Julie Sinistore June 30th Presentation

Life Cycle Assessment of Cellulosic Ethanol Julie Sinistore Research Experience for Teachers June 30th, 2010

Outline ! What is Life Cycle Assessment (LCA)? ! How do you do an LCA? ! Case study in the applicaGon of LCA  Corn grain and cellulosic ethanol

! Direct vs. Indirect Land Use Change ! Fossil vs. bioGc carbon emissions

What is LCA? ! Life Cycle Assessment (LCA) is the

invesGgaGon and valuaGon of the environmental impacts of a product or service. It is sGll a method in progress:

! “There is no single method for conducGng

LCA studies. OrganizaGons should have flexibility to implement LCA pracGcally as established in this InternaGonal Standard, based upon the specific applicaGon and the requirements of the user.”

(ISO 14040:1997)

iso.org

What can you do an LCA on?

Goods, services, anything!!

LCA Pieces: Boxes, lines, quantities Allocated outputs

Inputs

Good or Service Functional unit & Measurement quantity Conversion rates/Process Data

Allocated inputs

Assumptions Sensitivity Analysis

Primary output

+

Secondary output

Result Metric Comparison

Step 1. Pick the good or service and its functional unit ! Say you wanted to do an LCA on bo[led water  Do you want an LCA on one bo[le of water or all the bo[led water sold in a store or all the bo[led water Pepsi made or sold last year?

! Examples of reference quanGGes:  One unit – a bo[le of water, a gallon of milk, a bushel of corn, a liter of fuel, a plane, a car  One Gme step – yearly producGon at a factory, daily irrigaGon water use  One funcGonal unit (service) – one plane trip, one screening of a movie  Mix and match – gallons of ethanol per year

Step 2: Define your measurement quantities ! What do you want to

measure in the life-­‐cycle of this thing?       

Energy Greenhouse gas Water Air polluGon Water polluGon Money Social implicaGons

! Divide your measurement quanGty by your reference quanGty and you have a metric!  Energy per plane flight  Water use per gallon of milk  GHG emissions per bo[le of water

Step 3: Define the beginning and the end (boundary)  How far “upstream” and “downstream” do you want to go?  Sweet corn production LCA up to the farm gate, the store or your dinner table?  Ethanol production up to the refinery, the gas station or burning in your car?

Step 4: Think of every input/output of production Inputs

Outputs

Plastic

Bottles of water

Paper

GHGs

Water

Other?

Ink Energy Transportation Other?

Process and Conversion rates (not just what but how) ! You need to understand the manufacturing process of a product or the administraGon of a service  This may uncover hidden inputs and outputs  Product: What kind of plasGc is used to make the bo[le and what is the process for making the mold?  Service: What is required to operate a passenger train (e.g. personnel, wear and tear on equipment)?

! What are the conversion rates and losses?  How much plasGc does it take to make 1 bo[le (and how much is lost as waste)?

Step 5: Data compilation ! Decide what data do you need    

Electrical grid mix a state or region – Wisconsin or the US Conversion efficiencies – liters ethanol per kg corn Process energy – MJ from natural gas for process heat TransportaGon – distance from refinery to farm, truck or train, number of trips, fuel efficiency of a full and empty truck

! Be consistent about sources Literature – different papers use very different numbers Databases – some are free, some are not Experimental/observaGonal data – self-­‐generated data GeospaGal data – helps with landscape factors and transportaGon assumpGons  Industry standards – check ISO documents for data standards, industry standard values are a good starGng point    

Step 6: Allocation ! All inputs/outputs are not created equal.

Most are straightforward, but some are more “slanted,” so you need to figure out their “right-left” component.

Warning!

Math metaphor!

a

Inputs

Good or Service

a counts

doesn’t count

Allocated inputs

Allocated outputs

Primary output

counts = total·cosa unitless ratio

Allocation: How? ! How do we allocate some of the energy and GHGs

associated with making parts of a product in an LCA?  Economic/Market allocaGon: Energy required or GHGs emi[ed to replace an economically equivalent amount of the product on the market (could be an economic subsGtute).  Mass allocaGon*: Make a raGo of the mass of the input you used to make the product and the total mass and mulGply that by the total energy or GHGs from the input producGon.  Energy allocaGon: Same as with mass, but with energy. *This is tough if the product has no mass like electricity.

Allocation  You can also allocate energy and GHGs for co-­‐ products by all the same methods plus: • System expansion: Expand the analysis boundary to include the upstream and downstream costs of the products that co-­‐products displace.

• Eg. PlasGc is a valuable co-­‐product of oil refining, so you could apply an energy or GHG credit to oil refining which is proporGonal to the energy and GHG value of plasGc by the Economic, Mass, Energy or System Expansion systems.

Step 7: Comparison  LCAs are only valuable if you have something to compare your numbers to.  Let’s say the net energy used to make a 16oz water bo[le is 12Joules and 5gCO2eq are emi[ed.* • Is that high or low?

 What do you compare it to?

• Other bo[led water brands • Tap water • Other “economic subsGtutes”

*completely fictitious

Step 8: Sensitivity analysis ! IdenGfy variables and assumpGons which could

dramaGcally affect your analysis. ! Test the sensiGvity of your results to those assumpGons.  Eg. If you had a co-­‐product credit of 5MJ per liter of ethanol, try 10, 9, 8, 7, 6, 4, 3, 2, 1 and 0 and see how that changes your results.  Eg. If you did a market-­‐value co-­‐product credit, try a mass or energy balance credit.

