How five of the world’s biggest operators deal with their greenhouse gas emissions

Like all major users of electricity, ISPs have been striving to reduce their greenhouse-gas emissions.

Guest author

February 24, 2023

21 Min Read
Green technology tech environmentally friendly nature environmental protection on internet computer
F8EW66 Green technology tech environmentally friendly nature environmental protection on internet computer periodically invites expert third parties to share their views on the industry’s most pressing issues. In this piece, telecoms engineer Natalia Molinero Mingorance takes a look at the different ways major global telcos seek to mitigate their carbon footprints.

Of the world’s 8 billion people, 5 billion are regular users of the Internet. They have an average of 3.6 connected devices apiece, including smartphones and desktop computers. Each of them creates an average of 49.8 gigabytes of traffic every month, according to the networking company Cisco.

All of that activity has electrical underpinnings and results in the emission of hundreds of millions of tons of greenhouse-gas emissions every year. When you videoconference at work, stream a movie at night, or share content through social media, you’re tapping into planet-spanning networks with advanced resources powered by vast, diverse, and constantly-changing sets of electrical-generating facilities. The electricity powers the terminal devices we use to access the Internet—the smartphones, laptops, desktops, and televisions—and also the network itself, consisting of routers, base stations, repeaters, countless kilometers of microwave links and electrical and fiber-optic cable and, most of all, the massive data centers where servers run continuously to store, process, retrieve, and deliver all that information. Private companies and Internet Service Providers (ISPs) own and operate these data centers, of which there are more than 7.2 million globally.

Like all major users of electricity, ISPs have been striving to reduce their greenhouse-gas emissions. There are hundreds of ISPs in the world, of which 89 have revenues greater than a billion US dollars a year. Five of the largest of these are AT&T, Verizon, NTT, China Mobile and Deutsche Telekom.  They collectively serve more than a billion and a half Internet users, and they have wildly varying rates of greenhouse-gas (GHG) emissions per customer. At the high end is China Mobile, at 35,769 tons of CO2 per subscriber per year, according to their Sustainability Report. At the low end is NTT, the Japanese telecommunications giant, at 456 tons per subscriber.


Number of subscribers(million)

Power Cosumption (MWh)

CO2 emissions (million tons)

CO2 (tons) per subscriber

China Mobile




















Deutsche Telekom





Table 1.- Subscribers, power consumption, emissions and CO2 per subscriber for each ISP

How can two organizations doing essentially the same thing have emissions rates that vary by a factor of nearly 80? Part of the answer is simple. Among its electrical generating plants, China has a much higher proportion than Japan of coal and other fossil-fueled plants. But such facts don’t tell the whole story. After accounting for such differences in generating mix, it becomes clear that other factors are also playing an important role in the relative success of these giant firms in cutting emissions. The largest ISPs have been pursuing different strategies to reduce GHGs and have been having different degrees of success. Analysis of these strategies makes it clear that some tactics are working better than others.

These strategies will grow in importance as the pressure grows on these companies to curtail emissions. As more of the world goes online and as the data rates available in developed countries increase inexorably, GHG emissions are in an upward climb. Only smart policies will manage to keep these emissions under control while enabling the traffic growth and expansion of Internet that will be vital to supporting economic growth.

For any ISP, the network systems that consume the most electricity are, first, the data centers, centralized locations where computing and networking equipment is concentrated for the purpose of collecting, storing, processing, distributing or allowing access to large amounts of data. The main elements are the servers, physical or virtual, that are connected internally and externally through networking and communication equipment to deal with digital information. Each server can be seen as a super powerful personal compute.  Secondly, the wireless base stations that receive and transmit data to mobile users. So efforts to trim electricity use generally focus on these elements of the network.

There are four basic tactics that these large ISPs can deploy to cut emissions:

  1. They can monitor the energy performance of their key systems, such as network equipment and data centers, and tweak their operation as necessary to optimize their use of electricity. For example, Deutsche Telekom monitors the power consumption of their data centers by measuring the servers power consumption and the usage of air conditions. After periodical reviews, they can reserve funds to invest in solutions that optimize their performance and reduce the power consumption.

