As we saw in Section 16.4, performing a full LCI/A can be very time consuming, and such a study normally requires an extensive collection of data and a large database. When the results of LCI/A are intended for process or product development decision making, producing a full LCI/A is not always feasible due to limited data availability during process development.
Waiting to obtain a complete and well-validated data set that could stand up to the full rigor of
an LCA would very likely mean that assessment results would be produced long after any potential recommendations could be put to good use. At the same time, the most efficient and cost-effective time to introduce sustainability considerations into a process, product, or activity is precisely during development. In addition, the more holistic these considerations are (i.e., with life cycle thinking integrated), the greater the likelihood that the process, product, or activity will be aligned to the principles of sustainability.
One way to address this dilemma is to use a simplified or streamlined life cycle assessment method. According to SETAC, a streamlined LCA applies LCA methodology and covers the same aspects, but at a higher level. Thus, instead of using site-, time-, mode-, and technology- specific data throughout the assessment, a streamlined LCA would tend to use generic background data or standard modules for transportation, waste treatment, and energy production to conduct a simplified assessment that focuses on the most important phases or impacts. One would then assess the reliability of the results with uncertainty and sensitivity analysis.
Most simplified LCAs consist of three phases: an initial screening to determine the main points of focus; a simplification phase that uses the results of the screening to determine which areas can be simplified and which need more in-depth assessments, and a quality analysis phase that assesses the reliability of the results. As is common with a full LCA, a streamlined LCA can be used iteratively to identify those parts of the system that require further assessment, or it can be used to determine indicators, as a prior step to performing a full LCA, as a complementary study to a full LCA, or as a basis to evaluate similar systems in a faster manner. As might be expected, the quality analysis phase is a very important part of any streamlined LCA because as one streamlines the study the uncertainty increases, and there is an increased chance of obtaining significantly different results than would be obtained with a full LCA. However, there are many occasions where the risk associated with a streamlined LCA is acceptable, as in the case of process and product development, when there are insufficient data to perform a full LCA, when the time lines required to complete a full LCAwould hinder the integration of any results into the improvement assessment, when the effort is better spent on the most important subsection of the LCA, and so on. Given the increased importance of streamlined LCAs, some general guidance has been proposed by Hunt et al. for how to conduct streamlined LCAs and how to select a streamlining method so as to reduce the potential for error.43
One example of the application of a streamlined LCA is given in Chapter 6. In Figure 6.8 a company-specific solvent selection guide is shown. It can be seen that there is a column that ranks the life cycle profiles of the solvents against each other. Although there is underlying rigorous LCI data behind the one-digit comparative rankings, the final user is given a streamlined way to quickly assess and compare the life cycle effects of the solvent choice.
Another industrial example of a streamlined LCA tool is shown in Figure 16.17. This streamlined LCA tool is used to compare the life cycle impacts of materials used in synthetic chemistry routes and was designed based on a full LCA of an active pharmaceutical ingredient. The scores are shown on a scale of 1 to 5 (1, lowest impact; 5, highest impact), and the user is able to obtain a quick, high-level benchmark of the impacts of the materials used in the synthetic route. This assessment is typically performed in less than 30 minutes.44 Example 16.6 Ionic liquids have been of great academic interest as a means of avoiding some of the environmental impacts associated with organic solvents, such as those having high volatilities or high POCP. However, there have been many questions about whether or
not and to what extent they are truly green, due to toxicity and life cycle footprint concerns.
Use a streamlined life cycle assessment method to aid in optimization of the alkylation step of the production of 1-hexyl-3-methylimidazolium chloride fromN-methylimida- zolium:
N N H3C
C6H13X
X = halogen, Br, Cl N N
H3C C6H13 X–
+
Solution This reaction has been studied within a life cycle framework to help design an alkylation step having the smallest environmental footprint and the example is reported in the literature.45The researchers utilized the ECO method, a streamlined life cycle assessment method that seeks to combine environmental impact and cost optimization of chemical synthesis at the R&D stage. It utilizes three objective functions to account for the effects of materials, reaction, separation, use of products, and disposal:
. Energy factor(EF): assessing cumulative energy demand
. Environmental and human health factors (EHF): assessing environmental and toxicological aspects
. Cost factor(CF): intending to assess life cycle costing aspects (see Chapter 20 for more details)
The three objective functions are minimized to obtain the best parameters for optimizing the synthetic route. For this reaction, the initial experimental parameters were evaluated to obtain the conditions that minimized energy use, environmental and human health impacts, FIGURE 16.17 Output of a streamlined life cycle assessment tool used to compare the impacts of materials of synthetic chemical routes. The scores shown are on a 1 to 5 scale (1, lowest impact; 5, highest impact). The percentages over the bar charts show the relative average improvement on the environmental life cycle impacts of the materials.
and cost. The conditions evaluated were reaction temperature, types of solvents, initial reactant concentration, molar ratio (N-methylimidazolium/alkyl chloride), and reaction time. After the optimization procedure, the results given in Table 16.7 were found for the reaction conditions.
