Smart Tactics to Reuse Your Data Center’s Waste Heat


Many companies want to figure out ways to turn their waste heat into a positive. After all, data centers produce it in the normal course of operation. Figuring out how to turn it into a sustainability initiative can increase job satisfaction, provide opportunities for press, and even build your bottom line. Here are a few tips on how to reuse your waste energy wisely.

  • Transforming Energy Isn’t All Bad
  • It’s Getting Hot in Here
  • Collaboration with Power Plants

At Superb Internet, we are always looking toward the future in planning our business, and part of that forward-thinking focus includes addressing the growing concerns of climate change. Conservation is both our responsibility as a business and a way that we embrace efficiency for cost reductions that we pass on to our clients.

One innovation we’ve adopted is floor-mounted air conditioners with electronically commutated (EC) plug fans. They reduce energy use 30%, as described here.

Many data centers are now also moving underwater, where it’s easier to cool things down. Just like how a cold bath cools you down in summer, placing a data center on the seafloor can sap the heat straight out, improving efficiency and reducing the energy needed for artificial cooling. Obviously, this comes with its own issues, such as corrosion and leaks, but there are many products out there now, like these Bronze Marine Fasteners, that allow underwater data centers to be built pretty easily.

Sustainability isn’t just about reducing waste, though. It’s also about using waste wisely. Let’s look at how waste heat can smartly be used by your data center.

Transforming Energy Isn’t All Bad

Data centers around the world essentially serve as energy transformation facilities. They take in electric power, cause electrons to spin, and perform tasks. Almost all of the electricity – 98% – is released as heat energy. It’s similar to being the exact reverse of a wind turbine or hydroelectric dam that takes the kinetic energy of rushing water and turns it into affordable, portable power to be used in distant cities.

It’s possible, though, that data centers don’t have to be the opposite of a power plant or other energy generator. Energy transformation isn’t essentially negative. Sustainability expert and author William McDonough trains organizations on how to look at processed waste as something not just to limit but to reuse. Reusing is part of sustainability, which is practiced in many industries, including packaging companies like Impacked Packaging. A good example of this is how agricultural waste is utilized in mushroom-based packaging. Waste is a form of nourishment, either for the earth or for industry, he says. “We manufacture products that go from cradle to grave. We want to manufacture them from cradle to cradle.”

It’s possible to use this same line of thinking for pairing of facilities. Data centers could work in conjunction with facilities that use heat, such as district heating systems, so that waste isn’t just released but utilized to its full capacity.

The idea of reusing waste heat is not new. There are many situations worldwide in which data centers are partnering with nearby companies to use that heat that would otherwise be waste.

For instance, one corporation in Switzerland started reusing its heat to warm a public pool. A couple of firms in Finland offload their heat energy to local homes, which provides enough power for the annual needs of 500-1000 families. This reusing of heat, in some form or another, has been accomplished in the United States, the UK, and Canada as well.

It’s Getting Hot in Here

A couple major obstacles hold back these heat-reuse projects. First, heat waste isn’t at an exceptionally high temperature. It also is difficult to get from place to place – which is why many projects send the energy to a pool or greenhouse that’s directly adjacent.

Data center return air is typically not extraordinarily hot, usually about 80-95 degrees Fahrenheit. Transporting it means that you need insulated ducts or pipes (and in all probability expansion bellows if they are used in such or high power heat-producing machinery) rather than low-cost electrical cables. Everything from the heater and its capacity, to the ability of the pipes to handle such a load, is to be considered, explains Mark Monroe in Data Center Knowledge. “Trenching and installation to run a hot water pipe from a data center to a heat user may cost as much as $600 per linear foot,” he says. “Just the piping to share heat with a facility one-quarter mile away might add $750,000 or more to a data center construction project.” Right now, it isn’t easy to get those costs down.

In order to get the temperature higher so that the waste heat is worth more, data centers have started using heat pumps to boost the temperature. That can be done by contacting a local heat pump installation company that can equip the facility with pumps that can raise the heat. If it comes out in the range of 130-160 degrees, it can then be transported as a liquid for use in local heating, manufacturing, laundromats, or various other applications. You can get specific heat pumps that increase the temperature even more. However, you would need to get in touch with a specialized heat pump manufacturer to buy something of the sort.

You want a heat pump with a Coefficient of Performance (COP) between 3 and 6. It’s affordable. If you use heat pumps with COPs of 5.0, and your power costs $0.10 per kWh, you should be able to get the low-grade heat up to a valuable level for $0.0083 per kWh.

Your waste heat could make you money. Steam heat is generated by Con Edison at $0.07 per kWh. “For a 1.2MW data centers that sells all of its waste heat, that could translate into more than $350,000… per year,” says Monroe. “That may be as much as 14% of the annual gross rental income from a data center that size, with very high profit margins.”

Collaboration with Power Plants

It’s an interesting possibility to consider the idea of combining a data center and a power plant so that waste heat can be reused easily and immediately. A couple basic arguments for this type of arrangement are:

  1. 8-10% of power is lost in transmission throughout the US. Building data centers next to power plants would mean the data center doesn’t experience that reduction in energy or the cost of getting it to their facility.
  2. “[A] co-located data center could transfer heat pump-boosted thermal energy back to the power plant for use in the feed water heater or low-pressure turbine stages,” explains Monroe, “creating a neat closed-loop system.”

Working with a power plant is of course just one idea. When you look for a way to make the most of your waste heat, consider businesses or other projects that would benefit from the heat throughout the year. Also, be certain to choose heat pumps that are efficient and designed for high temperatures to make your heat energy as valuable as possible.

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