Carbon implications of different biofuel pathways Pep Canadell Global Carbon Project CSIRO Marine and Atmospheric Research Canberra, Australia.

Carbon implications of different biofuel pathways

Pep CanadellGlobal Carbon Project

CSIRO Marine and Atmospheric ResearchCanberra, Australia

Key Messages

1. Most biofuels on existing agricultural lands have a significant C offset capacity (20%-80%), there are exceptions.

2. Direct (or indirect) expansion of biofuels into forest systems leads indisputably to net carbon emissions for 10s to 100s.

3. Expansion of biofuels on abandoned and degraded lands can produce net C offsets immediately or in < 10 years and generate 8% of global current primary energy demand, an amount most significantly in regions such as Africa.

4. A full radiative forcing approach needs to be explored.

1. Industrial life-cycle• Cultivation, harvest, conversion, including fertilizers, energy requirements,

embedded C in machinery, etc. (sensitive to boundary conditions)• Co-products (easy for electricity and heat co-generation, difficult for others)• Full GHGs life cycle (CO2 equivalents)

Life-cycle and Impacts on Climate

Biofuels are NOT carbon neutral

Thow & Warhurst 2007

GHG

em

issio

ns re

duct

ion

Ethanol Biodiesel

Gibbs et al 2008, ERL, in press

Potential Annual C offsets (tons C/ha/year)

Most Studies Show Benefits from Corn Ethanol

Net GHG emissions to the atmosphere

Net GHG emissions avoided

Biofuel

GHG Emissions (kg CO2equiv/GJ)

CO2 CH4 N2O Total

Rape Methyl Ester 25 0.69 15 40.7Sugarbeet Ethanol 34 0.32 5.6 39.9Wheat Ethanol 24 0.69 3.7 28.4Wheat straw Ethanol 0 - 0.59 13.3 12.7Pure Rapeseed Oil 15 0.49 14.3 29.8

Full GHGs: Large contribution from N2OGlobal Warming Potential: 300 x CO2

Elsaved et al 2003; Crutzen et al. 2007, ACPD

Mid-range values

New inversion calculations by Paul Crutzen show that biofuels such as rapeseed may produce large quantities of nitrous oxides, and for corn and canola it is worse than using gasoline.

1. Industrial life-cycle• Cultivation, harvesting, processing including fertilizers, energy, embedded C

footprints in machinery, etc.• Co-products (easy for electricity and heat co-generation, difficult for others)• Full GHGs life cycle (CO2 equivalents)

Life-cycle and Impacts on Climate

2. Ecological life-cycle• Land use change and ecosystem carbon lost (Ecosystem Carbon Repayment

Time, ECRT)• Soil carbon sequestration• CO2 sink lost• Additional full GHGs work (N2O) emissions)

Ecosystem Carbon Payback Time (ECPT)

Fargione et al. 2008, Science

Number of years after conversion to biofuel production required for cumulative biofuel GHG reductions, relative to fossil fuels they displace, to

repay the biofuel carbon debt.

Ecosystem Carbon Payback Time (Tropics)

With current crop yields

Gibbs et al 2008, ERL, in press

Peatlands918 years

Only Carbon taken into account

Ecosystem Carbon Payback Time (ECPT)

Gibbs et al 2008, ERL, in press

Using 10% percentile global yield

Peatlands587 years

AbandonedCrop

AbandonedPasture

AbandonedAgriculture

Bioenergy Potential on Abandoned Ag. Lands

385-472 M haAbandoned agricultural land

4.3 tons ha-1 y-1

Area weighted mean production of above-ground biomass

32-41 EJ8% of current primary energy demand

Campbell et al 2008, ESC, in press

%Area

Cumulative avoided emissions per hectare over 30 years for a range of biofuels compared with the carbon sequestered over 30 years by changing cropland to forest

Righelato and Spracklen 2007, Science

Cumulative avoided emissions over 30 years

Land would sequester 2 to 9 times more carbon over 30-years than the emissions avoided by the use of biofuels

Biofuel Crops versus Carbon Sequestration

Lost of C Sink Capacity by Deforestation

Lost of biospheric C sink due to land use change

A1 SRES

Additional 61 ppm by 2100

1. Industrial life-cycle• Cultivation, harvesting, processing including fertilizers, energy, embedded C

footprints in machinery, etc.• Co-products (easy for electricity and heat co-generation, difficult for others)• Full GHGs life cycle (CO2 equivalents)

