More data centers are making their way underground. Colocation and data center providers such as Iron Mountain, Cavern Technologies and InfoBunker are already operating underground data centers, taking advantage of natural cooling and protection from the elements. However, are underground data centers a coming trend or a novelty? Is it time for data center providers to dig in and start putting their servers and computing hardware underground? What options should solution providers recommend to customers?
First, let’s consider the changes in operational costs for today’s data centers. The greatest costs of data center operations remain those of cooling and the power associated with cooling. Operating chillers to provide a consistently cool operating temperature remains one of the biggest line items in the data center operating budget. An IDC survey of 404 enterprise data center managers (each with at least 1,000 square feet and 100 servers) reports that power and cooling costs, along with IT infrastructure costs, each make up about 24 percent of the operating budget.
So how does moving underground affect operating costs and efficiencies? Let’s assess some of the variables.
It’s Cool to Be Underground
The primary reason to migrate data centers underground is natural cooling. Rather than powering up chillers to maintain a cool operating temperature 24/7, underground facilities maintain a naturally cooler, unchanging ambient temperature. Cavern Technologies, for example, says that its underground facility in Lenexa, Kansas, which is built in an abandoned limestone mine, maintains a consistently cool operating temperature of 68 degrees.
The operational challenge for any underground data center is bleeding off the excess heat. Underground facilities have air conditioning for comfort, but excess heat from the servers usually has to be vented through holes drilled to the exterior. The Underground, an Iron Mountain facility in a repurposed limestone mine in Pennsylvania, maintains a constant temperature of 55 degrees, and Iron Mountain executives say that the limestone walls of the mine act as a heat sink, absorbing up to 1.5 BTUs per hour per square foot. Most underground facilities, however, need some kind of heat management strategy.
Location, Location, Location
Then, of course, there are power considerations. Even if you don’t need a lot of energy to power chillers, you still need reliable power to run the equipment. This is where things can become expensive.
Rather than digging out an underground data center, most companies use natural or preexisting underground locations, such as abandoned military bunkers, mines or caverns. Most of these preexisting underground locations are in isolated areas, where power may not be available. Because you can’t “bring the mountain to Mohammed,” you have to bring a reliable power source to the data center, which drives construction costs up.
You have the same issues regarding reliable network connections. Because underground data centers tend to be remote, you also have to bring in fiber and high-speed networking to provide connectivity. One of the reasons to go underground is to eliminate weather as a risk factor, so to minimize climate risk, you should put cable underground as well, which will increase construction and maintenance costs.
When considering an underground data center location, you need to balance the cost savings from construction (you already have a hole in the ground) with the cost of power and connectivity. You may be saving on the cost of chillers while increasing the cost of delivering power and infrastructure access.
Is It Worth It?
There are some real advantages to taking a data center underground, but there are other considerations beyond cooling and power that could present obstacles. What about personnel? Is the underground data center in a location where you can attract skilled IT professionals to maintain the facility? What about external support systems? You won’t be able to install everything underground, so you want to be able to accommodate generators, climate control systems and other units housed outside the facility. All of these factors could add to overall construction and operating costs.
There also are new technologies and strategies that are solving the same problems that underground data centers solve, specifically cooling and power, but at much lower costs. Most of these cooling techniques can be retrofitted into existing data centers.
Hot-aisle and cold-aisle strategies, for example, have been around for some time and use airflow to facilitate cooling while reducing costs. Some estimate that savings in cooling costs from hot-aisle containment can be as high as 43 percent, without having to build a new data center. Hot-aisle designs have become more sophisticated and less expensive, making them a viable alternative for saving on operating costs.
Water-based data center cooling is another strategy that is gaining popularity. Water has 50 to 1,000 times the capacity of air to remove ambient heat, which makes it more efficient for equipment cooling. So, rather than building data centers underground, others are experimenting with underwater data centers and floating data centers. A less radical approach is using water-cooled racks for high-density computing, which can be easily installed in an existing data center.
While data centers may be ready to move underground, do you really need to? There are alternative cooling technologies available today that resellers can offer to customers to retrofit into their existing data centers. Cold-aisle and water-based cooling strategies are more effective and reduce energy costs, and you don’t have to move the operation to a bunker or a cave.