Could streaming video be as bad for the climate as driving a car? Calculating the Internet’s Hidden Carbon Footprint

Driving a small car to the movies with a friend can have lower carbon emissions than streaming the same movie alone at home

We are used to thinking that going digital means going green. While that’s true for some activities—like making a video call across the ocean is better than flying there—the situation is more subtle in many other cases. For example, driving a small car to a movie theater with a friend may have lower carbon emissions than streaming the same movie alone at home.

How do we come to this conclusion? Surprisingly, making these estimates is quite complicated. This is for two reasons: we don’t have good data to start with, and even when we do, comparisons with other human activities are often difficult to make. In a September 2022 report, “Data Centers and Data Transmission Networks”the International Energy Agency (IEA) said:

Comprehensive energy usage data for all data center operators globally is not currently available, so this estimated range is based on bottom-up modeling.

This is remarkable given that we have been able to fairly accurately estimate much more complex phenomena. In this case, we would only need quantitative information – the electrical energy and amount of data used – which can be determined with great precision. The current situation is not acceptable and should be addressed soon by policy makers.

About tons of CO2 emissions, kilowatt-hours of electricity, cubic meters of gas, liters of petrol and car horsepower is confusing to many, including academics. Most people would not be able to tell how much energy they consume each day or what level of emissions these activities cause. But they would be able to tell you the salary or the monthly rent right away. The ease of talking about money lies in the fact that we humans long ago decided that a commonly held currency was the best way to trade disparate things. We don’t do it for our energy use, hence the difficulty.

There is no reason not to change the situation, however: the beauty of the concept of “energy” is that nature has given it to us as a number which is mysteriously preserved even when we change its shape, for example from electric to thermal. Hence, we can always convert it into one convenient unit, which would make it easy for us to understand the impact of our activities on the planet, including digital ones.

Apples to apples

Let’s see how this could work by explaining some examples. We choose the unit of energy as kilowatt hour (kWh). This proposition was made by David MacKay in his 2008 book Sustainable energy, without hot air. Because the amount of energy used rather than CO2 issued? Globally the two concepts are equivalent, given that CO2 emissions are proportional to the amount of non-renewable energy produced. But hardly any of us have an intuitive idea of ​​what a ton of CO is2 is, not to mention its global scale values, or how it is generated. On the contrary, almost all of us can read an energy bill and relate it to what we do at home.

Here are three examples:

  • A 10W light bulb kept on for one hour will consume 0.01 kWh of energy (1 kWh = 1,000 Wh).

  • A car driven around town for an hour with an average power output of 10 kW (about 13 horsepower) will consume 10 kWh.

  • In Northern Italy during the winter, heating an apartment with 10 cubic meters of gas requires about 100 kWh per day or 4 kWh per hour.

When these activities are compared to the same units, it is clear that there are some (driving, warming up) that would have a much larger impact than others (lighting) if their use were reduced.

A two-hour film pollutes as much as a 45-minute car ride

That being said, let’s try to estimate internet usage in the same units. What we’re looking for now is the amount of power for a given amount of data transferred, expressed in gigabytes (GB). As mentioned, surprisingly no consistent numbers are available. Estimates range from 0.1 kWh per GB (AndraeHuwaei) to 10 kWh per GB (Adamson, Stanford magazine) — 100 times more. The lower number seems to assume an unrealistic amount of data, almost 10 times that reported by the World Bank, and imply an average worldwide data usage still uncommon even for the western world (3,000 GB per year instead of 300). On the other hand, the highest estimate seems not to have taken into account the latest developments in energy efficiency due to new technologies.

It appears that 1 kWh per GB may be a reasonable approximation of current data energy cost. Using that estimate, we can now more easily compare the data’s energy consumption with other human activities. For example, a two-hour 4K resolution movie is about 7 GB, or about 7 kWh of energy, comparable to a 45-minute car ride. This is staggering for something we perceive as immaterial. Similar estimates would imply that 300 Google searches use about 0.1 kWh, which is the same energy needed to boil a liter of water from 20 degrees Celsius, another mind-boggling realization.

It’s possible and plausible that technology will make the Internet more energy efficient — this is what many of us physicists are trying to help as we study new materials and approaches to storing and manipulating data. However, if we continue to increase our data usage, we will not reduce our energy consumption. For example, 8K resolution movies require four times more data than 4K resolution.

Consumption on the rise

Global Internet Usage, 2002-2022
In 2002, global internet usage was just 156GB. Twenty years later, traffic is around 150,000 GB per second, almost a thousand times that. WDR 2021, Cisco Visual Networking Index, 2017–2022, CC FROM

The proof is that for several years now, the annual energy consumption of information and communication technology infrastructures has consistently been at least 2,000 TWh, 5 percent of global electricity consumption. Projections suggest we will reach 10% by 2030indicating that technology may not keep pace unless we introduce new fundamental approaches.

There is no doubt that the internet and a more digital life offer an incredible opportunity to reduce our energy use and reduce our carbon footprint. For example, a single person on a fully loaded long-haul round-trip airline flight — say from Venice, Italy, to Los Angeles, California — has an energy cost of 10,000 kWh to attend an in-person meeting. Using the estimates above, it would take eight months of 12-hour video meetings at 4K resolution for that person to consume the same amount of energy. In this case, there’s no question that streaming, not flying, is the better choice.

As with all technology, however, using the Internet comes at an energy cost. It is proportional to the amount of data transferred and the usage is higher with images and especially videos. When used heavily, its impact becomes comparable to activities we already recognize as energy-intensive, such as driving a car. We clearly need more precise numbers to take the appropriate measures at the political level.

Two women looking at a computer screen
Watching a movie online may seem like an energy-smart choice, but research shows that carbon emissions can be significant. Cristina Morillo/Pexels, CC FROM

Before we have them, we individuals can use the data thoughtfully:

  • Turn off your camera when it’s not needed during a video call.

  • Decrease video resolution whenever possible, especially on small screens.

  • Watch movies as they stream rather than using on-demand services, which require dedicated computing power and data for each viewer.

  • Finally, let’s start thinking in kWh of everything we do and do our part to help implement that standard. In this way we will talk to the same energy currency as we do with money.

To make this happen, write to your gas company, car company, grocery store, and any other manufacturer to ask them to provide the kWh numbers of everything they sell. This would allow us to create individual “energy portfolios” and decide how to spend what we have sustainably and thus achieve our climate goals. Once these goals are clearly and concretely defined, it will be much easier for individuals, companies and governments to take a sensible course of action every day, in all things big and small.

Part of the frustration many of us experience these days is that we feel powerless against climate change because we don’t have a concrete representation of how to do something about it in our daily lives. By speaking about the problems in units that we understand and perceive, we will bridge the gap between the local and the global scale, and thus we will be more effective in our actions.The conversation

Stephen BonettiProfessor of Experimental Physics of Condensed Matter, Ca’ Foscari University of Venice

This article is republished by The conversation licensed under Creative Commons. Read the original article.