Annette Cowie

National Centre for Rural Greenhouse Gas Research

Biochar: Can it reduce pressure on the

land?

What is biochar?

Amazonian Terra preta

Source: www.biochar-international.org

Terra preta (dark earth) soilsHigh plant productivityHigh organic carbon – stable char (black carbon)

Amazonian Terra preta

Recreate Terra preta?

Pyrolysed biomass as a soil amendment

Source: Adriana Downie Pacific Pyrolysis

CSIRO Land and Water: Biochar

What is ‘pyrolysis’?

biochar

electricity

Slow pyrolysis process

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Wet

wei

ght (

g)

-N +N

CharA CharB Control CharA CharB Control

Poultry litter char applied to radish Y. Chan 2007

Paper sludge char applied to wheatL. Van Zwieten 2007

Source: L. Van Zwieten I&I NSW

Mitigation benefits of biochar

Reduced emissions from decay

Char lasts in soilTurnover time hundreds to thousands

of yearsDelays decayBiochar as a carbon pump

Terrestrial Carbon Cycle

Substrate Clitter & roots

MicrobialBiomass C

HumifiedOrganic carbon

Humification

-

Assimilation

Death

Fire

Charcoal

Photosynthesis

Particulatecarbon

Labile carbon:Microbial biomass,Soluble C

Humification

Fire

Charcoal

After J. Skjemstad, CRC Greenhouse Accounting

Humifiedcarbon

Atmosphere

Respiration

CO2Mineral-isation

RecalcitrantSource: S. Joseph UNSW

Source: E Krull CSIRO

Char-carbon turnover rate estimated as 130 -1800 years

Affected by

•feedstock

•pyrolysis conditions

BP Singh 2007

Source: BP Singh DPI NSW

least stable(<100 years)

most stable(>1000 years)

arom

atic

ity

Nutrient/mineral content

temperature

550°C wood

400°C manures (poultry, cow)

400°C wood550°C leaf

550°C paper sludge

C c

onte

nt

Why are there differences between chars?

Source: E Krull CSIRO

Increased plant growthPoultry biochar rate t/ha

Maize 07/08

weight of cobs (t/ha)

Faba bean2008

dry bean (t/ha)

Maize 08/09

weight of cobs (t/ha)

0 16.2 2.4 19.65 17.9 4.2 22.510 26.7 4.6 22.620 28.4 5.5 22.350 32.9 5.6 24.2

1200mm tall

1900mm tallSource: L. Van Zwieten DPI NSW

Reduced emissions due to fertiliser manufacture

Reduced nutrient leaching

Build soil N in microbial biomass

Increase P availability

Fertiliser requirements reduced

Less nitrogen fertiliser manufactured

Reduced emissions from fertiliser application Nitrous oxide is released when N fertiliser applied

powerful greenhouse gas – GWP 298 cf CO2

Nitrous oxide emission varies with temperature, moisture

Biochar can reduce soil N2O emissions

0

5000

10000

15000

20000

25000

30000

35000

4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug

The day of gas sampling

0

2000

4000

6000

8000

10000

12000

4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug

The day of gas sampling

Alfisol VertisolControl

Poultry manure_400

Poultry manure_550

Wood_550

Wood_550

14-73% reduction in N2O 23-52% reduction in N2O

Cum

ulat

ive

N2O

em

issi

ons

µg /m

2

BP Singh et al. 2010 (JEQ)

Enhanced soil carbon

Stimulates microbial activity

OM/mineral/char interactions protect soil OM

Avoided emissions from waste

In landfill, biomass decomposes anaerobically, releasing methane

GWP of methane is 25 cf CO2

Utilisation for char avoids methane from landfill/composting

Animal manures release methane and nitrous oxide

Utilisation for char avoids these emissions

Renewable energy

Pyrolysis produces syngas heat electricity

Avoids emissions from fossil fuel energy sources

CO2 emissionCO2 transferCO2 removal Non CO2 emission

Greenhouse gas balance of biochar system

Transport

Soil amendment

Pyrolysis to biochar and

syngas

Distribution of biochar

Distribution of energy carrier

Energy service (heat, electricity)

Biomassresidue

Biochar system

Transport

Biomassresidue

Fossil energy/carbon

source

Extraction

Conversion to energy carrier

Distribution of energy carrier

Energy service (heat, electricity)

Soil amendment

Fertilisermanufacture

Transport

Composting

Reference system

Distribution of compost

Distribution of fertiliser

Quantifying climate change benefit

Emissions reduction for whole system, across life cycle, compared with reference “business as usual” baseline

Same system boundary, same service

Consider all GHGs: N2O, CH4

C Stock change in biomass and soil Fuel use: Construction, start-up

Units: CO2e saved/ unit biomass used for biochar CO2e saved/ ha used to grow biomass CO2e saved/ unit product output

