Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 1 Cradle-to-Gate Life Cycle Assessment: Boral Industries Celceram ® vs. Calcium Carbonate Introduction In 2008, Boral Material Technologies (Boral) contracted Four Elements Consulting, LLC to perform an environmental Life Cycle Assessment (LCA) comparison of two materials: calcium carbonate 1 and Celceram ® , a processed fly ash that can replace calcium carbonate in polymeric applications such as filler in carpet backing. The 2008 study looked at environmental impacts of both materials on an equivalent mass basis. 2 This updated report builds upon the 2008 study by evaluating the materials in carpet backing systems so that the products can be evaluated on a functional basis. This report also addresses the 2008 study comments and suggestions from the peer reviewer (attached as Appendix B). The objective of this study is to provide good quality information on the life cycle environmental attributes of Celceram vs. calcium carbonate to support Boral’s environmentally preferred product (EPP) claim for Celceram in carpet backing. This study has been performed in accordance with the International Standardization Organization (ISO) standards for LCA, including: • ISO 14040:2006, the International Standard of the International Standardization Organization, Environmental management – Life cycle assessment – Principles and framework, and • ISO 14044:2006, Environmental management – Life cycle assessment – Requirements and guidelines. This report is intended to be shared with NSF International as a supporting document for Boral’s EPP claim. Dr. Shannon Lloyd of Concurrent Technologies Corporation performed a peer review on the 2008 study and, with the exception of some suggestions for improvement, concluded that the study met the ISO standards. According to ISO 14044, Section 6.1, the critical review process ensures the following: • “the methods used to carry out the LCA are consistent with this International Standard, • the methods used to carry out the LCA are scientifically and technically valid, • the data used are appropriate and reasonable in relation to the goal of the study, • the interpretations reflect the limitations identified and the goal of the study, and • the study report is transparent and consistent.” System Boundaries Overall System Boundaries and Functional Unit Celceram can be used in a number of applications, including polyurethanes, latex-based materials, PVC-based materials, and other thermoplastic and thermoset materials. For this study, two systems are being evaluated – Celceram vs. calcium carbonate as filler materials in 1) polyurethane (PU)-based carpet backing and 2) latex-based carpet backing. These were chosen because the data for the carpet backing systems was the 1 “limestone” in previous report. 2 Attached as Appendix A, and referred to as the 2008 study.
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Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 1
Cradle-to-Gate Life Cycle Assessment: Boral Industries Celceram® vs. Calcium Carbonate Introduction
In 2008, Boral Material Technologies (Boral) contracted Four Elements Consulting, LLC to perform an environmental Life Cycle Assessment (LCA) comparison of two materials: calcium carbonate1 and Celceram®, a processed fly ash that can replace calcium carbonate in polymeric applications such as filler in carpet backing. The 2008 study looked at environmental impacts of both materials on an equivalent mass basis.2 This updated report builds upon the 2008 study by evaluating the materials in carpet backing systems so that the products can be evaluated on a functional basis. This report also addresses the 2008 study comments and suggestions from the peer reviewer (attached as Appendix B). The objective of this study is to provide good quality information on the life cycle environmental attributes of Celceram vs. calcium carbonate to support Boral’s environmentally preferred product (EPP) claim for Celceram in carpet backing. This study has been performed in accordance with the International Standardization Organization (ISO) standards for LCA, including:
• ISO 14040:2006, the International Standard of the International Standardization Organization, Environmental management – Life cycle assessment – Principles and framework, and
• ISO 14044:2006, Environmental management – Life cycle assessment – Requirements and guidelines.
This report is intended to be shared with NSF International as a supporting document for Boral’s EPP claim. Dr. Shannon Lloyd of Concurrent Technologies Corporation performed a peer review on the 2008 study and, with the exception of some suggestions for improvement, concluded that the study met the ISO standards. According to ISO 14044, Section 6.1, the critical review process ensures the following:
• “the methods used to carry out the LCA are consistent with this International Standard,
• the methods used to carry out the LCA are scientifically and technically valid,
• the data used are appropriate and reasonable in relation to the goal of the study,
• the interpretations reflect the limitations identified and the goal of the study, and
• the study report is transparent and consistent.” System Boundaries
Overall System Boundaries and Functional Unit Celceram can be used in a number of applications, including polyurethanes, latex-based materials, PVC-based materials, and other thermoplastic and thermoset materials. For this study, two systems are being evaluated – Celceram vs. calcium carbonate as filler materials in 1) polyurethane (PU)-based carpet backing and 2) latex-based carpet backing. These were chosen because the data for the carpet backing systems was the
1 “limestone” in previous report.
2 Attached as Appendix A, and referred to as the 2008 study.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 2
most attainable from Boral’s customers. All systems have the same general system boundaries within a carpet life cycle, shown in the figure below.
Figure 1 Overall study system boundaries
Note: the “backing” process box refers to PU and latex systems with either filler choice. More detailed information on both systems is presented in the next figure and described in the Modeling and Assumptions section.
In each set of comparisons, the following key assumptions are made, according to Boral and its customers who contributed the data:
1) The mass quantity of backing applied on the carpet is the same for both the Celceram-based and calcium carbonate-based backing.
2) Performance of the finished carpet with Celceram is comparable in every respect to that finished with calcium carbonate filler, as demonstrated by routine, stringent testing by the manufacturers of the carpets containing Celceram.
