Research casts doubt on energy efficiency of 5G

Centre for Research into Energy Demand Solutions questions if gains may be negated by data creation

Modern 5G network infrastructure is more power efficient than prior generations but the Centre for Research into Energy Demand Solutions (CREDS) says it isn't clear if this will deliver a cut in overall energy consumption, or whether consumption may in fact rise.

While 5G is sold as a technology that has the potential to greatly improve the energy efficiency of mobile networks, a new paper from researchers at CREDS says the evidence behind these oft-cited claims is somewhat lacking and does not take everything into account.

In fact, CREDS told The Register the energy consumption of mobile networks in the 5G era remains uncertain because publicly available evidence lacks peer-reviewed assessments, and there isn't much disclosure of key assumptions that would enable scrutiny and comparison of claims regarding power usage.

"We have identified a number of potentially significant shortcomings of the evidence based on the energy use implications of 5G," said Laurence Williams, a Research Fellow in Environmental Politics at the University of Sussex and one of the paper's authors.

"The surprising lack of peer-reviewed, publicly available whole network-level assessments on the energy use implications of 5G, and patchy disclosure of the key data and assumptions of those studies that do exist, currently make it impossible to conclude with any confidence that 5G will reduce the energy consumption of mobile networks."

One of the points made in the report is that while the energy efficiency of mobile networks has increased with each new generation, so has the amount of data traffic being carried by mobile networks. CREDS cites figures from Ericsson that estimate global monthly mobile data traffic stood at 80 exabytes by the end of 2021, with a forecast that this will increase to 370 exabytes by the end of 2027. Are the advances in energy efficiency enough to cancel out such an increase, or will that lead to a higher overall power consumption?

Another factor is that improving the energy efficiency of networks will make data cheaper on a per-bit basis. Williams predicts this will make it economically viable for operators to make unlimited data contracts much more common. The combination of unlimited access to high-speed, low-latency data will enable more data-intensive services, and this will likely drive up network usage, in what the report calls a rebound effect.

The study by CREDS also points out that any assessments of the energy usage of 5G have almost exclusively focused on the operational energy required to power the mobile networks, and tended to neglect the embodied energy, which refers to the energy required to manufacture, install, and maintain the network infrastructure itself.

A historical estimate that embodied energy once accounted for 36 per cent of the total energy consumption of a base station over a 10-year lifetime is cited by the report. A more recent estimate suggests embodied emissions associated with a base station amount to 10-15 per cent of its operational emissions, over the same decade life span.

For handsets, the embodied energy situation is even worse, with the extraction of raw material and manufacturing phases accounting for around 75 per cent of the average carbon footprint of smartphones, according to one study.

The report offers a number of recommendations, the first of which is that more research is needed, and that funding bodies should support such work as a priority. The research should include peer-reviewed assessments of the effects of 5G on the energy consumption of mobile networks with better disclosure of the key data and assumptions used, CREDS adds.

Other recommendations are that embodied energy should be included in assessments of overall energy use, and the potential for 5G to produce rebound effects should also be included.

Network operators and device manufacturers take steps to increase user awareness of energy use implications, and that developers should factor energy saving considerations into the earliest design stages of mobile applications, says the report by CREDS.

Ericsson said in January last year that according to its test pilots with Telefónica, 5G tech was "up to" 90 per cent more efficient than 4G in terms of energy consumption per unit of traffic. Nokia made the same claim a month earlier.

Paolo Pescatore, founder and telecoms analyst at PP Foresight, agreed each new generation of network technology brings greater efficiency with it, but that everyone's appetite for data is also increasing.

"As data traffic grows, you would assume that the power consumption would also grow, but a concerted effort has been made by the industry to focus on efficiency with 5G," he told us, adding: "From what I've seen, the energy consumption per unit of data is much less for 5G than 4G, but overall power consumption is higher."

This, as highlighted by CREDS, is because while efficiency is improving, more data is also being transmitted. This is not a new phenomenon of 5G networks, but has apparently been observed with the rollout of every successive generation of mobile technology.

"One way to address this problem is to look at greater use of renewable energy sources to power mobile networks, and the industry is already doing this," Pescatore said.

Gartner senior director and analyst Sylvain Fabre agreed, saying that each new generation network is more efficient when comparing like for like, but that total electricity consumption goes up all the time because the overall amount of data being shifted goes up.

"Now a really interesting question is whether looking at the society level, we can see a lower total cost of ownership in terms of energy consumption, for example via enabling smarter cities, industry 4.0 and so on with 5G," Fabre said, but added this would be very hard to demonstrate.

The Register asked Nokia, Ericsson, and Huawei to comment. ®