Data Centers their CO2 and Water Footprint

Data centers are the bricks and mortar of the internet. These buildings store servers, digital storage equipment, and network infrastructure for the large-scale data processing and storage.  Our increasingly digital world has an ever-growing need for data creation, processing, and storage from businesses, online platforms, video streaming, smart and connected infrastructure, autonomous and driver assist vehicles, and artificial intelligence. The amount of data created and stored globally is expected to reach 175 Zettabytes by 2025, representing nearly a six-fold increase from 2018. The role of data centers in storing, managing, and distributing data has remained largely out of. Similarly, the environmental implications of data centers have been obscured from public view. 

The United States houses nearly 30% of data center servers, more than any other country; and northern Virginia houses more data centers than any other locality. In a study recently published in Environmental Research Letters, Landon Marston, an assistant professor at Virginia Tech and colleagues looked at how and where data centers consume energy and water in the United States. The results showed that it takes a large amount of water to support the internet and cloud service and that the water often comes from water-stressed basins. Physical location of data centers impacts the carbon and water footprint.  Below are excerpts from their study “The environmental footprint of data centers in the United States”

Citation Md Abu Bakar Siddik et al 2021 Environ.Res. Lett. 16 064017DOI 10.1088/1748-9326/abfba1

Though the amount of data center computing workloads has increased nearly 550% between 2010 and 2018, data center electricity consumption has only risen by 6% in that time due to dramatic improvements in energy efficiency and storage-drive density across the industry. However, the water and greenhouse gas footprint of the data center industry is huge. In addition, it is unclear whether energy efficiency improvements can continue to offset the energy demand of data centers as the industry is expected to continue its rapid expansion over the next decade.

In this study, Drs Marston et al used the records of data center operations to provide the first regional estimates of data center water and carbon footprints. The water footprint is defined as the consumptive blue water use (i.e. surface water and groundwater). The greenhouse gas footprint of a data center, expressed as equivalent CO2, is used to represent its global warming potential. The scientists looked at the operational environmental footprint of data centers which includes the power plants, water supplier, and wastewater treatment plant servicing the data centers. 

Power plant-specific electricity generation and water consumption data come from the US Energy Information Administration (EIA). The U.S. Environmental Protection Agency's eGRID database provided GHG emissions associated with each power plant.

The indirect water and carbon footprint of each data center consists of water consumption or GHG emissions associated with the generation of (i) electricity utilized during data center operation, (ii) electricity used by water treatment plants for treatment and supply of cooling water to data centers, and (iii) electricity used by wastewater treatment plants to treat the wastewater generated by a data center. 

Direct water consumption of a data center is based on heat generation related to the amount of electricity used. Estimates of data center specific electricity demand were multiplied by the typical water cooling requirement—1.8 m3 per MWh—to estimate the direct water footprint of each data center. Data center wastewater is largely comprised of blowdown; the portion of cooling water removed from circulation and replaced with freshwater to prevent excessive concentration of undesirable components. In general data centers recycle their water until the concentration of dissolved solids (which is essentially salts) is roughly five times the supplied water. 

Since water stress is expected to increase in many watersheds due to increases in water demands and more intense, prolonged droughts due to climate change. For these reasons, environmental considerations may warrant attention alongside typical infrastructure, regulatory, workforce, customer/client proximity, economic, and tax considerations when locating new data centers. However, placing all new data centers within a small area may strain local energy and water infrastructure due to their collective water and energy demands. The scientists suggest that data centers can be dispersed more broadly in areas that are favorable with respect to water footprint, water scarcity, or carbon footprint. As seen in the diagram below shows that seems to indicate that parts of the northeast and southern Florida are the best locations for data centers to minimize GHG and water impacts.

from Marston et al

The scientists also suggest the data center industry can make investments in solar and wind energy. Directly connecting data center facilities to wind and solar energy sources ensures that water and carbon footprints are minimized. However, data centers require level power supply and renewable sources are variable. Purchasing renewable energy certificates from electricity providers does not necessarily reduce the water or carbon footprints of a data center. However, these investments gradually shift the electrical grid toward more renewable energy sources, lowering the overall GHG impact for all energy users. 

Overall, the scientists show that strategically locating new data centers can significantly reduce their environmental footprint. Climatic factors can make some areas more favorable due to lower ambient temperatures, thereby reducing cooling requirements. Lower cooling requirements reduces both direct and indirect water consumption, as well as GHG emissions, associated with data center operation. Since most data centers meet their electricity demands from the grid, the composition of power plants supplying electricity to a data center plays a significant role in a data center's environmental footprint. The scientist show that real estate decisions may be as important as technological advances in reducing the environmental footprint of data centers.

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