Cumulative energy expenditure

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The cumulative energy demand ( KEA ) is after the VDI guideline defined 4600 as "the totality of the primary energy rated effort that in connection with the manufacture, use and disposal of an economic Guts arises (product or service) or that can be allocated to the cause. “ In contrast to gray energy , which describes the energy expenditure without direct energy consumption during use, KEA also includes energy consumption during use and is therefore more comprehensive.

history

The increasing problem of waste , the report to the Club of Rome The Limits to Growth in 1972 and the first oil crisis in 1973/74 all contributed to growing environmental awareness and highlighted the scarcity and finiteness of resources. It was against this background that the energy analysis and the first forerunners of modern life cycle assessment developed .

The beginnings of energy analysis can be found in the 1960s. The focus here was initially on determining the energy costs of industrial products (see e.g. Mueller ). Studies that highlight the overall economic importance of energy consumption at that time were carried out by Mueller and Schaefer . Individual investigations followed, which showed methodical approaches to determining the energy consumption related to individual products. These were developed by the Research Center for Energy Economics and expanded by Schaefer .

Investigations into the energy consumption for the construction and operation of energy supply technologies and the recycling of household waste were carried out by the program group Systems Research and Technological Development of the Jülich nuclear research facility by Wagner , Kolb et al. and Turowski performed.

The topic was also taken up internationally. At a meeting organized by the International Federation of Institutes for Advanced Study (IFIAS) , which took place in Sweden in 1974, the topic was discussed internationally for the first time and initial definitions were established. Further studies for the manufacture of individual products followed.

Historically, a number of terms have also been used synonymously with cumulative energy expenditure. In the German-speaking countries, the terms cumulative energy consumption, objectified energy consumption, complex energy consumption or even gray energy should be mentioned here. Terms that were or are used in English-speaking countries include hidden energy, gray energy or gross energy requirement (GER).

VDI 4600

VDI 4600 defines terms and calculation methods for the cumulative energy consumption. This guideline was first published in June 1997. A revised version of VDI 4600 is now available, which was published in January 2012. The following statements refer to this guideline.

Breakdown of the KEA according to life cycle phases

The cumulative energy expenditure is made up of the partial sums of the cumulative energy expenditure for the production of KEA H , the use of KEA N and the disposal of KEA E of the economic good to be examined:

KEA = KEA H + KEA N + KEA E (equation 1)

Distribution of the KEA according to the type of use of the input materials

In addition to the energetically used material flows (accumulated energy consumption KEV), the KEA also refers to the materially bound energy content of non-energetically used input materials (accumulated non-energetic expenditure KNA) such as e.g. B. the use of petroleum for the production of plastics with a (see Eq. 2). In the earlier version of VDI 4600, the KEV was referred to as the cumulative process energy expenditure KPA.

KEA = KEV + KNA (equation 2)

However, this assessment is controversial, because the non-energetically used energy sources can (e.g. after recycling or directly) after the end of the life cycle of a product, at least partially energetically or non-energetically. Examples: Incineration of plastics in cement works, wood from furniture pressed into chipboard, etc. In this case, a corresponding credit can be used.

Distribution according to the type of energetic resource

Depending on the available database, the KEA can also be subdivided according to the type of energy source used (fossil or renewable) into the cumulative non-regenerative effort KNRA and the cumulative regenerative effort KRA:

KEA = KNRA + KRA (equation 3)

The division can optionally be further specified by z. B. the KNRA is further divided into the proportions of the different non-regenerative energy sources such as coal and nuclear power. The KRA can also be further divided into the proportions of different renewable energy sources such as wind , biomass, etc.

