How much energy does the Internet use?

Data centers are collections of computers that make up the back end of a system. A data center isn't necessarily connected to the Internet -- it can be an internal system within an organization or company. But the Internet relies on massive data centers that contain hundreds of thousands of computers.

A data center could house database computers, Web servers and mainframes or some combination of all three. Several years ago, it was common for businesses to maintain their own data centers. Some were huge -- the size of a warehouse and filled with thousands of computers mounted in racks. Others were tiny and consisted of a single rack of machines.

Today, many businesses rely instead upon cloud services for their data center needs. This means they hire some other company to provide the physical devices upon which the business's data and services reside. Access to the business's information comes to us courtesy of the Internet. The cloud service data centers are truly massive with hundreds of thousands of machines stored in enormous buildings.

Cloud service companies will store a customer's data on multiple machines. This is for redundancy. If a computer fails for some reason, the customer's data remains intact because it exists on another machine. The downside of this arrangement is that each computer requires power to operate.

Computers also generate heat, which can be bad news. If electronic components get too hot, they can malfunction. To keep the machines operating at a safe temperature, data center owners must invest in cooling systems. The most common system is air conditioning. We should factor in the energy costs of air conditioning data centers in our final estimate since they are necessary to keep the Internet running.

Since 2008, the number of data centers in the United States has declined [source: IDC]. That's mostly due to companies shifting to the cloud-services model and offloading their data centers. But while there are fewer data centers, the ones that remain are growing larger. It's like trading a group of 50 hamsters for 10 elephants -- you have fewer animals in the end, but they take up a lot more room and use more energy.

Getting an exact count of data centers is impossible -- many companies keep information about their data centers private because it can be a competitive advantage. It's also impossible to say for certain how much power each data center requires without knowing all the details. That hasn't stopped people from trying. Next, we'll look at some of the methodologies people have used to estimate the Internet's power consumption.

In 2011, Barath Raghavan and Justin Ma of ICSI and University of California, Berkeley, took on the task of estimating the amount of electricity the Internet requires. They decided to take into account the energy we use to create the Internet itself. That includes all the power needed to build computers, network connections, cell-phone towers and other hardware. They called this embodied energy or "emergy."

Raghavan and Ma relied on general estimates for all their work and acknowledged in their report that their answer was not accurate. Their stated goal was to bring attention to the matter so that others might think on the issue more deeply. Their estimates included:

They also included other Internet infrastructure elements. They weighted each category of device with a minimum and maximum value to create a range of energy requirements because one computer might require less energy to produce and run than another. They also took into account the average life cycle of each piece of the infrastructure.

Ultimately, Raghavan and Ma estimated the Internet uses 84 to 143 gigawatts of electricity every year, which amounts to between 3.6 and 6.2 percent of all electricity worldwide. Taking emergy into account, the total comes up to 170 to 307 gigawatts. That's a lot of energy, but amounts to just under two percent of worldwide energy consumption.

A 2012 New York Times article by James Glanz examined how data centers can be wasteful and consume a great deal of energy. In order to provide reliability, data centers need to store the same information on multiple machines to create redundancy. These machines need to be on and accessible all the time. On top of the need for constant power flowing to the servers, the data centers require cooling systems that pull more power.

According to Glanz's sources, data centers use around 30 gigawatts of electricity [Glanz]. He also states that data centers can waste most of that energy -- up to 90 percent of it. With that massive amount of power going to waste, is the Internet doing more harm than it's worth?

Not according to Raghavan and Ma. They point out in their report that the Internet's energy consumption is a fraction of that of the transportation industry, which accounts for 61 percent of all oil production [source: Raghavan and Ma]. The two researchers suggest that because the Internet uses less power and causes a smaller environmental impact than transportation, moving more tasks to the Internet makes sense. Using teleconferencing rather than travel for meetings could save quite a bit of energy.

The real picture that emerges when you look at how much energy the Internet uses is that it's a complex issue. Without the Internet, we would have to rely on other methods to communicate and access data. Those methods might in turn require more energy and cause more pollution than the Internet does. If that's the case, decreasing our reliance on these activities and focusing more on the Internet makes sense from an energy perspective.