electricity in life cycle assessment...environmental life cycle assessment pse 476/wps 576/wps...

Environmental Life Cycle Assessment

PSE 476/WPS 576/WPS 595-005

Lecture 10: End of Life

Richard Venditti

1

Fall 2012

Richard A. Venditti Forest Biomaterials

North Carolina State University Raleigh, NC 27695-8005

[email protected]

Go.ncsu.edu/venditti

Waste Hierarchy

http://www.epa.gov/wastes/nonhaz/municipal/hierarchy.htm

http://www.epa.gov/wastes/nonhaz/municipal/hierarchy.htm

Reduce, re-use, recycle.

• Example: want to understand the burdens of containing

groceries during transport

• Reduce: don’t use a bag, 0 burden/trip

• Re-use (production of bag = 1 burden)

– Use bag once, 1 burden/trip

– Use bag twice, 0.5 burden/trip

– Use bag 3x, 0.33 burden/trip

• Recycle (to recycle costs 0.4 burdens, arbitrary)

– Then for using the bag and recycling once:

( 1 + 0.4 ) / 2 trips = 0.7 burdens/trip

– (data for example only, not meant to represent an actual

process)

3

Types of waste.

• Biodegradable waste: food and kitchen waste, green waste, paper (can also be recycled). – Can be broken down, in a reasonable amount of time, into its base compounds by micro-

organisms and other living things, regardless of what those compounds may be.

• Recyclable material: paper, glass, bottles, cans, metals, certain plastics, fabrics, clothes, batteries etc.

• Inert waste: construction and demolition waste, dirt, rocks, debris. Will not degrade due to microbial decomposition.

• Electrical and electronic waste (WEEE) - electrical appliances, TVs, computers, screens, etc.

• Composite wastes: waste clothing, Tetra Packs, waste plastics such as toys. • Hazardous waste including most paints, chemicals, light bulbs, fluorescent tubes,

spray cans, fertilizer and containers • Toxic waste including pesticide, herbicides, fungicides • Medical waste.

Municipal solid waste?

• MSW: everyday items that are discarded by the public

• Also referred to as trash, or rubbish

• Includes packaging, food scraps, grass clippings, sofas, computers, tires and refrigerators, for example.

• Does not include industrial, hazardous, or construction waste.

Trends in U.S. Waste Generation

Adopted from EPA 2011 MSW Facts and Figures

Trends in U.S. Waste Recycling


Current U.S. waste treatment

Adopted from EPA 2011 MSW Facts and Figures 8

136 million tons

Total: 250 million tons

29 million tons

20 million tons

65 million tons

%

%

%

%

Source of MSW?

• Residential waste (houses and apartments): 55-65% of total MSW generation

• Commercial and institutional locations (businesses, schools, hospitals..): 35-45%

Materials in MSW? • Dominated by organic matter, biodegradable

Products in MSW?

Durable vs non-durable goods.

• A durable good or a hard good is a good that does not quickly wear out, or more specifically, one that yields utility over time rather than being completely consumed in one use.

• Examples: Bricks, refrigerators, cars, or mobile phones, cars, household goods (home appliances, consumer electronics, furniture, etc.), sports equipment, and toys.

• Nondurable goods or soft goods (consumables) are immediately consumed in one use or ones that have a lifespan of less than 3 years.

• Examples: cosmetics and cleaning products, food, fuel, beer, cigarettes, medication, office supplies, packaging and containers, paper and paper products, personal products, rubber, plastics, textiles, clothing and footwear.

Source: Wikipedia

Products, Million tons, 2010

Recycling Rates of Selected Products


Products with highest % recovery.

• Lead acid batteries, 96%

• Corrugated boxes, 85%

• Newspapers, 72%

• Steel packaging, 69%

• Major appliances, 65%

• Yard trimmings, 58%

• Aluminum cans, 50%

• Mixed paper, 45%

Source: Wikipedia

Landfill: an introduction

Landfill Cross Section (simplified)

Water Table

Liner System

Leachate Collection System

Cover System

Monitoring Wells Gas Collection

Waste

Vegetation

Morton Barlaz, CE, NCSU

Decomposing Waste

Residential Industrial

Commercial Biosolids

Stored Carbon

Leachate (CO2, VOCs)

CO2, Energy Offset

Capture

Gas (CH4, CO2, VOCs)

Fugitive

Emissions

Carbon Flow In Landfills


Carbon Footprint

CO2e = fugitive methane emissions + emissions associated with construction,

operation, post-closure and leachate treatment - avoided emissions from energy recovery - carbon storage Notice: CO2 emissions from decay are not counted (biogenic).