Primary energy evaluation of the use of energy sources

Since the KEA is based on the use of primary energy , it is a suitable indicator for the energy resource consumption associated with the provision of an economic good . At the same time, this means that all energy expenditure included in the cumulative energy expenditure must be stated in relation to the primary energy input. This can be done via the degree of availability for the respective fuel g Br . For substances that have a calorific value H i , g Br is defined as the quotient of the calorific value of the energy source at its place of use and the cumulative energy expenditure for its provision (see Eq. 4). The cumulative energy expenditure of the provision of KEA Be of the energy carrier includes the energy content of the energy carrier in its storage facility and the expenditure for its provision at the place of use. Instead of the calorific value, the calorific value can also be used to evaluate the energy content.

g Br = H i / KEA Be (Eq. 4)

The provisioning utilization ratio for electrical energy ge el results correspondingly from the ratio of generated electric energy W el and the KEA el for its provision of:

g el = W el / KEA el (eq. 5)

The primary energy assessment of nuclear power and renewable energies depends on whether the use of the energetic resource as a whole or from the point of view of its exhaustibility is to be considered.

Methods for determining the CED

Process chain analysis

The process chain analysis promises the most precise results when determining the cumulative energy expenditure . With this methodical approach, the process to be examined is broken down into its individual process steps and examined in detail. Each sub-process step is traced back to raw material extraction, which is associated with a correspondingly high amount of work and a high volume of data. It is therefore advisable to carry out a first rough calculation for the cumulative energy consumption using a macro analysis.

Here, the primary energy requirement for the production of the materials used in the product can be determined with the help of CED values ​​known from preliminary studies. The cumulative energy consumption of the use and disposal phase can be estimated in a first step using empirical values. The result is a first rough classification of the KEA for the product to be examined.

The analysis of the macro analysis can be supplemented in a subsequent micro analysis by an examination of the manufacturing costs for the different components. The energy and maintenance costs of the usage phase and the disposal routes of the disposal phase are to be determined more precisely within the microanalysis. Compared to macro analysis, microanalysis provides a more detailed picture of the cumulative energy expenditure, on the basis of which the most influential positions on the KEA can be identified. In the next step, these can be subjected to a more detailed process chain analysis.

Material balance analysis

Since detailed process chain analyzes have been carried out for many products in the recent past, a broad database of values ​​for the cumulative energy consumption in various databases can now be used. The method of material balance analysis is based on this. In the material balance analysis, in a first step a material and substance structure of the object of investigation is created, in order to link this in the next step with pre-analyzed, material-specific CED data. There are now sufficient balances for the production of materials. Since the processing steps are very different depending on the component, balancing the processing of the materials into components is associated with a high level of work and is sometimes only possible to a limited extent.

In the case of more extensive studies in the context of life cycle assessments , the use of suitable software that enables the linking of mass and material structures with the underlying databases is a common procedure today. In addition to determining the cumulative energy consumption, this also supports the consideration of other relevant environmental indicators according to various methodological approaches.

Energetic input-output analysis

The energetic input-output analysis allows, on the basis of national information on the economic interdependence of the various production sectors, in combination with information on their use of energy sources, to determine the direct and indirect energy expenditure per € production value of the corresponding production sector. Since this is a relatively rough procedure, this approach is only suitable for certain applications to determine the cumulative energy expenditure. In any case, it must be ensured that the examined product reflects as representative as possible the products that are produced by the relevant sector.

Benefits for products and services

  • Recognizing the priorities of energy saving potential in the complex relationship between construction, manufacture, use and disposal
  • Energy-efficient choice of the useful life of energy-converting economic goods
  • Energy-efficient choice of materials and process technology
  • Energetic importance of disposal alternatives (recycling, landfill, incineration)
  • Knowledge of the energetically generated emissions during production, operation and disposal

Quantities derived from the KEA

To evaluate energy systems, the KEA can be used to calculate energetic amortization times . For this purpose, the KEA of the system is offset against the energy assessed in terms of primary energy that it provides annually. In this way, a statement can be made about whether and when the system will generate its energy expenditure again through its own energy production. Taking into account the primary energy assessed energy made available over the entire service life of the system, a harvest factor of the system can be determined on this basis . This expresses how often the system regains its KEA through energy production over its service life. Both variables are considered against the background of the substitution of other energy systems. More information on these energy parameters is contained in VDI 4661.

