A letter to Greta Thunberg: questioning Huawei's Green 5G report
By Miguel Coma
Dear Greta,
In August 2020, Huawei published a white paper called Green 5G: Building a Sustainable World.[1] (Huawei is the Chinese telecom corporation that has begun installing 5G infrastructure internationally.) The report claims that 5G can have a significant positive effect on climate by increasing energy efficiency and enabling industries to reduce their greenhouse gas emissions and reach their climate targets.
Before I discuss Huawei's report, let me first acknowledge how complex our world has become, even for engineers like me who love figuring out how things work. Writing this letter, I aim to decipher some controversies about 5G and its implications for climate change. I will do my best to stick to essential matters. If you think this letter is absurdly detailed and technical, you'd be right. But please bear with me. In response to Huawei's unproven claims, we need technical details.
To begin, I put figures about 5G's footprint on a bar chart. I love bar charts. You can compare and focus on important things. Bars can also reveal surprises. Here, they show the total, worldwide energy needed to manufacture (low part of the bars) and use (higher part of the bars) digital technologies in four categories: 5G, networks, devices and data centres. All bars show primary energy: the energy used from natural resources, renewable or not. For references and calculations, please check the end notes[2]
The left bar shows the additional energy needed to build and operate 5G networks. By "5G" I mean worldwide 5G public networks.
The second bar represents the energy footprint of all (wired and wireless) networks that connect digital devices today. It shows that 5G could double the energy used by all of these networks.
The third bar, the elephant in the room, shows the energy consumed to make and use tens of billions of user devices.
The last bar really surprised me: it shows that with or without 5G, compared to networks and user devices, data centres use the least amount of energy of all digital infrastructures.
If 5G becomes the backbone of our future connectivity as its providers aim, then it would increase mobile traffic 10-100 times.[3] Indirectly, more traffic would raise each bar. (In a future letter, I will describe viable wired and wireless alternatives to 5G that could absorb the increase in data trafficand use much less energy.)
For today, I want us to realize how much energy 5G would consume: over three times the total amount of energy that Sweden uses for industries, transportation, electricity, residences, schools, etc., combined.[4] Powering 5G globally would require building 36 new-generation nuclear reactor,[5]7800 massive offshore wind turbines[6] or equivalent power plants using other energy sources. In this bar chart, I did not calculate the energy required to build these giants of concrete and metalthough we should.
What would 5G's electricity bill mean for climate change? 5G would increase CO2 emissions by 250 megatons (Mt CO2).[7] This is seven times Sweden's total CO2 emissions, or one fourth of the emissions generated by aviation worldwide (before Covid-19).[8] It would most likely compromise our targets for carbon neutrality and reduced emissions.
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