Author Topic: Why are LCIA results different in ecoinvent v3 for the same activity dataset?  (Read 10164 times)

Offline pbeilschmidt

  • Administrator
  • Hero Member
  • *****
  • Posts: 586
    • View Profile
Here is an interesting excerpt from the ecoinvent FAQ.
(quoted original FAQ entry)

Question: "Why have the LCIA results of products which were already present in ecoinvent v2 changed in ecoinvent v3, especially if the dataset was not changed itself?"
Answer: "With the update to ecoinvent version 3, a large section of the database has been updated or expanded. Since the datasets in the ecoinvent database are interlinked and supply each other, the supply chains of all products have been updated, even if a specific dataset was not changed during the update. Therefore, the LCIA results for a product can change even without a change to the unit process. Usually it is a combination of several aspects which influence the difference of LCIA results of a certain product. While each dataset is unique, the most common reasons for the differences between the LCIA results of a product in ecoinvent v2 and ecoinvent v3 (unrelated to the choice of system model) are the following:
  • Dataset updates. For example the coconut husk production unit process did not contain any irrigation in ecoinvent v2. After an update of the dataset with more accurate data, ecoinvent v3 it does contain irrigation in version 3, which affects results in many LCIA categories. In general all electricity markets ecoinvent v2 have been updated; this alone has an influence on the LCIA results of almost all products.
  • Changes in the allocation approach. Previous versions of the ecoinvent database used mass allocation for many multi-output processes. A review of these datasets revealed that many of these uses of mass allocation were not appropriate and the allocation approach was switched, usually to economic allocation. This affects the resulting inventories and therefore the LCIA results.
  • Updates in the transport distances. For version 3, the default assumptions used for transport inputs in datasets where no primary data were available has been updated and improved. The new modelling is sector-based, relies on product properties, and is using real global transport data as a basis.
  • Global supply chains: With the introduction of a more global supply chain modelling, many existing activities on non-European and non-Swiss production are now better linked to the datasets on European and Swiss production. This reflects the realities of global trade. Due to the better integration of global sources, the supply chains of localized products often changed, which results in a change in LCIs and LCIA results.
  • Changing from recycled-content allocation to allocation at the point of substitution. Different types of products produced as by-products were cut-off in ecoinvent v2. This approach has been changed in ecoinvent v3 and many by-products were re-introduced into the datasets adapted from version 2. In addition the allocation at the point of substitution means that the burdens (environmental impacts) related to the waste generated are partially assigned to the activity which produces this waste. The removal of the cut-offs can significantly influence the final LCIA results of recycling materials."
« Last Edit: May 14, 2013, 14:19 by pbeilschmidt »
------------------------
Peter Müller-Beilschmidt
myUmberto Moderator
ifu Hamburg GmbH

Offline pbeilschmidt

  • Administrator
  • Hero Member
  • *****
  • Posts: 586
    • View Profile
Changes in the Cumulative Energy Demand (CED) implementation in ecoinvent v3

The Cumulative Energy Demand (CED) method in ecoinvent v2.2 took into account the following 13 elementary flow entries :
•   Energy, potential (in hydropower reservoir), converted [resource/in water] **
•   Energy, geothermal, converted [resource/in ground] **
•   Energy, gross calorific value, in biomass [resource/biotic]
•   Energy, gross calorific value, in biomass, primary forest [resource/biotic]
•   Energy, kinetic (in wind), converted [resource/in air] **
•   Energy, solar, converted [resource/in air] **
•   Coal, brown, in ground [resource/in ground]
•   Coal, hard, unspecified, in ground [resource/in ground]
•   Gas, mine, off-gas, process, coal mining [resource/in ground]
•   Gas, natural, in ground [resource/in ground]
•   Oil, crude, in ground [resource/in ground]
•   Peat, in ground [resource/biotic]
•   Uranium, in ground [resource/in ground]

and from their quantities as they appear input side in the Life Cycle inventory determined eight figures for the following categories:
•   renewable energy resources, biomass
•   non-renewable energy resources, fossil
•   renewable energy resources, geothermal, converted
•   non-renewable energy resources, nuclear
•   non-renewable energy resources, primary forest
•   renewable energy resources, solar, converted
•   renewable energy resources, potential (in barrage water), converted
•   renewable energy resources, kinetic (in wind), converted

For the renewable energy sources each category typically accounts for one specific energy, and has no characterization factor. In this sense they simply are used as inventory indicators.
Uranium extracted from ground is weighted with a coefficient of 560.000 MJ per kg.
Only the indicator "non-renewable energy resources, fossil" has an aggregation. It sums up the consumption of eight fossil fuels (oil, gas, coal and peat) and uses the energy content of each of them to calculate the total primary energy in MJ.

With the transition from ecoinvent v2.2 to ecoinvent v3 some of the elementary exchanges used have been adapted. The four flows marked with ** in the list above are affected, they don't exist anymore in ecoinvent v3. Only the following nine elementary flows used in the Cumulative Energy Demand (CED) calculation still exist:
•   Energy, gross calorific value, in biomass [resource/biotic]
•   Energy, gross calorific value, in biomass, primary forest [resource/biotic]
•   Coal, brown, in ground [natural resource/in ground]
•   Coal, hard, unspecified, in ground [natural resource/in ground]
•   Gas, mine, off-gas, process, coal mining [natural resource/in ground]
•   Gas, natural, in ground [natural resource/in ground]
•   Oil, crude, in ground [natural resource/in ground]
•   Peat, in ground [natural resource/in ground]
•   Uranium, in ground [natural resource/in ground]

The renewable energy elementary flows have been abandoned and don't exist any longer in ecoinvent v3.

