With California thought to have only one year of water left, Silicon Valley data centres are trying to reduce their needs for cooling
We hear a lot about what the tech giants are doing with our data, but what are they doing with our water?
Water keeps our internet-based economy afloat by ensuring equipment in data centres stays cool enough to funtion. Yet in California, the drought-ravaged epicenter of the technology industry, water is in ever-shorter supply. Nasa scientist Jay Famiglietti predicts the state has only one year of water left. This raises serious questions about the environmental impact of our burgeoning data demands.
The source of the problem
Water use in data centres has “flown under the radar for the longest time” but it’s something companies are starting to get to grips with, says Jack Pouchet, a board member with The Green Grid, a non-profit that promotes resource efficiency in information technology.
Water-cooled data centres use an estimated 13.25m litres (3.5m gallons) per MW each year, according to Pouchet. The data centres used by major players can range in scale from 5MW to 30MW. And with an estimated 800 data centres in California, those numbers add up.
These consumption levels can be traced to the industry’s historical concern with its power use. Data centres tend to use the power usage effectiveness standard (PUE), a metric developed by The Green Grid to gauge the efficiency of computer facilities. PUE, however, does not take water consumption into account. The result has been a shift to energy-efficient but water-intensive cooling methods.
“People have driven the efficiency up and the power consumption down,” says Peter Hopton, founder of Iceotope, a data centre cooling start-up based in the UK. “But one of the things that has been introduced to drive that has been evaporating water.”
Turning the tide
Now that California has imposed mandatory water restrictions to cut the state’s water use by 25%, general awareness of water scarcity is growing, and the possibility of higher water prices looms. Data centre owners and managers have taken notice and started looking for ways to cut water use.
For Vantage Data Centers, which runs three facilities on its campus in Santa Clara, the solution has been smarter buildings. Two of the company’s centres are cooled by a conventional system that channels cold water through the room. The used water is pumped through a cooling tower, over the outside of which more water is run, which then evaporates, drawing heat from the piped-in water.
Vantage, however, has minimised the amount of water-cooling required by installing air handling units that can, when conditions are appropriate, pull air in from outside to cool the room. Weather stations that measure temperature, humidity and dewpoint are deployed around the campus; when they agree conditions are right, the system automatically switches to air-cooling mode.
“The building opens up to outside air and sucks it straight into the air handlers,” says Vantage’s chief operating officer Chris Yetman. “That central chilling plant slows way down or even shuts off.”
Key to the strategy is convincing customers to let go of preconceived notions about how cool is cool enough for data centres. Traditional standards set the acceptable temperature range at about 18C to 27C. Today, however, technological advances mean wider ranges of both temperature and humidity are safe for most equipment, says Yetman. When tenants agree to work within these broader ranges, less water – and less money – is needed to achieve the perfect climate.
“We work with customers to explain to them: ‘look, you’re missing out on savings here’,” says Yetman.
The water challenge
Digital Realty, which operates 3.5m square feet of data centres throughout California, has responded to the governor’s call for reduced water usage by launching an internal water conservation challenge, says sustainability director Aaron Binkley. As part of this, the company is working with local water utilities to determine where and how it can use recycled rather than potable water in its cooling systems.
“We’re asking, ‘is that quality good enough for us to use, is the supply sufficient for our needs, is it reliable, is it cost effective’,” says Binkley.
Digital Realty’s efforts also include less dramatic yet still essential elements, such as reviews of internal processes to ensure equipment is precisely calibrated, optimally cleaned and serviced in the most efficient fashion.
Energy efficiency and sourcing are also important considerations. In California, power production is second only to agriculture in the amount of water it consumes, so cutting electricity use or buying energy from less water-intensive sources can shrink a data centre’s overall water footprint.
Equinix, one of the largest data centre companies in the US, recently announced plans to install a 1MW biogas-powered fuel cell at one of its Silicon Valley centres, reducing the amount of energy it needs to buy from fossil-fuel burning plants. The purchase is part of Equinix’s long-term plan to use 100% renewable energy.
The greatest hurdles
But obstacles remain to data centres tackling water scarcity. Largest among these: money. Water-efficient systems are often more costly than the alternatives, and water prices have not yet risen to such a degree that limiting water use would pay for itself, says Todd Boucher, founder of New Hampshire data centre design company Leading Edge Design Group.
“People are still choosing to go with designs that are more water-intensive because of the cost of construction,” he says.
The need for proximity is another challenge. Many companies have opted to locate some of their data centres in climates where facilities can be cooled by the outside air year-round, such as Facebook’s data centre in Luleå, Sweden. But for applications such as high-speed processing, data centres simply need to be close to end-users, wherever they live.
Despite these barriers, businesses are finding viable water-saving options, says Will Sarni , practice leader for water strategy at Deloitte Consulting.
“We live in a world where data goes into this mysterious cloud but it actually does have a physical presence,” he says. “And the physical presence absolutely can be part of the solution.”