Environmental Life Cycle Assessment PSE 476/WPS 576

Transcription

1 Environmental Life Cycle Assessment PSE 476/WPS 576 Lecture 10: End of Life Richard Venditti Fall 2016 Richard A. Venditti Forest Biomaterials North Carolina State University Raleigh, NC Richard_Venditti@ncsu.edu Go.ncsu.edu/venditti

2 End of Life End of life (EOL), in the context of manufacturing and product lifecycles, is the final stages of a product's existence Recycled Materials Energy Energy Energy Energy Energy Raw Materials Production Transportation Use Disposal Recycle Waste Waste Emissions to air and water Waste Emissions to air and water Waste Emissions to air and water Waste Emissions to air and water 2

3 Waste Hierarchy

4 Reduce, re-use, recycle. Example: want to understand the burdens of using a bag to transport groceries Reduce: don t use a bag, 0 burden/trip Re-use (life cycle of a 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 requires 0.4 burdens, arbitrary value for example) Then for using the bag and recycling once: ( ) / 2 trips = 0.7 burdens/trip (data for example only, not meant to represent an actual process) 4

5 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 microorganisms 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. Waste Electrical and electronic equipment(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 pesticides, herbicides, fungicides Medical waste.

6 Types of waste. All waste can not be treated equally We must be strategic in our end-oflife decisions for products.

7 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.

8 Trends in U.S. Waste Generation EPA: Municipal Solid Waste Generation, Recycling, and Disposal in the United States: Facts and Figures for 2012

9 Trends in U.S. Waste Recycling

10 Current U.S. waste treatment 20 million tons % 29 million tons % % 136 million tons % Total: 250 million tons 65 million tons 10 Adopted from EPA 2011 MSW Facts and Figures

11 Source of MSW? Residential waste (houses and apartments): 55-65% of total MSW generation Commercial and institutional locations (businesses, schools, government, offices, hospitals ): 35-45%

12 Materials in MSW? Dominated by organic matter, biodegradable Organic matter or organic material, natural organic matter, NOM is matter composed of organic compounds that has come from the remains of organisms such as plants and animals and their waste products in the environment

13

14 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

15 Products in MSW?

16 (cont. next pg)

17 Products, Million tons, 2012 (cont. from prev pg)

18 Recycling Rates of Selected Products Adopted from EPA 2011 MSW Facts and Figures

19 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

20 Landfill: a place to dispose of refuse and other waste material by burying it and covering it over with soil

21 Landfill Cross Section (simplified) Monitoring Wells Vegetation Cover System Gas Collection Waste Leachate Collection System Liner System Water Table Morton Barlaz, CE, NCSU

22 CO2, Energy Offset Carbon Flow In Landfills Emissions Capture Fugitive Gas (CH4, CO2, VOCs) Decomposing Waste Residential Industrial Commercial Biosolids Stored Carbon Leachate (CO 2, VOCs) Morton Barlaz, CE, NCSU

23 Carbon Footprint CO 2 e = 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 = CH 4 prodn. * (100- % collected) * (100- % oxidized) Morton Barlaz, CE, NCSU

24 Carbon Footprint "the total set of greenhouse gas emissions caused by an organization, event, product or individual."

25 Carbon Footprint CO 2 e = 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 = CH 4 prodn. * (100- % collected) * (100- % oxidized) Morton Barlaz, CE, NCSU

26 Biodegradable Substrates Paper, yard waste and food waste are comprised of cellulose and hemicellulose These compounds are converted to CH 4 and CO 2 by bacteria under anaerobic conditions Several groups of bacteria are involved Bacteria: ubiquitous one-celled organisms, spherical, spiral, or rod-shaped and appearing singly or in chains, comprising the Schizomycota, a phylum of the kingdom Monera (in some classification systems the plant class Schizomycetes), various species of which are involved in fermentation, putrefaction, infectious diseases, or nitrogen fixation. (dictionary.reference.com) Morton Barlaz, CE, NCSU 26

27 Refuse Decomposition Refuse decomposition is affected by: Climate, surface hydrology, ph, temperature, operations Exerts an influence on: Gas composition and volume Leachate composition 27 Morton Barlaz, CE, NCSU

28 CH4 yield (M 3 CH4/dry Mg) 350 Reactor Data: Methane Yields Mg = 1 tonne, m3 CH4 about.6 kg 300 Cellulose: (C150 6 H 10 O 5 ) n + nh 2 O 3n CO 2 + 3n CH Hemicellulose: (C 5 H 8 O 4 ) n + nh 2 O 2.5n CO n CH 4 Newsprint Office OCC Coated Paper Branches Grass Leaves Food Hardwood Softwood Plywood (SW) Morton Barlaz, CE, NCSU OSB Particle Board Medium Density Fiberboard

29 Methane Production Rate Curve for One Year of Waste 3.00E E+06 Methane Rate (m3/yr) 2.00E E E E E Time (Yr) Based on 286,000 short tons of refuse at time zero Copyright Morton A. Barlaz, and NC State Lo = 1.5 ft 3 /wet lb ( m 3 /wet Mg) University

30 Other impacts: Toxic liquids consisting of paints, cleaning chemicals, solvents. Effect wildlife. Land take Odor Unsightly Others.

