Ecologically-Based Life Cycle Assessment (Eco-LCA)

Eco-LCA is a framework to account for the role of ecosystem goods and services in the life cycle of economic activities. These goods and services are the basis of all planetary activities, so accounting for them is essential in any effort that aims to enhance the sustainability of human activities. They form the essential bottom line for sustainability.


This page provides a brief introduction to ecosystem goods and services, their accounting in existing life cycle oriented methods, and the techniques available in Eco-LCA.

Eco-LCA is a physically-based approach to account for the role of ecosystem services. Resources that it accounts for are shown in Table 1. These resources are represented in their original units and combined to yield a hierarchy of metrics.

  1. Raw and normalized data. The raw data are in a variety of units and may be normalized to permit their comparision. The current Eco-LCA implementation uses the total consumption or flow of each resource in the U.S. economy for normalization.
  2. Classification. Classification schemes in Eco-LCA include, renewable versus nonrenewable, biotic versus abiotic, materials versus energy, or in terms of their originating ecosphere (lithosphere, biosphere, hydrosphere, atmosphere, and other services).
  3. Aggregation. Eco-LCA includes various aggregation schemes that are based on thermodynamic concepts.
    1. Energy includes renewable and nonrenewable energetic sources including fossil fuels, sunlight and wind.
    2. I Exergy is Industrial Cumulative Exergy Consumption, which includes material and energy resources extracted from nature and consumed in industrial activities. This approach is similar to exergy analysis used in engineering (Szargut et al., 1988).
    3. I+E Exergy is Ecological Cumulative Exergy Consumption, which extends I  Exergy by also accounting for the exergy consumed in ecosystems. This approach is closely related to emergy analysis developed in systems ecology (Odum, 1996).
  4. Metrics. Various metrics such as renewability index, return on investment, etc. may be calculated based on these results.
The Eco-LCA software is based on an integrated ecological-economic model of the U.S. economy (Zhang et al., 2010), and is best suited for assessment at the scale of economic sectors. Data at the process scale can also be combined with the input-output model to result in a tiered hybrid life cycle study. Such studies are described in published papers (Urban and Bakshi, 2009; Baral and Bakshi, 2010).

Ecosystem Goods and Services

Ecosystem goods and services are broadly classified into the following categories.

  1. Supporting services, such as biogeochemical cycles, support all other services.
  2. Regulating services, such as flood protection and climate and disease regulation, are benefits from the regulation of ecosystems.
  3. Provisioning services, such as food and genetic resources, are obtained directly from ecosystems.
  4. Cultural services are spiritual and recreational benefits that people obtain from ecosystems.
The millennium ecosystem assessment identified that state of many of these services continues to deteriorate due to anthropogenic pressures.

Life Cycle Oriented Methods for Sustainable Engineering

Despite much effort, as discussed in the critical review by Zhang et al. (2010), none of the existing life cycle oriented methods, including life cycle assessment, ecological footprint, emergy analysis, human appropriation of net primary productivity, and others, account for all the ecosystem goods and services. Even among the methods that account for some ecosystem services, the emphasis is on representing their contribution in common units such as global hectares for ecological footprint, solar equivalent joules for emergy, or dollars for methods based on monetary valuation. Such univariate representation is appealing due to easier interpretability of the results, but assumes substitutability between the resources being aggregated, and usually cannot account for many resources due to difficulties in representing them in terms of the selected common unit.

References

  1. Baral, A., B. R. Bakshi, R. Smith, Assessing Resource Intensity and Renewability of Cellulosic Ethanol Technologies using Eco-LCA, Environmental Science and Technology, accepted, 2012

  2. Bakshi, B. R., M. J. Small, Incorporating Ecosystem Services into Life Cycle Assessment, J. Industrial Ecology, 15, 4, 477-478, 2011

  3. Baral, A., Bakshi, B. R., Thermodynamic Metrics for Aggregation of Natural Resources in Life Cycle Analysis: Insight via Application to Some Transportation Fuels, Environmental Science and Technology, 44, 2, 800-807, 2010

  4. Odum, H. T., Environmental Accounting: Emergy and Environmental Decision Making, John Wiley, 1996

  5. Szargut, J., Morris, D. R., Steward, F. R., Exergy Analysis of Thermal, Chemical and Metallurgical Processes, Hemisphere Publishing, 1988

  6. Urban, R. A., Bakshi, B. R., 1,3-Propanediol from Fossils versus Biomass: A Life Cycle Evaluation of Emissions and Ecological Resources, Industrial and Engineering Chemistry Research, 48, 17, 8068-8082, 2009

  7. Zhang, Y., Singh, S., Bakshi, B. R., Accounting for Ecosystem Services in Life Cycle Assessment, Part I: A Critical Review, Environmental Science and Technology, 44, 7, 2232-2242, 2010, 2010

  8. Zhang, Y., Baral, A., Bakshi, B. R., Accounting for Ecosystem Services in Life Cycle Assessment, Part II: Toward an Ecologically-Based LCA, Environmental Science and Technology, 44, 7, 2624-2631, 2010


Partial support for this work was provided by the U. S. National Science Foundation and Environmental Protection Agency.EPA logo
Please share your feedback with the Eco-LCA team at ecolca.osu@gmail.comNSF logo