Carbon Neutral

Climate Impact of Biofuels 

Glen Peters 

Center for International Climate and 

Environmental Research – Oslo 

(CICERO)

Key Questions 

• Does biofuel X have a climate benefit? 

• Is there sufficient resource of biofuel X? 

• (at a reasonable cost) 

• Does biofuel X have unintended 

consequences 

• Next presentations…

Conclusion 

• Biofuels can help meet climate objectives, but 

• Some biofuels are good 

• Some biofuels are bad (even ugly) 

• There are no silver-bullets 

• Case specific 

• Constraint issues 

• Research and Policy Question 

“What is the best utilisation of biomass resources?”

This presentation focuses on principles 

and not on specifics 

The principles to assess biofuels are static 

The specifics will change (biofuel X may go from bad to good)

CO 2 is CO 2 

Treat a molecule of CO 2 the same if is from 

fossil fuels, biomass, or wherever 

Fossil fuel 

Biomass

“Carbon Neutral” 

Used, Abused and Confused 

• “Biofuels are good because the carbon 

emitted equals the carbon absorbed” 

• Depends on the system boundary (area) 

• Depends on the time (how long) 

• Depends on management (e.g., early 

harvest, fertilizers, …) 

• Depends on biophysical factors (albedo) 

• Depends on use (replacing gasoline, 

construction timber, …) 

• Depends on indirect effects 

• …


Used, Abused and Confused 

• “Biofuels are good because the carbon 

emitted equals the carbon absorbed” 

• Depends on the system boundary (area) 

• Depends 

We can’t 

on 

just 

the time 

assume 

(how 

that 

long) 

all 

• Depends 

biomass 

on 

is 

management 

“carbon neutral” 

(e.g., early 

harvest, fertilizers, …) 

• Depends on 

…it 

biophysical 

depends 

factors (albedo) 

• Depends on use (replacing gasoline, 

construction timber, …) 

• Depends on indirect effects 

• …

SPATIAL BOUNDARIES


Where does the term come from? 

• Energy and land-use change reported in 

different categories 

• Bio-energy is both energy and LUC! 

• Energy: “CO 2 emissions resulting from 

bioenergy consumption should not be 

included in [the official inventory]” 

• LUC based on “stock-change”: If there is a 

change in stock, there is a source or a sink 

of carbon



• Energy and land-use change reported in 

different categories 

• Bio-energy is both energy and LUC! 

• Energy: Problem “COis 2 emissions linking bio-energy resulting from 

bioenergy from energy consumption and land-use should not be 

included in [the reporting official inventory]” 

• LUC based on “stock-change”: If there is a 

change in stock, there is a source or a sink 

of carbon



• National Emissions Accounting 

• Stock-change (this is used in policy) 

• If no change in carbon stock, then somewhere 

in the country biomass grew to replace the 

biomass used 

• Atmospheric-flow (alternative, not used) 

• Follows the fluxes of carbon in and out of the 

atmosphere 

• Both systems have (dis)advantages

“Carbon Neutral”


Key issues: 

• Ease of accounting 

• Linking sources and sinks of carbon 

• Inconsistent system boundaries (not all countries included) 

• International trade (transfer of carbon) 

• Harvested Wood Products (HWP) (storage of carbon) 

Glen’s view on spatial boundaries 

* National reporting: Stock-change approach 

* LCA, biofuels: Atmospheric-flow approach

TIME SCALES


CO 2 flux 

Time 

Assume no time dimension 

(or less than a year)

Sugar Cane 


CO 2 flux 

Time 

1 year – Sugar cane

Boreal Forests 


CO 2 flux 

Time 

100 years – Boreal forests

Fossil Fuels 

Not carbon neutral? 

CO 2 flux 

Time 

Millions of years - Fossil-fuels

Considering Time 

• There is a time lag between the sources 

(biofuel use) and sinks (biomass growth) 

• Is “carbon neutral” over 100 years the 

same as “carbon neutral” over 1 year? 

