Data Centres in Illinois Respond Positively to Rebates But How Sustainable is This?

ComEd rebates make the economics of energy efficiency for data centers more compelling.
Published: Tue 09 Sep 2014

While utilities make more money as power consumption grows, too much demand calls for costly construction of generating or transmission capacity. In response, power supplier, ComEd launched a programme in 2008 which was aimed at cutting demand by industrial users. But now, focus has been shifted to data centers which are even bigger power consumers.

Curbing energy consumption

Northern Illinois is host to the nation's largest data hubs, and in the past five years, the amount of power consumed by local data centres has almost doubled.

The number of data centres in the area have grown considerably since the dot-com boom in the late 1990s and early 2000s. In response, electricity consumption by data centres has been escalating about 10% percent a year.

Recognising the need to reduce data centres’ consumption, ComEd is working with data centre operators to curb their appetite for power by paying them for reducing their demand. Nearly one-third of the data centres in northern Illinois—which are used for everything from high-frequency trading to handling big chunks of Internet traffic—have projects underway.

CenturyLink has recently spent over US$2 million to retrofit its data centre in Chicago, reducing its electricity demand by 23%. ComEd gave the company a US$500,000 rebate. CenturyLink got US$248,000 for improvements at its Elk Grove facility. This does not take into account the reductions in annual spending on electricity.

The amount of data-centre space in Chicago is expected to grow 8% this year and 2015.

“Power is the single largest operating expense,” explains Joel Stone, vice president of data centre operations at CenturyLink Inc., a company based in Monroe, Louisiana, “If I improve cost of operations 1 or 2 percentage points, that's millions of dollars a year. If we get more efficient, we can do more with less, power more servers and not have to build another data centre.”

Rebates improve energy efficiency

ComEd rebates make the economics of efficiency more compelling, says Mr Stone, who estimates that they shortened the time it takes for CenturyLink to recoup its investment to just 16 months.

Data centres are upgrading their electrical gear, but one of the biggest expenses comes from cooling equipment. Servers, just like desktop computers or smartphones, are packing more computing power into the same device. But more of the equipment is in constant use, meaning it consumes more power and produces more heat.

Mr Stone's team replaced fan motors on chillers so they run continuously but at varying speeds, rather than cycling on and off. It even replaced fan blades on cooling towers with new ones that move more air even though they turn more slowly.

“The headache for a utility company is, a data centre is a 24-hour load—it's like a refrigerator,” says Mohammad Shahidehpour, director of the Galvin Centre for Electricity Innovation at the Illinois Institute of Technology.

ComEd is also offering incentives to small data centres to move into larger ones.


How sustainable is the rebate programme? Data centers worldwide use about 30GW of electricity. This figure is bound to escalate as data levels increase. Perhaps the way forward is for these data centers to draw on locally generated renewable power. This will reduce strain on the grid and utilities can even buy power from the excess generated. In Helsinki, the heat produced by data centres is used for district heating so the opportunities are endless.

Google, Apple and Microsoft (which recently signed its biggest renewable energy agreement, committing to buy the output of a 175MW wind farm in Illinois) are already seeing the benefit in powering their data centres with renewable energy. [Engerati-Big Name Data Centres and Project Could Instigate Change in the EU.]