ghgreenhouse gas eiie missions and energy balances from

G h G E i i dGreenhouse Gas Emissions and Energy Balances from Biomass

Heating Systems

Timothy A. VolkSUNY ESF, Syracuse, NY

Northeast Biomass Heat Expo April 2 – 4, 2013, Saratoga Springs, NY

OutlineOutline

• Influence of GHG balance and net energy studiesgy• Life Cycle Analysis

– Focus on greenhouse gas (GHG) emissions and net b l f ll t d d hi f h tienergy balance of pellets and wood chips for heating

applications• Results can vary widelyy y

– What is going on and how to make sense of it all• Goals and scope• Inventory – boundaries and allocationInventory boundaries and allocation• Impact assessment

• Where does this leave us?

NYS DEC RGGI for “Sustainably d” ( )Harvested” Biomass (DAR 12)

1. The biomass is obtained from land that has a . e b o ass s obta ed o a d t at as aplan and/or certification (the "Certification Criterion");

2. Land(s) will remain in a forested state for a time period sufficient to re‐sequester the carbon di id (CO ) l d th h th b tidioxide (CO2) released through the combustion of the biomass– (a) Documentation of a time period that is sufficient(a) Documentation of a time period that is sufficient to re‐sequester the CO2 that was released through the combustion of the biomass.

– (b) 100 years, with no additional demonstration to the Department.

CA Low Carbon Fuel StandardCA Low Carbon Fuel Standard

• The CA low carbon fuel standard requires anThe CA low carbon fuel standard requires an accounting for indirect land use change for biofuels

• Impacts the types of fuels that are permitted to meet this standard– Ethanol from Brazil made from sugar cane is acceptable and being imported to meet this t d dstandard

– Ethanol made from corn is not acceptable and is being exported to Brazil to meet their needbeing exported to Brazil to meet their need

Net Energy RatiosNet Energy Ratios

1 A Larger Bar is Better

0 60.70.80.9

0.30.40.50.6

Most Effecienct

00.10.2 Least Effeciency

6)s et al. 200

(Katers

Net energy ratio = net energy output/energy input

Net Fossil Energy RatiosNet Fossil Energy Ratios

4550

25303540

510152025

Most Effecienct

Least Effeciency

05

y

)et al. 2006

Fossil energy ratio = net energy output/fossil energy used

(Katers

GHG Emissions from Heating SystemsGHG Emissions from Heating Systems

• In most cases os casesgreenhouse gases from

d hiwoody chip or pellet heating systems aresystems are significantly lower than for fossil fuel based systemsLife cycle GHG emissions of heating

t i diff t f l i th UKsystems using different fuels in the UK (Bates and Henry 2009)

GHG Emissions from Heating SystemsGHG Emissions from Heating Systems

• In other cases CO• In other cases CO2emissions of heating systems using pellets areusing pellets are the same or higher than fossil fuel systemssystems

• Should biogenic CO2 be included or excluded fromexcluded from analysis

Lifecycle CO2 emissions from heating systems using different fuel sources insystems using different fuel sources in British Columbia.

Analytical ApproachesAnalytical Approaches

• Lots of differentLots of different approaches to analyzing this question

• No set standards acrossNo set standards across the field, so people conduct analysis with a certain bias and point ofcertain bias and point of view

• Add to the confusion that there area lot of differentthere area lot of different forms of biomass and conversion pathways

Life Cycle AnalysisLife Cycle Analysis

• LCA most common h f h fapproach for these types of

assessment• BUT no one LCA standard is

i lin place• Different groups use

different approaches…and it can ha e a big impactcan have a big impact

• Life cycle assessment following a set of agreed on protocols (i e ISO 14040) isprotocols (i.e. ISO 14040) is a good start but still lots of assumptions and decisions

Steps in a life cycle analysis

Be Aware Of….Be Aware Of….