Fugitive methane emissions =

CH4 prodn. * (100- % collected) * (100- % oxidized)


22

Biodegradable Substrates

• Paper, yard waste and food waste are comprised of cellulose and hemicellulose

• These compounds are converted to CH4 and CO2 by bacteria under anaerobic conditions

• Several groups of bacteria are involved


23

Refuse decomposition is affected by: – Climate, surface hydrology, pH, temperature,

operations

Exerts an influence on: – Gas composition and volume

– Leachate composition

Refuse Decomposition


Reactor Data: Methane Yields

(C6H10O5)n + nH2O 3n CO2 + 3n CH4

(C5H8O4 )n + nH2O 2.5n CO2 + 2.5n CH4

Cellulose:

Hemicellulose: 0

50

100

150

200

250

300

350

New

sprin

t

Office

OCC

Coat

ed P

aper

Bra

nches

Gra

ss

Leav

es

Food

Hard

woo

d

Sof

twoo

d

Plywood

(SW

)

OSB

Par

ticle B

oard

Med

ium

Dens

ity F

iber

boar

d

CH

4 y

ield

(M

3 C

H4/d

ry M

g)


Copyright Morton A.

Barlaz, NC State

University

25

Methane Production Rate Curve for One Year of Waste

Based on 286,000 short tons of refuse at time zero

and Lo = 1.5 ft3/wet lb (93.5 m3/wet Mg)

0.00E+00

5.00E+05

1.00E+06

1.50E+06

2.00E+06

2.50E+06

3.00E+06

0 25 50 75 100

Time (Yr)

Meth

an

e R

ate

(m

3/y

r)

An example: Paper Recycling

• Paper is collected and sometimes sorted

• The paper is slushed into water, separating fibers, pulping

• Contaminants are removed – Screening – Centrifugation – Washing – Bleaching – Others

• Fibers are then re-made into paper

Source: afandpa.org, 2011

US Paper Recycling Recovery Rate:

• 1999 – Total Paper Consumption: 105 million tons – Total Paper Recovered: 47 million tons – Recovery Rate: = 45%

• 2004 – Total Paper Consumption: 102 million tons – Total Paper Recovered: 50 million tons – Recovery Rate: = 49%

• 2011 – Total Paper Consumption: 79 million tons – Total Paper Recovered: 53 million tons – Recovery Rate: = 66.8%


Record high 66.8% RR.

Paper purchases declined (2.3 million tons) while recovered paper increased 1.3 million tons.


Paper/board Recovery Rate in the US:


Recovered and Landfilled Paper

Where Recovered Paper Goes:


19 MMT used domestically, 8 MMT exported,

Purchases increased 7.2% in 2010, Recovered OCC increased by 11.2%


Recovery of Corrugated Containers (OCC)

Includes ONP, uncoated mechanical, and coated ONP inserts.

7.5% decrease in consumption of ONP


Recovery of Old Newspapers (ONP)

Purchases of PW Papers declined by 5%.


Recovery of Printing-Writing Papers

End of Life Example: Catalog Paper

Carbon footprint

End of life: Catalog Paper

Source: NCASI

End of life: Printing and Writing Papers

Paper product Recovery Landfill* Burning and

energy recovery*

Office paper 71.8% 23.0% 5.2%

Catalog 32.7% 54.8% 12.5%

Telephone directory

19.1% 65.9% 15.0%

Magazine 38.6% 50.0% 11.4%

* Landfill and burning and energy recovery ratios are based on U.S. average for all municipal solid waste in 2006 (81.4% landfilled, 18.4% incinerated).

Table 4-5. End-of-Life of Printing and Writing Paper Products

Life Cycle Inventory: End of Life: Carbon in Products

• How much carbon exists in products. Needed for end of life and carbon storage in products. • Half life, number of years for the existing paper in use to halve itself • C permanently stored (in landfills)

Product Carbon content

(fraction)

Half-life

(years)

Carbon permanently

stored

(fraction)

bleached kraft board 0.50 2.54 0.12

bleached kraft paper (packaging &

industrial) 0.48 2.54

0.61

coated mechanical 0.50 2.54 0.85

coated woodfree 0.50 2.54 0.12

average containerboard 0.50 2.54 0.55

newsprint 0.46 2.54 0.85

recycled boxboard 0.50 2.54 0.55

recycled corrugating medium 0.50 2.54 0.55

32.7% to Recycle

12.5% Burning with Energy Recovery

54.8% to Landfill

X % stored as permanent Carbon (100yrs)

Methane

CO2 Burnt for Electicity

Emissions

How important is end of life?

