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his View comments on two articles that recently appeared in Environmental Science 6.Technology, examining life cycle assessment (LCA) methods. In "Broad-Based Environmental Life Cycle Assessment," Mary Ann Curran emphasized the importance of LCAs for comparing environmental and energy impacts of different products, addressed the difficulties i n conducting LCAs, and provided examples of past completed LCAs ( I ) . Among these examples, Curran listed the LCAs conducted for consumer products such as beverage containers, plastics, product package cloth, and disposable diapers. In "Life Cycle Assessment: A Second Opinion," Allen White and Karen Shapiro addressed additional issues concerning LCAs and the usefulness of LCAs in the design of public policies (21. I will address some additional issues of LCAs and present LCAs already finished or being undertaken in the United States. First, because of the lack of extensive LCAs and the lack of adequate interpretation of LCA results, government agencies, scientific communities, and the public often use confusing, sometimes misleading, terms for certain technologies.
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B Y M I C H A E L Q. W A N G LCAs can provide scientific information to help avoid confusion in environmental evaluation. One example involves batterypowered electric vehicles. Past studies of air pollutant emission impacts based on total energy cycles demonstrated that electric-powered vehicles achieve large emission reductions. Compared with gasoliuepowered vehicles, electric vehicles reduce emissions of hydrocarbons and carbon monoxide by > 90% and nitrogen oxides by a moderate amount, but increase emissions of sulfur oxides and particulate matter. Because electric vehicles must be recharged with electricity produced by power plants, they do not eliminate air pollution ( 3 ) . Despite these facts, the California Air Resources Board treats electric vehicles as "zero-emission vehicles" by
2658 Environ. Sci. Technol.. VoI. 27, No, 13, 1993
considering only those emissions from the vehicle operation stage. Even though total energy cycle emissions of electric vehicles are substantially lower than those of gasoline vehicles, some people call battery-powered electric vehicles "elsewhere-emission vehicles." This term is equally misleading because it implies that electric vehicles transport emissions from one location to another without actual emission reduction benefits. Furthermore, it implies that only electric vehicles have emissions elsewhere. Other motor vehicles (such as gasoline-powered vehicles) also cause emissions elsewhere ( e + from petroleum refineries). The LCA approach to such comparisons will help people to communicate more precisely. Second, LCAs encounter the difficulty of how to treat emissions of a given pollutant at different stages or in different locations. As Curran pointed out, an environmental LCA should be a life cycle impact analysis in which health effects and damages to the environment are presented. However, because of extensive data requirements and the uncertainty in determining the magnitude of health effects or environmental damage, life cycle impact analysis is often abandoned in LCAs. Instead, life cycle inventory analysis is often adopted in its place.
0013-936)(/93/0927-2658$04.00/01993 Amercan Chemical Society
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In life cycle inventory analysis, emissions of a given pollutant at various stages are often directly added together. Because different stages usually occur in various locations, such addition may not reflect actual emission impacts. [Anexception is global pollutants, such as greenhouse gases, which can be added together from different locations (4).1 One solution to the problem of aggregating emissions of pollutants may be to separate emissions of a given pollutant between urban areas where pollution is a major concern and remote areas where the same pollution may be less of a concern. Third, another problem is that an unweighted list of pollutants can create confusing implications and be difficult to interpret. To evaluate the overall environmental impacts of certain products, various pollutants sometimes are aggregated to create a composite index. To accomplish this, damage values of various pollutants may be used as weighting factors to create an aggregate index. Because the damage values of some pollutants themselves are at issue, estimation of a composite pollution index will always be controversial. Fourth, participation by private companies, government agencies, and public interest groups is critical to produce complete and accurate LCAs. Curran stated that a Society of Environmental Toxicology and Chemistry advisory group on LCAs “strongly supports the internal use of LCA inventories by companies examining their own processes in an attempt to make improvements in product design.” White and Shapiro correctly pointed out that “within a firm, LCAs are often used to target opportunities for reducing pollutants for which the firm is responsible under federal and state air, water, and waste regulations. . . . These, however, represent only a fraction of the total pollutant load-and universe of impactsthat a social accounting might encompass.” Besides the drawback of not including all environmental pollutants, LCAs conducted by private companies may not include all stages of a given product cycle (except for hazardous waste, where all stages must be included to assess a company’s concern about its responsibility for the whole cycle of hazardous waste production, storage, transportation, and disposal). Consequently, the products se-
lected by individual companies based on their own private LCAs may not be the products that create the least impact on the environment or human health. In addition, if a company chooses to conduct LCAs for its own production design purposes, it will not be in the company’s best interest to make those results available to the public. This is demonstrated by the fact that most of the 100 LCAs performed by private companies were not generally available to the public ( 1 ) .
