Chapter 10. LCA.pdf

f I G u RE 1 o. 1 Do you ever wonder what the true impacts of the choices you make are? Source: www.CartoonStock.com. For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception...

f I G u RE 1 o. 1 Do you ever wonder what the true impacts of the choices you make are? Source: www.CartoonStock.com. For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death. - ~CHEL CARSON, 1¢2 - GOALS 1)-IE GOAL OF THIS CHAPTER IS to introduce the concept of product life cycle thinking as well as present elementary principles of life cycle assessment methodologies. OBJECTIVES At the conclusion of this chapter, you should be able to: Develop an understanding of the concept Develop frameworks for and framework of life cycle assessment. conceptualizing complex materials Understand the role of life cycle balance problems.. assessments (LCA) in industrial ecology ' Model material and energy system and sustainability. · cycles. Describe the components and steps utilized Appreciate the limitations of LCA. to calculate a water footprint for a product l. , CH A PT E R 1 0 Life Cycle Analysis 10.1 Introduction In Chapt er 9, we learne d about the relatio nship betwe en te~hno lo~y and envi- ronme ntal impac ts. We also learne d about the conce pt of mdust nal metabo- lism, which is the proces s by which indust rial system s ~~nsu me materi als and energy from the enviro nment to make produc ts. In additi on to these products, a by-pro duct of indust rial metab olism is waste in the form of enviro nment al emissi ons. One of the object ives of sustai nable develo pment is to supply soci- ety's needs with minim al harm to the enviro nment and the ability of future genera tions to meet their needs. The curren t needs of societ y are met in a wide variet y of ways due to advan cemen ts in techno logy. It is a major challen ge to determ ine which of variou s option s are the least harmf ul and thus most sustain able. In the past couple · of decade s, studie s have shown that emissi ons produc ed during indust rial and techno logica l manuf acturin g are just a small percen tage of the overal l emissions that result from techno logica l produc ts. The extract ion of raw materi als, produc tion, transp ortatio n, the use and the eventu al dispos al of produ cts-al l result in emissions and variou s impac ts that have to be consid ered in the calcul ating the full impac t of techno logy on the enviro nment. There is a need for metho ds that can assess the sustain ability of differe nt techno logies or options over the entire life of a produc t. The life cycle of a produ ct is define d as "conse c- utive and interli nked stages of a produ ct system, from raw materi al acquis ition or genera tion from natura l resources to final dispos al" (ISO 14040). This has led to the use of the life cycle assess ment (LCA) , which has been define d as "the com.:. pilatio n and evalua tion of the inputs and output s and the potent ial environment al impac ts of a produc t system throug hout its life cycle" (ISO 14040, ISO 14044). In this contex t, produc t is define d in a broad sense to includ e physic al goods as well as services. As an example, your textbo oks may be printe d on paper that was produc ed from pulp that was extracted from wood obtain ed from trees using a chemic al process. After use, these textbooks may be disposed of in various ways. includi ng recycling, incineration, or burial in landfills. In addition, each of these stages require s energy drawn from various sources. Every stage in the life of your textbooks con- tribute s to the overall impact associated with the produc tion and use of textboo ks. Life cycle assessments allow us to compa re the impacts associated with differe nt produc ts or processes to determ ine which have the least impacts. It may also -allow us to determ ine which stage in the overall life cycle of produc ts contrib utes the most to the overall impact. The Food and Agricu lture Organ ization (FAO) of the United Nation s predict s that global meat consum ption will approx imatel y double betwe en 2001 and 2050. Consid er this: An averag e of 18 % of global greenh ouse gas emissions from all human activities comes from livestock produc tion (FAO). Transp ortatio n, which includ es emissions from fuel combu stion, accoun ts for approx imatel y 14%. The equiva lent of up to 36.4 kg of CO2 are