Since the carpet backing is in theory a functional part of the carpet life cycle, the full carpet should be studied (per Figure 1). However, given the two reasons above – equivalent mass of backing per square area and equivalent performance – all aspects of the carpet life cycle would be identical except for the backing. So the light colored boxes in the figure – the identical processes – are not included in this evaluation since we are interested only in the net differences of the systems. Thus, the system boundaries are more precisely presented as follows, for the PU backing:
Carpet
manufacturing
Transport to
installation
Installation and
Use
Carpet EOL
Facing
components
production
Backing
components
production
Other carpet
components
production
Upstream materials production
Carpet life cycle system boundaries
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 3
Figure 2 More precise system boundaries
Functional Unit In order to conduct a proper LCA under the ISO guidelines, all flows within system boundaries must be normalized to a unit summarizing the function of the system. This allows for the comparison of different product systems that perform the same function. Once this shared function is defined, a functional unit, or reference flow, has to be chosen in order to calculate the systems on the same quantitative basis. The function of carpet backing is to provide shape, structural stability, and protection to carpets. The functional unit has been defined for this study as covering one square yard of carpet. According to Boral customers, the latex-based formula is applied at 32 oz per square yard and the PU formula ranges from 32 to 64 oz per square yard. Since the quantity of backing material for each type of formula is the same regardless of filler used, both systems are modeled as 32 oz of backing per square yard of carpet. If necessary, the results can be scaled up or down as appropriate. Cut-off Criteria ISO 14044 requires a cut-off criterion to be defined for the selection of materials and processes to be included in the system boundary. Several criteria are used in LCA practice to decide which inputs are to be studied, including mass, energy and environmental relevance. The mass criterion was applied, and a cut-off goal of 99% of inputs was defined. Detailed information on the formula ingredients of the backing systems was gathered and an effort was made to include the production of as many of these materials as possible, regardless of mass contribution, in order to capture all materials that may be environmentally relevant. Furthermore, all energy that was understood to be consumed in the systems studied has been included, except where noted. Exclusion of Data from the System Boundaries In LCA, it is typical to exclude some aspects within the set boundaries of the LCA. The scope and boundaries exclude impacts for some human activities, such as employee travel to and from work. Additionally, impacts for some of the facility construction and capital equipment are excluded, as these impacts typically are negligible when allocated
Carpet backing system boundary – PU example
Carpet Backing
with Celceram
Filler
Polyol
production
Celceram
production
Isocyanate
production
Upstream
materials
production (inputs
& outputs)
Energy production
(inputs & outputs)
Transport of
materials
32 oz in 1 sq-yd
Celceram System
Carpet Backing
with CaCO3
Filler
Polyol
production
CaCO3
production
Isocyanate
production
Upstream
materials
production (inputs
& outputs)
Energy production
(inputs & outputs)
Transport of
materials
32 oz in 1 sq-yd
Calcium Carbonate System
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 4
over the total quantity of product manufactured over the life cycle of the facilities and equipment. It should be noted, though, that capital equipment plus energy usage such as office space, plus other process inputs and outputs, have been included in the model whenever the data sets in the software do contain that information. Finally, fly ash that does not get beneficially used is not evaluated in this study. Of the 72.5 million tons of fly ash produced in 2008, 30 million was used beneficially.3 The balance was disposed of in a landfill due to poor quality or uneconomical distance to market. Celceram in polymers is not in the ACAA publication due to the relative low volume (compared to other applications). The evaluation of other beneficial uses and the environmental aspects of when fly ash is not used in end applications is out of the scope of this current work. Modeling and Assumptions
The modeling accounts for the production of each of the materials in the carpet backing and their transportation to the carpet manufacturers. Ingredients in the Backing Systems The formulations themselves have varying amounts of Celceram and calcium carbonate, and using Celceram offsets not only calcium carbonate but also sometimes other ingredients in the backing material. The table below presents the PU backing ingredients. PU-based backing is essentially made up of PU precursors (isocyanates and polyol) and the filler. Note in the tables below that the trade names have been removed to protect confidentiality, and more generic descriptors have been substituted.
Table 1 PU backing system ingredients
The latex-based carpet backing components are presented in the table below:
3 Oct 2009 American Coal Ash Association fact sheet entitled “2008 Coal Combustion Product (CCP)
Production & Use Survey Report”.
Parts per
total
% in the
backing
Parts per
total
% in the
backing
Polyol 100 23% 100 29%
Isocyanate 34 8% 34 10%
Filler: Celceram 300 69% n/a n/a
Filler: CaCO3 n/a n/a 205 60%
Totals --> 434 100% 339 100%
Backing in 1 sq-yd carpet (oz)
Filler in 1 sq-yd carpet (oz)
Celceram CaCO3
32
22
32
19
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 5
Table 2 Latex backing system ingredients
The following aspects of backing production are excluded from the modeling due to lack of available precise data pertaining to carpet backing operations:4
• Process energy at the carpet manufacturing plant to mix and apply the carpet backing during carpet manufacturing; and
• Carpet backing material losses during manufacturing. Production of Celceram, Calcium Carbonate, and Other Materials in the Backing Celceram The data for Celceram is based on the Celceram produced at Boral’s Macon, Georgia plant. The description of Celceram production is found in Appendix A, and this data has not changed except for two aspects the peer reviewer wanted addressed: particulate matter and the grid power source (Appendix B, p. 2 and p. 3, respectively). In this update, we have added particulate matter emissions attributed to Celceram production, and changed the grid power source for both Celceram and calcium carbonate to be more geographically customized. Particulate emissions. Particulate emissions from the production of Celceram have been included in the model. Boral provided the consultant with a detailed listing of particulates from each aspect and area of the plant. The particulates have been calculated using total production, control device, its removal efficiency, and emission factor. The calculations to get 1.4 E-6 and 9.2 E-7 tons of particulates and PM-10 per ton Celceram are provided below.
4 However, it is assumed that these aspects are not significant and will not affect the overall results.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 6
Table 3 Celceram production PM and PM-10
a: The emission factor comes from AP-42
5
There are no other fugitive emissions associated with Celceram. The process for Celceram is the diverting of qualified fly ash (it must originate from a particular set of collectors that tend to accumulate a higher quality parent material) to an air classifier. It is a closed loop system and generates a coarse fraction and a fine fraction of material. The fine cut is transferred into a holding silo (Silo 5) for eventual loading onto trucks or railcars bound for Celceram customers. The coarse fraction is fed back into the silo for concrete so nothing is disposed of. Grid power. The reviewer made the comment that the study would be more robust with a more specific electricity grid mix of fuels instead of average U.S. grid. Because the calcium carbonate being compared is also produced in GA (see Table 5), both the Celceram and calcium carbonate have been modeled using Georgia Power grid mix, shown in the table below.
