Harnessing datacenter heat for savings

The heat that pours out of your datacenter machinery represents a hefty chunk of your monthly utility bills. After all, were it not for that heat waste, you wouldn't be pouring dollars into running that pricey cooling equipment to ensure your valuable hardware doesn't get fried. While many vendors out there are devising CRAC hardware and cooling technologies for more efficiently and inexpensively beating the dat

The heat that pours out of your datacenter machinery represents a hefty chunk of your monthly utility bills. After all, were it not for that heat waste, you wouldn't be pouring dollars into running that pricey cooling equipment to ensure your valuable hardware doesn't get fried.

While many vendors out there are devising CRAC hardware and cooling technologies for more efficiently and inexpensively beating the datacenter heat, some organizations are taking another tack: putting all of that hot air to valuable reuse, which can have pleasant financial and environmental benefits.

Datacenters are responsible for a goodly amount of heat waste, to be sure: "In many cases, a datacenter can generate enough heat to heat a building 10 to 30 times its size," says says Steve Sams, vice president of IBM Global Site and Facilities Services. "That's a lot."

Recycling heat

One of the most logical uses of datacenter heat waste is, indeed, to warm up the rest of an organization's building. Intel is doing just that with a heat-reuse system designed for its first LEED (Leadership in Energy and Environmental Design)-certified green building, a development center in Israel.

The system employs HR (heat recovery) chillers instead of standard chilled water systems. While a chilled water system releases hot condenser water directly into the atmosphere via the cooling tower, the HR chiller system uses that heated water to warm the rest of the building in the winter and provide hot water for bathroom and kitchen use year-round.

According to Intel, "reusing datacenter heat eliminates the need to add boilers for heating the rest of the building. This energy-saving approach accumulates points towards environmental certification and is highly cost-effective."

The company projects savings of approximately $235,000 annually due to reduced fuel consumption, resulting in an ROI of just over 19 months.

Sharing the warmth

Of course, not every datacenter has a nearby facility to heat up -- but that doesn't mean the excess heat it produces needs to go to waste. Co-location service provider GIB recently partnered with IBM to transform a former underground military bunker in Uitikon, outside of Zurich, into a highly secure data-storage facility. Operating at full capacity, the facility is expected to create 2,800 megawatts of wasted heat per year (the same amount of energy needed to supply up to 80 houses with heating and warm water for one year).

"Whenever we can, we encourage our clients to find opportunities to reuse waste heat in the datacenter environment," says IBM's Sams. In this case, however, there was no office building to reuse the facility's heat, given that it's out in the middle of the woods and hidden underground.

Turns out there was a better alternative to simply blowing cold air at the problem: GIB and IBM devised a direct heat exchange between the datacenter and local public swimming pool. Yes, the people of the town can now enjoy a swim in water warmed up for free by the datacenter's heat waste.

The green payoff here is pretty evident. The town is saving money by longer paying to heat its pool. GIB earns CSR (corporate social responsibility) points. As for the environmental benefits: "Through reclaiming the heat, approximately 130 tons of carbon emissions can be saved. This corresponds to the CO2 discharge of mid-size cars driving 500,000 miles," Sams says. "It's a nice solution. It's obviously a terrific example of the private sector and the public sector working toward each other's mutual benefit."

In addition, the approach demonstrates that you don't need to start from scratch with a new datacenter facility or office building to make use of heat waste. The public pool clearly had its water-heating system in place before GIB and IBM built this new datacenter -- yet they were still able to connect the two to reap the aforementioned benefits.

Talkin' 'bout co-generation

Here's one more example of an organization harnessing its heat waste for reuse: NetApp, based in Sunnyvale, Calif., has a rather different approach to reusing heat waste: cooling its datacenter hardware.

In NetApp's case, that heat isn't coming from its IT equipment, it's coming from its natural gas-powered co-generation system. The system is used to produce electricity for the 1MW datacenter -- though only when the temperature and energy prices in California peak. When the system is running, it produces heat waste, which NetApp uses to power its adsorption chiller that chills the water used in its cooling system.

According to NetApp, the co-generation system has an overall efficiency rating of 75 percent to 85 percent (compared to the 35 percent efficiency for a natural-gas utility). NetApp says its co-generation system saves the company $300,000 annually.

We'll no doubt continue to see approaches to reusing heat waste evolve. Perhaps, soon, there will be a way to efficiently transform it into power for the datacenter. Even today, though, there's already a potential ROI, both in terms of economic and environmental benefits.

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