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Your data centre UPS could feed power to the smart grid, suggests research

Don't all rush to sign up, DC operators

Data centre operators could deploy uninterruptible power supply (UPS) systems which 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 centre's own energy demands.

Data centres are traditionally viewed as cost centres and an operator's primary job is to maintain the availability and performance of the facility

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

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

"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 centre power, cooling and sustainability research practice.

Such "smart grid ready" UPS systems could be deployed by data centre 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 centre operators, as well as engineering, architecture and consulting firms and utility companies, across North America, the Nordic countries, UK, Ireland, France, Germany, and Australia. However, the sample size included no more than 380 respondents.

Of those, 77 per cent 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 per cent of respondents estimated that between 10 and 50 per cent of the capacity of the battery systems deployed in their data centre today is excess and can be potentially used to support the electricity grid.

This could be a key capability to help integration of variable renewable energy sources into the electric grid, Omdia said. Solar and wind are the two micro-grid applications which 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 have the drawback of a limited number of deep discharge cycles, meaning that 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 centre 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 centre 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 centres 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 at the data centre operators. As Carlini points out, data centres are traditionally viewed as cost centres and an operator's primary job is to maintain the availability and performance of the facility.

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