• Even if “carbon neutral” (flux concept) 

may not be “climate neutral” due to the 

time lag

FROM “CARBON NEUTRAL” 

TO “CLIMATE NEUTRAL”

“CARBON NEUTRAL” 

ZERO STOCK CHANGE

Carbon in the atmosphere 

Treating carbon dynamics 

explicitly… 

– Changes in carbon pools 

• E.g., biomass to 

atmosphere 

– Carbon in the 

atmosphere causes a 

forcing 

Above ground 

carbon stock 

Atmosphere 

22 

Y CO2 

in

“Fossil Fuel”, GWP=1 

“Carbon Neutral”, GWP=0 

23

“Fossil Fuel”, GWP=1 

All else equal, time makes bio-energy better 

than fossil fuels, but not “climate neutral” 

“Carbon Neutral”, GWP=0 

24

Open questions… 

• Carbon dynamics not thoroughly studied: 

– What initial conditions? 

– Single or multiple plots? 

– Different metric? 

• Radiative Forcing 

• Temperature 

Atmosphere 

Y CO2 

in 

Above ground 

carbon stock

Metric comparison 

Different metrics for a harvest 

cycle of around 40 years 

26

Experimental Set Up 

Set up 

Instantaneous 

Forcing and 

Temperature 

Integrated 

Forcing and 

Temperature 

Single plot, harvest first Warming TT 1 

Single plot, harvest second Cooling TT 2 

Infinite plots, harvest first Warming Warming 

Infinite plots, harvest second Cooling Cooling 

All else equal, all options better than fossil fuels…

Experimental Set Up 

Set up 

Instantaneous 

Forcing and 

Temperature 

Integrated 

Forcing and 

Temperature 

Landscape view perspective, if zero stockchange 

over time: 

• Moving from forest to forestry warms, but 

Single plot, harvest first Warming TT 1 

Single plot, better harvest than second fossil Cooling fuels TT forestry 2 cools 

Infinite plots, harvest first Warming Warming 

Infinite plots, harvest second Cooling Cooling 

All else equal, all options better than fossil fuels…

LANDSCAPE VIEW 

CHANGE IN STOCK

Norwegian examples 

• Transition to a situation of INCREASED 

harvest 

• Non-zero stock-change 

• A particular dynamic (ie, case study) 

– Results do not apply to all biomass, in all 

countries, in all situations… 

• NTNU, Holtsmark, Randers, outside of 

Norway, … studies show a period of “pay 

back”

Payback Norway 

Study Scenario for increased harvest Payback (years) 

Pellets replace coal 200 

Holtsmark 

Biofuels replace petrol 350 

Randers Biomass replaces oil heating >100 

Biofuel (FTD) replaces diesel 

RF no albedo >100 

integrated RF no albedo >100 

Bright et al 


RF with albedo ‐45 (30‐70) 

integrated RF with albedo ‐80 (45‐>100) 

Mix of assumptions on 

efficiency, forest growth, 

etc




HoltsmarkImproving 

• Biofuels Optimized replace usepetrol 350 

Randers • Biomass Technology replaces of conversion oil heating (efficiency) >100 

• Biofuel Forest (FTD) management replaces diesel 

• … RF no albedo >100 


Bright et al 

Reduces these numbers and makes 

biofuels Biofuel (FTD) better replaces diesel 





etc




Holtsmark 

Biofuels replace petrol 350 

Randers Biomass replaces oil heating >100 


RF no albedo >100 


Bright et al 




Albedo changes everything 



etc

ALBEDO

Albedo 

• Some incoming solar radiation is reflected 

back to space 

• Albedo gives the share reflected back 

• Albedo = 0, black, absorbs energy 

• Albedo = 1, white, reflects energy 

• Boreal areas have snow!

Bad 

Good 

In boreal areas, albedo 

gives biofuels a “kick start” 

Bad 

Good

INDIRECT LAND USE CHANGE

Payback global 

Concept of “carbon payback” or 

“carbon debt” 

• Just like most investments, it 

takes time to payback the 

initial investment 

• Cropland converted to 

biomass 

• Nearly always good 

• Forest converted to biomass 

• Takes time…

Good: Converting degraded land to biofuels 

Bad: Converting primary forests to biofuels 

Bad 

Good

WHICH BIOFUEL TO USE?

Gasoline 

Diesel 

Heat 

Biomass is “better” 

for electricity…

RESOURCES

Potential 

Resource 

Expert 

Opinion 

Technical 

Potential 

Model 

range

CONCLUSION

Conclusion 

• Biofuels can help meet climate objectives, but 

• Some biofuels are good 

• Some biofuels are bad (even ugly) 

• There are no silver-bullets 

• Case specific 

• Constraint issues 

• Research and Policy Question 

“What is the best utilisation of biomass resources?”

Carbon Neutral

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