Ericsson said in a report earlier this year that if 5G is deployed in the same way as previous mobile network generations, energy consumption of mobile networks would increase dramatically.

"This is unsustainable in terms of cost as well as environmental impact," the Sweden-based vendor said, and outlined ways to deploy a nationwide 5G while lowering energy consumption.

Now Nokia has carried out tests with Telefónica that it says show 5G is in fact a "natively greener technology with more data bits per kilowatt of energy than any previous wireless technology generation."

Following a three-month study that explored the power consumption of Telefónica's radio access network (RAN) in Spain, it found that 5G networks are up to 90% more energy efficient per traffic unit than 4G.

The tests examined 11 different predefined traffic load scenarios that measured the energy consumed per Mbit/s based on the traffic load distribution.

However, the vendor also noted that the rollout of 5G networks "is set to increase traffic dramatically, making it critical that the energy consumed does not rise at the same rate."

Nokia warned that 5G networks require further action to enhance energy efficiency and minimize carbon dioxide emissions that will come with much higher data traffic.

"There are several energy-saving features at the radio basestation and network levels, such as 5G power-saving features, small cell deployments and new 5G architecture and protocols, which can be combined to significantly improve the energy efficiency of wireless networks," the Finnish vendor said.

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Huawei has also previously warned that although watts per bit is much lower for 5G than 4G, overall power consumption will be much higher. Indeed, the China-based vendor said the power consumption of 5G hardware is between two and four times greater than 4G.

The conclusion seems to be that 5G networks are more energy efficient at the watts per-bit level, but operators and vendors will need to put measures in place to ensure that rising data traffic, and the higher power consumption of 5G hardware, do not scupper environmental targets.

Green goals

Pretty much all leading European operators have committed to reducing energy consumption and emissions in the coming years and have even stepped up their goals in recent months. Telefónica is certainly no exception and has already said it aims to be carbon-neutral by 2030 – compared with its earlier target of 2050.

Vodafone has also committed to reducing the company's total global carbon emissions to "net zero" by 2040. By 2030, Vodafone aims to eliminate all carbon emissions from its own activities and from energy it purchases and uses.

Deutsche Telekom intends to reduce its direct and indirect carbon dioxide emissions by 90% by 2030, using 2017 as its base line. The long-term goal is to no longer be a net source of emissions by 2050, making the group entirely carbon neutral.

A key ambition is to make it onto the Carbon Disclosure Project's (CDP) "A list" for actions on climate risks. The 2019 list includes 182 companies, of which only eight are telecom operators: BT, Deutsche Telekom, KPN, LG Uplus, Orange, Taiwan Mobile, Telefónica and Telstra. Tower company Cellnex Telecom is also listed.

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— Anne Morris, contributing editor, special to Light Reading