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Uninterruptible power in the datacentre: Choosing between sustainability and uptime

With datacentres under heavier pressure to decarbonise, could even the lowly UPS play a larger role?

New uninterruptible power supplies (UPS) are often based on lithium-ion (Li+) battery technology that is becoming widespread in everything from cars to computers. This often comes with a claim of greater sustainability that could help relieve the pressure on operators for greener datacentres.

Yet the sustainability picture around Li+ batteries is unclear, with global challenges around mining and manufacture still unresolved.

However, Janne Paananen, critical power systems technology manager at Eaton EMEA (Europe, the Middle East and Africa), says operators need to take a holistic view of all issues affecting power management, “thinking smarter” about the role of UPS rather than buying the greenest or most efficient.

Instead, Paananen suggests operators need to start making smarter use of existing assets, reducing overall consumption to save costs and environmental resources at the same time.

“When you are not thinking in silos anymore, that means you don’t need to make separate purpose-built systems for everything,” says Paananen. “Think about the whole electrical equipment system at once – everything that is connected, how it can contribute.”

Ciarán Forde, datacentre and IT segment manager at Eaton EMEA, agrees, noting that suppliers often develop sustainably orientated products with multiple commonplace elements. “Ask what that infrastructure can do to really move the needle on sustainability,” he says.

The core issue is that electricity is still primarily generated via oil and coal-fired plants, adds Forde. A datacentre reliant on fossil fuels for power can be maximally efficient while still not advancing the sustainability agenda of its operator or the users that depend on it.

Of course, the UPS reduces the chance of disruption when problems arise by delivering breathing space to ramp up on-site backup generation, securing resilience of applications and workloads. However, more sustainability can be achieved, Forde suggests, by understanding UPS as a focal point.

Smart ways to use UPS

UPS is part of the nerve centre of the energy network, which means that sustainable UPS, regardless of technology, must incorporate the right smarts.

For instance, intelligent UPS that monitors requirements and predicts demand can help offset datacentre energy consumption by enabling stored energy to be delivered back to the grid for others to use.

The datacentre can become a prosumer, increasing overall sustainability of its systems and operations, especially if it begins delivering power to the grid via renewable sources, perhaps by installing solar panels.

“By enabling the grid operator to adopt more renewable energy, your contribution to sustainability is then an order of magnitude higher than tweaks here and there on efficiency inside the four walls of the datacentre,” says Forde.

Paananen points out that old technologies such as lead-acid batteries are not necessarily less environmentally friendly, with new metallurgical and hydrometallurgical techniques being explored, recycling plants being built and component tracing strategies, such as the Global Battery Alliance Li+ battery passport, in development.

“You can recycle 99% of the lead from the batteries and so on. With lithium batteries so far, they’ll last 10-15 years in operation, so you don’t expect any reasonable amount of recyclable materials from new lithium batteries until 2030,” says Paananen.

Marc Garner, UK and Ireland vice-president of secure power at Schneider Electric, notes that environmental impacts of lithium at certain points in the lifecycle can be higher than some “competitive” alternatives. However, this can often be offset by benefits at other stages of the lifecycle.

“Studies found that, over 10 years, Li+ delivered a total cost of ownership 10-40% lower than equivalent systems using valve-regulated lead-acid [VRLA] technology,” he says.

Schneider sees legacy operators also selecting Li+ battery-powered UPS as “part of modernisation and energy management strategies”, especially since Li+ batteries are now only 1.2 to two times as expensive as VRLAs.

“They also offer two to three times the lifecycle of VRLA batteries, have two to three times faster charging recycles, a smaller footprint and are lighter weight. Some three-phase Li+ models offer intelligent energy storage options,” says Garner.

Schneider Electric has partnered with smart tech supplier Wärtsilä on creating a sustainable UPS, demonstrating average capital expenditure savings of 27% and a 20% reduction in emissions. Over time, regulatory compliance is coupling with evolving technology as well as take-back or trade-in options for UPS and end-of-life battery replacement, he adds.

What the science says

Nuria Tapia Ruiz, senior lecturer at Lancaster University, researches energy storage materials pertaining to battery technologies. She agrees the picture around sustainability is complex.

“Li+ is not so sustainable,” Ruiz confirms. “But lithium and a combination of nickel, cobalt and manganese ratios can provide the highest energy density to store quite a lot of charge.”

