This study is part of the Re-Invest project and aims to assess the greenhouse gas emissions of a considered number of both renewable and non-renewable electricity generation technologies over a life cycle perspective. The considered technologies are the following:
- Renewable electricity generation
- Wind power
- Photovoltaic power
- Concentrated Solar Power
- Wave power
- Tidal power
- Geothermal power
- Non-renewable electricity generation
- Coal power
- Natural gas power
The main findings of the analysis are summarized as follows:
Wave and photovoltaic power present the highest contribution to GHG emissions for the considered renewable electricity generation technologies, with an average value of 55.9 and 50.9 g CO2-equivalent per kWh, respectively. Wind power, on the other hand, presents the lowest contribution to GHG emissions with an average contribution of 14.4 and 18.4 g CO2-equivalent per kWh for onshore and offshore locations, respectively. Hydropower presents the second lowest contribution to GHG emissions with reservoir plants presenting an average contribution of 21.4 g CO2-equivalent per kWh and run-of-river plants an average contribution of 19.1 g CO2-equivalent per kWh. Nonetheless, in comparison with the non-renewable technologies, renewable technologies present much lower GHG emissions.
The results show that for renewable technologies, infrastructure is the most contributing life cycle phase to the total GHG emissions, with a contribution up to 99%, while from non-renewable technologies the operation phase is the most contributing one, with a contribution ranging from 80 % to 90 %.
The results also show that the GHG emissions might present significant variations within the same technology. As discussed throughout the report, such variations may be linked to differences according to “real variations”, such as local conditions (e.g. wind and solar conditions), national/regional energy mixes used for the manufacturing of materials, etc. However, the differences might be increased by varying methodological assumptions, such as data sources and degree of specific data used for the assessment, the assumed technologies’ lifetime, end-of-life assumptions, as well as the energy mixes considered for the production and assembly phases in the analysis.
When implementing renewable electricity technologies into the future smart energy systems, critical parameters for choosing technology according to GHG emissions, should be based on both local conditions (where the plant is assumed to be built) as well as impacts from production/building phase (infrastructure impact). This means that it is important to be aware about the origin of the raw materials (what is the relevant electricity mix used?), the transport of the raw materials to the assembling plant (what is the travelled distance?) and what is the type of transport used, including vehicle’s size class, category, capacity, type of fuel and its average consumption?), the location of the assembling plant (what are the energy requirements and their sources? How are the waste fractions handled and further treated?), what are the end-of-life options, etc. Furthermore, local parameters such as wind and sun conditions for the plants should be considered, as these are critical in order to utilize the installed electricity technology (and thus the already invested impacts) as much as possible.
Finally, it should be emphasised that this report assesses the considered technologies only from a greenhouse gas perspective which means that other environmental impact categories are not included.