emitte d. in the produc tion of 1 kg of beef withou t consid ering the emissions from transp ortatio n and manag ing infrastr UC· ture (Ogino et al.). The livestock sector emits 37% of all anthro pogen ic meth~ e and accoun ts for 65% of anthro pogen ic nitrous oxide (NOx) , mostly coming from manur e. Metha ne and nitrous oxide have global warmi ng potent ials (GwP) of 25 and 298, respectively, as illustra ted in Figure 10.2. Life cycle assessm e_:'11 studie s can help us determ ine which processes contrib ute the most to th_ese emis- sion numbe rs.  1 0.2 Life Cycle Thinking 551 On-fann fossil fuel use (1.2%) Other (3.6%) Artificial fertilizers (including indirect) (3.4%) Deforestation and Enteric fermentation desertification by ruminants (35.4%) (25.0%) Manure (direct and indirect) (30.5%) F I G U R E 1 0. 2 Proportion of greenhouse gas emissions from different parts of livestock production..· "· ' ' ,.-'·. Source: Based " McMichael et al., Adapted from the Food and Agriculture Organ~tion.. 10.2 Life Cycle Thi.nking In Chapter 9, we est~blished that the primary goal of industrial ecology is the development of technological systems that simulate the way materials and energy are handled within natural systems, leading to minimal impacts on the sur- rounding systems. This goal requires comprehensive tracking of the way materials and energy flow through the product system - from the extraction of virgin raw material from the environment through the various stages of processing, refine- ment, packaging, sales, and use all the way to the ultimate disposal back into the environment.. Let us consider products we use and conveniences that you have become accus- tomed to. Do you ever think of _the various stages and processes th~t were required to get these to you? For example, consider what it takes to make· a peanut butter sandwich. You need just two slices of bread and some peanut butter as illustrated in Figure 10.3. ·.· + '.. ' FI G U RE 1 O. 3 Ingredients to make a peanut butter sa nd wich. Source· Ph ' oto by Bradley Striebig. 552 CH A PT ER 1 0 Life Cycle Analysis F I Gu RE 1 o. 4. A loaf of bread and a jar of peanut butter used to manufacture, or make, a. peanut butter sandwich. Source: Photo by Bradley Striebig. But bread usually isn't made in individual slices, so your slices will likely come from a whole loaf and peanut butter will likely come from a jar, both of which have greater mass than the individual sandwich, as shown in Figure 10.4. Even though sliced bread and peanut butter are readily available in supermar- kets and stores, they have to be made first. Bread is made using flour, water, and yeast. Flour is obtained from the milling of cereal grains, typically wheat. Wheat has to be grown and requires land for planting, water, and sources of plant nutri- ents, as shown in Figure 10.5.. Similarly, the peanut butter is made from crushing and grinding roasted pean~ts that also have to be grown requiring land, water, and plant nutrients, as illustrated in Figure 10.6. · F I G U R E 1 0. 5 Simplified life cycle of bread. Sources: Photo by Bradley Striebig, Andy Sacks/Photographer's Choice/Getty Images.  10.2 Life Cycle Thinking 553 + ♦ F I GU RE 1 O. 6 Simplified life cycle of peanut butter. Sources: Photo by Bradley Striebig. Rick Rudnicki/Lonely Planet Images/Getty Images, nanao wagatsuma/Moment /Getty Images, Peeler Viisimaa/Vetta/Getty Images.. Note that, ~n this example, we have ignored crucial stages and processes that mclude packagmg and transportation in addition to the processes involved in the production of the other ingredients. However, we can appreciate the concept that all products come to us through processes that we often do not think about while we use the products. · Consider the following requirements for manufacturing a peanut butter sand- wich (National Peanut Board, 2014). It takes about 540 peanuts to make a 12-ounce jar of peanut butter. There are enough peanuts in one acre to make 30,000 peanut butter sandwiches. · The average American consumes more than six pounds of peanuts and peanut butter products each year.. The average child will eat 1,500 peanut butter and jelly sandwiches before he/she graduates high school. Americans consume on average over 1.5 billion pounds of peanut butter and peanut products each year. ,, Peanut butter is consumed in 90% of U.S. households.. Americans