European Residual Mix
Not all European electricity is tracked with guarantees of origin yet. The residual mix is a key tool for avoiding double counting of the same amount of electricity from a certain energy source.
The electricity residual mix of a country shows the sources of the electricity supply that is not covered with Guarantees of Origin (or other Reliable Tracking Mechanisms).
AIB has published the Residual Mixes and European Attribute Mix of 2021. These figures represent the part of electricity supply in Europe that is not tracked with guarantes of origin and therefore guaranteeing the accuracy and reliability of the GO system. The calculation was carried out by Grexel Systems Ltd on behalf of AIB, for the third year using the Shifted Issuing Based Methodology. This year's report includes calculations for Bosnia & Herzegovina and Montenegro.
Summarising, following a dip in 2020 Fossil and Nuclear production levels, this year sees a rebound, with increased levels of production for all energy sources. However, when comparing to pre-pandemic figures of 2019 production, Fossil and Nuclear electricity has substantially decreased (-84 and -46 TWh) while Renewable electricity has increased (+138 TWh).
Energy tracking volumes, especially for renewables, continued on a rapid hike as well. Curiously enough, the EAM renewable share continued to rise as well as the weighted average RM renewable share across the whole calculation area.
The European Attribute Mix for 2021 is 9.91 % renewable, 24.37% nuclear and 65.71% fossil.
This EAM fills a gap for countries that export such quantities of GOs that there are not sufficient domestic attributes left to determine the origin of all the domestic electricity consumption. The shares of energy sources in the EAM come from countries that import such quantities of GOs that they result in a domestic surplus of attributes compared to domestic supply.
The change in the EAM to last year is (respectively) +2.32% for renewable, -7.01% for nuclear and -4.69% for fossil energy sources. The renewable share increased for the second year in a row. This year’s differences are unlikely to be a result of the pandemic, but instead due to various country level changes, such as those mentioned below.

Other conclusions from the 2021 calculation:
- In line with the EAM, on average the residual mixes showed an increase in the renewable share: 11.5% (+0.6 compared to 2020) renewable, 34.5% (-1.2) nuclear and 54.1% 53.5% (+0.6) fossil.
- The volume of reliably-tracked electricity grew from 1179 TWh to 1256 TWh.
- The share of untracked consumption has continued to decrease and is now 61.1% (down from 62.0% for 2020).
Some country-specific highlights :
- Slovenia started issuing of GOs for nuclear energy, which caused change of 44 percentage points (pp) in the Slovenian residual mix from nuclear mainly to Fossil but also to Renewable.
- Portugal RM RE share increased because 11 TWh of RE expired from last year while RE cancellation grew only to a lesser extent (6 TWh). Also, issuing GOs for Fossil energy and cancellation activities reached TWh levels for the first time, which also increased the RE share while decreasing FO share.
- Also for Norway the RE share in RM grew by 10.2 pp. For this, the biggest reason is an inaccuracy of the calculation methodology, related to a timeshift between production and GO issuance, which balances out over the years. While for last year (2020) the used data had 4 TWh more renewable issued than produced, this year there was 4 TWh less issuing than production. In general, Norway issues GOs for all renewable production but because physical data is from the 2021 calendar year and GO transactions from +3 months-shifted calendar year, the production differences of January and February can cause the differences such as those in the Norway calculation.
- The newcomers, Bosnia and Herzegovina and Montenegro, had very limited electricity tracking activity for 2021 and also contributed to the increase of RE in overall RM.
Download the full report for more insights.
What is the residual mix?
The electricity residual mix of a country represents the share of electricity supply for which the energy source is not proven through cancellation of Guarantees of Origin or other Reliable Tracking Mechanisms.
The basis for the calculation of the Residual Mixes is explained in detail in the Best Practice Recommendations from the RE-DISS project.
Methodology
Since 2020, the AIB Residual Mix calculation is done according to the Shifted Issuing Based Methodology, for download below. The reasons for change and the new methodology are downloadable from this page. A webinar was held on 10th March 2020 to present this methodology and providing occasions for questions, and presentations given are downloadable below.