February 15, 2008 Dr. Arthur Rosenfeld Commissioner California Energy Commission 1516 9th Street Phone: (916) 654-4930 Sacramento, CA 95814 Email: ARosenfe@Energy.State.CA.us Life Cycle Cost and CO 2 Issues for Concrete Pavement Dear Dr. Rosenfeld: At the request of Mr. Tom Tietz of the California Nevada Cement Association, CTLGroup is providing this letter documenting the benefits of concrete pavements when based on life cycle cost analysis (LCCA) and life cycle assessment (especially CO 2 ). EXECUTIVE SUMMARY Four independent, third party, LCCA studies were prepared by ERES Consultants comparing actual agency costs for portland cement concrete (PCC) pavement and asphalt concrete (AC) pavement. Results indicate that PCC alternatives have 13 to 28% lower equivalent uniform annual costs (EUAC) in units of $/lane/mile/year and 66 to 69% lower EUAC in units of $/lane/mile/year/100,000 trucks. These costs did not include user costs. The LCCA savings would most likely be greater if the user costs had been considered because the PCC pavement life, in all cases, was greater than the AC pavement life. An independent, third party, report was prepared by the Athena Institute for six AC and PCC pavements using two life cycle assessment impact indicators: embodied energy and global warming potential. Results indicate the AC pavements have 31 to 81% more embodied energy than the PCC pavements. These results do not include feedstock energy (fuel content of the asphalt). The results for global warming potential index (GWPI), which includes CO 2, are mixed. The differences in GWPI for the AC and PCC pavements are considered insignificant by Athena. Sixty percent of the CO 2 emissions in the cement manufacturing process are from calcination and not from the burning of fossil fuels. Embodied energy and GWPI results are highly dependent on the cement content of the concrete. Using 25% fly ash as replacement for portland cement rather than the 10% assumed by Athena will improve the results for PCC pavement. Also, considering a full range of impact indicators rather than only embodied energy and GWPI will provide a more complete life cycle assessment. Main Office: 5400 Old Orchard Road Skokie, Illinois 60077-1030 Phone: 847-965-7500 Fax: 847-965-6541 Mid-Atlantic Office: 9030 Red Branch Road, Suite 110 Columbia, Maryland 21045-2003 Phone: 410-997-0400 Fax: 410-997-8480
Life Cycle Cost and CO 2 Issues for Concrete Pavement Page 2 of 6 LIFE CYCLE COST ANALYSIS (LCCA) The Federal Highway Administration (FHWA) has pursued a policy of promoting LCCA for transportation investment decisions since the Intermodal Surface Transportation Equity Act of 1991. 1 Methodology The FHWA provides extensive information on LCCA, including the following introduction, at http://www.fhwa.dot.gov/infrastructure/asstmgmt/lcca.cfm: LCCA is an engineering economic analysis tool that allows transportation officials to quantify the differential costs of alternative investment options for a given project. LCCA can be used to study new construction projects and to examine preservation strategies for existing transportation assets. LCCA considers all agency expenditures and user costs throughout the life of an alternative, not only initial investments. More than a simple cost comparison, LCCA offers sophisticated methods to determine and demonstrate the economic merits of the selected alternative in an analytical and fact-based manner. LCCA helps transportation agencies answer questions like these: Which design alternative results in the lowest total cost to the agency over the life of the project? To what level of detail have the alternatives been investigated? What are the user-cost impacts of alternative preservation strategies? The above link also provides information on LCCA requirements and procedures for California and selected other state DOT s. Procedures for performing LCCA are documented in publications by FHWA 2 and American Concrete Pavement Association (ACPA) 3. The FHWA publication emphasizes the need to include user costs. FHWA defines user costs as the differential costs incurred by the motoring public between competing alternative highway improvements and associated maintenance and rehabilitation strategies over the analysis period. User costs are an aggregate of three separate cost components: vehicle operating costs, user delay costs, and crash costs. FHWA gives detailed instructions on how to calculate these costs related to reduced lanes, construction detours, and traffic congestion during construction. These costs include costs of fuel due to delays and detours, the value of the driver s time, the increased delivery fleet size, and the potential for increased crashes. 1 Life Cycle Cost Primer, FHWA IF-02-047, Federal Highway Administration, U.S. Department of Transportation, 400 7 th Street SW, Room 211, Washington, DC 20590. www.fhwa.dot.gov/infrastructure/asstmgmt/lcca.cfm 2 Life-Cycle Cost Analysis in Pavement Design In Search of Better Investment Decisions, FHWA-SA- 98-079, FHWA, 1998. www.fhwa.dot.gov/infrastructure/asstmgmt/lcca.cfm 3 Life Cycle Cost Analysis: A Guide for Comparing Alternate Pavement Designs, EB220P, American Concrete Pavement Association, 5420 Old Orchard Road, Suite A100, Skokie, IL 60077. www.pavement.com
