Data centers consume a lot of electricity, but not yet threaten the climate

Fig. 1. Historical data center energy consumption in 2010-2018 and the forecast for the coming years, when the next doubling of the number of computing instances (cores) in data centers will take place

Demand for data center services (DPC) services has grown many times over the past decade. It is fueled by the growing popularity of social networks, video, mobile applications and various cloud applications.

In 2010, all data centers in the world consumed approximately 194 TWh, that is, 1% of world energy consumption. What will happen in the case of exponential growth in computing? There were estimates that the power consumption of the data center can grow three or even four times. For example, see the assessment by Belhira and Elmeligi in the article “Assessing ICT global emissions footprint: Trends to 2040 & recommendations”(Journal of Cleaner Production, Volume 177, p. 448).

But recent studies show that there is no cause for panic. So, from 2010 to 2018, the computing power of the data center grew by 6.5 times, but the energy consumption remained at about the same level (205 TWh, about 1%), so nothing threatens the planet yet.

Fears are based on the trends of 2005–2010, when the energy consumption of data centers actually increased from 153 terawatt hours (TWh) in 2005 to 203? 273 TWh in 2010, which totals from 1.1 to 1.5% of global electricity consumption (see JG Koomey, “Growth in data center electricity use 2005 to 2010,” Analytics Press for the New York Times, 2011).

However, since 2010 the situation has changed dramatically. In a new scientific work, the authors integrated data from various sources that have appeared recently. The article was written by several leading energy experts in data centers from Northwestern University, Lawrence Berkeley National Laboratory and research firm Koomey Analytics (USA).

A new analysis shows a very modest increase in energy consumption in recent years. In particular, by 2018, workloads and the number of computing instances increased by more than six times, IP traffic increased by more than 10 times. The capacity of data center storages for this period has grown 25 times. It would seem that energy consumption should be extrapolated on an appropriate scale. But no: since 2010, energy consumption per server has decreased four times , mainly due to technological improvements and a reduction in idle time.

The watts per terabyte of installed memory dropped about nine times due to the increase in the density and efficiency of drives.

In addition, the growth in the number of servers has slowed significantly due to a five-fold increase in the average number of instances on one server (due to virtualization).

At the same time, throughout 2010-2019, there was a steady improvement in the quality of energy consumption PUE (power usage effectiveness), which is calculated as the quotient of dividing the total energy consumption of the data center by the energy consumption of its IT equipment. The contribution of various components to the change in PUE is shown in the diagram below.


Fig. 2. Trends in power consumption of data centers

In 2018, the global energy consumption of data centers grew to 205 TWh, which represents an increase of only 6% compared to 2010, while the total number of “computing instances” increased by 550% over the same period of time (under computing instances) the computational cores of the CPU are meant in the first place).

If we calculate the energy use per computing instance, then the energy intensity of the number of global data centers has decreased by 20% since 2010.

The total energy consumption of data centers in 2010–2018 remained virtually unchanged, but the energy consumption of IT devices (servers, storage systems and network equipment) increased from 92 to 130 TW · h, which indicates an increase in data center efficiency. In other words, now more energy goes directly to the servers, and less to auxiliary systems like a cooling system. At the same time, this indicates an increase in the technological and operational efficiency of the infrastructure: “This decrease is due to the continued transition from small traditional data centers (79% of computing instances in 2010) to large and more energy-efficient cloud (including hyper-scalable) data centers (89% computing operations in 2018). ” The trend is clearly visible in the first figure in the article, see the third graph on the left.



Nevertheless, given the ever-growing demand for data center services, the question arises, how long will current energy efficiency trends continue? “Predicting the long-term performance limits of IT devices is notoriously difficult, especially in light of potentially disruptive technologies such as quantum computing, for which energy consumption is unclear,” the authors write. “Nevertheless, in the near future, market analysts predict even greater server virtualization, and technological studies indicate that IT devices still have the potential to improve energy efficiency, including more transitions to low-power storage devices.”

In terms of infrastructure, super-large world-class data centers are already running at PUE = 1.1 or lower, which is close to the lowest possible value.

Researchers predict that in the short term, the transition from smaller traditional data centers to more efficient hyper-scalable data centers will continue. At the same time, "there is a sufficient energy efficiency resource to absorb the next doubling of computing operations in data centers in parallel with a slight increase in global energy use."

The findings of this scientific work contradict previous forecasts of a rapid and inevitable increase in electricity consumption. No, rapid growth is not expected in the coming years. But the volume of computing will continue to grow for many decades to come, so energy consumption in the data center must be controlled. Researchers recommend monitoring compliance with standards such as Energy Star for servers, storage, and network devices, and require certification for government procurement. Equipment manufacturers need to create incentives to continue to produce innovative energy-efficient products.

Study publishedFebruary 28, 2020 in the journal Science. The work of a team of American authors is called "Recalibrating global data center energy-use estimates" (Doi: 10.1126 / science.aba3758.