  2. They can replace outdated network facilities such as base stations and server systems with more modern and efficient technologies

  3. Older data centers can be replaced with newer systems based on virtualization and artificial intelligence (AI). Virtualization helps to reduce the need for physical network elements in the data centers buildings, so they are part of the server’s software, reducing the need to power more equipment. With AI, thanks to the use of machine learning software the power supplied to data centers and cooling systems can be automatically adjusted in order to make them more energy efficient.

  4. ISPs can invest in low-emission generation facilities to power their data centers.

Many of the specifics describing how the largest ISPs are grappling with emissions are published annually in various reports, called Sustainability Reports, or Environmental Social Governance Reports, that are required by their host governments. These documents also explain how ISPs measure their power consumption and carbon footprints as well as the initiatives they are planning or following to reduce them.

Sustainability initiatives

Five of the major operators have well-established plans to limit emissions. For example, China Mobile has adopted a “Green Action Plan” in their “C2 Three Energy- Carbon Peaking and Carbon Neutrality Action Plan”, based in six green initiatives: networks, energy consumption, supply chain, offices, empowerment, and culture. Among these, the plans for internal energy savings and carbon decrease focus in the 5G network and data centers. Later in the article, we will see how they are proceeding. Similarly, NTT focuses their sustainability initiatives in improving their data centers and energy resources through energy management and R&D activities. AT&T developed the project “AT&T’s Energy and Building Management Solution (EBMS)”, to manage their operations so they can reduce the energy consumption. EBMS uses the network to gather and centrally manage performance data from facility equipment across the US, allowing to understand performance base years, monitor equipment status and move from reactive to predictive maintenance, while decreasing unnecessary energy use. In 2021, they deployed it in approximately 1,030 facilities. Verizon mainly focuses on two key drivers to reduce the emissions: maximizing the energy efficiency of the networks and facilities and transitioning to renewable energy. In the same manner, the majority of the Deutsche Telekom’s energy requirements come from operating the network infrastructure, which expands in Europe and the U.S. They are studying and developing new ways of making their network operations more energy-efficient and sustainable, looking especially carefully at the areas of energy transport, energy availability, and energy efficiency.

It seems that they focus on improving the energy efficiency of their networks and data centers, as they are the main source of GHG emissions. The following sections show what the carriers are doing with these two regards.

How do they reduce the emissions coming from their networks?

China Mobile promote a consumption-related criteria when selecting equipment, they have developed new technologies to dynamically allocate services and resources in terms of time, space, and frequencies (sub-frame silence, channel silence, shallow hibernation, and deep hibernation), they have centralized the radio access network (C-RAN), so they can reduce the number of air-conditioning facilities, and they have built AI algorithms to apply energy savings strategies on the base stations. NTT is heavily investing in its Innovative Optical and Wireless Network (IOWN) concept for networks and information processing. The aim is to use high-speed, high-capacity communication and new optical technologies combined with computational resources to substantially lower energy consumption and reduce greenhouse gas emissions by 45 percent. AT&T is decommissioning and removing obsolete and outmoded network hardware, shifting control from hardware to software to make the network simpler, faster, and more scalable. Like AT&T, Verizon is decommissioning switches and migrating to newer intelligent edge network platforms as well as migrating copper-based services to fiber technologies. Another way they optimize energy expenditure is through network cooling inventions, for example, by adjusting the cooling system settings at the network facilities so that cooling system demand is smaller. This is achieved with the deployment of smart cooling systems across a number of technical network facilities through AI and machine learning algorithms. Deutsche TeleKom is also updating the network infrastructure by migrating the fixed network to IP technology and removing equipment no longer needed, such as 3G antennas (the 3G network was switched off in Germany on June 30, 2021). Moreover, they have established specifications and requirements that firmly anchor energy efficiency in the architecture and design phase when selecting new technologies. They use green technology for networks, especially in cooling their infrastructure.


Figure 1.- Base station

What about data centers?

