LCA Bioethanol

7/28/2019 LCA Bioethanol

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Gurbakhash S. Bhander & Anthony HalogForest Bio-products Research Initiatives (FBRI),

School of Forest Resources, Nutting Hall,

University of Maine, Orono, ME 04469-5755;email: [email protected]

Life Cycle Assessment ofbio-ethanol


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Gurbakhash S. Bhander PhD, Eng. Eng.School of Forest Resources, 5755 Nutting Hall,

Goal of Study

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The goal of this case study is:to perform cradle-to-gate life cycle

assessment of bio-ethanol productionfrom hemicellulose extraction process toevaluate the potential human health and

ecological impacts associated with theproducts system


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System Description

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Acetic AcidPulp/Paper

ChipEthanol

E. Coli K011

Enzymes

A technical analysis is performed for a new process at FBRI that isolates

chemical feedstock (mainly hemicellulose material) from the hardwood inaddition to hardwood Kraft pulp production.

This new process termed the near neutral hemicellulose extraction

process, involves the extraction of wood hemicellulose using green liquor

and white liquor prior to Kraft pulping.

The extracted material is cooked and converted into bio-ethanol, acetic acidand other co-products.


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System Boundaries (Conti.)

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The product boundaries cover cradle-to-gate activities and

assumptions made as follow. Energy produced from the Hog Fuel Boiler and Recovery Boiler is

assumed to be used internally. Electricity consumption used for

working activities is not included.

Furfural (co-product) is used internally and therefore it is not

assumed to be marketed.

Gypsum (co-product), Ash disposal (Hog Fuel Boiler) and dregs

(causticizing) are assumed to be landfilled in a mineral landfill.

Industrial water (demineralized) is assumed to be used in washing,

slaking and extraction process. Wastewater from the causticizing process is neglected.

Odor from sulfide is neglected.

Internal transportation & other small activities are not included.

Working environment is not included.


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Data Specification & Sources

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Product

Specific

Site

Specific General 1 2 3 4 5 Comments

Raw wood extractionWood

procurement

Ecoinvent- database

Chip Production Ecoinvent- database

Hog Fuel Boiler Ecoinvent- database

Electricity recovery BUWAL 250 database

Production of ethanol, pulp & acetic acid

Extraction Inputs data on electricity,

ancillary substance,

consumables is estimated

from a model developed

for extraction process in

WinGEMS software.

Further datasets the life

cycle of used materials and

ancillary substance etc is

used from BUWAL and

ecoinvent database.

Kraft pulping

Washing

Evaporation

Recovery Boiler

Slaking

(Causticizing)

WL storage

Evaporation

Acid Hydrolyze

Lignin Filtration

Liquid Extraction

Liming & Filtration

Fermentation

Ethanol & Acetic

Acid Separation

Disposal Material

Landfill Ecoinvent- database

Disposal route Ecoinvent- database

Transportation

Transportation Ecoinvent- database

Note:

1. Measurements

2. Computation (from massbalance consideration andinput data for process of concern

3. Data obtained from similartype or technology

4. Data obtained from differenttype or process

5. ApproximationProductspecific data: Processesspecifically concern with thehandling of gold

Site-specific data: Data of interest obtained from actualsites in the product

system of gold, but inventory of

process data is not specified.General data: All others


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Results (Normalized)

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Raw Material & Manufacturing Stage Landfill (Ash & Gypsum)

24%76%

Life Cycle Assessment of bio-ethanol (Cradle-to-Gate)

PersonEquivlant

(PE)

Impact Categories

10% improvement optimization

in landfill materials:

Gypsum,

Ash


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LCA of bio-ethanol (Compare the Extraction Process)

Allocation 7% of the pulp production,

47% of the acetic acid production,

P

ersonEquivla

nt(PE)

Impact categories


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LCA of bio-ethanol (Compare Processes)

Processes: Wood yard (Red),

Lime burning (light Blue),

Recovery boiler (Green),

Extraction (Blue).

P

ersonEquivla

nt(PE)

Impact categories


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Sensitivity Analysis (Normalized)

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LCA of bio-ethanol (10% Improvement optimization)

Processes: Wood yard,

Lime burning,

Recovery boiler,

Extraction.

PersonEquivlan

t(PE)

Impact categories


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Conclusions

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We have learned from the study that wood yard, wood extraction, limeburning and recovery boiler are the significant processes in the system: Wood yard (raw materials stage) is a main contributor (29%). Fuel

consumption (transportation and cutting activities) is the main material

that contributes to all significant impact categories.

The fuel oil consumption in the lime burning process contributesignificantly (ethane & methane) to human toxicity.

Anthraquinone (AQ) material used in the extraction process contributeshuman toxicity and radioactive waste.

Heavy metals emission (dioxin, lead, arsenic, nickel etc) in the recoveryboiler process contributes to human toxicity.

The gypsum co-product (landfill material) contributes to bulk waste andAsh disposal contributes to human toxicity and others impact categories.

Overall bio-ethanol contributes to 4.8PE, 3.1PE and 2.6PE to humantoxicity, soil, air and water, 3.8PE to bulk waste, 2.2PE to global warmingand 1.4PE to ozone depletion and formation and 1.9PE to radioactivewaste.


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Further Improvements

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Most of the data are used from the different databases. Site-

specific data collection will be the first priority.

Research will also be extended on wood chip production and site

specific data will be collected from contractors & other sources.

The lime burning process data and assumptions will be

improved. Anthraquinone (AQ) material input is an optional input to the

extraction process, avoiding AQ material will improve the

extraction process significantly.

Outputs emissions data will be improved for the recovery boiler

process and new air emission cleaning techniques will be

evaluated.

Bio-ethanol production will be compared with its fossil based

and agricultural based counterparts.


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Gurbakhash S. Bhander PhD, Eng. Eng.

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LCA Bioethanol