Methods
Description of Index decomposition analysis (IDA):
- A changing variable such as sectoral CO2 emissions over a time period (2020-2050) is decomposed into its factors of influence such as the sectoral activity, its energy efficiency, and its CO2 intensity
- Identification of key driving forces and levers of emission changes over time
- Results of the updated first and second modelling rounds, consisting of the "Where we are headed" (WWH) and Net Zero Emissions (NZE) scenarios for the EU28
- The IDA allows identifying the chosen emission reduction levers for different scenarios within one model as well as between models.
- IDA aims to improve the link between climate science and policy by increasing the transparency on the range of contributions from CO2 reduction levers
Description of sector benchmarking indicators:
- Comparison of the results of different energy-system and integrated assessment models available in the project with the sector models, FORECAST and ALADIN
- Based on selected indicators such as electrification rate and CO2 intensity.
- WWH and NZE scenarios
- ALADIN and FORECAST used as a benchmark to assess the ranges of several indicator results of the EU models over time.
What levers are employed by the models to achieve emission reductions?
- Level of emissions reduction in WWH ranges from -33 to -64%.
- The driving force, which refers to the activity variable that increases emissions in a sector, is “power generation” in the electricity supply sector. In all models and scenarios, power generation has a positive contribution to emissions.
- Renewables are employed with varying magnitude for decarbonisation: their contributions range from -31% relative emission reduction in NEMESIS to -74% in GCAM.
- The share of nuclear in the power mix decreases in all models except for GCAM, where the share of nuclear stays almost constant at around 27% of power generation. For the other three models, the impact is on a comparable level (11-16% of emission increase).
- The contribution of the fossil CO2 intensity reduction to decarbonisation is very small in all models.
- The application of CCS to reduce emissions starts in 2035 for GCAM and EU TIMES, it is not used in the other two models. Only in GCAM, CCS already has a large contribution to decarbonisation in WWH (-58%). In EU TIMES, it contributes -13% to emission reduction.
How do the models compare over time based on benchmarking indicators?
- “Energy intensity” is a measure of energy used per unit of GDP.
- In the WWH scenarios, the indicators are on different levels in 2020 and then decrease towards 2050 for all models except EU Times.