China Mobile has re-designed them to achieve a better power usage effectiveness (PUE), a metric that tells how much power is used to run the ICT equipment from the total power that enters a data center. Additionally, they are replacing the air-conditioning by natural cold sources, they are using the heat produced during data centers operation to heat offices and boil water, and they monitor, analyze, model, optimize, and adjust data centers to guarantee smart operations. NTT built and operate data centers with high environmental performance, such as the Mitaka Data Center, that uses renewable energy, and it’s designed for energy conservation and intelligent energy management. The data center incorporates an outside air-cooling system (outdoor air during the spring, fall and winter) that utilizes photovoltaic power generation and natural energy. AT&T projects included replacement of older major air conditioning equipment (chillers and compressors) with newer, more efficient equipment. Other projects included retrofitting of existing equipment with variable frequency drives (VFDs), and other similar enhancements to use existing equipment in a more efficient manner. Following these strategies, the data centers of Kansas City (MO), Fairfield (CA) and Lynwood (WA) have achieved annually savings of 353,88 kWh, 613,234 kWh and 1,388,183 kWh, respectively. Verizon also focuses on the design and operation of the data centers for maximizing energy efficiency: for example, using a direct outside air (free) cooling system analogous to the China Mobile’s system. They also monitor and manage the power demand profile at each layer of distribution of the infrastructure. In some locations, they applied AI-machine learning algorithms to support energy conservation. In 2021, six of the eight Deutsche Telecom internal European Future Mode of operation (FMO) twin-core data centers, and one external FMO twin-core data center, were included in the “EU Code of Conduct on Data Centre Energy Efficiency” list, an European Union (EU) initiative introduced  in 2008.


Figure 2.- Data center

Renewable energy investments

As well as the R&D innovations, such as the intelligent systems to make a more efficient use of electricity, the main action these companies have taken is the purchase of green energy.

China Mobile has purchased of 2.47 billion kWh of renewable energy. In 2021, NTT introduced 1 billion kWh of green energy for their infrastructure and they plan to introduce around 7 billion kWh from 2030 to 2040. AT&T is one of the largest corporate purchasers of renewable energy in the U.S., supporting the production of more than 2.3 billion kWh of renewable energy. AT&T has invested in solar and fuel cell energy projects that produce more than 89 million kWh yearly to power their critical data centers and offices. Since 2021, Deutsche Telekom has covered 100% of the electricity consumption throughout the Group from renewable sources, with Power Purchase Agreement (PPA) contract of 920 million kWh from 2021 to 2030.

From the ISPs’ point of view, feeding their networks and data centers with renewable sources could be the fastest way to reduce their carbon footprint, as replacing or improving their electronic devices implies stopping them from working. On the of that, as we will see next, there are economic incentives in most of the countries here they are based for the use of green energy. These reasons, plus the fact that they don’t have to invest so much in R&D, testing, purchasing and installing new equipment, have made the renewables their principal bet.

Dependence on renewable energy

As we saw earlier, China Mobile is the ISP with a major burden on the environment. One of the main reasons is the strong dependence on green energy to solve this issue and the situation on China in this matter. According to the National Energy Administration (NEA), the renewable generation capacity in China accounts for 44.8% of the nation’s total power generation capacity. However, there are limitations within their current framework renewable energy policy and la that impede further development. Some issues are related to the multiple examinations and approvals the renewable energy programs have to pass from different departments which sometimes are inconsistent. Also, the exploitation of green energy is highly risky because it represents a tremendous investment that private companies cannot afford, as it’s much more expensive than traditional energy. Actually, China is the world’s largest emitter of greenhouse gases because most of the energy consumption and electricity generation are from coal.

Verizon and AT&T follow China Mobile in our ranking of CO2 pollution per subscriber. In the U.S., there are tax incentives to accelerate the energy transition. For example, in the Investment Tax Credit (ITC) that apply from 2022 till 2024. In 2025, these tax credits will change to emissions-based technology-neutral tax credits available to any power generation that is net-zero. The producers can also use the Production Tax Credits (PTC). In 2022, there were also $369 billion in energy and climate change investments. Nevertheless, the National Environmental Policy Act (NEPA) is a tedious process that severely slows down important infrastructure projects. On average, it takes 4.5 years and $4.2 million to complete the review process. This is a huge impediment for companies such as Verizon and AT&T and it causing the slow deployment of renewable sources on the U.S., which Is expected to be 22% of the country generation in 2022.

At a faster rate, the forecast for Germany is that, by 2025, 40 to 45 percent of electricity consumed in the nation is to derive from renewables. This is the aim set out in the Renewable Energy Sources Act. As well, there are incentive policies, such as feed-in tariffs and special subsidies that encourage renewable energies to enter the market. On the other hand, some difficulties arise regarding the transportation of green electricity from the north to the industrial centers in the south of Germany which increases the cost of the network management by network operators. However, Deutsche Telekom data centers are located in the north of Germany, so the transportation costs don’t affect the carrier allowing them to use 100 percent green energy, benefiting from the country’s incentives, which is reflected in their CO2 emissions, much more lower than AT&T and Verizon’s ones, having both approximately the same number of customers.

