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Carbon implications of different biofuel pathways. Pep Canadell Global Carbon Project CSIRO Marine and Atmospheric Research Canberra, Australia. Most biofuels on existing agricultural lands have a significant C offset capacity (20%-80%), there are exceptions.

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Carbon implications of different biofuel pathways


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carbon implications of different biofuel pathways

Carbon implications of different biofuel pathways

Pep Canadell

Global Carbon Project

CSIRO Marine and Atmospheric Research

Canberra, Australia

slide2
Most biofuels on existing agricultural lands have a significant C offset capacity (20%-80%), there are exceptions.

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

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.

A full radiative forcing approach needs to be explored.

Key Messages

slide3
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

slide4

Biofuels are NOT carbon neutral

GHG emissions reduction

Biodiesel

Ethanol

Thow & Warhurst 2007

slide5

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

Gibbs et al 2008, ERL, in press

slide6

Most Studies Show Benefits from Corn Ethanol

Net GHG emissions to the atmosphere

Net GHG emissions avoided

slide7

Full GHGs: Large contribution from N2O

Global Warming Potential: 300 x CO2

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.

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

slide8
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)
slide9

Ecosystem Carbon Payback Time (ECPT)

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.

Fargione et al. 2008, Science

slide10

Ecosystem Carbon Payback Time (Tropics)

Only Carbon taken into account

With current crop yields

Peatlands

918 years

Gibbs et al 2008, ERL, in press

slide11

Ecosystem Carbon Payback Time (ECPT)

Using 10% percentile global yield

Peatlands

587 years

Gibbs et al 2008, ERL, in press

slide12

Bioenergy Potential on Abandoned Ag. Lands

385-472 M ha

Abandoned agricultural land

4.3 tons ha-1 y-1

Area weighted mean production of above-ground biomass

32-41 EJ

8% of current primary energy demand

Abandoned

Crop

%Area

Abandoned

Pasture

Abandoned

Agriculture

Campbell et al 2008, ESC, in press

slide13

Biofuel Crops versus Carbon Sequestration

Cumulative avoided emissions over 30 years

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

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

Righelato and Spracklen 2007, Science

slide14

Additional 61 ppm by 2100

Lost of C Sink Capacity by Deforestation

A1 SRES

Lost of biospheric C sink due to land use change

slide15
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
slide16

5. Full Radiative Forcing

Temperatedeciduous

Tropicalforest

Full Radiative

Forcing

Albedo

Roughness

Evapotranspiration

Cloud formation

Borealforest

Cropland

Grassland

Bruce Hungate, unpublished

slide17

Monthly Surface Albedo (MODIS)

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

slide18
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
slide20
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.

slide21
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.

slide22

Direct N2O from annual crops, Germany

N2O from short-rotation willow, NE USA

GM, et al. 2002 (European study).

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

Heller, et al. 2003.

mitigation cost per ton of co 2 euros
Mitigation Cost per ton of CO2 (Euros)

Germany

800

700

600

500

400

300

200

100

0

Wind

Hydro

Bio-ethanol

Photo-voltaics

Bio-ethanol BRA

Biomasselectr.

Bio-diesel

ETS

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

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.

Striking features of LCA studies reviewed

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

outline