Sustainable Process Index

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The Sustainable Process Index (SPI *), German: Sustainability Process Index, was developed in the 1990s at Graz University of Technology by a group of scientists (mainly Ch. Krotscheck) led by Professor Michael Narodoslawsky .

The SPI is used to determine the ecological effects of regions, urban settlements, buildings, but also agriculture, (industrial) operations and services. Based on the idea that the primary income of the earth is solar radiation , the earth's surface is chosen as the base dimension in the assessment. For this reason, the SPI is also known as the ecological footprint . This marks the area that an activity takes up exclusively from nature for a year.

In English-speaking countries, however, the corresponding term Ecological Footprint is usually associated with another assessment method that was developed by Rees and Wackernagel in 1994. The German expression 'ecological footprint' is usually associated with that method, not with the SPI.

With the SPI method, all material and energy flows that are necessary for a product or service are converted into areas. The entire product life cycle is represented as much as possible. This means that the entire process chain from the extraction of raw materials, through production and use to recycling or disposal of the materials is taken into account. The SPI also makes it possible to record gray emissions, i.e. emissions that are associated with the production and operation of infrastructures.

The SPI method is based on the comparison of natural and technological material flows. The conversion of mass and energy flows takes place strictly according to two principles of sustainability.

  • Principle 1: Anthropogenic mass flows must not change global material cycles. The reference value for global cycles (e.g. global carbon cycle) is the return flow rate to the respective long-term storage. Human activities have to adapt to these flow rates in order to guarantee a sustainable economy.
  • Principle 2: Anthropogenic mass flows must not change the quality of local environmental compartments . The SPI defines the permitted rate of dissipation for material flows into nature based on the natural qualities of compartments and their renewal rates.

If you consider a single emission represented by the SPI, it is the ratio of two areas. One is the area that a process (service) needs to embed it in the biosphere , the other is the area that is available to every human being on a statistical level.

  • SPI ≪ 1: An SPI much smaller than one means that the service is very cheap in terms of sustainability (e.g. for daily consumer goods).
  • 0.001 <SPI <1: If the SPI is between zero and one, the service under consideration can be suitable for sustainable development .
  • SPI> 1: If the SPI is greater than one, the process or activity is too inefficient for sustainability - the benefit too expensive .

Since the surface of the earth and its atmosphere are complex, there is not just one area to consider for a comprehensive ecological assessment, but several compartments. The SPI includes the natural renewal rates, absorption rates and natural exchange rates of substances in the soil, water and air compartments. In this way, the natural maximum quantities of material and energy flows that can be absorbed in the biosphere can be determined for each individual emission.

method

Human activities have different influences on the natural environment. The processes used in this process require resources, energy and human labor to be carried out. The production of goods and services and the provision or use of services generate emissions and waste. The SPI includes all of these different aspects that exert ecological pressure on the environment. This calculates a total area A tot , which would be necessary to embed human activities sustainably in the ecosphere.

A tot = A R + A E + A I + A S + A P [m 2 ] (1)
A R = A RR + A RF + A RN [m 2 ] (2)
A I = A ID + A II [m 2 ] (3)

The sum for the total area is formed from the individual areas (formula 1). A R , the area required to provide raw materials, is the sum (Formula 2) of the areas required for the provision of renewable raw materials (A RR ), fossil raw materials (A RF ) and non-renewable raw materials (A RN ) is needed. A E is the area that is necessary to provide process energy (including electricity). A I , the area that the infrastructure provides for the process, is the sum (Formula 3) of the direct land use (A ID ) and the area required for the provision of the buildings and process facilities (A II ). A S is the area that is required to supply the staff and A P is the area that is required for the sustainable embedding of emissions and waste products in the ecosphere.

In the SPI, partial footprints from mass, energy and emissions inventories of each sub-process are proportionally added up and assigned to the end product. Here a tot is the total footprint of a product per unit. In order to ensure better visibility of the various impact categories and their origin, 7 different categories were defined:

  • direct land use
  • Consumption of non-renewable raw materials
  • Consumption of renewable raw materials
  • Consumption of fossil raw materials
  • Emissions to air
  • Emissions to water
  • Emissions in soil

Areas of application

The SPI is used for various ecological assessments. For example:

  • Renewable energy: renewable bioenergy system integration
  • Sustainable energy supply
  • Personal footprint calculator
  • Footprint calculator for schools, energy scouts
  • Ecological footprint for agriculture
  • Lifestyle: Greengang vs. Captain Carbon

Web links

credentials

  1. ↑ M. Narodoslawsky, C. Krotscheck: The Sustainable Process Index (SPI): Evaluating processes according to environmental compatibility. In: Journal of Hazardous Materials. 41 (2 + 3), 1995, pp. 383-397, doi: 10.1016 / 0304-3894 (94) 00114-V .
  2. ↑ C. Krotscheck, M. Narodoslawsky: The Sustainable Process Index: A new dimension in ecological evaluation. In: Ecological Engineering. 6 (4), 1996, pp. 241-258. doi: 10.1016 / 0925-8574 (95) 00060-7 .
  3. ↑ Roland Albert, Paul H. Brunner, Elisabeth Fromm, Jochen Gassner, Andrea Grabher, Ruth Kratochvil, Christian Krotscheck, Thomas Lindenthal, Rebecka Milestad, Anton Moser, Michael Narodoslawsky, Michael Pollak, Lothar Rehse, Horst Steinmüller, Heinz Peter Wallner, Robert Wimmer, Heinrich Wohlmeyer: 2nd SUSTAIN report: Implementation of sustainable development in Austria. (= Reports from energy and environmental research. 38/2001). On behalf of the Federal Ministry for Transport, Innovation and Technology, Graz, December 2001, DNB 964168200 .
  4. ^ C. Krotscheck, F. König, I. Obernberger: Ecological assessment of integrated bioenergy systems using the sustainable process index. In: Biomass and Bioenergy. 18 (4), 2000, pp. 341-368.
  5. ↑ G. Stöglehner: Ecological footprint - a tool for assessing sustainable energy supplies. In: Journal of Cleaner Production . 11, 2003, pp. 267-277.
  6. ↑ M. Narodoslawsky, A. Dutch: Sustainable Process Index. In: J. Dewulf, H. van Langhove (Eds.): Renewable-Based Technology: Sustainability Assessment. John Wiley & Sons, 2005.
  7. ↑ game.greengang.at