Using smart grids to unleash the true power of uninterruptible power supplies
Fri 6 Sep 2019 | Leo Craig
Riello UPS’s Leo Craig on why data centre operators should use the increasing popularity of smart grids to rethink the role of their uninterruptible power supplies, transforming an underutilised asset into a valuable money-maker
In the next five years, the number of connected devices in the UK will more than double from 270 million at present to 625 million. Whether it’s the smartphones that dominate our personal lives, or the automation and machine learning that’s revolutionising industry, all the evidence points to the fact we’re in the era of data.
Of course, this is music to the ears of the data centre sector. It’s why storage and processing capacity here will soon total more than 900,000m2 — that’s 140 full-size football pitches.
But there’s a price to pay for all that processing – power. Even though server room efficiency has come on in leaps and bounds, a data centre is still an energy intensive entity. Larger facilities can easily use 30 GWh of electricity a year. That’s a £3 million annual bill. Globally, trends suggest data centres will use a fifth of all energy by 2025 as demand grows.
In the UK, our energy network faces heightened pressures. Last year saw the amount of electricity produced in Britain drop to the lowest level since 1994. Renewables like solar, wind and tidal now provide a third of the country’s total energy supply. Despite the environmental advantages, shifting to low-carbon makes it harder for the National Grid to balance supply and demand. The obvious solution is a decentralised network of smart grids connecting together a variety of sources in real-time to provide a secure supply 365 days a year.
As the landscape changes, our industry can’t afford to be left behind. Luckily for data centre operators, the answer lies close to home in the form of their UPS systems.
Rethinking the role of the UPS
Despite its undoubted potential, data centre operators tend to view battery storage with a great deal of scepticism. To some extent that’s understandable. When downtime costs thousands of pounds a minute, using a UPS for anything other than its primary role as a back-up supply can be seen as adding an unnecessary layer of risk.
But what if resilience isn’t compromised? What if it’s actually enhanced? Recent research found that 83 percent of data centre managers would participate in demand side response (DSR) if it didn’t negatively impact on core activities. This means in principle they could be open to the idea of re-evaluating the role of their UPS.
While it’s a must-have back-up to keep server rooms running when the worst happens, a UPS often sits quietly in the background. Participating in battery storage transforms this essential, yet underutilised, asset into something that’s always working 24/7 for your data centre. It saves you money with lower energy bills and even offers additional revenue streams through several National Grid DSR incentives.
Everyone knows how competitive the data centre industry is, so why would operators look such a potential gift-horse in the mouth?
What batteries work best for UPS energy storage?
While sealed lead-acid (SLA) batteries can be used for UPS energy storage, lithium-ion (Li-ion) cells tend to be amore effective option. Li-ion does require a greater upfront investment, but its cost has dropped significantly in recent years, a trend that is likely to see its price fall to £50 kWh by 2030.
Li-ion batteries have a 10-15 year lifespan, over which time SLA packs would, in all probability, need replacing two or even three times. Then there are other advantages, such as delivering the same power in less than half the space and weight, faster recharging times, and up to 50 times the cycle life.
Overall, the total cost of ownership for Liion could be anywhere from 10-40 percent less, so any greater initial investment should be balanced out over time.
What’s on offer?
As briefly touched on, there are various incentives on offer for data centres taking part in DSR. There’s what’s known as Reserve Services, which help overcome a temporary lack of power generation or any unexpected spikes in demand. But probably the most practical route for operators is Frequency Response. This aims to ensure a consistent network frequency of 50 Hz, with 1 percent latitude above or below.
Dynamic Firm Frequency Response (FFR) offers guaranteed payment to organisations that can either reduce their demand or supply the grid inside 30 seconds of an incident like a power station tripping out. Make no mistake, that’s not easy. But lithium-ion cells in a UPS system are up to the task because of their fast ramp times and ability to continually generate and absorb power.
According to National Grid’s latest ‘Power Responsive’ annual report, FFR provision from DSR providers rocketed from 392 MW in 2017 to 2,720 MW in 2018. That’s an increase of 594 percent and a clear demonstration of a fast-growing market data centre operators could tap into.
Powering the future
Turning your data centre into a ‘virtual power plant’ offers obvious advantages. Lower energy bills because mains supply isn’t needed during expensive peak times. Potentially reduced grid tariff charges worth thousands of pounds per megawatt per year. And additional revenues from schemes like FFR.
But think back to that one underlying stumbling block – the perception that using a UPS and batteries for DSR will reduce reliability.
Battery failure is a major reason why a UPS doesn’t kick in when it’s truly needed. Because of the significant cost of a comprehensive monitoring system for SLA batteries, many operators don’t take up the option. But if the batteries haven’t been used for a while, can you be 100 percent certain they’ll work when you really need them?
Battery monitoring is mandatory for Li-ion though, with each cell individually analysed to help ensure balanced states of charge. Consequently, this ongoing monitoring means system resilience is actually enhanced, even when the batteries take on the additional task of storing electricity from the mains.
So that’s a financial boost without undermining performance. A win-win no data centre operator can afford to ignore, especially in such a competitive and uncertain environment. The Government’s own National Infrastructure Commission predicts UK battery storage capacity will top 15 GWh by 2030. The tide is clearly turning. Rather than sitting on the sidelines, data centres can be out in front leading this ongoing energy revolution by unlocking the true power of their UPS systems.
This article appeared in the Summer 2019 edition of DCM Magazine. Click here to see if you qualify for a free DCM subscription.
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