Table 4 Electricity grid mix
GA Power6
Coal 55%
Nuclear 20%
Hydropower 4%
Natural gas 20%
Fuel oil 1%
Calcium Carbonate System The production data for calcium carbonate is described in detail in Appendix A. For clarification purposes, the European data set was used, with its energy and transportation data customized to US production.7 The EcoInvent data sets used were Limestone, milled, loose, at plant/CH U, Limestone, crushed, for mill/CH U; and Limestone, at mine/CH U. To summarize, the data for these are primary data, coming from one company in Switzerland. While EcoInvent data is generally trustworthy and of good quality, the peer reviewer pointed out a potential
5 Emission factor based on AP42-TBL 11.12-2 (Cement unloading to elevated storage silo- pneumatic),
found at: http://www.epa.gov/ttn/chief/ap42/ch11/final/c11s12.pdf. 6 Data found at: http://www.georgiapower.com/about/pdf/generating_electricity.pdf . 2005 mix.
7 The peer reviewer had noted on p. 2 (Appendix B) that the report was not clear as to which data for
total per 1 ton throughput--> 0.00000144 0.00000092
Particulate Matter (PM)
EmissionsPM10 Emissions
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 7
uncertainty issue associated with using data for only one producer and requested that a sensitivity or uncertainty analysis be performed (Appendix B, p.4). This was done, and the analysis shows the data to be quite robust. The uncertainty results are summarized in Appendix C. Polyol Data for the polyol is based on US industry-average production in the 2000’s and comes from the U.S. LCI database.8 This data is of very good quality: according to the Polyol for Flexible Foam Polyurethane Data Module Report9, data were provided by five producers in North America and represents the years 2003 and 2005. The polyol producers who provided data for this module verified that the characteristics of their plants are representative of a majority of the North American production. Data quality for the collection methods, technology, industry representation, time period, and geography were extensively assessed. Isocyanate The data for the isocyanate comes from the US LCI database, and the isocyanate used for this analysis is methylene diphenyl diisocyanate (MDI) resin. The data set includes manufacture of the resin and raw materials transportation to the plant as well as solid waste transport from the plant. The data is based on European production, but energy and transportation have been customized / adjusted for US production. Acrylic-based latex binder EcoInvent data was used for the acrylic-based latex binder, specifically the data set Acrylic binder, 34% in H2O, at plant/RER U. The data set includes manufacturing energy, production of raw materials, emissions to air, water, and waste, and includes transportation of raw materials to the plant as well as solid waste transport from the plant. The data is based on European production.
Surfactant-based dispersion agent The surfactant-based dispersion agent was assumed to be alcohol ethoxylate (AE) surfactant, and is based on the process to ethoxylate alcohols from petrochemical resources. The data for this material comes from Life Cycle Inventories for the Production of Detergent Ingredients, Report #244, Section Ecology, St. Gallen, commissioned by German Fed. Env. Agency (Berlin) and Oko Institut, 1999. Data are an average of several producers representing over 50% of European production. No other information was available on this material, but using this data is probably all right, given that it comprises less than 0.1% of the calcium carbonate-based backing. Stabilizer (alcohol ethoxylate) See above. Stabilizer (boric acid) EcoInvent data was used for boric acid, specifically the data set Boric acid, anhydrous, powder, at plant/RER U. The data set includes manufacturing energy, production of raw materials, emissions to air and water, and includes transportation of raw materials to the
8 National Renewable Energy Laboratory (NREL): U.S. Life-Cycle Inventory Database. 2005. Golden,
CO. All data from the U.S. LCI database can be found at: http://www.nrel.gov/lci/database. 9 Ibid.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 8
plant as well as solid waste transport from the plant. The data is based on European production. Thickener (polyacrylate) The polyacrylate thickener is based on data for an acrylate copolymer adhesive. Data come from an MSDS,10 which includes the raw materials production. No energy or emissions data were available. No other information was available on this material, but using this data should be all right, given that this material comprises less than 0.1% of both the Celceram- and calcium carbonate-based latex backings. Transportation to the carpet manufacturers Shipment of materials from the suppliers to the carpet manufacturing plants is included in the model. Transportation distances from the location of each of the backing formula ingredients to the carpet manufacturers are presented in the table below. The carpet manufacturers in Dalton and LaGrange represent approximately 90% of Boral’s Celceram customers.
Table 5 Transport distances of carpet backing ingredients
Note 1: the calcium carbonate from Marble Hill and Ellijay goes to both Dalton and LaGrange; the 56 miles is already an average of both distances to both locations.
All of the materials except for the Marble Hill calcium carbonate are transported by diesel truck. The Marble Hill calcium carbonate is shipped by rail to a location in Dalton, GA, where it is then trucked to carpet manufacturers. All of these transportation modes have been accounted for, and their data come from the U.S. LCI database. Results and Interpretation
Explanation of Categories The first outcome of an LCA is the LCI, i.e., the quantification of all elementary flows into and out of the systems studied. The LCI results for the product comparisons are classified into impact categories, that is, categories in which a set of related flows may contribute to impacts on human or environmental health. The following table presents the LCIA categories used in this study which come from the latest available method, ReCiPe.11
11 The ReCiPe method was created by RIVM, CML, PRé Consultants, Radboud Universiteit Nijmegen and
CE Delft. More information on the method can be found at www.lcia-recipe.net.
