Your data center UPS could feed power to the smart grid
Your data center UPS could feed power to the smart grid

Your data center UPS could feed power to the smart grid

Datacenter operators could deploy uninterruptible power supply (UPS) systems that link up with the electricity grid so as to increase its reliability by smoothing out the unpredictability of renewable energy resources, according to research firm Omdia.

The research, which is bound to raise a few eyebrows in the risk-averse DC community, said the UPS feedback could also be used to reduce energy costs by smoothing out the peaks in the data center's own energy demands.

Omdia claims that data centers are in a unique position to increase the reliability of the electricity grid by allowing it to access a portion of its backup power capacity.

By tying their UPS systems into a smart grid, data center operators will be able to support energy management initiatives that contribute to the pursuit of a more sustainable data center.

"The integration of renewable energy into the smart electric grid can benefit from smart grid ready UPS, to smooth out the unpredictability of renewable resources, balancing energy supply and demand, and to reduce or defer electric grid infrastructure investment," said Moises Levy, principal analyst and lead of Omdia's data center power, cooling and sustainability research practice.

Such "smart grid ready" UPS systems could be deployed by data center operators within the next four years, the firm said. UPS suppliers such as Eaton, Schneider Electric, and Vertiv already have systems available with these capabilities.

Omdia's survey covered a number of data center operators, as well as engineering, architecture, and consulting firms and utility companies, across North America, the Nordic countries, the UK, Ireland, France, Germany, and Australia. However, the sample size included no more than 380 respondents.

Of those, 77 percent indicated they do not believe that using a smart grid-ready UPS in this way would put mission-critical workloads at risk.

Instead, about 80 percent of respondents estimated that between 10 and 50 percent of the capacity of the battery systems deployed in their data center today is excess and can be potentially used to support the electricity grid.

This could be a key capability to help integrate of variable renewable energy sources into the electric grid, Omdia said. Solar and wind are the two micro-grid applications that would most benefit from this approach.

According to Schneider Electric, these changes have been made possible by newer UPS systems using lithium-ion battery technology rather than the valve-regulated lead-acid (VRLA) batteries traditionally used.

The latter has the drawback of a limited number of deep discharge cycles, meaning that the lifetime of a VRLA system may be very short, as little as one to two years. Lithium-ion systems, by contrast, have the capability of being tapped thousands of times for energy discharge with little degradation.

"This opens new and exciting application possibilities for data center UPS systems," Schneider Electric's veep for Innovation and Data Centre Steven Carlini told The Register.

"In addition to voltage and frequency regulation plus power back-up, a data center UPS can be used for peak shaving, demand response, and even to send excess power into the utility grid for profit," he said.

Of course, this latter point depends on the energy companies being prepared to support data centers feeding power back to the grid in such a fashion. We asked Omdia if it knew of any that were planning to support this, but had yet to receive an answer at the time of posting.

Even if they are, this will likely require a change in thinking about the data center operators. As Carlini points out, data centers are traditionally viewed as cost centers and an operator's primary job is to maintain the availability and performance of the facility.

"In many cases, the IT manager and data center operator do not even have access to the utility bill and are not responsible for managing this cost. Many data centers are also not designed with excess power reserves, and so the risk/reward equation is non-favorable," he said.

However, those spiffy new UPS systems can be useful in other ways, with Schneider keen to talk up "peak shaving." This refers to using battery backup systems to deliver top-up power during periods of peak demand, to limit the total amount of power the data center is drawing from the grid to below a defined threshold. The motivation for doing this is naturally to save on energy costs.

"There are various ways utilities can assess a data center's demand charge, but it's typically associated with the time when demand for electricity is highest and measured over some defined interval, such as 15 minutes," Carlini explained.

These demand charges can vary widely, with Carlini giving an example of between $4 and $51 per kilowatt in the United States. A data center operator can therefore reduce their demand charges by placing some or all of the IT load on UPS battery power for a limited period, then recharging the UPS batteries once the load falls below the threshold again, possibly at a later point in the day when the electricity rates are lowest.

The profile of a data center's IT load is relatively flat, according to Carlini, and therefore peak shaving might only make sense during hot days when cooling system energy demand peaks. This might otherwise set a higher demand charge for the entire month or even year. 

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