Data centers need backup generators for emergencies. Those generators need to be tested on a regular basis.
A Canadian architecture firm has an idea for turning the power generated during those tests into something other than wasted energy: using it for gravity-based energy storage.
Toronto-based WZMH Architects, which designed Toronto’s iconic CN Tower, estimates that a typical data center with eight 3-megawatt diesel generators may waste enough energy each month to power a 125-unit residential building for one day a week.
“One data center will have somewhere in the order of 10 to 20 generators that are in the range of 2.5 to 3 megawatts each,” WZMH principal Zenon Radewych said in an interview. Those emergency backup systems — mostly diesel generators — are tested at least once a month, or sometimes once every 20 days, for up to around 30 minutes a time.
“That’s a lot of power that’s being tested monthly, even at half load,” he said. “That power is not being used for anything, so let’s use it.”
WZMH’s proposal is to feed it into a gravity-based energy storage tower, called a Gen-e-blok, essentially similar to the concept being commercialized by the Swiss-U.S. company Energy Vault. This energy storage system would be connected to a low-voltage, direct-current microgrid serving mixed-use buildings in the vicinity of the data center.
Backup generators don’t have to be the only thing charging it — renewable energy and off-peak electricity supplies could also provide a lift for later use. The direct-current microgrid could also be equipped with batteries or more novel technologies such as capturing energy from thermoelectric generators, elevator-based regenerative drives and even exercise bikes.
This combination of technologies is obviously more complex than just feeding the energy from genset tests into the grid. Data center operators are notoriously hesitant to experiment with the backup power systems that keep their critical equipment running during emergencies. Understandably, this hurdle has limited efforts to tap into data centers' flexibility in the past.
But major data center operators such as Google, Amazon, Facebook and Microsoft are looking for ways to clean up the energy profile of their operations. Some, including Google, are moving beyond commitments to achieve 100 percent clean energy supplies on an annual net basis and toward a goal of obtaining data center power that’s carbon-free on a 24/7/365 basis. This could boost the value of energy storage as a tool to shift loads to match that goal.
According to Radewych, previous attempts by data centers to organize power-sharing arrangements with utilities have often broken down “because the negotiations...become too onerous on both sides.”
That may change as data centers come to represent a larger portion of utility loads, however. Technology developments such as the rollout of fifth-generation mobile networks and the growth in internet-of-things devices are pushing a rapid expansion of data center capacity. Analyst firm Frost & Sullivan expects global investment in data centers to sustain a compound annual growth rate of almost 10 percent through 2025.
Radewych said Gen-e-blok units will be relatively cost-effective to build because the structures don't require cladding, heating or cooling. WZMH estimates construction costs would be on the order of $150 to $200 per square foot per floor, compared to around $600 per square foot for data center space.
That could end up totaling $10 million for a Gen-e-blok with up to 2 megawatts of storage capacity, Radewych said.
Although WZMH has been responsible for a number of data center projects in Canada and China, it remains to be seen whether clients will adopt the studio’s gravity storage and microgrid concept. “There’s been a lot of interest,” commented Radewych.
“We’ve received a lot of phone calls asking about how doable it is. Whenever we do things like this, it’s usually the beginning of a discussion that leads to something else. These ideas [may not be] ready today — but we should be looking at things differently.”
(Article image courtesy of Joshua Sortino)
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