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How data centres can help secure energy supplies

Image: Adobe Stock / Connect world

As the clocks go back and winter approaches, there are concerns that Britain is about to be hit by an upcoming energy crisis that could even lead to rolling blackouts. 

While National Grid ESO’s latest Winter Outlook forecast suggests there’ll be enough power to meet demand over the coming months, the margins will be tight. 

And if the Europe-wide shortage of gas intensifies, the electricity system operator’s worst-case scenario would see households and other energy consumers facing three-hour blackouts similar to those last seen during the notorious Three Day Week of 1974.    

To mitigate against such scenes, National Grid is deploying mitigation measures such as securing 2 GW of additional power from coal-fired plants, enough energy to supply 600,000 homes. 

From 1 November, it also introduced a Demand Flexibility Service which will incentivise both domestic and commercial energy users to reduce-peak time consumption, a scheme it believes will reduce demand by up to another 2 GW of electricity. 

Households will receive around £10 a day to use power-hungry appliances such as dishwashers or tumble dryers overnight, while companies will also be paid to either reduce demand or switch to battery power during peak times.

By their very nature, data centres are energy-intensive operations. And the industry is only too aware of the need for sustainability. So is there anything operators can do to help the grid cope with these upcoming demand and supply pressures?

One possibility lies in the uninterruptible power supplies (UPS) and batteries data centres use as their ultimate insurance against damaging downtime. 

Thanks to rapid advances in communications software and protocols, as well as improved battery technologies such as cycle-proof or Lithium-ion cells, many modern data centre UPSs are compatible with today’s smart energy grids. This offers the opportunity to transform the UPS from a reactive piece of equipment into a dynamic ‘virtual power plant’. 

Smart grid-ready UPS communicate with local power networks. Depending on the real-time conditions, they either push stored battery power back into the grid or draw electricity from it as and when required to help balance supply with demand and maintain a stable frequency. 

Peak shaving potential

The first area where a data centre’s UPS can potentially help the electricity network is peak shaving. This concept basically uses the UPS batteries to effectively limit how much power a site draws from the mains supply.

So in practice, if the load on the UPS output goes above a set level, the UPS takes a proportion of the load from the mains and the rest comes from the battery set.

Peak shaving comes in various formats. The first option – static – is straightforward in that the UPS has a fixed setting and simply peak shaves to that limit.

Type two is user-controlled peak shaving, where the data centre operator can reduce the input mains power as and when required by sending commands to the UPS. You can do this either with volt-free contacts or communications protocols such as Modbus.

If your site has a weak power source or a reliance on generator sets, the third option is called impact load buffering, which in effect sees the energy stored in the batteries slow down the incoming mains supply.

Finally, we have dynamic peak shaving, the most common application. As the name suggests, it works hand-in-hand with the real-time conditions on-site.

Take a data centre with a contractual limit of 1 MW mains electricity supply. Your typical load ranges between 500-900 kW, while your critical load is another 300 kW. 

At peak time, you might have a maximum load of 1.2 MW, which is obviously in breach of your contractual obligations.

So when this happens, the UPS automatically pushes the energy stored in its batteries to reduce the power required from the mains. During periods when loads are lower, the UPS recharges the batteries for future use. 

Stabilising grid frequency

Another area where a smart grid-ready UPS can play a demand side response role is helping to maintain a stable grid frequency.

This is something Riello UPS has experience with thanks to our Master+ solution, which we developed in partnership with RWE Supply & Trading specifically for data centres and other large-scale energy users.

It brings together a high-efficiency, smart grid UPS using cycle-proof lead-acid batteries, although it can also work with Lithium-ion batteries too. Because of a very compact battery arrangement, the solution provides up to four times the usable capacity whilst requiring just a 20% increase in footprint.

Crucially, this offers ample battery capacity for both emergency backup and for commercialisation.

The solution also incorporates a highly secure, integrated monitoring and control system that allows for two-way communication with the grid. Such monitoring also aids with predictive maintenance.

The final element is a route-to-market contract so that the data centre can participate in the energy market without taking on any of the risks.

In practice, the battery is split into two distinct parts. The first is a backup segment comprising roughly 30% of the total capacity. This is controlled by the UPS and can only be used to support the critical load if there’s a mains failure, so you’re not compromising on availability.

The other 70% makes up the ‘commercial’ segment, which RWE can deploy to grid balancing schemes such as Firm Frequency Response, which helps National Grid maintain a safe grid frequency within one hertz of 50 Hz.

If the frequency goes above 50 Hz, the UPS takes power from the grid into its batteries to pull the frequency down. And vice versa, when the frequency drops, the UPS pushes stored power from the batteries back into the grid.

During system operation, the typical state of charge ranges between 60-70%. So in the event of a mains failure, not only do you have the power in the backup segment, but there’s also whatever’s left in the commercial part to top up your autonomy.

In return for RWE gaining the usage rights for the commercial element of the batteries, data centre operators reap the rewards in terms of a significantly discounted premium battery system, extended backup time, 24/7 monitoring, lower maintenance costs, reduced grid tariffs (potentially worth up to £6,000 per MW per year), and additional revenue-generating opportunities. 

Securing supplies for the greater good

Just a couple of months ago, Microsoft revealed that its entire data centre portfolio across Ireland would use Lithium-ion batteries to push stored power back into the grid by the end of 2022.

This will reduce the reliance on gas and coal-fired plants to maintain vital spinning reserves and help to significantly cut the Irish energy sector’s carbon emissions.

With the ongoing advances in UPS, battery, and smart grid technologies, other data centre operators can follow in Microsoft’s footsteps and harness their standby power systems for the greater good. 

Not only are there hard-headed financial reasons to do so (i.e. lower energy costs and reduced tariffs), but in such

Jason Yates
Jason Yates
Technical Services Manager at Riello UPS

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