Google makes a green case for the cloud

Findings confirm that cloud computing's economy of scale means less energy consumption and fewer carbon emissions

Google released a study (PDF) today concluding that using cloud-based email is more energy efficient than running email in-house. The company isn't the first to preach the green advantages of cloud computing, but Google stands to gain from successfully working the case as it looks to make Gmail converts out of shops running Microsoft Office and other rivals.

The underlying theory that cloud computing is more energy efficient than on-premises hosting is pretty sound, generally speaking: Cloud service providers have the advantage of economies (more users per server), as well as shared power and cooling resources. Additionally, their business model is based on providing services as efficiently as possible.

For the study, Google determined the average amount of energy necessary to run email in-house at a small business with 50 email users, a medium-size business with 500 users, and a large business with 10,000 users. The study assumed that the small and medium-sized businesses would require 2 servers (a primary and a backup), whereas the large company would require 12 (10 plus 2 backups).

All told, combining the costs of powering and cooling the servers along with the other IT infrastructure necessary to deliver email to a user's PC, Google determined that providing email to a single user at a small business uses 175 kWh (kilowatt hours) per year (70 kWh from the two 200W servers and 105 kWh from power, cooling, and the like). A user at a midsize business would use 28.4 kWh per year (16 kWh from operating two 400W servers and 12.4 kWh from cooling and such). Finally, the large-business user would burn through approximately 7.6 kWh per year (4.7 kWh from 12 450W servers and 3.1 kWh from the non-IT resources).

Tthese figures point to the energy-efficiency gains that can be reaped through higher scalability, increased users per server, and shared power and cooling. In that vein, Google assumed at PUE (power usage effectiveness) of 2.5 for the small business, 1.8 for the medium-size business, and 1.6 for the large business.

By comparison, Google claims that, thanks to its various feats of data center efficiency, it is able to provide Gmail at an annual energy-per-user rate of less than 2.2 kWh. Google attributes this to its highly efficient servers, its server-optimized software, and a PUE of 1.16.

Again, Google is not the first cloud vendor to roll out research on the benefits of cloud computing. A couple years back, NetSuite released a third-party study concluding that "the aggregate reduction in electricity used by NetSuite and its customers is approximately 595 million kWh per year." The study was fuzzy on details, such as direct comparisons between organizations hosting their ERP or CRM in house versus going with NetSuite.

Microsoft, meanwhile, released a third-party study last November that supported Google's findings, though the report measured CO2-equivalent emissions, not kWh. The report said that small organizations (100 users) that move from on-premise software to cloud-based alternatives can cut their CO2 emissions by more than 90 percent. Midsize companies (around 1,000 users) can slash emissions by 60 to 90 percent. Finally, large companies with around 10,000 users can reduce emissions by 30 to 60 percent.

There are certainly caveats to the assessment that "cloud computing is green," as there are plenty of factors to consider. For example, two data centers with the same PUE might have different-sized carbon footprints because one uses dirty energy (such as coal), whereas the other uses clean sources. Also, a large enterprise may well manage its data centers as efficiently as the Googles, Facebooks, and Microsofts of the world.

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Copyright © 2011 IDG Communications, Inc.