-1000 -500 0 500 1000 1500 2000 2500 3000 3500 4000

Carbon footprint (kg CO2 eq./BoC)

Total emissions, including transport (kg CO2 eq./BoC):

Of which, total transport (includes all transport components):

Emissions from fuel used in manufacturing (including transport)

Emissions from purchased electricity and steam

Emissions from wood and fiber production (including transport)

Emissions from other raw materials (including transport)

Emissions from manufacturing wastes

Emissions from product transport

Emissions from end of life (including transport)

Total carbon storage changes (kg CO2 eq./BoC)

Changes in forest carbon (kg CO2 eq./BoC)

Carbon in products in use (kg CO2 eq./BoC)

Carbon in landfills from products at end of life (kg CO2 eq./BoC)

Carbon in mill landfills from manufacturing wastes (kg CO2 eq./BoC)

Ctd Mech

Ctd Free

How important is end of life? (ctd free = catalog)

Fuel Mfg End of Life

Paper Recycling: Other environmental impacts (avoid parts thinking):

Life Cycle Inventory: End of Life

• Allocations in recycling.

Two Main Allocation Situations:

• Recycling Allocation: a virgin product is recycled or re-

used in a subsequent life

– There exists operations that are required by the virgin and the

recycled products (shared operations)

– Example shared operations: virgin raw material production,

final disposal

– Many ways to allocate the burdens of the common operations

• Open loop recycling allocation is the most controversial

issue in LCA currently!!!!

43

Closed and Open Loop Recycling:

• Closed loop: material or products are returned to the same

system after use and used for the same purpose again

(Baumann, Tillman, 2004)

• Open loop: a product is recycled into a different product

44

Production of P Use Product Disposal

Production of P Use of Product A Disposal

Production of Product B Disposal

Recover

Recover

Allocation Methods in LCA:

• Example: virgin paper recycled twice and then disposed.

Closed loop recycling example with products P1, P2, and P3.

45

Primary material production

(V1)

Production of Product P1

(P1)

Use of Product P1

(U1)

Recycling of Product P1

(R1)


(P2)

Use of Product P2

(U2)

Recycling of Product P2

(R2)


(P3)

Use of Product P3

(U3)

End of life(W3)

Allocation Methods in LCA:

• Example: virgin paper recycled twice and then

disposed. Closed loop recycling example.

46

Raw Matl Virgin Prod Collect/transp Recycle

Process

Collect/transp Recycle

Process

Waste

Mgmt

V1 P1 R1 P2 R2 P3 W3

Shared

Operation

Potentially

Shared

Operation

Potentially

Shared

Operation

Not Shared

Operation

Potentially

Shared

Operation

Not Shared

Operation

Shared

Operation

CO2e

Lb/ton

product 300 3000 230 3350 230 3350 2500

CO2e

ton/ton

product

.15 1.50 .12 1.68 .12 1.68 1.25

Table 7. Net GHG of office paper from various life cycle stages from the Paper Task Force (2002, pg. 132), waste management is 80/20 landfill/incinerate.

Allocation Methods in LCA: • Choice of allocation method determines whether virgin or recycled

products are promoted:

• Recycled result is the average of products 2 and 3.

47

0

1000

2000

3000

4000

5000

6000

7000

Cutoff MLWMBR 50/50 Closed LoopRecycling

Quality Loss RMAGWT

Virgin Burden Recycled Burden

Net

GH

G, l

b C

O2

eq/t

on

Paper Task Force

Shared Burden

Homework assignment #6

• Using the methods described in HHG to LCA, page 114-119, verify the preceding results.

• Show the individual results of product 1, 2 and 3 and also the average of the two recycled products, 2 and 3, which is the data that appears in the bar graph.

• Show all work.

Summary

• Waste management hierarchy • Biodegradable waste • Inert waste • Municipal solid waste • Durable goods • Non-durable goods • Fugitive Methane Emissions • Steps in Paper Recycling • Recovery Rate • Closed loop recycling • Open loop recycling • Shared operations • Allocation

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