Additional Points to Ponder Are ionic liquids green? Why or why not? What other factors would you consider in this streamlined LCA? Do you see any issues with the proposed optimal reaction parameters?
The importance of streamlined LCAs has increased over the past decade and the development and application of reliable streamlined methods is one of the main areas in the LCA arena that would improve the uptake of LCA significantly in the research, development, and industrial sectors in general. Many streamlined life cycle assessment methods have been developed in industry and academia,46–55reflecting the generalized need for adequate LCA screening methods and indicators.
In Chapter 17 we explore the application of several examples of streamlined LCA to evaluate the environmental footprint of materials in the supply chain and to help us understand the impacts associated with the transportation of goods. In the following chapters we present additional examples of applying streamlined (simplified) LCA to cover several of the big building blocks of a life cycle inventory, such as energy production (Chapter 18), waste treatment (Chapter 19), and life cycle costing (Chapter 20). These separate LCA assessments can be used in a modular form as building blocks that simplify the work of conducting a life cycle assessment either through streamlining it or having ready-to-use modules that would reduce the time needed to perform a full life cycle assessment.
PROBLEMS
16.1 Provide three examples in which a full cradle-to-grave boundary might be unnecessarily wide.
16.2 Provide three examples in which a cradle-to-gate boundary might be too limited for a life cycle assessment.
16.3 What functional unit would you propose to compare the life cycle impacts of two types of paint used for car painting and water protection? Explain why.
16.4 What functional unit would you propose to compare two light bulbs? Explain why.
16.5 Define your data quality goals for the life cycle inventory to be developed for Problem 16.3.
TABLE 16.7 Reaction Condition Results
Reaction Conditions Reduction of Factors
Temperature: 80C EFẳ78%
Time: 30 h EHFẳ98%
Molar ratio (N-methylimidazolium/alkyl chloride): 1 : 1.2 CFẳ87%
Concentration of theN-methylimidazolium: 3 mol/L Solvent:n-heptane
Problem 16.4.
16.7 Describe what type of issues can arise from allocation methods when conducting a life cycle inventory in a multiproduct facility.
16.8 Develop a chemical tree to produce hypochlorous acid, following the process described in Example 9.5.
16.9 Develop a chemical tree to produce ethanol:
(a) Using bioprocesses (b) Using a synthetic route
16.10 What would you suggest doing when characterization factors are lacking? Provide examples.
16.11 Estimate the global warming potential, ozone depletion potential, photochemical ozone creation potential, acidification potential, and eutrophication potential for the results of Example 16.2 using the characterization factors in Tables 3.1 through 3.5.