31 Waste To Energy First in 1885 in NY, NY Recognized mercury and dioxin emissions Clean Air Act 1970s and Maximum Achievable Control Technology (MACT, 1990s), many plants retrofitted or shut down Economics Plant costs million dollars Plants about tons per day Receive tipping fees Revenue from energy Revenue from ferrous and non ferrous scrap Carbon credits? 31 Morton Barlaz, CE, NCSU

32 Waste To Energy 32

33 Waste To Energy: Trade Off A typical WTE plant generates about 550 kilowatt hours (kwh) per ton of waste. At an average price of four cents per kwh, revenues per ton of solid waste would be $20 to $30. Source Is It Better to Burn or Bury Waste for Clean Energy Generation? (PDF) Typically provide a 75% weight reduction and 90% volume reduction G%20folder/Waste%20Incineration.pdf 33

34 Waste To Energy: Trade-off Gas emissions Solid emissions 34 Morton Barlaz, CE, NCSU

35 Waste To Energy: trade off 35

36 Waste To Energy 36

37 Waste to Energy

38 Recycling Single stream recycling: a system in which all paper fibers, plastics, metals, and other containers are mixed in a collection truck, instead of being sorted by the depositor into separate commodities (newspaper, paperboard, corrugated fiberboard, plastic,... (Wikipedia) Sorted stream recycling Understanding economic and environmental impacts of single-stream collection systems, Container recycling institute, Source: afandpa.org, 2011

39 An example: Paper Recycling Paper is collected and sometimes sorted Collected from municipalities, and from individual sources Brokers collect, sort, bale and re-sell to recyclers 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

40 Paper/board Recovery Rate in the US: Record high 66.8% RR. Paper purchases declined (2.3 million tons) while recovered paper increased 1.3 million tons. Source: afandpa.org, 2012

41 Recovered and Landfilled Paper Source: afandpa.org, 2012

42 Where Recovered Paper Goes: Source: afandpa.org, 2012

43 Recovery of Corrugated Containers (OCC) 19 MMT used domestically, 8 MMT exported, Purchases increased 7.2% in 2010, Recovered OCC increased by 11.2% Source: afandpa.org, 2012

44 Recovery of Old Newspapers (ONP) Includes ONP, uncoated mechanical, and coated ONP inserts. 7.5% decrease in consumption of ONP Source: afandpa.org, 2012

45 Recovery of Printing-Writing Papers Purchases of PW Papers declined by 5%. Source: afandpa.org, 2012

46 End of Life Example: Catalog Paper Carbon footprint Reference: American Forest and Paper Association (AF&PA)

47 End of life: Catalog Paper Source: NCASI

48 32.7% to Recycle 12.5% Burning with Energy Recovery Emissions Methane 54.8% to Landfill X % stored as permanent Carbon (100yrs) CO2 Burnt for Electicity

49 End of life: Printing and Writing Papers Table 4-5. End-of-Life of Printing and Writing Paper Products Paper product Recovery Landfill * Burning and energy recovery * Office paper 71.8% 23.0% 5.2% Catalog 32.7% 54.8% 12.5% Telephone 19.1% 65.9% 15.0% directory 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).

50 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 bleached kraft paper (packaging & industrial) 0.61 coated mechanical coated woodfree average containerboard newsprint recycled boxboard recycled corrugating medium

51 How important is end of life? Carbon in mill landfills from manufacturing wastes (kg CO2 eq./boc) Carbon in landfills from products at end of life (kg CO2 eq./boc) Carbon in products in use (kg CO2 eq./boc) Changes in forest carbon (kg CO2 eq./boc) Ctd Mech Ctd Free Total carbon storage changes (kg CO2 eq./boc) Emissions from end of life (including transport) Emissions from product transport Emissions from manufacturing wastes Emissions from other raw materials (including transport) Emissions from wood and fiber production (including transport) Emissions from purchased electricity and steam Emissions from fuel used in manufacturing (including transport) Of which, total transport (includes all transport components): Total emissions, including transport (kg CO2 eq./boc): Carbon footprint (kg CO2 eq./boc)

52 How important is end of life? (ctd free = catalog) End of Life Fuel Mfg

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

54 Life Cycle Inventory: End of Life Allocations in recycling.

55 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 Production of P Use Product Disposal Recover Production of P Use of Product A Disposal Recover Production of Product B Disposal 55

56 Two Main Allocation Situations: Recycling Allocation: a virgin product is recycled or reused 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 between virgin and recycled products Open loop recycling allocation is the most controversial issue in LCA currently!!!! 56

57 Allocation Methods in LCA: Example: virgin paper recycled twice and then disposed. Closed loop recycling example with products P1, P2, and P3. Primary material production (V 1 ) Production of Product P1 (P 1 ) Recycling of Product P1 (R 1 ) Production of Product P2 (P 2 ) Recycling of Product P2 (R 2 ) Production of Product P3 (P 3 ) Use of Product P1 (U 1 ) Use of Product P2 (U 2 ) Use of Product P3 (U 3 ) End of life (W 3 ) 57

58 Allocation Methods in LCA: Example: virgin paper recycled twice and then disposed. Closed loop recycling example. CO2e Lb/ton product 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 ton/ton product 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. 58

59 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 Virgin Burden Recycled Burden Paper Task Force 5000 Shared Burden Net GHG, lb CO2eq/ton Cutoff MLWMBR 50/50 Closed Loop Recycling Quality Loss RMAGWT 59

60 Summary End of Life Waste management hierarchy Biodegradable waste Inert waste WEEE Hazardous waste Municipal solid waste Durable goods Non-durable goods Recycling Waste to Energy Waste to Energy Tradeoff Landfill Carbon footprint Fugitive Methane Emissions Single stream recycling Steps in Paper Recycling Recovery Rate Closed loop recycling Open loop recycling Shared operations Allocation