eat enough peanut butter in a year to make mo~e than 10 billion peanut butter and jelly sandwiches. The amount of peanut butter eaten in a year c~ul~ wrap the Earth in a ribbon of 18-ounce peanut butter jars one and one-third times... Peanuts account for two-thirds of all snack nuts consumed m the Umted StMes.. Peanut butter is the leading use of peanuts in the United States. Each of the process steps considered in making peanut butter involves the use of materials and energy and may generate wastes, as illustrated in S54 CH A PT E A 1 O Life Cycle Analysis Distribution center Jar i-------t _T , manufacture..., Ud manufacture Retailer User T. Cardboard Carton Carton Municipal ackaging recycling waste (!) = Transponation FI GU RE 1 O. 7 The life cycle of packaged peanut butter. Source: Bradley Striebig. Figure 10.7. We must also consider the potential impacts associated with eating a peanut butter sandwich, possibly relating to the use of Jertilizers, herbicides, and pesticides· in crop production. Considera tion of unintende d consequences and impacts associated with products and manufactu ring are presented in the cartoon presented in Figure 10.8, which illustrates the impacts associated with using ethanol as a gasoline additive. Figure 10.9 shows a simple schematic of the inputs and outputs from a single stage in a product life cycle system. This is the basic building block of life cycle assessments. Figure 10.10 shows the connected multiple stages in the life cycle of a product. Electrical energy is generated from other forms of energy in facilities called power plants and must be transmitted through high-voltage wires to local utility companies before being transmitted to useful electricity for work in _our homes, schools, and offices. Carbon-ba sed forms of chemical energy such as coal, petro- leum, and natural gas are combusted to generate heat, which in turn generates electrical energy. The combustio n of these fossil fuels generates CO that h~s 2 been linked to global climate change, as discussed in Chapters 6 and 8. nus means that when generated form fossil fuels, every unit of electrical energy we use has a direct impact on the global climate. Companie s may market "zero emissions" electrical processes as illustrated by the cartoon in Figure 10.11, but this is deceptive marketing since the production of electricity has measurable environme ntal impacts. In technological systems, all raw materials are initially extracted from the envi- ronment in one form or another. The environment is often called the cradle; the source of all materials. These materials are processed in various industrial stages  10.2 Life Cycle Thinking 55S ·/PESTICIDES ETHANOL SAVES OIL ANO REDUCES POLLUTION I 1. ~c~e~:r:p;~i~:. Cartoon showing the complexity of choices that become apparent from a life Source: Andy Singer Cartoons http://www.andysinger.com/. I FI GUR E 1 o. 9 Simple schematic of a single stage In a product Source: Bradley Striebig. and processes called gates and are ultimately disposed into the environment. The methods and location of waste disposal are often described as the grave for the ~aste material. Thus, the environment is both the cra_dle ~d _the grave. The changes hat occur to materials from cradle to grave and the unplications of extraction pro- · and disposal can be evaluated using life cyd e assessment (LCA). cessing, ' 556 ◄ CH A PT ER 1 0 Life Cycle Analysis - Waste Wnstc Waste Waste Wnste nnd. and and and and emission~ emissions emissions emissions Raw mmriala I I I I Production t, Transportation.t Use t 1.I~-: I t ! t Energy I I I I Energy Energy Waste Energy Energy I I and I emissions I I I I I I I I ------------------------ Recycling i ◄ -----------------J t Energy. ( F I G U R E 1 O. 1 O A simple schematic of the life cycle of a product. Source: Bradley Striebig. NUCLEAR THESE HYDROGEN FUEL CELL CARS ARE ENTIRELY POLLUTION FREE! F I G U R E 1 o. 1 1 A cartoon showing how life cycle assessments may reveal unapparent Impacts. Source: Andy Singer Cartoons http://www.andysinger.com/.  