Lithium not only reacts with air and water, but its mining is associated with multiple environmental issues. Nickel extracted from sulphates generates toxic sulphur dioxide.

Congolese cobalt mines use child labour and cause pollution-related health problems, including through contamination of drinking water. Meanwhile, gaining full transparency on battery manufacturing and supply chains to close the loop and eliminate unnecessary waste remains difficult.

About 70% of the cobalt in batteries comes from the Democratic Republic of Congo. “On the anode side, we have some carbon, which, again, comes with sustainability problems because carbon is made from coke,” says Ruiz.

Current battery technology seems a stepping stone in the right direction rather than a sustainability solution.

“If we’re looking at sustainability, we’ll move towards changing cathode materials [for] phosphorus, oxygen, iron and lithium – getting rid of the cobalt and nickel,” says Ruiz. “Other sustainable technologies we are looking at include sodium-ion [Na+].”

Na+ technology is a research interest of Ruiz’s and a strong next step for battery technologies, especially considering that the second-largest battery maker, CATL, unveiled its first generation of Na+ batteries as a Li+ alternative in July 2021, forecasting supply chain readiness by 2023.

“And in 20 years’ time, calcium or magnesium batteries show quite a lot of promise,” says Ruiz. “They have more potential in the performance matrix.”

Meanwhile, research continues on improving Li+ technologies and applications.

Best practice UPS sustainability for today

Tony Lock, distinguished analyst at Freeform Dynamics, says datacentre operators should achieve sustainability goals through first focusing on the basics: assessing business criticality of applications and services, which platforms they should run on, the efficiency of the servers and storage, and so on.

“What are you actually running inside your datacentre that you really need continuous availability for? Not all workloads are created equal. Even though nearly everybody who uses a workload will claim it is mission-critical, many of them aren’t,” says Lock.

Some may need less battery backup, shutting loads down smoothly when not required, limiting the size of UPS and alternative power systems needed in the event of an outage.

“I have been in the datacentre when all of the power disappeared, actually about 15 minutes before we tested the battery of the backup diesel generator,” says Lock. “We did blame the electricians for that, but it was actually a fire alarm.”

As for alternatives, Lock advises: “Use some of the flywheel technologies, like large springs, that have come along – really good if you don’t need to keep things running for hours. These can be taking a trickle charge.”

It all comes back to only keeping things running if you really need to, he emphasises.

Datacentres, too, should have alternative electricity providers on hand, via diverse routing. That way, there are other supplies via different wires that can be accessed.

“Minimise the amount of less environmentally friendly systems, including UPS systems that store capacity,” says Lock. “A more educated population is growing up and will be shareholders intent on making organisations as green as possible – that social factor has changed dramatically in the past five years.”

Chris Brown, chief technical officer of Uptime Institute, adds that a rotor UPS or a big flywheel has mass on it and therefore inertia, which will be advantageous in some situations – for example, if producing the power rather than just consuming it – but not others.

“On the static UPS side, you can use a small flywheel to replace the batteries. The issue with that is your typical battery runtime on a static UPS – somewhere between five minutes and hours, depending on how many batteries you want to put in a flywheel – will give you about 18 seconds,” says Brown. “So you do need a fast start engine generator or something of that nature associated with it, but it does eliminate the need for batteries.”

Another option is double-conversion stack UPS, using a rectifier to convert AC to DC that will then be used to charge batteries and then convert the DC via inverter back to AC to drive the UPS. When some features are converted from AC to DC, you take out all power anomalies. You can also use an “eco” mode which bypasses the UPS until the power disappears, says Brown.

What the datacentre needs for sustainability is the best possible energy efficiency and battery storage with the lowest overall environmental impact throughout the lifecycle – “burning the lowest number of dead dinosaurs” in the process, he says.

Brown says Uptime has heard that some insurance companies are pushing back on the use of Li+ because of the fire risk. But there’s no perfect answer to the question of optimal power management via UPS.

“You can control the space that the batteries exist in, for optimal conditions that will extend their life – selecting battery technology that’s right for what you’re going to use it for,” says Brown.

“The other thing is support. When you’re talking about battery technicians who can extend the life of the battery just by knowing what to do with it – that’s as much as an art as a science. With a lot of experience they’re worth their weight in gold, but not every datacentre has that kind of expertise available.”

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