Finally, although Japan only generates 20.2 percent of its electricity from renewables, at present, the Japanese government encourages their development by using special tariffs to promote a carbon-neutral society. There is a concept of “benchmark utilization” that requires electric power enterprises to complete certain amount of renewable energy exploitation and utilization obligations each year. Otherwise, regular improvements will be mandated or the companies may even be punished by a high penalty of 1 million yen. Also, different types of business have recently joined the renewable sector such as trading companies, financial institutions, real estate companies, as well as foreign investors with experience in developing renewable projects. Banks are also financing such projects. This could be one of the reasons why NTT, the second biggest carrier in the world, is the less pollutant.

Reductions achieved

Considering all these facts, let’s take a look at the improvements obtained by each company, so we can argue whether these approaches, focusing on the use of renewables, are the best.

Regarding China Mobile, even if the annual power consumption is still huge, they saved 4.3 TWh in 2021. Similarly, they avoided 106,000 tons in CO2 emissions, thanks to their low carbon base stations, server rooms and data centers. They plan to reduce their Scope 1 and Scope 2 GHG emissions by 20 percent by 2025 from the 2020 baseline, although they reduced their emissions from 2020 to 2021 only 1 percent.  From 2020 to 2021, NTT achieved 30 percent reductions on GHG emissions of Scopes 1 and 2. In 2021, AT&T combined Scope 1 and market-based Scope 2 emissions decreased 4.16 percent relative to 2020; this is annual savings of almost 8 billion kWh. With their measurements, in 2020, Verizon reduced emissions 14 percent. Surprisingly, Deutsche Telekom’s claims that their Scope 2 emissions in 2021 were about 90 percent lower than in the previous year. At this point, it is worth it to remind that they also affirm to use 100 percent renewable energy, so is this the solution?

An alternative solution for sustainability

As a consequence of their tremendous energy demand, these 5 telecom carriers in the world concentrate on modernizing their network and data centers. By carefully designing and selecting the network equipment, using more efficient cooling systems, and applying innovative AI energy-saving algorithms, they aim to reduce the pollution caused by their networks. With regards to data centers, the approaches are to optimize PUE and, again, re-designing their air-conditioning systems, but the major measure for the 5 carriers analyzed is their high investment on renewable energy to overcome the GHG emissions issue, as it seems to be the fastest solution although, as we have seen, except Deutsche Telekom, the yearly GHG reductions for the ISPs hasn’t been very high.

It is a common assumption that green energy is a solution to achieve sustainability. However, is the use of it really sustainable?

As we mentioned at the beginning of the article, digital data consumption is increasing more a more and, if it keeps growing at the same speed as we have seen in the last decade, accommodating this enormous amount of data while saving energy seems to be challenging. Indeed, the Cisco’s forecast report highlights that nearly two-thirds of the global population will have Internet access by 2023, so there will be 5.3 billion total Internet users (66% of global population), up from 3.9 billion (51% of global population) in 2018.  There were 8.8 billion global mobile devices and connections in 2018, which will grow to 13.1 billion by 2023. It is important to track the changing mix of devices and connections and growth in multidevice ownership as it affects traffic patterns. Video devices, in particular, can have a multiplier effect on traffic. Studies show that almost 80% of all data flows through the network in the form of moving images. Online videos account for almost 60% of global data transfer, making video streaming one of the main causes of the internet’s high-power consumption. For example, an Internet-enabled HD television running three hours of content per day from the Internet would result in as much Internet traffic as an entire household today, on an average, and of course, the higher the resolution, the more data is sent and received and the more processing time and storage capacity is needed in the data centers. These parameters are proportional to the energy expenditure. Cisco estimates that today’s traffic demands are a small slice of the future needs.

All this information is processed in the ISPs data centers that we already talked about. Actually, the current estimates for data centers range from 200 to 500 billion kWh per year, about 1 to 3% of the world’s electricity consumption. By 2030, the range is estimated to be between 200 billion and 3,000 billion kWh.