Compare project with reference

System boundary

All greenhouse gases CO2 and non-CO2

Deliver equivalent service (area fertilised, electricity produced)

Consider whole system life cycle

Direct and indirect emissions

Include C stock change in biomass, soil

Express as emissions reduction per unit limiting resource (biomass, land area)

Result is specific to each situation

Quantifying climate change benefits of a biochar system

GHG mitigation benefits of biochar

Long term carbon storage in soil ie avoided decomposition

Avoided fossil fuel emissions due to use of syngas as renewable energy

Avoided emissions from N fertiliser manufacture

Reduced nitrous oxide emissions from soil

Avoided methane and nitrous oxide emissions due to avoided decay of residues

Increased plant growth

Increased soil organic matter

Reduced fuel use in cultivation

Factors contributing to mitigation

Greenwaste biochar applied to canola

Poultry litter biochar applied to broccoli

Life cycle emissions reduction

-0.20

0.20.40.60.8

11.21.41.61.8

22.2

papersludge/w oodw aste charapplied to

canola

papersludge/w oodw aste charapplied tobroccoli

feedlot w astechar applied to

canola

poultry litterchar applied to

broccoli

greenw astechar applied to

canola

greenw aste forelectricity+ char

on canola

greenw astechar applied to

broccoli

greenw aste forelectricity+char

on broccoli

Emis

sion

s re

duct

ion

tCO

2e/t

CO

2e o

f fee

dsto

ck

Biomass transport Displaced fossil energy Char/fertiliser transport Avoided N2O Avoided fertiliser Sequestered carbon Yield increase Avoided landfill/storage

1.1-2.7 tCO2e/t feedstock1.3-5.9 tCO2e/t feedstock Gaunt and Cowie 20090.8-0.9 tCO2e/t feedstock Roberts et al 2010 (-0.04-0.44 for purpose-grown)

Life cycle emissions reduction –including energy options

-0.20

0.20.40.60.8

11.21.41.61.8

22.2

papersludge/w oodw aste charapplied to

canola

papersludge/w oodw aste charapplied tobroccoli

feedlot w astechar applied to

canola

poultry litterchar applied to

broccoli

greenw astechar applied to

canola

greenw aste forelectricity+ char

on canola

greenw astechar applied to

broccoli

greenw aste forelectricity+char

on broccoli

Emis

sion

s re

duct

ion

tCO

2e/t

CO

2e o

f fee

dsto

ck

Biomass transport Displaced fossil energy Char/fertiliser transport Avoided N2O Avoided fertiliser Sequestered carbon Yield increase Avoided landfill/storage

1.1-2.7 tCO2e/t feedstock1.3-5.9 tCO2e/t feedstock Gaunt and Cowie 20090.8-0.9 tCO2e/t feedstock Roberts et al 2010 (-0.04-0.44 for purpose-grown)

The time dimension

Payback time 2.5 years

-60000

-40000

-20000

0

20000

40000

60000

80000

100000

0 20 40 60 80 100

Years

Emis

sion

s re

duct

ion

tCO

2e

CO2 from feedstockfuel emissionsN fert manufactureN2O from soilfossil energynet avoided emissions

Payback time 2.5 years

Emissions reduction per 50,000tdm feedstockGreenwaste char applied to broccoli

Available biomass

“Wastes” Urban green waste Feedlot manure, poultry litter Bagasse, sugar cane tops Biosolids Sawmill residues

Available biomass?

Forest harvest residues

Crop stubble?

Purpose-grown crops Oil mallee

Potential mitigation through biochar -global

Woolf et al 2010 Total mitigation predicted: 1.8Gt CO2-e pa =12% current emissions

Integration with bioenergy

Syngas from pyrolysis – heat, electricity, biofuel

Pyrolysis of residues unsuited to energy applications“contaminated” – high ashhigh moisture

Pyroysis of residues from biofuel production

Biochar for remediation of degraded land and to enhance land productivity so produce more biomass for energy increase resilience to climate change

Biochar for EnvironmentalManagement

Science and TechnologyEdited by

Johannes Lehmann and Stephen Joseph

Earthscan 2009

International Biochar Initiativewww.biochar-international.org

ANZ Biochar Researchers’ Networkwww.anzbiochar.org/

What is the best use of biomass resources?

Biomass properties

How can land be used to produce biomass for biochar and bioenergy, while meeting other needs?

Location (Land use, land constraints, productivity, energy system)

Conclusion

Biochar systems based on residues, where syngas used to displace fossil fuel can deliver net reduction in GHG emissions

Major contribution to mitigation from OM stabilisation, avoided N2O and CH4, displaced fossil fuels

Least benefit from manure biochars (less stable)

Benefit can be greater than if used for energy alone

Assumptions need further testing

Biochar can be integrated with bioenergy greater mitigation in some cases sustainable land management adaptation to climate change

Thank you

annette.cowie@une.edu.au