10.3 Life Cycle Assessment Framework 557 LCA is an _objecti~e process used to quantitatively evaluate the environmental burdens associated with a product, process, or activity throughout its entire life cycle (through the cradle, through all the gates, to the grave). It utilizes various mass and energy_ bala?ce protocols as well as environmental impact evaluation techniques described m Chapters 3 through 8 to model the associated impacts across every stage of the life of a product. This may include the impacts associated with processing materials as well as the impacts associated with subsidiary actions. for example, in the extraction of natural resources, LCA includes the impacts associated with the extracted materials as well as the impact associated with the extraction precess. · Consider the cutting of trees to make wood products. Toe impacts associated with this acttvity include the environmental impacts from the loss of the trees as well as from the logging technology itself. Depending on the objective for which an LCA is performed, the scope may range from 1. Raw materials extraction to the disposal of finished goods (i.e., cradle-to- grave) 2. Raw materials extraction to finished goods (i.e., cradle-to-gate) 3. One processing stage to another (i.e., gate-to-gate) 10.3 Life Cycle Assessment Framework.- An LCA contains three phases: goal and scope definition, inventory analysis, and impact analysis, and each phase is followed by interpretation according to the gen- erally agreed structure shown in Figure 10.12. · ·· · 10.3.1 Goal and Scope Definition Toe goal specifies the ~easons for carrying out the LCA. The goal is important because the parameters to be used in the assess~ent are.usually depeI>:de~t on what the intended objectives are. The goal also specifies the mtended application of the LCA as well as the intended audience... Toe scope helps to establish the system boundaries and the limits of. th_e LCA. p 0 ·r example, if an LCA is to be performed_ to compare pr?ducts, 1t 1s usually not the products themselves that are the basis of the comparison but the FIG u RE 1 o·. 1 2 The LCA Framework. ,: 7 vironmental management, Life cycle assessment - Principles and framework. Source: Based on ISO 14040'.2006 E 0 558 C H A p T ER 1 0 Life Cycle Analysis lied the functional unit is defined functions they provide. So a useful term ca n the scope. bl" h basis for comparison of two products The functional unit is used to esta is a h oduct achieves that fun ti by identifying a common function and how eac pr bl d fulc on..... u·t t·ve and measura e, an a care and over its hfe. The functional urut 1s quan a 1 ·...... l ·t · crucial particularly if the LCA 1s USed proper identification of the functiona um 1s , for comparisons.. For exampl~, if an LCA is to be perfo~med comparmg reusable. plastic cups and disposable paper cups, it would be m~orrect. to compare ~he imp_acts associated with one paper cup and those a~sociate~ with one plastic cup sm~e the plastic cup will continue to perform its function. after the pap~r cup 1s discarded. Rather, it will be more appropriate to determme how ~any t11:11es one plastic cup will be used before disposal and to calculate the _eqmva.lent number of paper cups to fulfill the same function. So the co_mpanson_will be of the impacts associated with one plastic cup an_d the functional eqmvalent number of paper cups. Another example involves comparing the life cycle impact of incandescent bulbs and compact fluorescent lamps. One fluorescent lamp uses significantly less energy than an incandescent bulb to produce the same amount of visible light. Since the function of the bulb and the fluorescent lamp is to produce light, it would be incorrect to compare a 40 W incandescent bulb to a 40 W fluorescent lamp. From Table 10.1, we see that a 9 W fluorescent lamp produces approxi- mately the same amount of light as a 40 W bulb. So the functional unit would be the amount of visible light required, and then LCA would be performed comparing the number of incandescent light bulbs and compact. fluorescent lamps required to provide the required amount of light. However, a fluorescent lamp also lasts significantly longer than an incandescent bulb, so one would have to use multiple incandescent bulbs over the lifetime of one fluorescent lamp. Incandescent light bulbs are typically rated to last an average of 1,000 hours, while compact fluorescent lamps are rated to last up to 8,000 hours. This means that, in addition to comparing the two choices based on the amount of light that is needed, the functional unit will also include the length of time that the light will be provided. · [";ABLE 1 o. 1 Energy consumption of incandescent bulbs_and compact fluorescent lamps MINIMUM LIGHT OUTPUT ELECTRICAL POWER CONSUMPTION (Watts) (Lumens) INCANDESCENT COMPACT FLUORESCENT _ 450 800 40 60 9-13 - 1,100 13-15 - 75 18-25 - 1,600 2,600 100 23-30 - 150 30-52 - Source: USEPA, https://www.energystar.gov/index.cfm?c-cfls.nr ~ - cf\s_1umens. :J  559 1 o.3 Life Cycle Assessment Framework So, consider that our functional unit is 450 lumens of lightfior 5 000 hours. For this we would compa · re theli life cycle lillpact ' · W d of one 9 W compac t fluorescent lamp to five 40 mean escent ght bulbs. 