! You may adjust or throw out some assumpGons based on sensiGvity analysis.

Sensitivity Analysis

Result Metric Comparison

Rules of LCA 1. Know your system.

2. Know your data and data sources.

3. If you must allocate, allocate fairly and

always remember why you are allocaGng.

4. Be consistent with data and allocaGon. 5. Clearly state all assumpGons and the reasons for the assumpGons.

6. QuesGon everything.* * This is a good rule for life too.

Case Study: Ethanol

! FuncGonal Unit

 Liter of fuel or all the liters produced in a year at a refinery

! Measurement quanGty  Energy (MJ)  GHG (gCO2eq)

! Metrics  Energy or GHG per liter or year  Net Energy RaGo (output energy/input energy)  GHG Intensity (gCO2eq/MJ output)

! Boundaries  Farm or field to fuel (as it leaves the refinery)

! AllocaGon  Eg: co-­‐products and farm machinery

! Comparison  Gasoline  92 gCO2eq/MJ* and LHV 32MJ/L * CA Low Carbon Fuel Standard value for gasoline

How is corn ethanol made?

Corn Ethanol Feedstock production

Liquefaction

 Corn grain

 Heating & enzymatic  Ethanol, animal feed hydrolysis (WDG)

 Inputs: NPK, lime, natural gas, pesticides, diesel, gasoline, tillage practices, equipment

 Inputs: Natural gas, electricity, enzymes Fermentation

Products

 Allocation of energy and GHG values for ethanol and co-products

 Yeast CO2

Remember: if you burn a fossil fuel you get GHGs.

 Inputs: Natural gas, electricity, yeast, nutrients Fuel processing  Distillation, dehydration, denaturation  Inputs: Natural gas, electricity, gasoline

Drying WDG to get DDG requires natural gas To market  Transportation

Cellulosic Ethanol Feedstock production

Saccharification

 Corn stover, switchgrass, wood

 Enzymatic hydrolysis

 Inputs: NPK, lime, natural gas, pesticides, diesel, gasoline, tillage practices, equipment

Pretreatment  Dilute Acid, AFEX, SPORL  Inputs: Natural gas, electricity, chemicals

 Inputs: Natural gas, electricity, enzymes

Burn lignin for process heat or electricity

Products

 Yeast or bacteria

 Ethanol, animal feed, electricity, heat, ligninderivatives

 Inputs: Natural gas, electricity, microbes, nutrients Fuel processing

 Allocation of energy and GHG values for all products

Fermentation

 Distillation, dehydration, denaturation  Inputs: Natural gas, electricity, gasoline

To market  Transportation

Ethanol production differences for various feedstocks Produc1on step

Corn grain

Corn stover

Switchgrass

high

allocaGon

low

medium to high

allocaGon

low

mature

developing

developing

not necessary

necessary

necessary

cheap

expensive

expensive

animal feed

electricity

animal feed & electricity

Biomass produc1on FerGlizer input Soil Gllage Equipment legacy Pretreatment Enzymes Co-­‐products

You tally the inputs and outputs Net GHG emission Inputs

Net Energy Use

Does this input add to GHG emissions or use energy?

Natural Gas (NG)

Yes

Yes

Petroleum fuels (transportaGon/Gllage)

Yes

Yes

Soil Gllage

Yes

No

NPK and Lime

Yes

Yes

Yes and No*

Yes

Yes

No

Electricity Land use change Outputs

Does this output abate GHG emissions or provide energy?

Ethanol

Yes**

Yes

Co-­‐products (feed, electricity)

Yes

Yes

*Yes for coal or NG power, no for nuclear or renewable solar or wind energy **Carbon released from burning the ethanol was sequestered from the air by the plant

Direct vs. Indirect Land Use Change from Biofuels ! Direct Land Use Change (DLUC): A farmer

decides to grow an energy crop where no other crop was grown or a non-­‐energy crop was grown. ! Indirect Land Use Change (ILUC): A naGon or region grows less of a food-­‐crop or diverts a food crop to bioenergy uses. Demand for that food crop does not decrease, so producGon shiss elsewhere (another state or country).

Direct LUC example ! A farmer decides to take land a current land

use e.g. ConservaGon Reserve Program (CRP) land, forest, food-­‐crop land or fallow land and grow a bioenergy crop on that land.

Indirect LUC example ! A U.S. farmer takes a replaces a food-­‐crop

(e.g. soybeans) with a bioenergy crop (e.g. switchgrass). ! Demand for soybeans remains the same or increases. ! Land in another country (e.g. Brazil) is taken out of forest, pasture or other producGon to produce soybeans to make up for this lost supply in the U.S.

Why does ILUC matter? ! An indirect change in land use could cause more GHGs to be emi[ed than if the bioenergy crop did not cause ILUC.

! What if producing soybeans in Brazil emits

more GHGs than producing soybeans in the U.S.?

Important differences between energy and GHG LCA ! There are processes/inputs which produce GHGs that do not use energy  Soil Gllage pracGces  N applicaGon, runoff and leaching

! There are processes/inputs which use energy and don’t produce GHGs  Nuclear, wind and solar electricity

Caution: What counts in the GHG LCA? Follow the carbon!

CO2 CO2

CO2

CO2

Ethanol

CO2 CO2 CO2

CO2

CO2

Trapped Carbon

Gasoline

CO2 > CO2

Questions?

Visit www.glbrc.org for more information on the GLBRC’s scientific publications and education and outreach programs.

Or, email me: sinistore@wisc.edu