Backing ingredient Production Location
To Dalton, GA
(mi)
To LaGrange,
GA (mi)
Average
(mi)
Celceram Macon/Juliette, GA 164 128 146
CaCO3 (note 1) Marble Hill, GA; Ellijay, GA 56 56 56
Acrylic-based latex binder Midland, MI 740 890 815
Surfactant-based dispersion agent Dalton, GA 10 152 81
Stabilizer (alcohol ethoxylate) Cartersville, Ga 50 110 80
Stabilizer (boric acid) Cartersville, Ga 50 110 80
Thickener (polyacrylate) Calhoun 22 132 77
Polyol Midland, MI 740 890 815
Isocyanate Midland, MI 740 890 815
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 9
Table 6 Impact Categories
ReCiPe is based on a synthesis of the CML and Ecoindicator 99 methods, which were well-established European methods developed in the 1990s and 2000’s.12 ReCiPe boasts an improvement of data in the categories, and incorporates globally-accepted information on human health, eco-toxicity, and other traditionally data-limited categories.13,14 Despite the improvement in all of the data categories, it should be noted that not all impact results provide the same level of reliability in the results. These intrinsic limitations of LCIA are described as follows:
1. Spatial and temporal resolutions are not reflected in an LCA. When emissions are normalized to a functional unit (in this case, one square yard of carpet), all impact results are relative and potential. The temporal and geographical characteristics which are needed to assess local environmental impacts are not available in LCA impact results. 2. Threshold effects are lost in an LCA. LCA is based on a linear extrapolation of mass loadings with the assumption that this loading contributes to an environmental effect. This is contrary to threshold-driven environmental and toxicological mechanisms. Thus, while the linear extrapolation of mass loadings is a reasonable approach for more global and regional impact categories such as global warming potential and acidification potential, it is not as appropriate a measure for human health- and ecotoxicity- related impacts because of the lack of concentration and exposure data. More conventional risk assessment methodologies for human health and ecotoxicity must then be applied.
12 For more information on these two methods, please go to www.pre.nl.
13 Although, please note the limitations discussed later.
14 It should be noted that the U.S. EPA’s Tool for the Reduction and Assessment of Chemical and Other
Environmental Impacts (TRACI) had been used to calculate the impact assessment results for the 2008
study. TRACI was well-accepted by LCA practitioners in the US at the time of that study, but since then,
RECIPE was released. TRACI is now considered to be outdated, and many practitioners are using the
more recent methods and characterization factors in newer methodologies like RECIPE.
Impact Category Name Unit
Climate change kg CO2 eq
Ozone depletion kg CFC 11 eq
Human toxicity kg 1,4 DB eq
Photochemical oxidant formation kg NM VOC eq
Particulate matter formation kg PM 10 eq
Terrestrial acidification kg SO2 eq
Marine Eutrophication kg N eq
Terrestrial ecotoxicity kg 1,4 DB eq
Freshwater ecotoxicity kg 1,4 DB eq
Water depletion m3
Fossil resource depletion kg oil
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 10
Finally, impact assessment methodologies, especially human health-related, are constantly evolving as the science to relate holistic life cycle flows of a more local nature (as described above) becomes more understood. In light of these limitations, LCA results for human health- and toxicity- related impacts, such as human cancer and non-cancer potentials and ecotoxicity, should be used with caution and transparency on the limitations or else not used as all. It should also be disclosed that in some cases, these impact categories are being removed by consultancies from LCA studies due to their limitations and sometimes controversial application for LCA. Reading Results Tables Impact categories are independent from one another so the data in the tables should be read across rather than down. It is not valid to compare results for one impact category to a different category, e.g., to directly compare GWP impacts with acidification impacts. Presentation of Results The two results tables below present the comparisons between the backings with Celceram vs. calcium carbonate. The final column presents the Celceram backing as a percentage of the calcium carbonate backing. The values are based on the functional unit of carpet backing for 1 square yard of carpet, or 32 oz of the backing alternatives.
Table 7 PU backing in 1 square yard of carpet
Table 8 Latex backing in 1 square yard of carpet
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 11
In all of the categories for the PU and latex backing, the Celceram-based backing performs better environmentally than the calcium carbonate on the square yard basis. This is in part due to the lower environmental profile on the strictly Celceram and calcium carbonate basis (see Appendix A) but also to the fact that where Celceram is used, less of some of the other backing elements are needed, when assessed on the basis of carpet area (see percentages in Table 1 and Table 2). Please see the Uncertainty and Limitations section for a discussion on significant differences of results. Data Quality Requirements and Evaluation
This LCA adheres to the ISO standards on data quality to help ensure consistency, reliability, and clear-cut evaluation of the results. The following aspects of the study’s data quality are described in accordance with ISO 14044:
• Representativeness;
• Consistency;
• Reproducibility;
• Precision; and
• Completeness. Representativeness Representativeness includes the following:
• Time/temporal coverage – describes the age of data and the minimum length of time (e.g., one year) over which data are collected;
• Geographical coverage – describes the geographical area from which data for unit processes are collected to satisfy the goal of the study; and
• Technological coverage (or the technology mix) – describes the technology mix of the data sets, which may include weighted average of the actual process mix, best available technology, or worst operating unit.
The Celceram data is considered representative, as it is primary data based on current information and technologies. It should be noted that Celceram is produced elsewhere in the US, but it is representative here since it is applied to the Georgia carpet customers. The calcium carbonate data is current, and despite the fact that it is based on one company’s data, an uncertainty analysis (see Appendix) has shown that it is still robust for most of the results categories. Data for the other materials in the backing are generally based on fairly recent data and on current technologies. Much of the data is US-based. Wherever the data has been based on European production, those data sets have been customized to US production, using US data on energy, fuels, and transportation. Consistency Consistency is a qualitative understanding of how uniformly the study methodology is applied to the various components of the study. Consistency was maintained in the handling of the comparisons of materials and in the project boundaries as described in this report. The models for all materials were built consistently, as shown in Figure 2.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 12
Reproducibility The level of detail and transparency provided in this report allow the results of this study to be reproduced by another practitioner as long as the practitioner has access to the datasets. The datasets used have been listed out or described in sufficient detail for a practitioner to easily locate the data. Precision Precision represents the degree of variability of the data values for each data category. The data for the Celceram was based on primary data measured at the facility. The peer reviewer questioned the precision of the calcium carbonate data, and this issue has been addressed in Appendix C. Completeness ISO 14044 section 4.2.3.6 defines completeness as the “percentage of flow that is measured or estimated.” The data in this study can be considered complete since for the most part data for the materials are based on site-specific information. The latex backing is quite detailed and represents a full bill of materials. The PU backing provides over 99% of the backing constituents. While it does not include a full bill of materials, it is assumed that the remaining materials in the each backing alternative are close enough in quantity such that the net difference is minimal. Uncertainty and Limitations
Uncertainty Both primary and secondary data are used in modeling the materials. Primary data was used to for both the Celceram and calcium carbonate site data, while secondary data was used for other materials in the system plus energy, materials, transportation, and fuels used in the systems. While the quality of secondary data, especially EcoInvent data and datasets based on other LCA studies, have improved over time, secondary data is never as good as primary, so its use becomes an inherent limitation to the study (secondary may cover a broad range of technologies, time periods, and geographical locations). However, from a practical standpoint it is impossible to collect actual process data for each of the hundreds or thousands of unit processes included in a complete life cycle model so the use of secondary data in an LCI is normal and necessary. Nonetheless, the use of secondary data does present some margin of error. And because hundreds of data sets are linked together and it is often unknown how much the secondary data used deviate from the specific system being studied, quantifying uncertainty for the complete system becomes very challenging. As a result, it is not possible to provide a reliable quantified assessment of overall data uncertainty for the study. In this study we did address some of the uncertainty aspects identified in the 2008 study, such as particulates from Celceram manufacturing, thus reducing some of the manufacturing process-specific uncertainty. Needless to say, as a result of overall system uncertainty and some unquantifiable margin of error in the system, the comparative results should be viewed as indicative of the benefits of one material over the other, but not necessarily the exact or absolute results differences. In other words, the environmental benefits of the PU backing system with Celceram (over 20% in all categories) are more clear and definitive than the benefits of the latex system (about 10% in most categories).
