Advanced Computing in the Age of AI | Monday, June 24, 2024

The Myth Of The Green Datacenter 

Here's the reality when it comes to datacenter energy consumption: If the cloud industry were a country, according to a recent study, it would be the fifth largest energy consumer in the world.

The survey of datacenter energy consumption has a definite slant: It was funded by the National Mining Association and something called the American Coalition for Clean Coal Energy. Still, the reality in the U.S. and emerging markets like China is that most of the electricity the industry consumes is produced in coal-fired plants. Moreover, energy consumption at datacenters will only increase as more users with more wireless devices tap into cloud services.

Not that cloud services providers haven't attempted to decrease energy usage. But those efforts appear to have hit a point of diminishing returns. Indeed, a datacenter survey by market researcher and industry consultant Uptime Institute warned in June that investments aimed at improving datacenter power usage efficiency, or PUE, are hitting a wall.

"The inherent nature of the mobile Internet, a key feature of the emergent cloud architecture, requires far more energy than do wired networks," concludes the coal industry study on energy usage in the cloud. "The remarkable and recent changes in the technology mean that current estimates of global ICT energy use, most of which is pre-iPhone era data, understate reality. Trends now promise faster, not slower, growth in ICT energy use."

Sharing computing and storage in the cloud "is, in energy efficiency terms, equivalent to taking the train instead of driving," the study concedes. Nevertheless, it cites calculations that wireless networks connecting users with the cloud services consume the equivalent energy in 1 pound of coal to transport 1 GB (the report does not specify whether this calculation represents 1 GB of data, video or some other dataset. Here's the math: 1.5 kWh/GB; 10,000 BTUs/kWh; 15,000 BTUs/pound of coal).

The drive to reduce energy consumption in datacenters is linked to global efforts to reduce carbon emissions. During the recently concluded U.N. Climate Summit, the European Union announced ambitious plans to reduce emissions by as much as 95 percent by 2050. While Europe has taken the lead in adopting green energy sources, few observers believe such a goal is realistic, especially with power-hungry datacenters springing up across the continent.


European datacenter operators like the colocation specialist Interxion are stressing what they consider sustainable energy initiatives aimed at cutting datacenter power usage. The question is whether those efforts have reached a point of diminishing returns as more computing, storage and applications moved to cloud platforms.

Datacenter operators have stressed cooling alternatives as a quick and relatively easy way to reduce energy usage. In a blog post, U.K.-based Interxion listed five cooling options that are being adopted by cloud providers. The most common is "free air cooling," in which cold outside air is drawn into datacenters to cool rows of server racks. While cold air can also be drawn from rivers and lakes, "free air" still must be extracted by industrial air conditioners if it is too cold, notes Interxion chief engineer Lex Coors.

Other techniques for drawing off the heat from server racks in datacenters include evaporative, liquid, and containment cooling. Containment cooling involves arranging servers and other datacenter components, then separating hot and cold air using solid barriers.

Google has pioneered another technique called "hot hut" cooling in which individual racks and rows of servers are sealed off from the datacenter floor to promote energy efficiency. In addition, heat transfer techniques are used to limit the amount of wasted energy in the datacenter.

But as the number of datacenters explodes along with the uptake of cloud services, some service providers are looking to power sources other than coal-fired plants. One option under consideration are thorium-based nuclear reactors which are being promoted for their shorter atomic half-life, higher energy density, and lower carbon footprints.

China, where datacenters are popping up like mushrooms in a damp forest, has accelerated development and construction of thorium reactors. Still, other parts of China are attempting to lure cloud providers not with cheap labor but cheap electricity generated from high-sulfur coal.

Thorium reactors, like other nuclear power options, have yet to solve waste issues that could likely offset any "green" benefits. Hence, the booming cloud services industry is likely to continue relying on electricity from coal for the foreseeable future while cooling techniques provide only a modicum of energy savings and carbon emission reductions.

Meanwhile, the coal industry study of cloud energy usage notes that cloud computing will likely consume more energy than computing on a local PC as more users access cloud services more frequently. "If lower costs and greater convenience of using cloud services leads to significantly more data use – and collaterally more greater use of networks – overall energy consumption will rise," the study asserts.

Along with nuclear options, perhaps the cloud industry should also be looking at power plant scrubber technologies since it appears likely the industry will continue to rely on coal-fired plants for the bulk of their electricity.

About the author: George Leopold

George Leopold has written about science and technology for more than 30 years, focusing on electronics and aerospace technology. He previously served as executive editor of Electronic Engineering Times. Leopold is the author of "Calculated Risk: The Supersonic Life and Times of Gus Grissom" (Purdue University Press, 2016).