10.3.2 Inventory Analysis ls and Inventory ~nalysis involves determ ining the quantit ative values of the materia within the life cycle. This include s the energy mputs and output s of all process stages Raw materia ls/ener gy needs Manufa cturing process es Transp ortation , storage , and distribu tion require ments Use and reuse... Recycle and end-of-life scenarios such as incineration and landfilling Invento ry analysi s is usually initiate d with a flowchart or process tree identi- energy fying the relevan t stages and their interrelations. Releva nt materia ls and data are then collect ed for each process stage using materia ls and energy balance cal- protocols to accoun t for unknow n values. Standa rdized units are used to make that the system bounda ries culations and compa risons easy. It is also in this phase LCA are determ ined. necessary to meet the predete rmined goal and scope of the e, if The system bounda ries are the limits placed on data collection. For exampl some life the goal of the LCA is a compar ative study of two produc ts for which values, cycle stages are the same with the same materials and energy input-o utput be drawn to exclude the data related to those then the system bounda ry_may burden the LCA withou t providi ng additio nal stages. Includi ng these would only information. · 10.3.3 Impac t Assessment Impact assessment entails determining the environmental relevance of all the inputs and outputs of each stage in the life cycle. This includes the environmental nt impacts associated with the production, use, -and disposal of the products. Releva on impact categories are selecte d such as degradation of ecological systems, depleti e, if of natural resources, and impacts on human health and welfare. For exampl we conduc ted the LCA of paper-b ased textboo ks, exampl es of ecologi cal systems als degradation can include the impact of cutting trees as well as the impact of chemic Trees as natural resourc es are renewa ble discharged during pulping on water quality.. The but not replace able rapidly enough to immediately offset the impact of logging ions directly connec ted to impact of the chemicals used on the health of the populat the paper processing industries will also be assessed. 10.3.4 Interpretation - LCA results present the opportunities to reduce or mitigate identified environ product s. The mental impacts arising from the manufacture, use, and disposal of less product design may be changed; the materials used may be replaced with d based impactful materials; and the entire industrial process may even be change ly on the results of an LCA. The LCA represents the most objective tool current and available to inform decisions on the environmental sustainability of products processes.  scce. ◄ 560 CHAPT ER 1 0 Ufe Cycle Analysis 10.4 Materials Flow Analysis Materials Dow analysis is a method that can be used to develop the inventory for an LCA. It is used to evaluate the metabolism of anthropogen ic systems. It is a sys- tematic assessment of the flows of materials within the boundaries of a system in space and time. Materials flow analysis relies on the law of conservation of mass and is performed by simple mass balances comparing inputs, outputs, depletions, and accumulations within systems and subsystems. Some relevant terminologies that are used in materials flow analysis are Materials: Substances as wells as goods. Process: The transport, transformation, or storage of materials. Reservoir: A system that holds materials. It can be a source, from which materials come, or a sink, into which materials go, or both. Stocks: The quantity of materials held in reservoirs within a system. Flows/Fluxes: The ratio of the mass per time that passes through a system boundary is termed the flow while the flux is the flow