Recently, Greenpeace launched a series of coordinated protests at Amazon, Apple and Microsoft locations to draw attention to the companies’ use of GHG intensive fuels in powering their data centers. The protests were a follow up to their recently released report, “How Clean is Your Cloud,” which criticized the companies for expanding their data centers without regard to the source of electricity.
While some have questioned the report’s details, it nonetheless highlights an important issue. Major IT and cloud computing companies have been working to improve energy efficiency in their data centers, and yet mitigation of GHG impacts from power use has lagged. This matters because recent growth of the internet and cloud-based computing is resulting in rapid proliferation of data centers and massive incremental power requirements.
To date, the cost and availability of power have been primary concerns for operators when siting data centers. Green power options for data centers have been low on the priority list, or otherwise deemed impractical, expensive, or geographically limited.
Yet going forward, is a natural match emerging for data centers and green power? After all, there is flexibility in siting data centers, especially when compared to other types of industrial facilities. Incremental power requirements from new data centers are large and physically concentrated. At the same time, the IT industry is sensitive to consumer opinion, and is increasingly influenced by data center efficiency and carbon intensity metrics. As noted in a recent Rackspace Survey, sustainability is now important to a significant majority of hosting services customers and is a factor in purchasing decisions. Finally, an emerging set of solutions is making green power a more realistic option for many new data centers.
IT companies are currently exploring a wide range of green power solutions, including sourcing cleaner forms of energy from utilities and energy suppliers, purchasing renewable energy, and deploying onsite renewable energy systems.
Energy Use in Data Centers
Data center energy use now accounts for approximately 1.7-2.2 percent of US electricity consumption. This power requirement was estimated to be on the order of 75 million megawatt hours in 2010, according to consulting Stanford professor Jonathan Koomey. The vast majority of this power currently comes from the utility electric grid, and the GHG intensity of grid electricity varies by as much as 500 percent – depending upon whether power is coming from clean hydro-based or dirtier coal-fired generating stations. With demand for cloud services and digital information provided by data centers expected to grow exponentially, IT companies are investing billions of dollars in new data centers.
Data center energy use requirements are highly intensive and continuous – traditionally a difficult match for many green energy sources. That said, meeting growing energy demands and reducing GHG emissions from data centers will require IT and cloud computing companies to adopt an “all-of-the-above” energy strategy—comprising of a combination of different green power approaches and energy efficiency initiatives.
New Data Center Energy Use Metrics
The expanding view of data center energy use has led companies to adopt new metrics for measuring their computing facilities. Power Usage Effectiveness (PUE), which is total facility power divided by IT equipment power, is now a common efficiency metric for data center operators. However, PUE does not address carbon emissions from a data center’s energy consumption. Even the most energy efficient data center can be powered by fossil fuels and produce significant carbon emissions.
In response, The Green Grid has established Carbon Usage Effectiveness (CUE) as a metric by which data center operators can gauge the intensity of their carbon emissions per kilowatt-hour of energy used. It also allows them to evaluate the impact of different energy sourcing options, whether it is electricity from the grid or an onsite renewable system. Together, the CUE and PUE metrics help describe a data center’s relative energy efficiency and emissions intensity.
The ideal “green data center” is extremely energy-efficient, with a low PUE, high asset utilization, and a low CUE through use of green power. Thus, environmental impacts are mitigated from two essential angles — through a high degree of energy efficiency and the use of clean energy.
In my next article, I will discuss clean energy options for data centers.
Don Bray is cofounder and president of AltaTerra Research. He has led a broad range of research and consulting engagements in corporate sustainability, resource efficiency, and renewable energy systems. He has deep expertise in enterprise information systems, and has authored several reports on enterprise sustainability management solutions. He is a frequent writer, speaker, and moderator on emerging developments in resource efficiency and corporate sustainability.