16.12 Table P16.12 shows the cradle-to-gate life cycle inventory results for the production of 1000 kg of acetaldehyde. Estimate the global warming potential, ozone depletion
TABLE P16.12 Cradle-to-Gate Results
Total Raw Material (kg)
Air 6.18102
Alum 3.74102
BaCO3 7.14102
Chlorine 4.38
Crude oil 8.59102
Ethylene 7.41102
Hydrofluosilicic acid 5.31103
Hydrogen chloride 1.7410
Lime 2.43102
Na2CO3 2.41102
Naphtha 8.37102
Oxygen 4.48102
Salt rock 6.04
Sodium chloride 9.66
Sodium hydroxide 1.8110
Water for reaction 2.99
Water, including water for reaction 1.33103 Energy [MJ]
Coal 1.25102
Cooling water 2.1010
Diesel 1.35103
Electricity 2.49103
Heating fuel 1.4610
(continued)
TABLE 16.8 (Continued)
Total
Heavy oil 1.18103
Hydro power 8.37
Natural gas 2.80103
Nuclear power 8.37
Potential energy recovery 4.65103
Refrigeration 5.63102
Steam 1.18104
Total 7.77103
Air Emissions (kg)
1,2-Dichlorethane 9.55102
Acetic acid 1.15
Acetaldehyde 4.2210
C2H6 5.93101
CH4 6.08
Cl2 2.44101
CO 1.9310
CO2 1.43103
CxHy 1.85
Ethylene 6.72
Ethylene chloride 2.9610
H2 7.90
H2S 2.5010
HCl 9.86102
HOCl 1.73104
NMVOC 1.0410
NOx 7.22
SOx 5.59
Vinyl chloride 1.93102
Water Emissions (kg)
Acetaldehyde 4.2210
Acetic acid 1.09102
BaSO4 4.18102
BOD 2.74101
CaCO3 1.78102
COD 1.95102
Hg 3.12106
Mg(OH)2 2.98103
Na2S 6.30
TDS 4.73
TOC** 6.6810
Wastewater 1.31103
Solid Waste (kg)
s_BaSO4(g) 4.34 102
s_CaCO3(g) 1.93102
s_Mg(OH)2(g) 4.82104
Solid waste 2.8710
TABLE P16.12 (Continued)
Total
and eutrophication potential for this system using the characterization factors in Tables 3.1 through 3.5
16.13 Table P16.13 shows the results of a gate-to-gate estimation for a plant producing ethylene glycol, diethylene glycol, and triethylene glycol. They are produced from TABLE P16.13 Gate-to-Gate Estimation
UID CAS Chemical Amount Purity (%) Units
Inputs
750-21-8 750-21-8 Ethylene oxide 799 kg/h
7732-18-5 7732-18-5 Water 310 kg/h
Total 1109 kg/h
Products
107-21-1 107-21-1 Ethylene glycol 1000 99.7 kg/h
111-46-6 111-46-6 Ethylene glycol,di 94.6 89.3 kg/h
112-27-6 112-27-6 Ethylene glycol, tri 10 91.1 kg/h
Total 1104.229894 kg/h
Amount
UID CAS Chemical Gas Liquid Solid Solvent Units
Chemical Emissions
75-21-8 75-21-8 Ethylene oxide 3.97 kg/h
107-21-1 107-21-1 Ethylene glycol kg/h
111-46-6 111-46-6 Ethylene glycol,di- kg/h
112-27-6 112-27-6 Ethylene glycol, tri- — 0.0893 kg/h
UID higher glycols
Higher glycols — 0.434 kg/h
Total 3.97 0.523 0 0 kg/h
Mass balance difference
0 kg/h
Source Amount Units Comments
Energy Use
Electricity 412 MJ/h
DowTherm 0 MJ/h
Heating steam 1.51104 MJ/h 85% efficiency has been included to determine how much steam is needed for heating process fluid Direct fuel use in high-
temperature heating
0 MJ/h
Heating natural gas 0 MJ/h
Energy input requirement 1.56104 MJ/h Electricityþsteamþdirect fuel oilþDowTherm
Cooling water 1.45104 MJ/h
the reaction of ethylene oxide and water and then separated in a separation train that produces, first, ethylene glycol, with the di- and tri- products separated from the higher glycols in two additional distillation columns. Propose a way to allocate the gate-to-gate results.
16.14 The cradle-to-gate life cycle assessment of an active pharmaceutical ingredient was undertaken and reported in the literature. The pretreatment life cycle impact assessment results are shown in Figure 16.11.
(a) What conclusions would you draw from these results?
(b) What additional questions would you have?
16.15 The post-treatment life cycle impact assessment results of the life cycle impact assessment of Problem 16.11 are shown in Figure 16.12.
(a) What conclusions would you draw from these results?
(b) How would you couple these with the results from Figure P16.10?
(c) What additional insights do post- and pre-treatment results bring to the interpretation of the assessment?
16.16 Figure 16.12 shows some results from an LCA comparing two complex compounds.
(a) What interpretations can be drawn from the data in the figure?
(b) What additional questions would you have?
16.17 You are the president of a corporation that develops, manufactures, and sells electronic equipment globally.
(a) How would you propose to include life cycle assessment in your business decisions?
(b) How would you propose to include life cycle assessment in your marketing plans?
16.18 Investigate the details of the ecoefficiency method developed by BASF and list its advantages and disadvantages.
16.19 Describe, compare, and contrast the considerations for the two mandatory LCA critical reviews: comparative assessments and environmental product declarations.
16.20 Describe the advantages and disadvantages of using streamlined life cycle assess- ment methods.
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