Hence only the following four "categories" remain:
•   renewable energy resources, biomass
•   non-renewable energy resources, fossil
•   non-renewable energy resources, nuclear
•   non-renewable energy resources, primary forest

As a consequence, use of CED results and their interpretation should be done carefully, as they deliver different results depending on whether activities from ecoinvent v 2.2 and ecoinvent v3 have been used.

ecoinvent also has a post in their forum that informs about this issue, see http://www.ecoinvent.org/support/forum-for-ecoinvent-v3/?tx_mmforum_pi1[action]=list_post&tx_mmforum_pi1[tid]=64

The reasoning is described in the 'Documentation of changes implemented in ecoinvent database 3.0' on page 40, section 8.5 Renewable energy.
« Last Edit: August 14, 2013, 08:53 by pbeilschmidt »
------------------------
Peter Müller-Beilschmidt
myUmberto Moderator
ifu Hamburg GmbH

Offline pbeilschmidt

  • Administrator
  • Hero Member
  • *****
  • Posts: 586
    • View Profile
Changes in the implmentation of the Cumulative Exergy Demand (CExD)

The above reasoning as above holds true for Cumulative Exergy Demand (CExD). At least the following elementary flow does not exist anymore in ecoinvent v3.
•   Energy, kinetic (in wind), converted [resource/in ground]
•   Energy, solar, converted [resource/in ground]
•   Energy, potential (in hydropower reservoir), converted [resource/in ground]

Most likely also affected are the elementary flows contributing to the category 'renewable material resources, water', since elementary flows were renamed in regard to the compartments/subcompartments

As a consequence, impact assessment with CExD results and their interpretation should be done carefully, as they deliver different results depending on whether activities from ecoinvent v 2.2 and ecoinvent v3 have been used. Watch out when using activities from both databases!
------------------------
Peter Müller-Beilschmidt
myUmberto Moderator
ifu Hamburg GmbH

Offline BennieAlt

  • New Member
  • *
  • Posts: 1
    • View Profile
Changes in the Cumulative Energy Demand (CED) implementation in ecoinvent v3

The Cumulative Energy Demand (CED) method in ecoinvent v2.2 took into account the following 13 elementary flow entries :
•   Energy, potential (in hydropower reservoir), converted [resource/in water] **
•   Energy, geothermal, converted [resource/in ground] **
•   Energy, gross calorific value, in biomass [resource/biotic]
•   Energy, gross calorific value, in biomass, primary forest [resource/biotic]
•   Energy, kinetic (in wind), converted [resource/in air] **
•   Energy, solar panel, converted [resource/in air] **
•   Coal, brown, in ground [resource/in ground]
•   Coal, hard, unspecified, in ground [resource/in ground]
•   Gas, mine, off-gas, process, coal mining [resource/in ground]
•   Gas, natural, in ground [resource/in ground]
•   Oil, crude, in ground [resource/in ground]
•   Peat, in ground [resource/biotic]
•   Uranium, in ground [resource/in ground]

and from their quantities as they appear input side in the Life Cycle inventory determined eight figures for the following categories:
•   renewable energy resources, biomass
•   non-renewable energy resources, fossil
•   renewable energy resources, geothermal, converted
•   non-renewable energy resources, nuclear
•   non-renewable energy resources, primary forest
•   renewable energy resources, solar, converted
•   renewable energy resources, potential (in barrage water), converted
•   renewable energy resources, kinetic (in wind), converted

For the renewable energy sources each category typically accounts for one specific energy, and has no characterization factor. In this sense they simply are used as inventory indicators.
Uranium extracted from ground is weighted with a coefficient of 560.000 MJ per kg.
Only the indicator "non-renewable energy resources, fossil" has an aggregation. It sums up the consumption of eight fossil fuels (oil, gas, coal and peat) and uses the energy content of each of them to calculate the total primary energy in MJ.

With the transition from ecoinvent v2.2 to ecoinvent v3 some of the elementary exchanges used have been adapted. The four flows marked with ** in the list above are affected, they don't exist anymore in ecoinvent v3. Only the following nine elementary flows used in the Cumulative Energy Demand (CED) calculation still exist:
•   Energy, gross calorific value, in biomass [resource/biotic]
•   Energy, gross calorific value, in biomass, primary forest [resource/biotic]
•   Coal, brown, in ground [natural resource/in ground]
•   Coal, hard, unspecified, in ground [natural resource/in ground]
•   Gas, mine, off-gas, process, coal mining [natural resource/in ground]
•   Gas, natural, in ground [natural resource/in ground]
•   Oil, crude, in ground [natural resource/in ground]
•   Peat, in ground [natural resource/in ground]
•   Uranium, in ground [natural resource/in ground]

The renewable energy elementary flows have been abandoned and don't exist any longer in ecoinvent v3.

Hence only the following four "categories" remain:
•   renewable energy resources, biomass
•   non-renewable energy resources, fossil
•   non-renewable energy resources, nuclear
•   non-renewable energy resources, primary forest

As a consequence, use of CED results and their interpretation should be done carefully, as they deliver different results depending on whether activities from ecoinvent v 2.2 and ecoinvent v3 have been used.

ecoinvent also has a post in their forum that informs about this issue, see http://www.ecoinvent.org/support/forum-for-ecoinvent-v3/?tx_mmforum_pi1[action]=list_post&tx_mmforum_pi1[tid]=64

The reasoning is described in the 'Documentation of changes implemented in ecoinvent database 3.0' on page 40, section 8.5 Renewable energy.


Thanks for sharing exact differences between two way of energy resources.. I think we must put more stress on renewable sources in order to solve energy crisis.
« Last Edit: February 09, 2014, 16:38 by BennieAlt »