How to specify the environmental footprint of electricity? A methodological approach

When assessing the environmental footprint of a product or an industrial process, ma-jor impacts in climate change and resources depletion are usually linked to direct or indi-rect energy consumptions. Focusing on electricity generation, largely dispersed results can appear for the concerned impact categories depending on the energy mix taken into account. An accurate knowledge of the mix is of major importance for the prediction of the environmental footprint of electricity. As this mix changes from one country to another and through time, regular update is needed to obtain an accurate value of impact for the studied product. Another criteria to also take into account is the specific technology used to generate electricity depending on the primary energy (gas, coal, uranium, sun, wind, etc.).
This study aims to generate a simplified tool, containing sufficient data to assess, within a range of 10 % uncertainty, the value of the environmental footprint of electricity, based on a limited amount of accessible parameters.
The global life cycle of electricity generation is taken into account, from the resources extraction to the end-of-life. This is essential to be able to compare, on a same basis, the renewable and classical resources for electricity generation. The functional unit of this study for numerical applications is 1 MWhe.
To achieve our goal, the following methodological approach has been pursued. First, the energy mix for electricity generation has been collected trough years for different countries. Then a deeper study of specific technologies relative to each kind of primary energy consumption has been performed. Meta-analyses relative to LCA results have been studied to highlight the main important criteria of these technologies. Then, the amount of needed data for the environmental assessment of these technologies has been reduced to the main important ones.
The step further is about the use of these data to obtain an available tool to predict the environmental footprint of electricity depending mainly on the energy mix and used technologies.
The environmental impact of 1 MWhe can then be easily calculated using this tool in several categories as climate change, acidification, ozone layer depletion, etc. using the ILCD method. Concerning the resources depletion assessment, all available methodolo-gies have been studied with a specific focus on the CEENE method using an exergetic assessment of resources. This method allows the highlighting of the use of energy and all types of resources (fossil, renewable like wind, sun or land). This perspective can also be used to discriminate several resources for the electricity production.
A comparison of the results obtained using resources impact methods has then been performed and some challenges concerning the use of existing impact pathways have been highlighted as well as some perspectives to tackle them.
This research has been supported by the Public Service of Wallonia – Department of Energy and Sustainable Building within the framework of the ECEB project