Life Cycle Cost and CO 2 Issues for Concrete Pavement Page 3 of 6 Results Four independent, third party, LCCA studies were prepared by ERES Consultants comparing actual agency costs for portland cement concrete (PCC) pavement and asphalt concrete (AC) pavement. Results indicate that PCC alternatives have 13 to 28% lower equivalent uniform annual costs (EUAC) in units of $/lane/mile/year and 66 to 69% lower EUAC in units of $/lane mile year 100,000 trucks. These costs did not include user costs. Specifically, savings were: Interstate 40, Tennessee, 13 to 21% LCCA savings for PCC 4,5 The average pavement life of the PCC sections was 2.1 to 2.5 times the average life of the AC sections (25.5 to 31.1 years for the PCC versus 12.3 years for the AC). Interstate 15, Utah, 20 to 28% LCCA savings for PCC 6,7 The average pavement life of the PCC sections was 2.5 times the average life of the AC sections (31.4 years for the PCC versus 12.6 years for the AC). Interstate 40, Oklahoma, 21 to 27% LCCA savings for PCC 8,9 The average pavement life of the PCC sections was 3.4 times the average life of the AC sections (30.9 years for the PCC versus 9.0 years for the AC). Interstate 985 and State Route 400, Georgia, 66 to 69% LCCA savings on I-985 and 70 to 71% LCCA savings on SR-400 for PCC when normalized for traffic 10,11,12 The 4 A Comparison of Pavement Performance and Costs, Interstate 40, Tennessee, SR991P, American Concrete Pavement Association, 2000. www.pavement.com 5 Gharaibeh, N.G., and Crow, T.L., Comparative Performance and Costs of In-Service Highway Pavements I-40,Tennessee, PCA R&D Serial No. 2209, Portland Cement Association, 5420 Old Orchard Road, Skokie, IL 60077, 2000. www.cement.org 6 A Comparison of Pavement Costs and Performance, Interstate 15, Utah, SR992P, American Concrete Pavement Association, 2000. www.pavement.com 7 Hoerner, T.E., Darter, M.I., Gharaibeh, N.G., and Crow, T.L., Comparative Performance and Cost of In- Service Highway Pavements, I-15, Utah, PCA R&D Serial No. 2209a, Portland Cement Association, 2001. www.cement.org 8 A Comparison of Pavement Costs and Performance, Interstate 14, Oklahoma, SR993P, American Concrete Pavement Association, 2001. www.pavement.com 9 Smith, K.L, Gharaibeh, N.G., Crow, T.L., and Ayers, M.E., Comparative Performance and Cost of In- Service Highway Pavements, I-40, Oklahoma, PCA R&D Serial No. 2209b, Portland Cement Association, 5420 Old Orchard Road, Skokie, IL 60077, 2001. www.cement.org 10 A Comparison of Pavement Performance and Costs, Interstate 985 and State Route 400, Georgia, SR994P, American Concrete Pavement Association, 2003. www.pavement.com 11 Shami, H., Gharaibeh, N.G., and Crow, T.L., Comparative Performance of In-Service Highway Pavements, I-985 and SR 400, Georgia, PCA R&D Serial No. 2209c, Portland Cement Association, 2001. www.cement.org
Life Cycle Cost and CO 2 Issues for Concrete Pavement Page 4 of 6 average pavement life of the PCC sections was 1.6 to 1.9 times the average life of the AC sections for I-985 (19.5 to 23 years for PCC and 12 years for AC) and 2.6 times for SR-400 (37 years for the PCC versus 14 years for the AC). The LCCA savings would most likely be greater if the user costs (as previously described) had been considered because the PCC pavement life in all cases was greater than the AC pavement life. Additional references are available upon request for determining user costs. The ACPA publication EB220P, Appendix 2, provides examples of state agency expenditure streams for PCC and AC pavement. These take into account the different time lines and types of reconstruction and rehabilitation for PCC and AC pavement. CTLGroup recommends LCCA studies for California pavements utilize CALTRANS estimates of reconstruction and rehabilitation schedules. LIFE CYCLE ASSESSMENT Life cycle assessment (LCA) is a methodology for assessing the social and environmental aspects associated with a product over its life cycle from raw material acquisition through production, use, and disposal. An LCA is used to assess a product s environmental aspects and the potential impacts the product has on the natural