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, page 13
General Use Limitations It should be borne in mind that LCA, like any other scientific or quantitative study, has limitations and is a far from perfect tool for assessing the environmental impacts and attributes associated with product systems. As mentioned above, there is inherently a margin of error due to various limitations such as data quality differences and/or unavailability of potentially relevant data. Additionally, LCA results should not be considered to be the only source of environmental information should claims or assertions be made on the environmental performance of the product. While LCA is quite powerful, it does not address all issues; it is one environmental tool within many (e.g., risk assessment) that should be accounted for when evaluating the use of one product over another. Also, as described in the impact category limitations in the Results section, the reader should be reminded that not all impact categories have the same degree of certainty and confidence. Should claims or assertions be made on the environmental performance of the product, the public should understand these inherent limitations of LCA, as well as uncertainties. Other limitations This study evaluates two applications of Celceram replacing calcium carbonate. While these results, plus the material-only comparison in Appendix A, indicate environmental preferability of Celceram over calcium carbonate, other end-use applications should be evaluated on a case-by-case basis before environmental preferability claims can be made. The evaluation of other beneficial uses of fly ash and the environmental aspects of when fly ash is not used in end applications is out of the scope of this current work. Conclusion
The 2008 material-only study in Appendix A showed Celceram to be favorable to calcium carbonate. While it looked carefully at the production of both materials and was peer-reviewed, it did not account for these materials’ performance in end-products. This current study set out to evaluate how the materials compare in two end-use applications, and the results demonstrated that substituting Celceram for calcium carbonate indeed result in a more favorable environmental profile. This is in part due to the lower environmental profile on a material basis (see Appendix A) and to the fact that where Celceram is used, less of some of the other backing elements are needed (when assessed on the basis of carpet area, as shown in Table 1 and Table 2). Users of comparative LCA studies should always be aware of the study-specific limitations and uncertainty in the LCA studies yet should understand that limitations and uncertainty of some degree are always going to be present in LCA.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, Appendix
Appendix A 2008 Study: Celceram vs. Calcium Carbonate
See next page.
Boral Materials LCA Comparison Four Elements, page 1/10
Cradle-to-Gate Life Cycle Assessment: Boral Industries PV20A Fly Ash vs. Calcium Carbonate Introduction
Boral Material Technologies (Boral) produces a fly ash product, PV20A (also called Celceram 20A), that displaces limestone (calcium carbonate) in various applications including floor backing systems. Boral has requested a comparison of PV20A and limestone in order to evaluate the production impacts of these two materials. Life Cycle Assessment (LCA) has been used to model and evaluate the production of both materials. This study aims to highlight the environmental differences of the two materials on a mass basis so that Boral may:
• use results in their pursuit of Environmentally Preferable Purchasing (EPP) or related certifications, and/or provide results to customers to do the same,1
• use the results to market its product to prospective new customers; and
• provide results to customers for use in their own product LCAs. This study has been performed in accordance with the International Standardization Organization (ISO) standards for LCA, including:
• ISO 14040:1997(E), the International Standard of the International Standardization Organization, Environmental management – Life cycle assessment – Principles and framework, and
• ISO 14044:2006, Environmental management – Life cycle assessment – Requirements and guidelines.
This report is intended for Boral users. Boral may also share it with other interested parties and customers. Boral is considering an external critical review on this study. A peer review is essential for an LCA if any sort of comparative assertion is made publicly. ISO’s definition of a comparative assertion is an "environmental claim regarding the superiority or equivalence of one product versus a competing product that performs the same function."2 ISO states that "in order to decrease the likelihood of misunderstandings or negative effects on external interested parties, a panel of interested parties shall conduct critical reviews on LCA studies where the results are intended to be used to support a comparative assertion intended to be disclosed to the public."3 Life Cycle Assessment Principals and Terminology
LCA is a tool for the systematic evaluation of the environmental impacts of a product through all stages of its life cycle, which include extraction of raw materials, manufacturing, transport and use of products, and end-of-life management (e.g., recycling, reuse, and/or disposal). The four main parts of an LCA according to ISO 14040 include:
1 Disclaimer: Four Elements can not guarantee that this study or the results therein will result in certified
products using PV20A. 2 ISO 14044 Section 3.5.
3 ISO 14044 Section 6.1.
Boral Materials LCA Comparison Four Elements, page 2/10
1. Goal and Scope definition: specifying the reason for conducting the study,
intended use of study results, intended audience, system boundaries, data requirements, and study limitations.
2. Life Cycle Inventory (LCI): collecting, validating and aggregating input and output data to quantify material use, energy use, environmental discharges, and waste associated with each life cycle stage.
