Driving a small car to the cinema with a friend can have lower carbon emissions than showing the same movie alone at home
We’re used to thinking that going digital means going green. While that’s true for some activities — for example, 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 the cinema with a friend can generate less carbon emissions than showing the same movie alone at home.
How do we come to this conclusion? Surprisingly, making these estimates is quite complicated. This is due to two reasons: We don’t have good data to begin with, and even when we do, comparison with other human activities is often difficult to make. In a September 2022 report, “Data Centers and Data Transmission Networks,” the International Energy Agency (IEA) stated:
There is currently no comprehensive data on the power consumption of all data center operators in the world. This estimated range is therefore based on bottom-up models.
This is remarkable given that we were able to estimate much more complex phenomena quite accurately. In this case, we would only need quantitative information – the electrical energy and the amount of data used – which can be determined with high precision. The current situation is not acceptable and should be addressed quickly by policy makers.
Speaking of tons of CO2 emitted, kilowatt hours for electricity, cubic meters for gas, liters of gasoline, and the horsepower of cars confuse many, including academics. Most people would not be able to tell how much energy they use daily or what level of emissions these activities cause. But they might tell you their monthly salary or rent right away. The ease of talking about money is that we humans decided long ago that a common currency was the best way to exchange disparate things. We don’t do it for our energy consumption, hence the difficulty.
There is no reason not to change the situation, however: the beauty of the concept of “energy” is that nature gave it to us as a number which mysteriously persists even when we change its form – for example , from electric to thermal. Therefore, we can always convert it into one convenient unit, which would allow us to easily understand the impact of our activities on the planet, including digital activities.
From apples to apples
Let’s see how it could work by giving some examples. We choose the kilowatt-hour (kWh) as the unit of energy. This proposal was made by David MacKay in his 2008 book Sustainable energy, without hot air. Why the amount of energy used rather than the CO2 issued ? At the global level, the two concepts are equivalent, since CO2 emissions are proportional to the amount of non-renewable energy produced. But almost none of us have an intuitive idea of what a ton of CO is.2 is, not to mention its values on a global scale, or how it is generated. On the contrary, almost all of us can read an energy bill and relate it to what has been done at home.
Here are three examples:
A 10W bulb left on for one hour will consume 0.01 kWh of energy (1 kWh = 1000 Wh).
A car driven in town for an hour with an average power of 10 kW (about 13 horsepower) will consume 10 kWh.
In northern Italy in winter, heating an apartment with 10 cubic meters of gas requires about 100 kWh per day or 4 kWh for each hour.
When these activities are compared to the same units, it is clear that some (driving, heating) would have a much wider impact than others (lighting) if their use were reduced.
A two-hour movie pollutes as much as a 45-minute car ride
With this in mind, let’s try to estimate internet usage in the same units. What we are looking for now is the amount of energy for a given amount of data transferred, expressed in gigabytes (GB). As mentioned, there are surprisingly no consistent numbers available. Estimates range from 0.1 kWh per GB (Andrae, Huwaei) to 10 kWh per GB (Adamson, Stanford magazine) — 100 times more. The lower number seems to imply an unrealistic amount of data, nearly 10 times that reported by the World Bank, and implies an average global data usage that is still scarce 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 seems that a value of 1 kWh per GB might be a reasonable approximation of today’s energy cost of data. Thanks to this estimate, we can now more easily compare the energy consumption of the data with other human activities. For example, a two-hour movie at 4K resolution is about 7 GB, or about 7 kWh of energy, comparable to a 45-minute car ride. It’s mind-boggling for something we perceive as intangible. Similar estimates would tell you that 300 Google searches use around 0.1 kWh, the same energy needed to boil a liter of water from 20 degrees Celsius, another mind-boggling achievement.
It’s possible and plausible that technology will make the internet more energy efficient – that’s what many of us physicists are trying to help with while studying new materials and approaches to storing and manipulating data. However, if we continue to increase data usage, we will not decrease our power consumption. For example, movies in 8K resolution require four times more data than in 4K resolution.
Proof of this is that for several years, the annual energy consumption of information and communication technology infrastructures has been constantly at least 2,000 TWh, or 5% of global electricity consumption. Projections suggest that we will reach 10% by 2030, indicating that technology may not keep up unless we introduce fundamental new approaches.
There is no doubt that the internet and a more digital life offer an incredible opportunity to decrease our energy consumption and reduce our carbon footprint. For example, a single person on a fully loaded round-trip long-haul flight – say from Venice, Italy to Los Angeles, California – to attend an in-person meeting has an energy cost of 10,000 kWh. Using the estimates above, it would take eight months of 12-hour video meetings at 4K resolution for that person to consume the same energy. In this case, there is no doubt that streaming, not stealing, is the better choice.
However, like any technology, the use of the Internet has an energy cost. It is proportional to the amount of data transferred, and the use is maximum with images and especially video. When heavily used, its impact becomes comparable to that of activities we already recognize as energy-intensive, such as driving a car. We clearly need more precise figures to take the appropriate measures at the political level.
Before we have it, we as individuals can use the data thoughtfully:
Turn off the camera when you don’t need it during a video call.
Lower the video resolution when possible, especially on small screens.
Watch movies when they’re streaming rather than using on-demand services, which require dedicated computing power and data for each viewer.
Finally, let’s start thinking in kWh in everything we do, and do our part to help establish such a standard. In this way, we will speak with the same energy currency, as we do with money.
To help you do this, write to your gas company, car manufacturer, grocery store, and all manufacturers asking them to provide kWh figures for everything they sell. This would allow us to set up individual “energy portfolios” and decide how to spend what we have in a sustainable way and thus achieve our climate goals. Once these objectives are defined in a clear and concrete way, it will be much easier for individuals, companies and governments to adopt a sensible course of action every day, in all things big and small.
Part of the frustration many of us are experiencing these days is that we feel helpless in the face of climate change because we have no concrete picture of how to do something about it in our daily lives. By talking about issues in units we understand and perceive, we will bridge the gap between local and global scales, and therefore be more effective in our actions.
Stefano Bonetti, Professor of Experimental Condensed Matter Physics, Ca’ Foscari University of Venice
This article is republished from The conversation under Creative Commons license. Read the original article.
We are a voice for you; you have been a great support to us. Together, we are building independent, credible and fearless journalism. You can still help us by making a donation. It will mean a lot to our ability to bring you news, insights and analysis from the ground up so that we can effect change together.
#streaming #video #bad #climate #driving #car #Calculating #Internets #Hidden #Carbon #Footprint