per cross section. Consider the reservoir system shown in Figure 10.13, where m1,1 and mi.2 are mass flows into the reservoir; m and m0.2 are mass flows out of the reservoir; 0 ,1..1m, is the change in quantity of stock in the reservoir; and m, is the rate. of change of 'stock in the reservoir. Let us recall the general mass balance equation: _ Input - output = accumulation (10.1) For a steady-state system, accumulation will be zero and Input = output (10.2) but steady-state systems are rare. Solving the mass balance for the reservoir: _"1J m = m ~ m. - "" "" I O I (10.3) By definition, 11m, m,=- dt (10.4) F I G U R E 1 O 1 3 A materials reservoir system showing input and output flows. Source: Bradley Stricbig. m1.1  -- 10.4 Materials Flow Analysis 561 Combining the two equations Am,= (~,;.,; - ~ nicJdt (10.5) The change in the s~ock in a reservoir is given by the expression Am,= J::(~m, - ~ mJd, (10.6) 10.4.1 Efficiencies in Mass Flow Systems One of the applications of mass flow analysis in industrial systems is the ability to track how much ~f the original materials going into the process actually end up as part of the desrred product stream. Applying the principles of conservation of mass to the system shown in Figure 10.10, we can see that only a portion of the raw materials entering the system becomes the product, while the rest ends up in the waste streams. Toe efficiency of the process is defined as the ratio of the mass in the desirable product and the total mass entering the system. For a 100% efficient system, no emissions are generated, and all of the raw material is converted to useful product. This is probably not a realistic goal for industrial systems. A more feasible aspiration is for industrial systems to mimic a type II biological ecosystem as defined in Chapter 9, in which limited waste is generated across the entire industrial systems. Figure 10.14 represents a typical industrial materials flow system of a substance where m E' is the mass of the substance in raw materials extracted and processed m M' is the mass of the substance in materials sent to product manufacturing m p t is the mass of the substance in the consumer product m D' is the mass of the substance recovered after consumer use m R' is the mass of the substance in recycled material wE' is the mass of the substance in the waste from extraction and processing w is the mass of the substance in the waste from product manufacturing M' w is the mass of the substance of the unrecovered waste after consumer use P' w is the mass of the substance of the waste from recycling R' w is the total mass of the substance in all waste streams - V. I W5 ----------------------------- ,-.-s,=._..~~ ' I r-~-!fd~mi!=~=-!~:!R.. ~~-----, I I ! o-~- - -~ mp I I I I Wp _ _ ____ _ II II I I I I I I I WR I ~------------------------------------- F I G u R E 1 o. 1 4 Materials flow system of a substance In an Industrial system. Source: Bradley Stricbig. 562 C H APT ER 1 0 life Cycle Analysis The efficiencies of each stage within the system can be define d as 111M ,nM Extraction efficiency: Eorr = + nt R = m + w (10.7) mB M B mP mP Manufacturing efficiency: M.rr = - = m P + wM (10.8) mM. mo mo Recovery efficiency: D.rr = - = + wP (10.9) mP mp.. mR mR Recycbng efficiency: R er, = - = mR + WR (10.10) mo In each stage, reducti on of the mass in the waste stream increas es the efficien cy of that stage. The system efficiency can be calcula ted as (10.11) (10.12) The most efficient system will be the one in which the total waste emitte d from the system is minimal. The reuse factor is defined as the amoun t of recycled materi al that can be recov- ered and used in the process to make a produc t. This can calcula ted as (10.13) Becaus e of the large values of the masses that are someti mes encoun tered in materials flow analysis, unit prefixes listed in Table 10.2 are used to make assess- ments easier. · f;A BL E 1 o. 2 Unit prefixes used in materials flow analysis PREFIX ABBREVIATION MULTIPUER VALUE kilo k 103 mega M 106 giga G 109 tera T 1012 peta p 1015 exa E 1011 zetta z 1021 yotta y 1024 Source: Bradley Strlebig. _J  10.4 Materials Flow Analysis 563 - 11,588 - 5,189 Batteries I < 5,189 ~ :§ I Li-carbonate 5,405 ,, 5,66S Glass and ceramics I. j Li-min.cone. 1,297 < 1,297 3,605 Air conditioning I ~ Spodumene 7,130 25,750 C 0 Li-hydroxide i 865 Aluminium production I