Energy efficiency trade-offs cannot be made between investing in renewables such as photovoltaic (PV) for lowering emissions and managing higher densities at rack level, meaning operators will be increasingly required to juggle multiple sustainability strategies.
Steve Campbell-Ferguson, global lead for design at NTT Global Data Centers, says investing more in renewables on its own will not mitigate any concurrent need to push rack densities or invest in more efficient cooling.
“The IT is, basically in my role, a big electric heater. And obviously, a more dense electric heater introduces other problems, but that’s it in terms of the link with solar,” Campbell-Ferguson points out.
Squaring the circle will continue to mean stepping back and looking at what is going on with power procurement, and further investment in other energy efficiency technology, such as liquid-cooled racks and whether immersive or direct to chip designs will typically be needed. This is especially since liquid cooling can benefit other ambitious projects later on, such as district heating.
Considerations multiply
Bruno Berti, senior vice-president of global product management at NTT Global Data Centers, agrees that high-density heat exchange and advanced cooling will still be required for efficiencies and cost-effective moves, such as increasing ambient temperatures. For instance, while higher densities at the rack can need less space, more room is required for on-site solar, he points out.
For multiple reasons, versus a larger direct spend on solar, NTT’s bigger focus is on developing its power procurement ecosystem to meet renewables demand.
“[Increasing power demand] is really just causing us to accelerate buying of more of those renewable sources, because our commitment regardless is to be 100% renewable and help our clients get there because they’re demanding that as well,” Berti confirms.
Helen Munroe, head of environment and sustainability at Pulsant, explains that roof PV can typically only provide “a tiny fraction” of the power needed by a datacentre: “For an existing building retrofit, energy produced is less than can be avoided through similar investments in energy efficiency works.”
On-site power generation needs proximity to some kind of private wire arrangement, such as a solar or wind farm build that can connect directly.
And achieving consumption of 24x7x365 carbon-free energy (CFE) can’t be done with PV alone – today, you’ll need to combine intermittent solar and wind, battery storage, and baseload CFE such as geothermal and nuclear. That’s why operators are looking so much at power purchase agreements (PPAs) to fund specific renewable developments across a region or even a country, says Munroe.
“We are also seeing innovations such as ‘cool roof’ paints and radiative cooling panels that claim to save up to three times as much energy as solar panels generate for the same area,” she says. “On-roof PV can play a role, but a small one and currently not the most impactful.”
Uptime Intelligence’s research director of sustainability, Jay Dietrich, tells Computer Weekly that Uptime itself does not have data on how much solar the datacentre industry consumes, yet research does suggest solar use is rising in the datacentre, with the cost of installed capacity per kilowatt (kW) falling through 2021-2022.
Direct or financial PPAs are a popular way for datacentres to match electricity use with solar power to reduce their overall carbon footprint, instead of investing directly in solar, for a range of reasons. In fact, datacentres are currently among the biggest buyers of PPAs – despite rising demand and higher interest rates, he says.
“[However] these arrangements vary widely, are often highly complex, and carry significant financial risks,” Dietrich warns.
Adding solar panels to a datacentre rooftop will typically only cover 5-20% of the energy demand, and makes a building a lot heavier, increasing structural and fire risks. At the same time, power densities of solar are low and output intermittent, which means a “very large area of outdoor space” can be required for a practical, cost-effective deployment.
Output ramps up from zero in the morning, and down to zero in the evening, and varies during the day due to cloud cover, smoke, or other factors – not forgetting that other “forces and factors” that can be specific to facilities, including market forces and supply chain issues. All of these have limited predictability and will typically limit the advantage from a given installation of any technological system or infrastructure.
Yet renewables investment remains urgent
So far, many operators deem the risks of on-site solar deployments unacceptable, and this is likely to remain the case for the foreseeable future, according to Uptime analysis. But Dietrich also hastens to add that investing in renewables, including solar, remains increasingly urgent for many reasons not directly tied to Power Usage Effectiveness (PUEs) or rack densities.
Therefore, datacentres, it seems, must continue to look at all angles of attack when it comes to server room investments to meet their goals for energy demand and sustainability.
A site can operate relatively efficiently, with a PUE below 1.2 and average IT equipment utilisation of 50%, yet be run completely on energy generated from fossil fuels, Dietrich notes.
“Just because a datacentre is energy-efficient does not necessarily mean that it is low-carbon or environmentally friendly – and vice versa,” he says. “An operator could run a facility inefficiently, with high PUE, or low average utilisation of IT equipment, yet be powered by a local grid that exclusively uses a combination of wind, solar, hydropower, and geothermal generated energy.”
Meanwhile, large UK solutions provider SCC has just retrofitted 737 kW-peak (kWp) of roof-mounted solar in its flagship Birmingham datacentre, partnering with Conrad Energy “who are essentially funding it”, says Paul Southall, head of sustainability and projects at parent Rigby Group.
He confirms the company has so far brought forward its 2050 net-zero target to 2042, but looking at combining a range of initiatives and considering all options in a bid to achieve their targets faster still.
“Solar in the datacentre is part of that, alongside commissioning and building a new refurbishment and disposal recycling facility a little bit off campus, and we’ve installed a heat pump, trying to avoid gas,” Southall adds. “Even though the gas deadlines were just moved.”
Alex Groves, net-zero lead at SCC, says they’ve put as many solar panels on the roof as possible, but there is no overspill for the grid: “100% of what is generated will be consumed on site.”
Groves adds: “There’s at least two other targets for other buildings, which would be similar sized installations. And in the wider group, other opportunities come to probably about five megawatts [MW], fingers crossed.”
Customers in the public sector are increasing demanding bigger moves to sustainability and efficiency, while remaining cost sensitive and requiring a high degree of resilience. On the whole, that means “sharing, managing and optimising” as well as working to improve overall utilisation as well to meet demand and sustainability targets too, he says.
“We’ve done projects to optimise fan use which have saved more energy than the solar panels generate. Energy you do not use that’s not wasted is worth loads more than what you can generate in renewables,” says Groves.
Points of connection must match in the right places and any negative implications considered – such as how many days of electricity load the commercial building actually has. Even if you have a big roof for PV, the payback calculations become “a little bit questionable” if you do not use all the energy generated on site, he points out.
As a result, SCC is constantly looking at how it can operate better and improve its “game” on energy efficiency and emissions, using less energy. “I’ve got loads of aspirations. I’d love to cover the car park with solar, which is a little bit more expensive,” says Groves.
Uptime’s Dietrich confirms new technologies and designs are needed to raise the industry standard of efficiency “in a significant way” – especially for facilities located in areas without access to low energy use strategies such as free air cooling.
“These breakthroughs and the expansion of carbon-free energy generation are urgently needed to help combat the climate crisis, but they are not dependent on one another,” he says. “The case is the same for rack density configurations.”
Hot and cold aisle containment must not be forgotten either for high density IT. Increased temperature differential of the heat exchange process can drive higher cooling system efficiencies. The use of these types of cooling systems can both reduce energy consumption and the associated carbon emissions, he notes.
Once again, there are few if any shortcuts to the cost-effective, lower-emissions, energy-efficient datacentre.