3. Life Cycle Impact Assessment (LCIA): using impact categories, category indicators, characterization models, equivalency factors, and weighting values to translate an inventory into potential impact on human health and the environment.
4. Interpretation: assessing whether results are in line with project goals, providing an unbiased summary of results, defining significant impacts, and recommending methods for reducing material use and environmental burdens. Examples of life cycle interpretation include contribution analyses and scenario analyses, both of which are used to help understand the results of this study.
The system boundaries for the product or process being studied may encompass the entire life cycle, illustrated in the figure below. LCA may also cover only materials acquisition through to the gate of the facility as long as the reasoning for this choice of system boundaries has justified.
System Boundaries
Overall System Boundaries and Functional Unit The products being studied are assessed as “cradle-to-production facility gate”, i.e., from raw material extraction through to the completion of production of the material. Delivery of the products to the customer has been excluded since the purpose of the study is to look at the materials on strictly a mass basis.
Raw Materials Acquisition
Manufacturing and Processing
Distribution and Transportation
Use, Re-use, and Maintenance
Recycling
Waste Management`
-
-
Outputs
Product or
Service
Inputs
System Boundaries
Boral Materials LCA Comparison Four Elements, page 3/10
Normally under the ISO guidelines, all flows within the system boundaries must be normalized to a unit summarizing the function of the system. This allows for the comparison of different industrial systems performing the same function. Once this shared function is defined, a functional unit, or reference flow, has to be chosen in order to calculate the systems on the same quantitative basis. Boral previously commissioned a study that evaluated the use of PV20A in a carpet backing, in which it displaced a certain quantity of limestone and resin. For this analysis, since Boral desired to understand the impacts of the two materials solely on an equivalent mass basis regardless of function, the unit quantity used for comparison is 2000 pounds. Cut-off Criteria ISO 14044 requires a cut-off criterion to be defined for the selection of materials and processes to be included in the system boundary. Several criteria are used in LCA practice to decide which inputs are to be studied, including mass, energy and environmental relevance. The mass criterion was applied, and since both products consist primarily of one main material, 100% of the mass was included for each material. Exclusion of Data from the System Boundaries In LCA, it is typical to exclude some aspects within the set boundaries of the LCA. The scope and boundaries exclude impacts for some human activities, such as employee travel to and from work. Additionally, impacts for facility construction and capital equipment are excluded, as these impacts typically are negligible when allocated over the total quantity of product manufactured over the life cycle of the facilities and equipment. Product Modeling and Assumptions
PV20A System PV20A is a conditioned fly ash product. It starts at the production of coal power as a coal combustion byproduct (CCB) and undergoes some processing to produce the product ready for shipping to the customer. The figure below presents the system boundaries for PV20A.
Figure 1 PV20A system boundaries
Fly Ash Production Fly ash is a CCB, i.e., it is produced as a result of coal power production. In LCA terms, it is considered a coproduct/byproduct of a multi-output system. According to the ISO standards on LCA, coproducts must be addressed in some form, including, where
Processing and
Conditioning
Coal Fly Ash (CCB)
PV-20A
Electricity
usage
Air emissions, water
effluents, and solid
waste associated
with electricity
production
Boral Materials LCA Comparison Four Elements, page 4/10
necessary, assigning allocation rules to the multiple outputs. Model the CCB in terms of an allocation was assessed – specifically, an economic allocation on coal-generated electricity and fly ash. However, it was determined that an allocation of any sort was unnecessary since fly ash is generated completely as a result of coal electricity; it would not be produced at all for any market if coal electricity was no longer produced. As such, fly ash has been modeled as free of upstream environmental burdens (see Figure 1 above). PV20A Manufacturing The PV20A plant is located in Macon, Georgia on the property of the power plant. The equipment to process the fly ash was engineered and built to pneumatically convey the fly ash from the Electrostatic Precipitators (ESP) to a series of storage silos about 100 yards from the ESPs. A baghouse is used in the silo area to collect dust. In the silo area, fly ash is loaded into trucks for delivery to ready mixed concrete facilities, or the fly ash is further processed into PV20A which is then loaded onto trucks and sent to the carpet manufacturing facilities. The only process input for the above description is electrical power. Data for electrical power was based on an average of 18 months of utility bills, which covered the processes to move fly ash from the utility to the silo area, process the PV20A, and office space. The average power usage is 28.22 kilowatt-hour (kWh) per ton PV20A. As a double-check, electricity was also calculated based on motor specifications. This came to 25.1 kWh/ton PV20A. It was decided that the utility invoices were more complete, since they accounted for the actual electrical usage associated with PV20A and the facility, not just theoretical usage based on motor specs. US average electricity was used, and data for that comes from the US LCI database, a publicly-available database based on North American data and current technologies and production practices.4 No other process inputs are required to produce PV20A, and no water is used in the process (so water effluents are not applicable). No data on process air emissions, including fugitive particulate matter, were available. While this latter data is not available, emissions for the plant meet all Federal and state emissions limits. Calcium Carbonate (Limestone) System The figure below presents the limestone system boundaries for this study.
4 Found at http://www.nrel.gov/lci/.
Boral Materials LCA Comparison Four Elements, page 5/10
Figure 2 Limestone system boundaries
The initial scoping document called for the use of the limestone dataset from the US LCI database, encompassing limestone quarrying by blasting from open pits followed by mechanical crushing and screening. Data sources include:
• AP-42 Emission Factors. Chapter 11.19.2. Crushed Stone Processing and Pulverized Mineral Processing. US EPA. August 2004;
• U.S. Geological Survey; and
• Industry sources (unnamed for confidentiality purposes). We then looked at European data,5 which entailed three separate, linked data sets, including:
• Limestone mining, which includes blasting, all transportation at the mine site (for mining and recultivation), and some heating energy for "administration" buildings. Explosives used include Tovex and Amolith;
• Limestone crushing, which includes: primary crushing, washing, and transportation by conveyor belt; and
• Limestone milling, which includes milling, sieving, filtering and storing the limestone.
