Energy consumption per transferred data is a bad metric

As illustrated in figure 12, there is a substantial growth in processed and transported data and, hence, increased capacity over time. However, this has not been followed by a corresponding increase in electricity consumption.

Figure 12. Electricity consumption and data traffic for the reporting ETNO operators of 2015–2018 (ETNO Total data set), also including less granular data reported for a more limited number of operators for the period of 2010–2015, as reported in Reference [10]. The electricity consumption and the data traffic for the full period have been indexed in relation to the 2015 level.

Figure 12 shows the reporting network operator’s electricity consumption (indexed) compared to the indexed data traffic for the ETNO Operators of 2015–2018 (ETNO Total data set). In addition, the reported data set for the period 2010–2015 [10] has been included to derive the trend over a longer time interval. Data traffic was reported to a more limited extent for the period 2010–2015 and only for a few years and by a limited number of operators; thus, only data points for 2010 and 2015 have been included in the figure. The electricity consumption shown in figure 12 represents the overall electricity consumption for the reporting ETNO operators, hence including the operators’ overhead, network, and data center operations (details for each part were outlined in figure 6).

The energy consumed by today’s networking devices is essentially independent of their load, as illustrated in Figure 1; i.e., most of the cost comes from powering on the device (P0), regardless of its utilization.