eBay pioneers energy efficient data centers

Data centres represent a significant share of today’s global energy demand. eBay Inc. decided to improve its servers’ efficiency by launching a new system called Digital Service Efficiency (DSE)  as well as a practical initiative known as Project Mercury. Here is how the internet giant is moving towards energy efficiency.

Data centres too energy intensive

Data centres are proliferating all over the world (over 500,000) as a result of the dramatic increase in digital data circulation. Such centres and their servers where digital data is processed and stored turn out to be extremely energy intensive: a single 10,000 m2 centre can use up as much energy as an entire city with 50,000 people.  Every year, the world’s 509,147 data centres use about 30 billion watts, which is equal to the output of 30 nuclear plants. Energy use by data centres represents 1.4% of global power consumption and releases 2% of global CO2 emissions, i.e. as much as global air traffic.

The share of data centres in some countries’ overall power consumption can be even higher. Several US-based Google and Facebook data centres use as much power as a city with over 200,000 people. France provides another telling example, with 9% of overall energy use attributable to data centres.

The reason for this high energy reliance is twofold; first, servers must be working round the clock to ensure that their clients’ data does not get lost. As a result, storage servers are active 24/7, all year round. Second, these electronic devices release a lot of heat and require cooling systems that use nearly half of a centre’s power.

The boom in mobile internet access and increasing storage needs from businesses continue to boost demand. As a result, energy use by data centres worldwide is set to keep growing: in 2012 alone global electricity demand from data centres had increased by 63.3%.

A dashboard to measure data centres’ energy efficiency

eBay positions itself as one of the major players in the green computing sector and ambitions to become a role-model. With its 52 075 servers releasing 740 tons of CO2 per million users in late 2012, eBay understood that energy efficiency was crucial to cutting costs and improving corporate image. That is why at the 2013 Green Grid Forum the company announced it would launch a new system to assess servers’ energy efficiency: Digital Service Efficiency (DSE). It consists of a dashboard using four criteria to assess the company’s entire IT infrastructure: revenue, performance, environment and cost. Fine-tuning the analysis (results for each year quarter, sales and purchases, etc) helps focus on the most energy-intensive elements. For instance, sales use more energy than purchases, as one kilowatt-hour consumed corresponds to 18,000 sales or 28,000 purchases.

DSE is a way for eBay to assess the “mileage per gallon” of its data centres: based on these figures, the company can set itself goals to improve their energy efficiency and gauge progress. eBay wants to cut transaction costs and CO2 emissions per transaction by 10% in 2013 compared with 2012 levels. The company also intends to increase the number of transactions per kilowatt-hour used by 10%.

Project Mercury, a step towards energy efficiency

While cooling down servers is vital to keeping data centres working, eBay performed the feat of building an energy-efficient facility in one of the hottest parts of the United States: in 2011 project Mercury was launched in Phoenix, Arizona, where temperature sometimes exceeds 45°C. It achieved an impressive result: cutting the share of cooling systems in energy consumption. According to eBay, this share is over 43% in average American data centres, whereas project Mercury managed to cut it to 24% and even only 5% in some cases.

To that end, one of the project’s main innovations was to rethink the data centre’s architecture. In the Phoenix-based centre, servers are located in small modular structures rather than in oversized rooms, which has multiple benefits, such as saving significant space and making the IT infrastructure denser and more profitable. These modular structures also bring down cooling needs and help save energy. Besides, they are easy and cheap to install and allow for quick adaptation of IT systems.

The project’s other major innovation is a water-based cooling system which saves energy by using the temperature gap between computers and the outside: free year-round cooling. As soon as the outside air is below a certain temperature, part of the water from the regular cooling unit is diverted into the free cooling system where the outside air naturally cools it down.

Thanks to project Mercury eBay achieved unprecedented levels of energy efficiency. According to the power usage effectiveness (PUE) indicator developed by Green Grid, eBay’s energy efficiency is almost 400 times higher than that of an average data centre. PUE is the ratio of total amount of power used by a data centre facility to the power delivered to computing equipment. A conventional data centre’s PUE is around 2.5, whereas project Mercury facilities and their modular design have a PUE of 1.043, despite Arizona’s hot climate.

For more information :

-          Power, Pollution and the Internet (New York Times)

-          Building a Greener Company (eBay)

-          Inside eBay’s project Mercury

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