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Geothermal cooling is energy-efficient and environmentally responsible, but space is its biggest caveat. Horizontal loops occupy a huge area, especially when you're dissipating a data center's large cooling loads.
There's a lot of excavation necessary to accommodate a geothermal horizontal loop. Unless it's a greenfield site where you re-grade the land, you'll do significant landscaping to restore after crews dig large trenches -- which are continuous and interconnected -- throughout the property. Geothermal cooling systems work below the frost line; depending on your location, that could be four to six feet deep. Horizontal loop trenches are several feet wide.
Excavation piles up a lot of dirt, and disturbs the land. When you cover the pipes, the back-fill has to settle before you can re-landscape. If you're digging in woodlands, you'll undoubtedly uproot some trees, which might create drainage problems or raise environmental concerns in protected natural areas. If trenches fall into the water table, it will increase cooling effectiveness substantially, and could mean fewer trenches and pipes in the build. A professional assessment will tell you any concerns about the specific site.
Does this mean you shouldn't consider horizontal geothermal cooling for your data center? Absolutely not. Vertical loops are narrower, but the trenches are deeper. Except for the possible cost of land restoration, horizontal geothermal cooling systems should be significantly less expensive than drilling large numbers of deep holes for vertical loops.
Appoint experienced engineers, with backgrounds in geothermal implementations and data centers, to study your proposed build. That won't be an easy combination to find, but such firms do exist.
Geothermal is cool
You will see more geothermal cooling in the future, but right now the combination of land, cost and reliability, and its new technology status, are holding back implementation.
Geothermal cooling has an upfront cost premium. But with the power demands of a data center, and the cost of energy, payback time for the initial investment could be short.
Concerns about newness are uninformed; geothermal cooling is proven and the number of installations continues to grow.
In terms of reliability, a correctly designed and installed geothermal system is far more reliable than a total mechanical system because there are so few moving parts. Further, the cooling loops are thoroughly protected. In regions with severe weather concerns, it is the most reliable option.
About the author:
Robert McFarlane is a principal in charge of data center design for the international consulting firm Shen Milsom and Wilke LLC. McFarlane has spent more than 35 years in communications consulting, has experience in every segment of the data center industry and was a pioneer in developing the field of building cable design. McFarlane is one of several regular contributors to SearchDataCenter's Advisory Board, a collection of experts working in a variety of roles across the IT industry.
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