This overlooked piece of data center tech could be the key to protecting energy grids from disruption

Researchers have found that data centers' unused batteries could be re-purposed to support the grid and assist the switch to renewable energy.
Written by Daphne Leprince-Ringuet, Contributor

Uninterruptible power supply (UPS) systems are found in all data centers, typically in the form of battery backups, to provide emergency power for workloads to keep running even in the event of an unexpected outage.  

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Generators in data centers could play a key role in helping the local grid manage some of the challenges tied to the transition to renewable energy, according to new research published by Microsoft and power management company Eaton. 

Uninterruptible power supply (UPS) systems are found in all data centers, typically in the form of battery backups, to provide emergency power for workloads to keep running even in the event of an unexpected outage.  

Because such events are rare, however, UPSs spend most of their lifetime untouched. Data centers, therefore, currently sit on banks of underutilized battery banks – which is why Microsoft and Eaton are now investigating whether the buildings' UPSs could also support the local grid against anomalies and failures. 

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Pumping more renewable energy into the grid comes with additional complexity, and a particular area of concern is the instability that solar and wind power generate.  

Conventional sources of power such as coal and gas offer what is known as inertia to the grid: when there is a shock to the system, their turbines are able to keep spinning temporarily due to the kinetic energy of the turbine's spin, so that there is still some power generated for a time period even in the event of an issue. In other words, the spinning generators have a stabilizing effect on the grid.

Wind turbines and solar panels work differently, and can't provide inertia. Transitioning to renewable energy, therefore, also means losing the shock-absorbing benefit of traditional sources of power, which makes the electricity grid a lot more vulnerable to unexpected disturbances.  

In practice, low inertia can trigger hugely disruptive blackouts. In 2019, for example, a lightning strike in the UK that brought a wind farm and a gas power station to a halt eventually led to loss of power and disruption to more than one million consumers, with major system failures on the rail transport network affecting commuters in London. 

"If we have assets that secure the reliability of the grid even with low inertia, it means that the grid operators can allow higher penetration of renewable energy," Janne Paananen, technology manager at Eaton, who co-wrote the whitepaper, told ZDNet.  

One solution consists of providing what is known as a Fast Frequency Response (FFR), for example by immediately feeding power to the grid while slower reserves react to a disruption. In other words, a short-term fix that is essentially the same thing as what UPSs are designed for. 

"UPSs are tailor-made for that need," says Paananen. "They can tackle short-term moments of imbalances in the system, and because those last for a short time, then UPSs with smaller batteries are excellent for that purpose." 

UPSs are already connected to the local grid, but only to draw power from it. Eaton has developed a software-based technology which the company describes as a "grid-interactive UPS" called EnergyAware, which enables UPSs in the data center to take on a double role: protect IT equipment, but also serve as a source of energy for grid operators. 

The technology has already been tested and proven in several pilot projects, including at the Microsoft Innovation Center in Boydton, Virginia, where a lithium-ion battery-powered UPS was fitted with Eaton's software algorithms and controls to interact with the power grid.  

The UPS successfully tracked grid signals and quickly responded by charging or discharging the battery to balance the grid, meeting the operator's requirements for accuracy, response time and precision.  

Eaton also carried out pilots with the new UPS technology in Ireland, where the company is based, and in Finland and Norway. "But Microsoft is the first really large player showing interest," says Paananen. "When the big bosses are doing it first, others will follow. It will show an example for the rest of the industry." 

With the whitepaper, Eaton and Microsoft are hoping to bring a better informed view of the technology to data center operators who may be interested – for example by answering questions around the economics of the concept. 

Paananen argues that there are no drawbacks to opening up data center UPSs to the grid. In Nordic countries, for example, the grid only needs to be supported for up to 30 seconds in the event of a disruption – an amount of energy that most data centers already have in their batteries on top of what they need for their critical loads, meaning that they wouldn't even need to invest in more capability. 

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Of course, different grids come with different requirements, but contributing to grid stability is also an additional revenue stream for operators. Paananen estimates that the typical payback time will range from one to three years. In the UK, for example, Eaton's estimates show returns as high as almost £130,000 ($178,000) per megawatt allocated to grid support. 

"The nice thing is if you get some compensation, it means it doesn't cost you anything to be green," says Paananen. 

That is not to say that data center UPSs alone will solve the renewable power inertia equation. Paananen, rather, believes that the switch to wind and solar energy will require adopting an "everything-as-a-grid" perspective in which any asset that could contribute to maintaining the grid's balance should be connected to the system.  

This makes more sense than building new systems for the same purpose but will require breaking silos in current infrastructure. Data centers, while key to the success of the switch, are therefore only one part of the process. 

Microsoft, for its part, seems keen to develop and implement the idea. "Data centers are at the heart of our digital economy and have the ability to provide a readily available, better means to support the grid. This support helps enable electrical grids to reach higher levels of renewable energy," says Ehsan Nasr, senior engineer of data center advanced development at Microsoft. 

"Once stored energy in data center systems is leveraged to provide flexibility and optimization services, it becomes an asset with an increased value, so it's a triple win, for the grid operator, data center operator and the environment." 

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