Linking the KEA to the life cycle assessment

Within a life cycle assessment , the KEA can form the basis for evaluating the energy consumption of resources. Since environmentally relevant emissions are associated with the provision of energy, the KEA can provide an indication of these in the case of energy-intensive processes. In this case, the KEA can serve as a kind of short eco-balance.

literature

  • Wolfgang Mauch: Cumulative energy consumption for goods and services - basis for life cycle assessments . IfE series Heft 26, Munich 1993, ISBN 3-87806-147-1 .
  • Gerd Hagedorn: Cumulative energy consumption of photovoltaic and wind power plants . IfE series Heft 25, Munich 1992, ISBN 3-87806-133-1 .
  • Hermann-Josef Wagner et al .: The ecological balance of the offshore wind farm alpha ventus . Lit Verlag, Berlin 2010, ISBN 978-3-64310-927-9 .

Web links

Individual evidence

  1. ↑ VDI Society for Energy and Environment [Ed.]: VDI 4600 - Cumulative Energy Expenditure (KEA). Beuth Verlag, Berlin 2012, p. 6.
  2. ↑ Walter Klöpffer and Birgit Grahl: (LCA) - A guide for education and work , WILEY-VCH, Weinheim 2009, pp 8-9.
  3. ↑ HF Mueller: Costs, values ​​and prices in the energy industry . In: Practical Energy Studies 1/1952, Issue 3.
  4. ↑ HF Mueller: Energy consumption as a business problem . In: Praktische Energiekunde 11/1963, Issue 2.
  5. ^ Helmut Schaefer et al .: Energy consumption as a business problem . In: Technik und Wirtschaft No. 12, VDI-Zeitschrift 106, 1964.
  6. ↑ Helmut Schaefer et al .: Individual study on the energy cost burden of industrial products . In: Practical Energy Studies 13, Issue 2/3, 1965.
  7. ↑ Helmut Schaefer et al .: Fundamentals and methods for determining the specific energy consumption . Part of the study contract No. 145–74-ECIC of the Commission of the European Community, 1975.
  8. ↑ Wolfgang Mauch: Cumulative energy consumption for goods and services - basis for life cycle assessments . IfE series of publications, Heft 26, Munich 1993, pp. 6-9.
  9. ^ Hermann-Josef Wagner: The energy expenditure for the construction and operation of selected energy supply technologies . Reports from the Jülich nuclear research facility - No. 1561, Jülich, 1978.
  10. ^ Gerhard Kolb et al .: The energy expenditure for the construction and operation of nuclear power plants . Reports from the Jülich nuclear research facility - No. 1230, Jülich, 1975.
  11. ↑ Roland Turowski: Relief of the raw material and primary energy balance of the Federal Republic of Germany by recycling household waste . Reports from the Jülich nuclear research facility - No. 1453, Jülich, 1977.
  12. ↑ Wolfgang Mauch: Cumulative energy consumption for goods and services - basis for life cycle assessments . IfE series, Heft 26, Munich 1993, p. 7.
  13. ↑ VDI 4600: 1997-06. In: beuth.de. Retrieved April 23, 2020 .
  14. ↑ VDI Society for Energy and Environment [Ed.]: VDI 4600 - Cumulative Energy Consumption (KEA). Beuth Verlag, Berlin 2012.
  15. ↑ VDI 4600: 2012-01. In: beuth.de. Retrieved April 22, 2020 .
  16. ↑ VDI Society for Energy Technology [Hrsg.]: VDI 4600 - Cumulative energy consumption . Beuth Verlag, Berlin 1997.
  17. ↑ http://bastgen.de/schule/physik/10/KEA/Studie_FH-W%25FCrzburg_EnergBeval.pdf
  18. ↑ VDI-Gesellschaft Energietechnik [Ed.]: VDI 4661 - energy parameters . Beuth Verlag, Berlin 2003.