In the section Climate demand we regularly answer questions from readers. This week: how much CO2 emissions do data centers actually cause?
Facebook’s plans to build a gigantic data center in Zeewolde recently led to a lot of commotion. The tech giant canceled the plans when it turned out that there was hardly any political support, but in the meantime we will of course continue to use internet services.
Every time you scroll through your Instagram timeline, stream Netflix, or WhatsApp a photo to friends, you’re connecting to a data center. Worldwide, there are many millions of servers to store all our data and to send it around the internet at the touch of a button.
On our response platform NUj, readers wondered: how much CO2 emissions does that actually cause? After all, the amount of data stored around the world continues to grow steadily, and that costs energy.
To start at the beginning: a data center has little or no ‘direct’ emissions. The servers and associated cooling are electric, so the emissions come almost solely from the generation of that electricity. If the power goes out, data centers sometimes want to switch back to diesel generators, but that is rare.
Previous climate questions answered
Energy consumption data centers is stable
It International Energy Agency (IEA) estimates that data centers account for 1 percent of global electricity consumption. In 2020, consumption amounted to 200 to 250 terawatt hours, approximately double the total Dutch electricity consumption. Scientists came earlier in the journal science to a comparable estimate.
The Netherlands has a relatively large number of data centers, because we have a large internet node with good connections to other countries. That is why the electricity consumption of data centers here is higher than average: they used 2.8 percent of the domestic total in 2020. That doubled in three years, according to figures from the statistical office. CBS†
Yet worldwide, no such growth can be seen. In 2020 there was almost seventeen times as much internet traffic as in 2010, the IEA calculated. The workload of data centers also increased significantly during the same period: almost ten times as many calculations had to be performed. However, energy consumption hardly increased.
This is because data centers have become much more energy efficient. This allows them to store, process and circulate more data over the internet without consuming much more electricity.
The question is whether this trend can continue in the coming decade. Governments and companies must continue to innovate to continue to limit energy demand and greenhouse gas emissions, says the IEA.
Tech companies buy a lot of wind power
It is not easy to calculate how much CO2 emissions all data centers cause with their electricity consumption. Many tech companies purchase green energy, for example from wind farms, and then claim that their data centers are emission-free. But if there is no wind, the servers will continue to run on electricity from gas or coal. So they are not really emission-free.
Worldwide, an average of 475 grams of CO2 is emitted per kilowatt hour of electricity generated. Calculated with that value, data centers worldwide cause 95 to 119 megatons of CO2 emissions per year. That is 0.3 to 0.4 percent of all global emissions.
It should be noted that data centers are good customers for renewable energy projects. For example, Microsoft buys almost all the electricity from a large wind farm in the Wieringermeer and Amazon buys half of the electricity from one of the new wind farms in the North Sea. According to the industry, data centers finance the greening of our electricity production in this way.
Critics believe that the purchase of such ‘green certificates’ is only sustainable on paper, especially if companies purchase their green electricity at a great distance from the places where they actually use electricity.
One thing is certain: in the long run, data centers can run entirely on green energy, because our electricity is getting a little greener every year. For other industries, which currently still run on oil, gas or coal, becoming climate neutral is a much greater challenge.