Being able to power data centers solely with clean energy may sound like a dream – and, unfortunately, it is in most cases. Although plenty of data centers now source much of their energy from solar, wind, and other low-carbon renewables, most data centers can't operate off of renewable energy alone.
That doesn't mean that seeking clean energy isn't worth it as part of a data center sustainability strategy. It certainly is. But it's also important to recognize the limitations of sustainable energy sources in the data center market.
Clean energy for data centers: What works, and what doesn't
Currently, there are three main types of clean energy for data centers that are practical to use to power large-scale operations: wind, solar and geothermal. All three of these energy sources are already being relatively deployed to help energize data center infrastructure and/or to help cool data center equipment (especially in the case of geothermal energy systems, which can dissipate heat by moving it deep into the earth).
Other clean energy sourcing options exist for data centers, but they're not pragmatic choices in most cases. For instance, the idea of biomass-powered data centers, which would rely on energy produced by burning or otherwise consuming organic material, stretches back more than a decade. But outside of some exceptional cases (like an Apple data center in Denmark), biomass has yet to take off as a common source of clean data center energy, probably because the amounts of organic matter necessary are too great to make biomass a reliable energy solution.
Similarly, although hydroelectric power has long supplied energy for some data centers, the limitation of hydroelectricity is that you can only build hydroelectric plants in certain places – namely, those with fast-moving streams of water. That makes hydroelectric energy impractical for data centers located far from rivers.
The limitations of wind, solar and geothermal energy sourcing
Compared to biomass and hydroelectricity energy sources, wind, solar and geothermal are more practical to use on a large scale. But they still have clear drawbacks.
In the case of wind and solar, probably the most obvious challenge is that energy availability can vary based on the weather. If it's a cloudy day, your solar-powered data center will need an alternative energy source to keep running. If it's calm, your wind farm may not generate enough megawatts to keep servers and data center equipment operating.
Geothermal is not subject to this drawback; it functions independent of weather conditions. But because generating energy with geothermal requires the construction of specialized power plants, geothermal energy sourcing requires a larger upfront investment than sourcing energy from wind or solar farms, which are not as costly to build. Indeed, less than 0.5 percent of all electricity in the U.S. is generated using geothermal energy sources.
Another drawback of clean energy sourcing is that it can increase the physical footprint associated with data center facilities. Wind and solar farms, in particular, take up a lot of real estate, leading potentially to larger amounts of habitat destruction. They might reduce your carbon emissions, but not without some cost to the natural environment.
Storing sustainably generated electricity can be a challenge, too. Unless you have massive arrays of batteries – which themselves come with a high sustainability cost – on hand, you can't retain excess electricity produced by wind, solar and geothermal. You use it or lose it.
As a result, if you want to power your data center purely with clean energy, you typically need to build clean energy sourcing facilities that have a much higher total output capacity than your data center will require at most times, if you want to ensure that they can handle periods of peak energy consumption. Or, you have to use non-clean energy to supplement your clean energy sources during high-demand periods.
Clean energy: Imperfect, but worth it
The challenges described above mean that, in most cases, powering data centers solely with wind, solar, geothermal or other renewable, low-carbon sources is impractical for most data centers. Traditional energy is almost always needed either to supplement clean sources, or as a backup for times when clean energy is unavailable.
But that doesn't mean, of course, that investing in clean energy isn't worth it. Even if you only source 20 percent of your data center's energy from renewables, that's still a 20 percent reduction in carbon emissions associated with energy production, which is hardly negligible. Combine that achievement with investments in measures to improve energy efficiency, like liquid cooling and smart power management systems, and you could make a real dent in data center sustainability.