• Items you need to be aware of include:te s you eed to be a a e o c ude:– Goals and scope– Inventory Analysis

• Boundaries• Allocation

Impact assessment– Impact assessment

• These may sound like less than exciting topics, but they are important and we need to at least bebut they are important and we need to at least be aware of them and some of us need to understand them

Goal and Scope DefinitionGoal and Scope Definition

• This is where is all startsThis is where is all starts

• What is decided at this first stage sets the framework for the entire study and influencesframework for the entire study and influences important decisions later in the process

Sh ld b i f f di i d• Should be a main focus of discussion and effort at the start of a study

Boundaries Boundaries BoundariesBoundaries, Boundaries, Boundaries

• Determines which unit processes are included in pthe LCA

• Defining system boundaries is partly based on a subjective choice made during the scope phasesubjective choice, made during the scope phase when the study is defined

• No hard and fast rules for setting up yourNo hard and fast rules for setting up your boundaries, but they should be clear and EASY to understandA d di f h l k h l• A good diagram often helps to make these clear

• All inputs and emissions that move across the boundary and are accounted for should be clearboundary and are accounted for should be clear

Boundaries Do Matter!Boundaries Do Matter!

• Premium wood pellet manufacturing study inPremium wood pellet manufacturing study in WI (Katers et al. 2012)

• Goal: Determine the environmental impacts ofGoal: Determine the environmental impacts of ‘premium’ wood pellets manufactured in WI

• Two boundary levels in this studyTwo boundary levels in this study– Pellet manufacturing boundary for on site energy and emissions assessment

– Total production system boundary for all energy and emissions assessment


(Katers et al. 2012)

Energy InputEnergy Input

10,000

7 000

8,000

9,000

rt to

n)

5,000

6,000

7,000

ut (M

J/Sho

Off Site Energy

2 000

3,000

4,000

nergy Inpu On Site Energy

0

1,000

2,000

Whole Logs Wet Coprod ct Dr Coprod ct

E

Whole Logs Wet Coproduct Dry Coproduct


Energy Input – On and Off SiteEnergy Input On and Off Site

10,000

7,000

8,000

9,000

Btu)

4 000

5,000

6,000

,

Used (M

M

Wood Pellet Production

Transportation

2,000

3,000

4,000

Energy Coproduct Production

Timber Harvest

0

1,000

Whole Logs Wet Coprod ct

Dry CoproductCoproduct


Net Energy Ratios/ /(Assume 17.3 GJ/ton – 16.4 MMBtu/ton)

h l i h dWhole Logs

Wet Co‐product

Dry Co‐product

Weighted Average

All Energy SourcesAll Energy Sources

On Site Energy

2.9 3.1 7.5 4.7

On + Off Site Energy

2.8 2.5 1.8 2.1



• What if the scope of the analysis is focused onWhat if the scope of the analysis is focused on delivered heat?

• Need to include conversion system and should• Need to include conversion system and should include transportation of the material from the pellet plant to the end userthe pellet plant to the end user

• In order to compare systems effectively the b d i d b isystem boundaries need to be consistent

between the two systems

Allocation Does Matter!Allocation Does Matter!

Goal: Document the cradle to grave LCI of manufacturing bagged wood pelletsGoal: Document the cradle to grave LCI of manufacturing bagged wood pellets made from residues from hardwood flooring production in SE U.S. Reed et al. 2012)

Allocation Method Are Important!Allocation Method Are Important!

• Five common approachesFive common approaches– Mass

Energy Content– Energy Content

– Market value

P P– Process‐Purpose

– Displacement

(Wang et al. 2011)

Allocation Does Matter!Allocation Does Matter!• Mass allocation assessed

at 50% flooring and 50%at 50% flooring and 50% residues in this study

• Using a mass approach, 5 5 MMBtu of fossil5.5 MMBtu of fossil energy are invested to make one ton (16.4 MMBtu) of pelletsMMBtu) of pellets– 3.3 MMBtu to make the

residues– 2.2 MMBtu to pelletize2.2 MMBtu to pelletize

• Net is 10.9 MMBtu per ton or a net energy ratio of 1 : 2 9of 1 : 2.9

Mass based allocation (Reed et al. 2012)

Allocation Does Matter!Allocation Does Matter!• Allocation based on value of

the products involved is diffdifferent– Wood flooring at $2/ft2 and

residues at $20/ton– 98 8% of burden is flooring and– 98.8% of burden is flooring and

1.2% is residues• Using a value approach, 2.3

MMBtu of energy are invested gyto make one ton of pellets (16.4 MMBtu) – 0.08 MMBtu to make the

idresidues– 2.2 MMBtu to pelletize

• Net is 14.1 MMBtu per ton or a net energy ratio of 1 : 7 1

Value based allocation (Reed net energy ratio of 1 : 7.1et al. 2012)


• Residues are a waste product pand that the flooring manufacturers are not in the business of making residuesbusiness of making residues

