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The reality of renewable energy resources for data centers

A combination of renewable energy resources and geographical planning can create a sustainable data center that avoids reliance on grid power.

With energy prices on the rise and carbon footprints front of mind, it's time to look at renewable energy resources for data center power.

Powering a data center often means tying into a national grid for the primary power source and backing this up with uninterruptable power supplies (UPS) and auxiliary generators. Environmentally conscious data center designs include more energy-efficient equipment and renewable energy sources of power. But alternative energy sources -- hydroelectricity, solar panels, wind turbines -- require geographical freedom and/or energy storage to balance out the intermittent nature of energy production. A better approach is to combine alternative energy sources and use fuel cells for power.

Data center renewable energy pros and cons

For companies that are free to locate a data center wherever they want, hydroelectricity is a prime renewable choice. Google built one of its data centers in Oregon to access cheap hydro power from The Dalles Dam. As a large energy consumer, Google was able to negotiate a good deal on energy prices while gaining better green credentials. Advania's Thor Data Centre in Iceland uses a mix of hydro and thermal power, along with free air-cooling to control its energy usage and minimize its carbon footprint.

A basic rethink of the approach to how energy is used within a data center can have massive effect on overall energy usage.

Some data centers have used solar energy to provide part of the energy required to run the facility. Apple's data center in Maiden, North Carolina, has a large solar array combined with a fuel cell system to provide 60% of its energy. Apple is working with a renewable energy company, NC GreenPower, to source the other 40% from other renewable sources, such as wind power. As with many renewables, solar power has its issues -- it only generates electricity during the day and is heavily degraded by any level of cloud cover.

The problem with these renewable energy resources is that they are location-dependent. Don't try to implement hydro and thermal electricity in a flat country such as the Netherlands. Solar photovoltaic is most effective in the "Sun Belt," a region around the equator where days are of a predictable, adequate length and sun's strength is relatively constant. For companies that need their data centers close to home, this underlines a need to look for other possible energy resources.

Ecological Hosting's Smartbunker facility is described as the first U.K. facility to be 100% wind-powered. Contracted through Ecotricity, the facility is backed up by latest generation uninterruptable power supplies and biodiesel auxiliary generators. However, wind power is even less predictable than solar power, making it a contender for the least-useful alternative energy to power a data center. Not only are turbines dependent on the presence of wind -- which is very unpredictable in most locations -- but the wind strength must be within a certain range. Too low, and the effectiveness of power generation is minimal. Too high, and brakes are applied to prevent possible damage to the rotors and bearings. 

Without energy storage systems in place, solar and wind power must be continuously backed up with other energy sources. However, as a secondary energy source used to provide a small amount of a site's needs, these renewables have a part to play. A primary renewable energy supply that doesn't depend on the presence of a variable resource such as sun or wind is not easy to find. However, a basic rethink of the approach to how energy is used within a data center can have massive effect on overall energy usage.

Reconsidering renewable energy resources

The distribution of energy within a data center is, on the whole, fairly efficient. As virtualization and cloud computing grow, the overall energy efficiency of a data center will only improve. Energy wastage is most notable during the primary creation of the power.

Whether coal, gas or oil power the data center, massive energy losses occur during the generation stage. Most fossil fuel systems are also located far from large urban areas. More modern, smaller energy generators can improve this energy equation. High-temperature fuel cells take a range of hydrocarbon fuels, break them down into hydrogen, and then add oxygen from the air to create electrical energy -- along with heat and water.

The key here is to capture as much of the output as possible. The fuel cell's heat energy can be used in colder locations for space and even water heating. Collecting the pure water produced by fuel cells frees up data centers to exist in drier geographical locations. Renewable energy sources such as solar and wind can also be recruited to electrolyze water, creating hydrogen for the fuel cells. It may then be possible to build a truly renewable continuous primary power system for data centers. This approach may not be the cheapest way to create electrical energy at a simple dollars-and-cents level, but it can be a long-term effective means of powering the data center.

About the author:  Clive Longbottom is the co-founder and service director of IT research and analysis firm Quocirca, based in the U.K. Longbottom has more than 15 years of experience in the field. With a background in chemical engineering, he's worked on automation, control of hazardous substances, document management and knowledge management projects.

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