Data are primary data, from one company in Switzerland. According to the data source, the company uses technically advanced machinery. Heavy machinery are operated electrically. At the mining facility, building machines use diesel. For crushing and milling facilities, the air is recirculated in closed loops to minimize particulate emissions. When the US and European datasets were compared side-by-side, it was found that the data were not comparable since the US data was not nearly as complete as the latter. The table below presents selected impact comparisons for a pound each of limestone from the US and European data sets:
5 From the Ecoinvent Database produced by the Swiss Centre for Life Cycle Inventories
(www.ecoinvent.org). This is a proprietary database accessible by a paid license.
Mining
Limestone
Crushing
Milling
Energy and
materials in
Air emissions, water
effluents, and solid
waste associated
with energy and
materials in
Boral Materials LCA Comparison Four Elements, page 6/10
Table 1 US vs. European limestone production
Impact category Unit
Limestone US
LCI Data
Limestone Europe
Data
US data as % of
Europe data
Global Warming kg CO2 eq 2.8 E-03 1.6 E-02 18%
Acidification kg H+ moles eq 7.3 E-04 4.5 E-03 16%
Eutrophication kg N eq 4.6 E-08 4.8 E-07 10%
Total Primary Energy MJ 3.6 E-02 2.1 E-01 17% Because of the large discrepancies between the two data sets and seeming paucity of the US data, the European data was used in this analysis. However, it should be noted that the European data has been customized to US production in terms of US energy and fuels as well as US transportation data sets. Two changes beyond that have been made. First, capital equipment impacts have been removed from these datasets so the comparison would be based on the same system boundaries. Second, the site providing the data utilizes 50% electricity grid and 50% hydropower. In the US-customized data, this pure hydropower was changed to regular average grid electricity (that includes hydro) to simulate a more realistic situation for the average US limestone production. Results and Interpretation
The U.S. EPA’s Tool for the Reduction and Assessment of Chemical and Other
Environmental Impacts (TRACI)6 have been used to calculate the impact assessment
results for this study. TRACI is used since it is one of the only publicly-available North American-based methodologies that is well-accepted by practitioners. Total primary energy (bottom line in the table below), not a part of TRACI, is also included as part of the results. The table below shows the comparison between the PV20A and limestone. The final column presents PV20A as a percentage of the limestone.
Table 2 Boral PV20A vs. Limestone, per 2000 lbs of each material
Impact category Unit PV20A Limestone PV20A as % of
Limestone
Global Warming kg CO2 eq 22 32 70%
Acidification kg H+ moles eq 7.6 9.1 84%
Carcinogenics kg benzene eq 0.02 0.02 75%
Non carcinogenics kg toluene eq 34 219 15%
Respiratory effects kg PM2.5 eq 0.03 0.11 31%
Eutrophication kg N eq 1.6 E-04 9.7 E-04 17%
Ozone depletion kg CFC-11 eq 1.8 E-09 3.3 E-09 53%
Ecotoxicity kg 2,4-D eq 0.6 77 1%
Smog kg NOx eq 4.5 E-04 1.3 E-03 35%
Total Primary Energy MJ 289 419 69%
The figure below presents these results in terms of limestone in relation to PV20A, with all PV20A results normalized to 100%. Eutrophication, the nutrifying effect of water effluents on water bodies, is about six times higher than the PV20A, largely due to the fact that electricity production, the only process requirement for PV20A, has very little
6 Information on TRACI can be found at: http://www.epa.gov/nrmrl/std/sab/traci/.
Boral Materials LCA Comparison Four Elements, page 7/10
water effluents in the life cycle of electricity production, relative to the numerous processes and materials used for limestone production.
Figure 3 Limestone Results in Relation to PV20A
Other very high results in relation to PV20A include non-carcinogen effects, respiratory effects, and ecotoxicity (shown in the table). Energy and more global environmental impacts, such as global warming potential, acidification, and total primary energy, are quite reliable. However, users of LCA studies should be aware that not all impact results, most notably ones related to carcinogens or human health, provide the same level of reliability in the results. The intrinsic limitations of life cycle impact assessment are described as follows:
1. Spatial and temporal resolution is lost in an LCA. When emissions are normalized to a functional unit (in this case, an equivalent mass quantity of each material), all temporal and geographical characteristics which are needed to assess local environmental impacts are lost. LCA results do not distinguish between emissions released instantaneously and locally and those released over a large geographical area over a long period of time. 2. Threshold effects are lost in an LCA. LCA is based on a linear extrapolation of mass loadings with the assumption that this loading contributes to an environmental effect. This is contrary to threshold-driven environmental and toxicological mechanisms. Thus, while the linear extrapolation of mass loadings is a reasonable approach for more global and regional impact categories such as global warming potential and acidification potential, it is not as appropriate a measure for human health- and toxicity- related impacts.
3. Evolving methodologies. Finally, impact assessment methodologies, especially human health-related, are constantly evolving as the science to relate
Limestone in Relation to PV20A
0%
100%
200%
300%
400%
500%
600%
700%
Global
Warming
Acidif ication Carcinogenics Non
carcinogenics
Respiratory
effects
Eutrophication Ozone
depletion
Smog Total Primary
Energy
PV20A
Boral Materials LCA Comparison Four Elements, page 8/10
holistic life cycle flows of a more local nature (as described above) becomes more understood.
In light of these limitations, LCA results for human health- and toxicity- related impacts, such as human cancer and non-cancer potentials and ecotoxicity, should be used with caution. Limestone Analysis When one thinks about all the steps that go into limestone production, it would intuitively seem that its cradle-to-gate impacts would be much higher relative to the PV20A, which requires only pneumatic blowers and some further processing of the fly ash. We therefore looked at the three main stages of limestone production, found in the table below for selected impacts. According to the table, most of the impacts come from milling, and less than 10% make up the mining and crushing stages.7
Table 3 Limestone Analysis
Impact category Unit
Total Limestone
Production
Limestone
mining
Limestone
Crushing
Limestone
Milling
Global Warming kg CO2 eq 32 5% 2% 94%
Acidification kg H+ moles eq 9.1 6% 2% 93%
Eutrophication kg N eq 9.7 E-04 58% 4% 38%
Smog kg NOx eq 1.3 E-03 26% 6% 68%
Total Primary Energy MJ 419 5% 2% 93% Data Quality Requirements and Evaluation
This LCA adheres to the ISO standards on data quality to help ensure consistency, reliability, and clear-cut evaluation of the results. The following aspects of the study’s data quality are described in accordance with ISO 14044:
• Representativeness;
• Consistency;
• Reproducibility;
• Precision; and
• Completeness. Representativeness Representativeness includes the following:
• Time/temporal coverage – describes the age of data and the minimum length of time (e.g., one year) over which data are collected;
• Geographical coverage – describes the geographical area from which data for unit processes are collected to satisfy the goal of the study; and
• Technological coverage (or the technology mix) – describes the technology mix of the data sets, which may include weighted average of the actual process mix, best available technology, or worst operating unit.
