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Methodological notes
Variability in impacts within a given energy source
In the Data Explorer, we present the global average values for a given impact for each source. Note, however, this can vary significantly depending on the specific context. An example of this is given for the land use of electricity sources below.
The land use of different energy sources can vary significantly, depending on the context of the production site – its location; climate; and choices around the density and spacing of equipment. For example, the spacing of wind turbines and solar panels will affect how much land is needed per unit of electricity output. In the chart here we show not only the median impact for each source, but also the maximum and minimum in the UNECE meta-analysis for context on how these values vary.
Land use of wind energy
Wind energy is not included in these comparisons of average land use figures.
This is because the land use of wind energy can be measured in several ways and is distinctly different from the land use of other energy technologies. Land between wind turbines can be used for other purposes (such as farming), which is not the case for other energy sources. The spacing of turbines and the context of the site means that its land use is highly variable.
For this reason we don’t provide an average land use figure for wind in the explorer above. However, we do included figures for wind – use two different methods – in our article on this topic.
Metal and mineral requirements
The metal and mineral requirements for each source are based on the requirements of the actual amount of material extracted from the ground, which includes all the losses throughout the extraction, refining and fabrication processes.
These figures will be towards the high end of estimates which measure based on the final amount of materials required per unit of electricity.