By applying the aforementioned measures, focusing on the purchase of green energy as their main bet, operators can contain the CO2 emissions up to a point, as renewables also have some drawbacks. The main ones are:

  • There won’t be enough renewable energy in the world till 2050, which will limit the usage in all industries

  • The speed of the society consumption is greater than the green energy development

  • Building the infrastructure is expensive

  • Not all types of renewable sources are available everywhere: some regions are less sunny or there isn’t wind so often

  • The manufacturing of the required equipment is mainly achieved with non-renewable sources, so it produces contamination

  • They also produce electronic waste, mostly non-recyclable

  • Their placement has an environmental impact, for example: windmills in the sea or mountains, solar panels in the fields, etc.

Therefore, the mentality of obtaining every time more energy (renewable or not) is not sustainable. Even using 100% green energy, if carriers need every time more energy, it means that they actually need to invest every time more money to purchase them. Also, the network and data centers equipment are mostly made up of materials that are not recyclable, that have been produced with traditional energy and that is occupying a space, in most cases, destroying an ecosystem.

This process would be accelerated by acting at the source of the issue: the way the digital information is generated, stored, transmitted, and received. An alternative path to shorten IT pollution is minimizing the processing time of the information (specially, of heavy traffic information such as video), hence mitigating the associated energy consumption and carbon footprint. The companies are also starting investing in solutions to optimize the computational load of their network equipment and data centers, so the energy consumption is lowered, as well as the associated emissions. For example, NTT is part of the Green Software Foundation which promotes these principles. These solutions, which required investment in R&D resources, are truly sustainable, as an alternative to the massive energy purchases.


Figure 3.- Harmony Valley post on Instagram

On these principles, projects such as Harmony Valley aim to contribute to make digital communications sustainable. Its Instagram profile is targeted to help people understand the consequences of their Internet habits and the linked use of energy. After analyzing the main type of traffic flooding our networks, video, and how it’s compressed at present by streaming platforms, social media, etc., an Android app, Wamboo, was recently launched so the users can reduce their videos to save memory in their phones and in the social media servers if they share them. This way, with smaller videos, they reduce their carbon footprint when sharing files. In addition, Wamboo is efficient because it minimizes the battery usage of the phone while compressing the videos and it shows the associated pollution when some battery is wasted. In traditional compression methods the phone’s resources are not used efficiently and the battery usage is maximized leading to pollution as the phone needs to be charged more often, consuming more electrical energy (with the associated costs of electricity for the users). In such manner, the users help the ISPs to reduce their carbon footprint by reducing the amount of data they transmit and receive through their networks and store in their data centers. Harmony Valley’s long-term goal is to provide new methods and solutions for the different standards bodies (radiocommunications algorithms, network protocols, etc.) and multimedia private companies, so energy efficiency is a parameter as important as quality when designing a new technology. Harmony Valley estates that it would be more beneficial if the digital data were created in a sustainable way since the beginning: at the stage where voltages are mapped with 0s and 1s. Maybe disruptive developments such as quantum computing, neural networks or approaches used in other sciences can provide solutions to the exponential traffic growth and its impact on the environment.


Natalia-Molinero-Mingorance-150x150.jpgI’m Natalia Molinero Mingorance, a Telecommunications engineer and MSc. in Wireless Communications Systems. I worked in the University of Sheffield (U.K.), as a researcher, and I also worked in industry, providing services to the main European telecom carriers. In April 2022, I was awarded the first prize in a competition run by the European University of Madrid (Spain), the “Singular Alumni”, for my project proposal “New Methods for Energy Efficiency Optimization: Information, generation, storage, transmission and reception”, which is the first stage of Harmony Valley. Harmony Valley is a research project (expecting to be an R&D company) whose main goal is to contribute to making digital communications sustainable. In this first stage, I launched an Android app, Wamboo, to compress videos minimizing the battery waste during the process and to save memory in the phone. This is a beta version, and I created a survey to know what other features the users need. The long-term goal of Harmony Valley is to provide new methods and solutions to the different standards bodies (radiocommunications, network protocols, etc.) and multimedia private companies, so energy consumption is a parameter as important as quality when designing a new technology. I created a social media profile in order to make the research and the topics that addresses accessible by everyone (


Get the latest news straight to your inbox. Register for the newsletter here.

Read more about:

Get the latest news straight to your inbox.
Register for the newsletter here.

You May Also Like