research Centre (UKBRC)
www.biochar.org.uk
SAGES Annual Meeting
Hilton Hotel, Dunkeld, UK (23rd November 2010)
Talk outline
• What is biochar and the Biochar Pyrolysis
System (PBS)
• Value of biochar in climate change mitigation
• Key issues in biochar deployment
• Biochar potential in Scotland
• Introduction to the UK Biochar Research Centre
(UKBRC)
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Drivers for biochar
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
What is biochar?
Char made of biomass and for use in soil
20 mm
Photo: Shackley & Cook, UKBRC
may include and outwardly resemble
charcoal but can be quite different
(functionally) in soil
0.2 mm
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar – can give a complex and
perhaps confusing picture
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
The pyrolysis-biochar system (PBS)
?
CO2
photosynthesis
6 Gt y-1
biomass C
(energy)
60 Gt y-1
soil C
?
pyrolysis
biochar C
fossil
carbon
fossil
C
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar production
- Carbon rich product of
biomass pyrolysis
- Can take many forms
and have different
properties
Traditional charcoal burning
air
smoke
char
Batch pyrolysis kiln
char
oil, tar, liquids
Industrial unit for continuous production
char
gas, oil, tar
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Value of biochar in climate change
mitigation
“Carbon equivalents” over defined timeframe:
1.
Permanent C storage (direct avoided CO2 emission)
–
2.
stabilisation of C from degradable organic matter
Production of renewable energy
–
3.
direct CO2 offset (depends on current and future energy mix)
Suppression of N2O
–
4.
indirect emission avoided (unpredictable but accruing)
Net increase in soil organic matter
–
5.
indirect carbon storage (unpredictable and reversible)
Impacts on agricultural resource and land-use
–
–
reduced requirement for energy (fertiliser, irrigation, machinery)
relative reduction in rate of land-use change
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
1.Permanent C storage - Biochar stability
• Key factor in determining the GHG reduction potential of
biochar.
• Not yet well understood.
• Tools for rapid assessment of stability of different biochars
are needed.
• Stability in the order of centuries to millenia is needed, this
appears to be the case for most biochars, however
scientific verification is needed.
UKBRC accelerated aging tool
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar stability
The yield of stable carbon is critical!
yield [wt.% feedstock (db.)]
35
stable ash free char
30
25
20
expected
15
10
5
stable ash free char
0
300
350
400
450
500
550
600
temperature [C]
Results from the accelerated aging analysis clearly show that the yield of
stable fraction in biochar decreases with increasing pyrolysis temperature
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
2. Production of renewable energy
biomass
pyrolysis
gases
solids
(biochar)
liquids
Woolf et al., 2010, Nature Communications
power generation
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar and indirect GHG reduction
N 2O
CO2
CH4
a) reduced GHG emissions
b) improved/reduced water usage
c) reduced or no use of
synthetic fertilisers
Other …
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Key issues in biochar deployment
• Stability of biochar
• Energy balance of biochar production technologies
• Contaminants (PAHs, heavy metals, dioxins, etc.)
• Feedstock availability issues – need to expand the range of
suitable feedstock
• Impact of biochar on crop productivity / quality
• Impact of biochar on water holding capacity
• Impact of biochar on soil GHG emissions
• Predictive capacity sufficient to guide selection (short-listing of
biochar) on basis of feedstock and process conditions
• Practical tools for direct comparison of short-listed products
• Biochar economics - Adding value to biochar is critical for
beginning deployment with a small or zero price for carbon
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar economics
(UK deployment)
Marginal Abatement Cost Curve for biochar in UK (cost per t biochar versus amount): high
feedstock supply scenario. Small and large pyrolysis unit technology available. Costs vary
greatly depending on feedstock and scale.
500
309
360
298
404 416
298 342
309
298
cost (£ per tonne CO2e)
400
300
200
36
196
138
229 229 229
Ø 178
100
0
-100
-200
-117 -117
-220
Imported Canadian chips
-300
Commercial organic waste
Miscanthus chips (large)
domestic organic waste
SRC chips (small scale)
Sewage sludge
Waste wood
Short rotation forestry (chips)
Sawmill residues
Forestry residue (chips)
Arboricultural arisings
SRC chips (large)
Oil seed rape straw (small)
Wheat straw bales (large)
Barley straw bales (large)
Barley straw bales (small)
Oil seed rape straw (large)
Wheat straw bales (small)
Shackley, 2010 (unpublished)
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
UK biochar potential
Preliminary and provisional estimate of UK production of biochar per
annum and carbon equivalent abatement per annum under three
feedstock scenarios and resulting land-use implications (using virgin
biomass feedstock-derived biochar only)
Shackley, 2010 (unpublished)
UK agricultural land over 18 mil. ha => NOT a limiting factor
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar economics
While the cost of CO2 (or C) is low, other functions of biochar in
addition to its carbon sequestration potential are necessary to make it
economically viable.
Lower fertiliser use
Improved yields
Lower water demand
The need for certainty of these added benefits is the main driving
force for the development of specified and bespoke biochar.
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
Biochar Potential in Scotland
• Stabilisation of carbon in organic waste streams
• Potential for both:
– A) large-scale integrated systems
-Utilisation of organic residues from medium to
large point sources (e.g. alongside AD facilities)
-Co-generation of heat and electricity, and
potentially chemicals (biorefinery)
-Use of biochar for soil amendment and carbon
storage
– B) smal-scale community-based systems
-Integrated waste management and
co-generation of heat and biochar
-Use of biochar by local farmers for
soil amendment and carbon
storage.
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
The UK Biochar Research
Centre (UKBRC)
Ondřej Mašek, Dunkeld, 23rd November, 2010
SAGES Annual Meeting
UKBRC team (19 researchers)
Professor Stuart Haszeldine
Professor of Sedimentary Geology
Andrew Cross
Teri Angst
Miranda Prendergast-Miller
Maria Borlinghouse
Dr. Saran Sohi
Soil Science
Dr. Ondřej Mašek
Engineering Assessment
Dr. Simon Shackley
Biochar Social Science
Peter Brownsort
Jason Cook
Sohel Ahmed
Rodrigo
Ibarrola
Wastes
pyrolysis
Jim
Hammond
Systems
Gary
McClean
Tom
Maxfield
Kyle
Crombie
Sarah
Carter
Rebecca
Rowe
Juan
Turion
Gomez
UKBRC team (19 researchers)
Professor Stuart Haszeldine
Professor of Sedimentary Geology
Andrew Cross
Teri Angst
Miranda Prendergast-Miller
Maria Borlinghouse
Dr. Saran Sohi
Soil Science
Dr. Ondřej Mašek
Engineering Assessment
Dr. Simon Shackley
Biochar Social Science
Peter Brownsort
Jason Cook
Sohel Ahmed
Rodrigo
Ibarrola
Wastes
pyrolysis
Jim
Hammond
Systems
Gary
McClean
Tom
Maxfield
Kyle
Crombie
Sarah
Carter
Rebecca
Rowe
Juan
Turion
Gomez