Life-cycle and Impacts on Climate

2. Ecological life-cycle• Land use change and ecosystem carbon lost (Ecosystem Carbon Repayment

Time, ECRT)• Soil carbon sequestration• CO2 sink lost• Additional full GHGs work (N2O) emissions)

3. Full radiative forcing life-cycle• All GHGs• Biophysical factors, such as reflectivity (albedo), evaporation, and surface

roughness

Tropicalforest

CroplandGrassland

Temperatedeciduous

Bruce Hungate, unpublished

AlbedoRoughnessEvapotranspirationCloud formation

Full RadiativeForcing

5. Full Radiative Forcing

Borealforest

Jackson, Randerson, Canadell et al. 2008, PNAS, submitted

Monthly Surface Albedo (MODIS)

1. Industrial life-cycle• Cultivation, harvest, conversion, including fertilizers, energy requirements,

embedded C in machinery, etc. (sensitive to boundary conditions)• Co-products (easy for electricity and heat co-generation, difficult for others)• Full GHGs life cycle (CO2 equivalents)

Life-cycle and Impacts on Climate

2. Ecological life-cycle• Shifting from GHG emissions per GJ biofuel or per v-km to emissions per ha y -1.• Land use change and ecosystem carbon lost (Ecosystem Carbon Repayment

Time, ECRT)• Soil carbon sequestration• CO2 sink lost

3. Full radiative forcing life-cycle• All GHGs• Biophysical factors, such as reflectivity (albedo), evaporation, and surface

roughness

End

• Lignocellulosic biofuels will be able to achieve greater energy and GHGs benefits than highly intensive crops such as corn and rapeseed because:– require less fertilizer– can grow in more marginal lands– allows for complete utilization of the biomass (which can

compensate smaller yields per ha.

Most studies focus on GHG emissions per GJ biofuel or per v-km. Emissions per ha/yr may give different ranking.

Elsayed, et al. 2003.

GM, et al. 2002 (European study).

Direct N2O from annual crops, Germany N2O from short-rotation willow, NE USA

Heller, et al. 2003.

N2O emissions depend on type of crop (e.g., annual vs. perennial), agronomic practices, climate, and soil type.

Courtey of Gernot Klepper; Quelle: BMU, BMWi, DLR, meó

Wind Hydro Biomasselectr.

Photo-voltaics

Bio-ethanol

Bio-diesel

Bio-ethanol

BRA

ETS

Mitigation Cost per ton of CO2 (Euros)

Germany

0

100

200

300

400

500

600

700

800

From eric larsen presnetation

Striking features of LCA studies reviewed• Wide range of biofuels have been included in different LCAs:

– Biodiesel (fatty acid methyl ester, FAME, or fatty acid ethyl ester, FAEE)• rapeseed (RME), soybeans (SME), sunflowers, coconuts, recycled cooking oil

– Pure plant oil • rapeseed

– Bioethanol (E100, E85, E10, ETBE)• grains or seeds: corn, wheat, potato• sugar crops: sugar beets, sugarcane• lignocellulosic biomass: wheat straw, switchgrass, short rotation woody crops

– Fischer-Tropsch diesel and Dimethyl ether (DME)• lignocellulosic waste wood, short-rotation woody crops (poplar, willow), switchgrass

• LCAs are almost universally set in European or North American context (crops, soil types, agronomic practices, etc.). One prominent exception is an excellent Brazil sugarcane ethanol LCA.

• Extremely wide range reported for LCA results for GHG mitigation– Across different biofuels – Across different LCA studies for same biofuel

• Lack of focus on evaluating per-hectare GHG impacts.– Most analyses report GHG savings per GJ biofuel. – Some report GHG savings per-vkm. – Few focus on understanding what approaches maximize land-use efficiency for GHG mitigation

• All studies are relatively narrow engineering analyses that assume one set of activities replaces another.

From eric larson

outline

• Evolution of the components and boundaries of life cycle

• Range of variation but have a general sense for ethanol and biodiessel for main crops , largely Eu and USA conditions

• When land use change is taking into account– Show science paper with years needed to become

beneficial.– Palm oil example

• When carbon sequestration is taking into account