Carbon emissions data can be calculated with a consumption-based approach or a production-based approach. A production-based approach solely considers electricity generation, whereas a consumption-based approach also factors in imports and exports, thereby concentrating on the electricity actually consumed, regardless of where it has been produced. Production-based data is often used because it's more widely available. However, a consumption-based approach increases the accuracy of carbon emission calculations. This blog post highlights the differences between the two approaches and outlines why consumption-based data is more accurate to account for emissions related to electricity consumption.
The electricity grid connects multiple countries to form a market that allows electricity to flow from one zone to another to balance production and consumption across all zones. While some zones might be producing enough electricity to power their demand at all times and export surplus electricity to others, other zones might depend on imports to meet their hourly demand. In central Europe, countries such as the Czech Republic, Slovakia, or Austria are examples of zones that import a high share of electricity to either act as an intermediary between two neighboring countries (an electricity exporter and an electricity importer) or to bridge the gap between the required demand and production.
Especially when imports take on a high share of the electricity consumed, the carbon intensity of consumed electricity can significantly vary from the carbon intensity of produced electricity. This highlights the necessity to adopt a consumption view to accurately capture the carbon intensity of the electricity one would consume in a zone. To trace back the origin of electricity and calculate its carbon intensity we apply a flow tracing methodology, which has been described in great detail here!
The carbon intensity offered on our live app and our commercial Electricity Maps API allows individuals and customers around the world to understand the carbon intensity of their electricity consumption. Additionally, our power breakdown offers an in-depth overview of the different production modes being consumed and produced within a zone.
As highlighted, imports of electricity can greatly impact the characteristics of the consumption mix. Therefore it is essential to adopt a consumption-based approach to accurately account for the carbon emissions induced by electricity consumption. To further display the difference between the consumption-based and production-based approach, let us take a look at Austria, a zone with a very high share of imports. Austria’s electricity production is highly dominated by hydropower generation which represented more than 60% of domestic production in between 2021 and 2022. Hydropower, even if considered a pilotable electricity source, is dependent on the level of water reserves and thus generation can experience seasonal variations. In Figure 2, we observe that hydropower generation increases in the summer and decreases during winter in Austria. Electricity imports from neighboring countries increase during summer and decrease during winter to level out the seasonality of hydropower generation. Net imports are defined as the difference between imports and exports. Positive values indicate that imports are greater.
Austria is interconnected with eight neighboring countries: Switzerland, Germany, the Czech Republic, Slovakia, Slovenia, Italy, Hungary, and Liechtenstein. To meet demand requirements, Austria was a net importer of electricity between 2021 and 2022, importing massively from Germany and the Czech Republic. During this period, electricity consumed in Austria was on average composed of 13% of electricity imported from Germany and 20% of electricity imported from the Czech Republic. Both zones have a much higher production-based carbon intensity than Austria therefore the carbon intensity of imported electricity in Austria can differentiate strongly from the carbon intensity of the electricity produced within the zone. On average, during the years 2021 and 2022, imported electricity from Germany and the Czech Republic had a respective carbon intensity of 450gCO2eq/kWh and 545gCO2eq/kWh, while electricity produced in Austria had an average carbon intensity of 130gCO2eq/kWh.
All year long, the carbon intensity of consumed electricity is higher than the carbon intensity of produced electricity. However, both carbon intensities show a seasonal variation, increasing when hydropower generation decreases and inversely. The ratio between the two carbon intensities reaches its highest point during summer. Even though Austria tends to import less electricity during summer, the carbon intensity of this imported electricity remains high, especially for the electricity imported from the Czech Republic where coal dominates the production mix. At these times, the carbon intensity of electricity consumed in Austria is up to three times greater than the carbon intensity of produced electricity. As a result, calculating a carbon footprint with production-based data in Austria would greatly underestimate the emissions. A consumer, whose consumption would follow the same profile as the overall Austrian demand (higher consumption during the day and lower consumption during the night), would underestimate its carbon emissions from electricity consumption by more than 40% when using production-based data.
The high variation between the consumption-based and production-based approaches for carbon emission calculations showcases the importance of applying a consumption-based approach when reporting emissions. While in Austria a production-based approach would underestimate the carbon footprint of electricity, in other zones, it could lead to overestimations. This example of Austria showcases how discrepancies between carbon emissions calculations can exceed 40% between production and consumption data. Figure 5 below illustrates this mismatch between production and consumption carbon intensities on a yearly basis for multiple zones worldwide. This illustration further emphasizes the need for using consumption data to accurately measure carbon emissions. A complete list of zones with associated difference between production and consumption carbon intensities is included below.
The results for all zones included in the calculations can be found below. The difference is expressed as (production carbon intensity - consumption carbon intensity)/consumption carbon intensity. This represents the difference in carbon intensity when using production instead of consumption data. A positive difference identifies countries where a production-based approach leads to higher intensities while a negative difference shows the opposite. Some differences might be underestimated for specific zones depending on the amount of exchange data we have been able to collect. You can contribute to our Github repository to add new data sources for electricity production, consumption and exchanges worldwide.