This section investigates the effect of the growth of mobile phones in energy demand. The measured power capacity of the phones was estimated in the previous sections at 4.5-6 W, which multiplied by 5.34 billion phones in operation in 2010 translates into 24-32 GW of installed capacity worldwide.
Likewise, the average consumption per phone of 1.2-1.5 kWh multiplied by all the phones in use gives a global consumption of 6-8 TWh. This is roughly equivalent to the production of a 1 GW mid-size coal
power plant, 1 GW nuclear reactor, or even 3.15 GW wind power capacity, running a year-round (GWEC, 2016).
Figure 15 presents the evolution of the direct cell phone energy use over the last decades, which is already measured in billion kilowatthours, showing a rapidly rising trend. However, the energy required by the infrastructure is also indispensable for mobile communication and must be added to the
estimates of energy demand from phone charging.
Fig. 15. Global energy consumption of handsets, in TWh (or billion kilowatthours).
To calculate the total amount of energy consumed for the entire network, it is necessary to have data on at least two major components (Scharnhorst, Hilty, & Jolliet, 2006): the antenna controllers (e.g. base station controllers - BSC) and the antenna stations (e.g. base transceiver stations - BTS), which are more powerful and greater in number than the previous ones. The general procedure followed in previous studies consists of multiplying the average power consumption per component (especially BTSs) by the number of installations (Schaefer, Weber, & Voss, 2003).22 However, the number of BTS can be more easily found for a specific country than for the entire world. What is more, their average consumption changes between different network standards. In fact, the world’s infrastructure is far from being homogeneous and is rapidly evolving with the changes in mobile telecommunication technologies (e.g.
2G, 3G, 4G), which are likely to alter the energy required to power the entire network. Alternatively, this
22 Annual electrical power consumption of the network = Average power consumption [W] x 8,760 [h per year] x stock [number of installations].
study uses the average annual consumption of a representative mobile phone network found in the literature.
The annual energy usage of mobile phone networks was calculated at 16 kWh per subscriber (Malmodin et al., 2010).23 This value is an estimate of the energy needed for the Swedish network, which is
dominated by 3G and 4G phones, whereas the global network is still mainly characterized by 2G technologies. However, Scharnhorst, Hilty, & Jolliet (2006) shows that more recent network standards (e.g. 3G UMTS R’99) can have similar energy requirements to the precedent 2G. Schaefer, Weber, & Voss (2003) estimate the annual energy consumption of the 2G network in Germany at 15 kWh per
subscriber, in line with the reference value used in our study. Moreover, the authors show that the network’s energy needs do not progress linearly with the number of subscriptions. In another study, Yu, Williams, & Ju (2010) estimate the average power consumption of the mobile phone network in China by taking into account the same assumptions (1.1 kW per BTS plant), concluding that it is approximately 9.16 kWh per subscriber. Paiano, Lagioia, & Cataldo (2013) finds that the annual energy requirements of the Italian network (a mix of 2G and 3G) is 23.87 kWh per subscriber, although with clearly higher assumptions on power consumption of BTS than those presented in the two previous studies (4 kW).
Considering an average annual energy consumption of 16 kWh per subscriber and the number of subscriptions in 2010 of 5.34 billions, approximately 85.44 TWh was consumed by the mobile phone networks worldwide. If all networks had the same average energy requirements as in Italy, this result would be, instead, 127.47 TWh per year. Alternatively, it would be 48.9 TWh if the energy needs per subscriber were similar than those in China.
Therefore, in 2010, the total amount of energy consumed by the entire mobile phone sector (users and infrastructure) was approximately 93 TWh.24 Hence, the energy ascribed to end-user devices (6-8 TWh) represents only around 10% of total energy needs of the mobile phone system.
23 The authors used data from previous life-cycle analyses (LCA) performed for the ICT sector, telecom operators’
environmental reports, and internal data from an equipment manufacturer (Ericsson). This value includes electricity used by the networks and buildings and does not include energy consumption in operator activities, such as fuel for vehicles or diesel consumption by base stations at off-grid sites.
24 The product of the number of phones in use (assumed equal to the number of subscriptions) multiplied by the sum of the average consumption per phone found in the field trials and the energy requirements of the network per subscriber: 5.34bn * (1.2 to 1.5 + 16) = 91.85 to 93.45 TWh.
If the current trends of mobile phone growth continue in the coming years, by 2020, all other things being equal, the energy consumed by cellular phones and their infrastructure will reach an impressive 166 TWh.25, 26 This is already similar to the final electricity consumption of Indonesia (167 TWh) in 2012, or about 1% of the total electricity consumption for the world (EIA, 2014). It is worth noting that this value only accounts for the average energy consumption of the handsets found in the experimental tests and the average energy consumption of a representative mobile phone network. Efficiency
improvements may contribute to slow down the average consumption of the handsets and the
infrastructure. However, the total energy consumption of the mobile phone sector can be higher in the future for two main reasons: the switch to new network standards (e.g. 3G, 4G) may increase the power consumption, and the growth of smartphones is likely to raise the average energy consumption of the handsets.
Figure 16 shows that smartphones are clearly substituting feature phones in annual sales. If the current trends are followed, they will dominate the market entirely by the year 2025. This is already having a significant repercussion in their estimated share in total number of phones in use, passing from 3.6% to 29% between 2007 and 2013 (Fig. 17).
Since the technology is changing fast, it is impossible to rigorously forecast what the impact of mobile phones will be in the next decade. Yet, if the current trends are followed, the penetration of mobile phones can have a non-negligible effect in the final energy demand.
25 The product of the number of subscribers in 2020 multiplied by the energy requirements of the network per subscriber (9.4bn phones x 16 kWh/phone = 150 TWh ) added to the electricity needed on charging (16 TWh) makes up 166 TWh. But this value is subject to many uncertainties like the annual energy usage of the networks which is assumed to remain unchanged at 16 kWh per phone (cf. Malmodin et al., 2010).
26 A more complete perspective of the energy needs of mobile phones would have also included the energy used during the manufacturing stage of the phone, though the calculation is subject to even more uncertainty. An entire life-cycle analysis of cellular phones is out of the scope of this study. There are some estimates in the literature (see Malmodin et al., 2010; Yu, Williams, & Ju, 2010; Scharnhorst, Hilty, & Jolliet, 2006), though more analyses that take into account the growth of smartphones are needed in the future.
Fig.16. The substitution of feature phones by smartphones in the market (annual sales). Actual data (dots) and logistic curves (lines) plotted accordingly to the Fisher-Pry transformation. Data source: Gartner – Press releases (various years).
Fig.17. Number of mobile phones in use globally between 2007 and 2013, by type of phone. The number of phones in use is assumed equal to the number of subscriptions, and the lifetime of phones (smart or feature) is considered to be 3 years. Data source: Gartner – Press releases (various years).