environment. An independent, third party, report was prepared by the Athena Institute 13 on two impact indicators, embodied energy and global warming potential, for AC and PCC pavements. The global warming potential index (GWPI) is from the International Panel on Climate Change s 100- year time horizon factors: GWPI (kg) = CO 2 kg + (CH 4 kg x 23) + (N 2 O kg x 296) The report compared six PCC and AC pavements in Canada as follows: A typical Canadian arterial road with two different subgrade foundation types A typical Canadian high volume highway with two different subgrade foundation types A Quebec urban freeway A section of Highway 401 freeway in Ontario Results indicate the AC pavements have 31 to 81% more embodied energy than the PCC pavements. Accepted practice in the LCA industry is to also include the feedstock energy 14 of the AC when performing LCAs. The AC pavements have 2.3 to 4.1 times more embodied energy than the PCC pavements when the feedstock energy is included. Results for individual pavement types are shown in Table ES1 from the Athena report, reproduced below. 12 Some of the PCC pavement had not yet received rehabilitation and this age was estimated. The units of EUAC for this study were $/lane/mile/year/100,000 trucks. 13 A Life Cycle Perspective on Concrete and Asphalt Roadways: Embodied Primary Energy and Global Warming Potential, Cement Association of Canada, 1500-60 Queen Street, Ottawa, ON K1P 5Y7 September 2006. www.cement.ca 14 Feedstock energy is the gross combustion heat for any material input to a product system which may be considered as an energy source, but is not being used as such. It can be considered the fuel content.
Life Cycle Cost and CO 2 Issues for Concrete Pavement Page 5 of 6 The results assume no recycled asphalt pavement (RAP). For 20% RAP in the binder coarse for the arterial and high volume highway designs, the PCC pavements have 3.5 to 5% less embodied energy. The RAP affects the PCC pavements because they have AC shoulders and AC overlay as part of the rehabilitation. The AC pavement options have 5 to 7.5% less embodied energy when 20% RAP is used. While 20% RAP reduces the differences between AC and PCC pavements, the overall results are still significant. The results assume 10% fly ash as a replacement for portland cement in the PCC pavement. Up to 25% fly ash replacement is commonly used in construction. A 1% replacement of cement with fly ash or slag cement results in approximately 1% reduction in embodied energy per unit of concrete 15. Therefore, using 25% fly ash as replacement for portland cement rather than the 10% assumed by Athena will improve the results for PCC pavement. The results for GWPI for the six pavements are mixed, as indicated by Chart 2 from the Athena report as reproduced below. These differences are considered insignificant by Athena. Sixty percent of the CO 2 emissions in the cement manufacturing process are from calcination and not from the burning of fossil fuels. Since CO 2 emissions from cement manufacturing are two orders of magnitude larger than any other stage of concrete production, approximately 60% of the CO 2 emissions embodied in concrete are from calcination. Using 25% fly ash as replacement for portland cement rather than the 10% assumed by Athena will reduce the GWPI of the PCC pavement options. 15 Marceau, M.L., Nisbet, M.A., and VanGeem, M.G. Life Cycle Inventory of Portland Cement Concrete, R&D Serial No. 3011, Portland Cement Association, 2007. www.cement.org
Life Cycle Cost and CO 2 Issues for Concrete Pavement Page 6 of 6 Also, the Athena study considered only two impact indicators, embodied energy and GWPI, rather than a full set generally considered in LCAs. A limited set of impacts, such as only CO 2, negatively impacts concrete because of the calcination of limestone during the manufacturing process. A full set of impact indicators includes land use (or habitat alteration), resource use, climate change, ozone layer depletion, human health effects, ecotoxicity, smog, acidification, and eutrophication. Considering a full range of impact indicators rather than only embodied energy and GWPI will provide a more complete life cycle assessment and more balanced results for PCC. Please do not hesitate to contact us. Sincerely, Martha G. VanGeem, PE (Illinois) John Gajda, PE (California) LEED TM Accredited Professional License No. C67953, expires 2009-06-30 Principal Engineer, Building Science and Sustainability Principal Engineer MVanGeem@CTLGroup.com JGajda@CTLGroup.com Phone: 847-972-3156 Phone: 847-972-3140 Copy to: T. Tietz, California Nevada Cement Association H. Akbari, LBNL Attachments: References submitted in a separate distribution.