7 The exceptions in this table are eutrophication and smog, but the actual values for these impact categories
are quite small.
Boral Materials LCA Comparison Four Elements, page 9/10
The PV20A data is considered representative, as it is primary data based on current information and technologies. The limestone data is current, however, it may be slightly less representative, since its one plant’s technologies may (or may not) be representative of the average limestone production. It is also based on a European site. But the individual data sets have been customized to US data on energy, fuels, and transportation. Consistency Consistency is a qualitative understanding of how uniformly the study methodology is applied to the various components of the study. Consistency was maintained in the handling of the comparisons of materials. The models for all materials were built consistently. Reproducibility The level of detail and transparency provided in this report allow the results of this study to be reproduced by another practitioner as long as the practitioner has access to the datasets. Precision Precision represents the degree of variability of the data values for each data category. The data for the PV20 was based on primary data measured at the facility. There was variability between the electric invoices and the calculated power requirements, but a decision was made to use the utility invoices since it encompassed all possible electricity usage, and not strictly the machines. Completeness ISO 14044 section 4.2.3.6 defines completeness as the “percentage of flow that is measured or estimated.” The data in this study can be considered complete since data for the materials are based on site-specific information. Limitations and Uncertainty
General Use Limitations It should be borne in mind that LCA, like any other scientific or quantitative study, has limitations and is a far from perfect tool for assessing the environmental impacts and attributes associated with product systems. There is inherently a margin of error due to various limitations such as data quality differences and/or unavailability of potentially relevant data. Should claims or assertions be made on the environmental performance of the product, the public should be informed of these inherent limitations. Additionally, LCA results should not be considered to be the only source of environmental information should claims or assertions be made on the environmental performance of the product. While LCA is quite powerful, it does not address all issues; it is one environmental tool within many (e.g., risk assessment) that should be accounted for when assessing products or processes. Uncertainty Both primary and secondary data are used in modeling the materials. Primary data was used to for both the PV20A and limestone site data, while secondary data was used for all energy, materials, transportation, and fuels used in the systems. Because the quality of secondary data is not as good as primary data, the use of secondary data becomes
Boral Materials LCA Comparison Four Elements, page 10/10
an inherent limitation to the study (secondary may cover a broad range of technologies, time periods, and geographical locations). However, from a practical standpoint it is impossible to collect actual process data for each of the hundreds or thousands of unit processes included in a complete life cycle model so the use of secondary data in an LCI is normal and necessary. Because hundreds of data sets are linked together and because it is often unknown how much the secondary data used deviate from the specific system being studied, quantifying data uncertainty for the complete system becomes very challenging. As a result, it is not possible to provide a reliable quantified assessment of overall data uncertainty for the study. Conclusion
In all of the categories, the PV20A performs better environmentally than the limestone on a pound-per-pound basis. Despite that, these results are not very intuitive. Intuitively, one would think that only the last couple stages of limestone production would be comparable to the whole production of PV20A in energy requirements alone. In a sense, that is the case; the milling stage, we found, is actually the most energy intensive. Since we do not have inside contacts to the limestone production industry, we were not able to verify the European data; we can only trust that the European data is reliable and complete. The data quality for that data seems to be good (see the Data Quality Evaluation section). On the other hand, maybe the energy to move and condition the PV20A is truly higher than initially expected. Another way to present the actual benefits and environmental impacts of PV20A is to compare it to competing materials on a functional basis, as was done in a previous Boral study. It might be interesting to pick several typical or average applications of PV20A to highlight the benefits in downstream products. This study would be an excellent starting point for this future work.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, Appendix
Appendix B Peer Review Report for 2008 Study: Celceram vs. Calcium Carbonate
See next page.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, Appendix
Appendix C Sensitivity Analysis on Calcium Carbonate
To summarize, the data for calcium carbonate were primary data, coming from one company in Switzerland. While EcoInvent data is generally trustworthy and of good quality, the peer reviewer pointed out a potential uncertainty issue associated with using data for only one producer, and requested that a sensitivity or uncertainty analysis be performed on this data (Appendix B, p.4). This was done as a Monte Carlo analysis. A Monte Carlo simulation was run, in which the calcium carbonate data set was calculated 1000 times, using varying factors in the calcium carbonate data sets that had uncertainty ranges unspecified.15 The Monte Carlo graphs the distribution of the 1000 sets of results, presenting the results for every possible data combination. As shown in Figure 1Figure 3 for global warming potential, the calcium carbonate data set follows a normal distribution, with 95% of the values falling within the normal distribution curve. Figure 4 presents the results for all categories in ReCiPe (note that not all of these categories have been used in this report). The way to understand this figure is, the closer the red “cat whiskers” are to each blue bar, the lower the uncertainty. Natural land transformation shows extremely high uncertainty and a couple other categories show moderate uncertainty. However, most of the categories show very low uncertainties, and these are ones we included in the main results of this analysis (see Table 6). Therefore, we can feel confident that the calcium carbonate data is all right to use for this comparison.
15 Within almost every EcoInvent data set are uncertainty factors for data points. This is so that LCA
practitioners can evaluate the uncertainty in data.
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, Appendix
Figure 3 Calcium carbonate uncertainty distribution results for climate change
Boral Materials LCA Comparison in Support of an EPP Claim Four Elements, Appendix
Figure 4 Calcium carbonate uncertainty ranges for all impact categories