• So all the energy and environmental burdens

d h dassociated with residues should go to flooring and not pelletsp

• Result is 2.2 MMBtu invested to make a ton of pellets

N t i 14 4 MMBt

Value based allocation (Reed et al 2012) – Net energy is 14.4 MMBtu

– Energy ratio is 1 : 7.5

(Reed et al. 2012)


Mass AllocationNet energy ratio 1.29

Value AllocationNet energy ratio 7.1

Processing AllocationNet energy ratio 7.5


F l

0 0625

Fuel Combustion

Productiond k

0.0198‐0.018

0.0625Feedstock

CO2 Absorption

(Reed et al. 2012)

Allocation Does MatterAllocation Does Matter

• Which allocation method is the right one?Which allocation method is the right one?

• None are perfect and the selection depends on the objectives and scope of the study andon the objectives and scope of the study and the people involved

BUT i i i h d d h• BUT….it is important that you understand the method used before you make use of the

bnumbers

I t A t D M tt !Impact Assessment Does Matter!

• Should biomass energy used in the pellet production process be included or not?

• Should CO2 from biomass combustion be included or excluded in GHG assessments?

• These decisions have an impact on the results and it needs to be clear how the assessment part of the process is being done

I t A t D M tt !Impact Assessment Does Matter!

• Premium wood pellet manufacturing study in WI (Katers et al. 2012)

• Determine the environmental impacts of ‘premium’ wood pellets manufactured in WI

• Two levels in this study (Katers et al. 2012)– Pellet manufacturing boundary for on site energy

d i i tand emissions assessment– Total production system boundary for all energy and emissions assessmentand emissions assessment


h l i h dWhole Logs

Wet Co‐product

Dry Co‐product

Weighted Average

All Energy SourcesAll Energy Sources

On Site Energy

2.9 3.1 7.5 4.7

ary Issue

On + Off Site Energy

2.8 2.5 1.8 2.1

Boun

da



Whole Wet Co‐ Dry Co‐ Weighted Logs product product Average

All Energy Sources

iOn Site Energy

2.9 3.1 7.5 4.7

On + Off 2 8 2 5 1 8 2 1On + Off Site Energy

2.8 2.5 1.8 2.1

Only Non ‐ Renewable Energy

On Site Energy

6.2 6.1 7.6 7.0

O Off 5 2 6 3 5 4 5 6On + Off Site Energy

5.2 6.3 5.4 5.6

GHG Potential for HeatGHG Potential for Heat

Pellets Cordwood

Biogenic C Question


Challenges and LimitationsChallenges and Limitations

• The steps in any LCA are important to e steps a y C a e po ta t tounderstand. It is not just an academic question!– Objectives and scope influence study design choices and results

– Boundaries mattersAllocation matters– Allocation matters

• Hard to compare results from different regions – Different biomass sources– Different biomass sources – Processes and transportation distances are different– Local source of electricity generation has impacty g p

General ConclusionsGeneral Conclusions

• Definitions matter!• Net energy ratios of pellets and wood chips are similar to fossil fuels for when total energy input is usedis used

• Net energy ratios using fossil fuel inputs only for green wood chips are higher than for pellets duegreen wood chips are higher than for pellets due to the increased energy invested to make the pelletsTh i i f il f l i l• The net energy ratio using fossil fuel inputs only of both wood chips and pellets is greater than fossil fuel heat systemsy


• The way C stored in biomass is accounted for is a e ay C sto ed b o ass s accou ted o s akey question

• If C stored and released in biomass is accounted for then wood chips and pellet GHG emissions are similar to fossil fuel systems

• If the C cycled in the biomass is considered a cycle then both wood chips an pellets have much lower (>75%) GHG emissionslower (>75%) GHG emissions – Over the entire life cycle GHG emission from pellets are usually higher than wood chipsy g p


• Boundaries allocation inventoryBoundaries, allocation, inventory, analysis….does it really matter?

• Probably not in terms of making a decision on• Probably not in terms of making a decision on whether or not to install a heating system in your home or organizationyour home or organization

• BUT…..it does have a strong influence on li d i i d d b fpolicy decision and we need to be aware of

the issues and be ready to address them


• Other items are important in the comparisonOther items are important in the comparison of pellets and wood chips– Emissions – not just from the end unit but also– Emissions – not just from the end unit but also across the entire system from fuel production to delivered heat

– Economics

– LogisticsLogistics

– System operation/dynamics

Questions

ghgreenhouse gas eiie missions and energy balances from

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