Chris Cutler, Riello UPS business development manager, explains how improvements in UPS technology enable data centres and other critical sites to keep their energy use in check as they adjust to the ‘new normal’ of shifting demand.
Climate change has understandably taken something of a back seat in recent months as the world grapples with the coronavirus pandemic. But it remains the biggest challenge facing both the data centre industry and society as a whole.
The Covid-19 crisis thrust data centres into the public consciousness more than ever. Organisations across the country relied on the cloud to facilitate remote working in unparalleled numbers.
Total worldwide Microsoft Teams users shot up from 20 million to more than 75 million. While a staggering 4.1 billion minutes of virtual meetings occurred on the platform on a single day in April.
And where would we have been without the streaming services,the online gaming and shopping that lightened the lockdown boredom? Many broadband providers reported a 60% surge in weekday web usage. Netflix obtained an extra 16 million subscribers.
It’s forecast that many organisations will embrace the move to permanent remote-working. Indeed, a Gartner survey revealed that almost 74% of businesses will encourage more home working.
The likely consequences of such a fundamental change in our day-to-day way of life include a quicker migration to the cloud and a greater reliance on edge processing. Combine this with the continued rollout of superfast 5G, and data centres will face huge pressure to keep up with this increased demand.
All this comes at a time where the Uptime Institute’s latest survey of global data centre trends finds that energy efficiency across the industry is flatlining – this places operators in a precarious position.
How can they make sure that meeting demand doesn’t come at too much of an environmental cost?
Several solutions are at hand, such as exploiting liquid cooling and increasing rack density. While they can find further energy savings in another key piece of critical infrastructure – the uninterruptible power supplies that ensure a site’s clean and continuous electricity.
Here are three ways in which recent improvements to UPS technology can help sites keep their power consumption in check.
Upgrading a legacy UPS
Industry best-practice recommends replacing a UPS system around year 10-12 of its service life. But in certain circumstances, it may make sense to refresh the unit earlier in the life cycle.
This appears at odds with the recent trend for organisations to leave a longer gap between hardware refreshes as the gains of Moore’s Law begin to level off. Looking again at the Uptime Institute’s latest report, for instance, and it shows the most common timescale for replacing servers has lengthened from three years in 2015 to five years.
But when you’re talking about a legacy UPS, there’s every chance you can recoup the upfront infrastructure cost of upgrading through improved performance and higher efficiency.
For example, if you’re currently running an old, transformer-based UPS system, replacing it with a modern transformerless unit could produce anything up to a 5-6% efficiency boost.
Transformerless UPS’ have a flatter efficiency curve too, which means many models can reach high efficiency (above 95%) even at loads as low as 25%. Compared to a new unit, an old 400 kVA UPS could have a 3.5% difference in efficiency, depending on the applied load.
Then there are the other benefits of replacing old with new to consider. Transformerless UPS’ are smaller, lighter, and generate less heat, thus taking up less floor space and reducing your air conditioning requirements.
Moving to modular UPS
If you do opt for a hardware refresh, choosing a modular UPS offers significant scope for efficiency gains.
Many legacy UPS installs are designed to carry a much bigger load than they’ll ever need. Oversized systems are inefficient, waste energy, and cost more money to run and maintain.
The main advantage of a modular solution is that you only install the power you actually need. Modular UPS’ comprise a frame that you populate with individual power modules – almost like building blocks – to match your load and redundancy requirements. This eliminates any possibility of wasteful oversizing.
While the principle of modularity means that if your circumstances change, for example, a sudden surge in customers buying more rack space, you can quickly scale up by adding extra modules and cabinets.
Modular UPS’ offer the vertical and horizontal scalability to deliver capacity ranging from as little as 25 kW to more than 1 MW plus redundancy in a single UPS. This enables any site manager to future-proof their power needs without wasting unnecessary energy, air conditioning, or floor space.
Modular solutions offer the added benefit that the modules – which are individual UPS’ in their own right with a rectifier, inverter, and static switch – are all hot-swappable, which ensures downtime-free maintenance.
Exploring ECO mode
Practically every modern UPS manufacturer now offers some sort of economy or energy-saving operating mode.
In practice, these ECO modes see the unit run like a standby UPS. The bypass line (i.e. the mains supply) powers the load, while the inverter remains switched off. If there’s an interruption to the mains electricity, there’s a temporary break in continuous power of a few milliseconds while the inverter switches on and takes the load.
Running in ECO mode delivers operating efficiency of up to 99%. This is a considerable improvement on the typical 93-97% rating of most UPS’ in online mode. When even a 1% improvement in efficiency could equate to thousands – or even tens of thousands – of pounds worth of savings a year, the potential benefits are undeniable.
However, using ECO mode exposes your critical load to raw utility power without any of the power conditioning provided by double-conversion online UPS’.
That might not be too much of a problem if you have a stable mains supply and loads that tend to generate low harmonics. But if your site is prone to power quality issues, then you could be compromising your reliability.
And if there’s an interruption to the mains supply, your equipment is also susceptible to the damage a short break in power can cause.
To try and overcome these drawbacks, suppliers have used improvements in firmware controls and electrical design to develop what’s known as Advanced ECO mode.
Often referred to as Active ECO, it is similar to standard ECO mode with the bypass line still powering the load. The crucial difference, however, is that the UPS’ inverter remains powered at all times. Even though it doesn’t carry the load current, it runs in parallel with the input.
This means that in the event of a mains failure, power transfer is far quicker – almost instantaneous – than standard ECO. Another advantage is that the inverter also absorbs harmonic currents and provides power filtering in the same way online operating mode does.
The extra energy required to keep the inverter powered at all times means that Active ECO is roughly 0.5-1% less efficient than ‘pure’ ECO mode. But it still offers higher efficiency than online mode.
Many mission-critical sites such as data centres are justifiably cautious about running in ECO or Active ECO mode. The balance of risk and reward between the energy savings on offer and potentially undermining resilience is too big an ask.
But while it might not be practical to run your UPS in one of these energy-saving modes all of the time, it could be an option when a site’s most critical loads are inactive, for instance overnight or out of hours.
There’s another possibility for larger parallel redundant (N+X) UPS systems too. This would see one of the units running in online mode as the ‘master’, with the other UPS’ supporting in ECO or Active ECO mode until the condition of the mains supply changes and they’re called upon to support the load too.
As demands on data centres grow in the months and years to come, effective use of modern UPS technology will prove pivotal in ensuring operators can keep offering a seamless service whilst stopping their energy use from spiralling out of control.
