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The smart way to unlock data centre power

Data centre operators will cut costs and enhance system resilience if they ditch their doubts about demand side response, says Riello UPS managing director Leo Craig.

Much of the recent focus on 5G has fallen on the fierce debate about the involvement (or not) of Huawei in upgrading the UK’s wireless telecoms network.

But there are real questions for us in the data centre sector to consider too. The rollout of 5G places huge pressure to provide the promised low latency processing. And all that processing comes at a great cost – power.

Reading a recent report from the Uptime Institute, it staggered me to learn that every time footballer Cristiano Ronaldo (or more likely his PR reps) post on Instagram, his 200 million-plus followers consume 30 megawatt hours of energy just to view it.

Data centres are already some of the world’s biggest energy users. Industry body TechUK claims if you combine commercial and in-house data centres, they account for 2% of all UK electricity use.

The biggest facilities have annual energy bills of £3 million a year and consume the equivalent power of 300,000 homes, roughly the populations of Leicester, Sunderland or Belfast.

Winds of change

This all comes at a time where our electricity network is going through huge changes. Last year saw more UK electricity generated from zero-carbon sources (48.5%) than fossil fuels (43%) for the first time.

Our growing reliance on renewables such as wind and solar, which by nature are more unpredictable than coal or gas, poses major challenges for National Grid. Namely balancing supply with demand and ensuring a stable grid frequency.

It is turning to smart grids, energy storage and mechanisms such as demand side response (DSR) as the answer. The latter incentivises customers to store power and shift their energy use from busy to off-peak periods.

It rewards participants with reduced grid tariffs and energy bills, as well as offering opportunities to sell surplus electricity back into the grid.

Data centres appear an ideal candidate for DSR. They have sizeable battery-based uninterruptible power supplies providing the perfect tool – on paper – to store energy and feed it back into the grid.

But so far operators have been somewhat reluctant to take the plunge. In an industry where downtime and even the slightest service interruption can cost thousands or even millions of pounds, it’s understandable that they’re unwilling to use their expensive UPS and batteries – their de facto last line of defence – for anything else.

Operators see it as a big risk that isn’t worth the reward. But is that argument true anymore?

The Master+ model

We’re working alongside RWE Supply & Trading, the energy trading arm of Germany’s largest electricity supplier RWE, on a pilot project that transforms a reactive data centre UPS into a proactive ‘virtual power plant’ that can participate in DSR whilst at the same time enhancing, rather than undermining, system resilience.

It involves one of our Master+ units fitted with a special rectifier that enables power to flow both from and to the grid.

The smart grid-ready UPS is backed with premium lead-acid or lithium-ion batteries. It’s also equipped with RWE’s dedicated monitoring and communications software, which allow for real-time condition analysis and two-way interaction with the grid.

Battery capacity is split into two distinct roles. To start, there’s a section purely providing the standard UPS safety net of emergency backup power in the event of a mains failure. The remaining ‘commercial’ batteries feed stored electricity into the Firm Frequency Response DSR scheme, which helps maintain grid frequency within the safe range of 49.5-50.5 Hz.

If there’s a power cut, any remaining energy in the ‘commercial’ batteries tops up the primary backup, offering users longer autonomy.

Rethinking the role of a UPS

Think back to the main stumbling block data centre operators have about DSR. Using a UPSs batteries adds an unacceptable layer of risk.

But it’s difficult to monitor traditional sealed lead-acid batteries effectively unless you install hugely-expensive battery monitoring and management systems. Hand on heart, can you be 100% sure they’ll work when you really need them?

With the Master+ model, the mandatory battery monitoring system alerts you when there’s any deterioration. It identifies blocks that need replacing. So rather than undermining your resilience, it actually improves it.

There are other benefits for operators too. RWE Supply & Trading significantly subsidises the cost of the more expensive premium batteries, reducing the upfront investment. It also takes on the risk of trading on the energy market.

So far, tests at our two pilot sites – one at RWE’s HQ in Essen, Germany, the other here in the UK – have proved positive. Based on a data centre with a 1 MW load and batteries providing 10 minutes autonomy plus a 1 MWh ‘commercial’ segment, installation costs are roughly a fifth lower than a standard UPS, thanks to the subsidised batteries.

While the monitoring software reduces ongoing maintenance costs compared against time-consuming manual servicing. These ongoing savings would add up to tens of thousands of pounds over the typical 10-15 year lifespan of a UPS.

Then depending on the data centre’s location, operators could also save up to £6,000 per MW every year through reduced grid tariffs.

The August blackout – sign of things to come?

Think back to the events of 9 August last year when lightning strikes saw two power stations go offline. The resulting loss of generation sent grid frequency tumbling, triggering load shedding that saw 1.1 million people cut off to save the rest of the electricity network.

Thankfully, the blackout was short-lived. Frequency returned to safe operating limits inside four minutes, with power fully-restored inside an hour.

One of the reasons for this was that National Grid deployed 1 GW of backup power to plug the shortfall in generation. Nearly half of this reserve capacity (472 MW) came from battery storage – around 200 MW from National Grid’s own portfolio, with the remainder from various DSR contributors and aggregators.

National Grid already spends around £170 million a year on frequency response contracts. One likely fallout from 9 August is that the system operator will significantly increase its reserve capacity to deal with similar incidents in the future.

As we transition towards a more distributed, renewables-led electricity system, battery storage and demand side response will play an increasingly important role in keeping the lights on. And with solutions such as the Master+ model now making energy storage not just feasible but advantageous for data centres, there’s no excuse for operators to carry on sitting on the sidelines.

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