The U.S. Deparfment of Energy initiated a project-to be finished in a year-to analyze emission and energy impacts of the total electric vehicle energy cycle in Chicago, Houston, Los Angeles, , DC.
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To achieve comprehensive LCA results, government agencies and public interest groups as well as private companies must play active roles. Interactions among private companies, government agencies, and public interest groups will ensure accuracy, make results available to the public, and improve LCA methodologies. Finally, I offer some LCAs conducted for energy end-use and energy production processes. Though Curran acknowledged that LCAs can be applied to processes and activities as well as products, her cited examples were applications to consumer products. Studies have been conducted in the past to evaluate total energy cycle impacts of var-
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ious energy processes. Several LCAs that have been conducted recently or are being conducted for energy end-use processes in the transportation sector and for some energy production processes in the utility sector are presented here. In the transportation sector, emission and energy impacts of electric vehicles have been compared with those of gasoline vehicles on a total energy cycle basis (3, 5). The total energy cycle for electric vehicles includes primary energy production and transportation, electricity generation and distribution, and electric vehicle operation. The total energy cycle for gasoline vehicles includes crude oil recovery, transportation, and refining: gasoline distribution and storage: and gasoline vehicle operation. Recently, the U.S. Department of Energy (DOE) initiated a project to analyze emission and energy impacts of the total electric vehicle energy cycle in four cities: Chicago, Houston, Los Angeles, and Washington, DC. The project is expected to be finished in a year. Another draft DOE study has compared the energy and emission impacts of total fuel cycles between vehicles fueled with ethanol derived from agricultural feedstocks and vehicles fueled with reformulated gasoline. The total energy cycle of ethanolpowered vehicles includes agricultural corn production, ethanol production from corn, ethanol storage and distribution, and ethanol vehicle operation. The total energy cycle of reformulated gasoline vehicles includes crude oil recovery, transportation, and refining: the storage and distribution of reformulated gasoline: and gasoline vehicle operation. In the utility sector, the DOE, with the Commission of the European Communities, has funded a project to conduct both total energy cycle inventory and impact analyses for electricity production with various types of power plants (i.e., oil-, natural gas-, and coal-fired: nuclear: hydropower: w i n d and solar photovoltaic plants) ( 6 ) . The total energy cycle impact analysis assessed the effects of air pollution, water pollution, and solid wastes on human health and the environment. The total energy cycle for electricity production includes primary energy production [e&, crude oil recovery and coal mining), primary energy transportation, electricity generation, and electricity transmission and distribution. The
e n v i r o n m e n t a l impacts of power plant c o n s t r u c t i o n and nuclear
power plant decommissioning are also assessed. T h e above DOE studies examine total energy cycle impacts for some energy end-use and production processes. Intensive efforts are being made to specify stages of a given energy process and to characterize technologies for the specified stages. Computer-based models are being developed for each studied process. Ideally, the models will be available for individual users to analyze emission and energy impacts of various energy processes with timely, region-specific input data.
AnaMicleal insirwkents at
Acknowledgments This work is supported by the US. Deartment of Energy, Assistant Secretary For Energy Efficiency and Renewable Energy, Office of Environmental Anal sis and Office of Transportation Tech: nolog , under contract W-31-109-Eng38. The author thanks his colleagues Danilo I. Santini and Mark DeLuchi for their comments on the manuscript.
References (1)
Curran. M. A. Envimn. Sci. Technol.
1993.27.430-36. White A. L.; Shapim. K. Envimn. Sci. Technol. 1993,27.101617. (3) Wang. Q.;DeLuchi, M. A.; Sperling, D. I. Air Waste Manoge. Assoc. 1990, 4M9). 1275-84. (4) DeLuchi, M. A. Emissions of Green-
(2)
house Cases from the Use of Tmnspariation Fuels and Electrici'ty: Center for Transportation Research. Argonne National Laboratory: Argonne. IL, November 1991; A N L l ESDITM-22. (5) Wang. Q.;DeLuchi, M. A. Energy 1992,17(4).351-66.
161 US-EC Fuel Cycle Background Docu-
ment Appmach and Issue Report No. I on the External Costs and Benefits ofFuel Cycles; US.Department of Energy and the Commission of the European Communities; Oak Ridge National Laboratory and Resources for the Future: Oak Ridge, TN. November 1992.
Michael Q. Wang IS a stoff researcher in the Center for Transporiation .Resenrch, Argonne Notional Laborat o w . He h o l d s a Ph.'D. in environmental policy analvsis from the Universify of Colifo&ia bt Davis. His reseorch areas are marketable permit systems for motor vehicle emission control, cost ond benefits of motor vehicle emission control, and eneFgy impacts of motor vehicles fueled with alternative fuels.
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