You don’t have to be Greta Thunberg to find the numbers terrifying. The Swedish activist has been talking for years about the dangers of what we’re doing to the planet and those living on it, including us humans, but she has mainly left digital infrastructure alone.
Fortunately, ever since the day in August 2018 when she sat outside Sweden’s parliament, the Riksdag, with her famous sign “Skolstrejk för klimatet” – “school strike for the climate” – she’s proved to be a brilliant user of digital technology in order to warn the world.
But people in the digital infrastructure sector should examine their own navels. According to Infrastructure Masons, an industry organisation for the data centre world, there were 7 million data centres across the world in 2021 with a total capacity of 105GW. And over that year they consumed 594TWh of energy – 2.4% of global consumption.
The average European used 40,000kWh in 2021 heating their homes, driving to work, cooking their meals and watching TV, according to the open-source data site Our World in Data. That means the global data centre industry used as much energy as 15 million Europeans. Or 7.6 million Americans or 5.8 million Canadians.
And this load is set to increase, as total global mobile data traffic will quadruple in the next five years to reach 282 exabytes (EB) a month, according to Ericsson’s June 2022 Mobility Report.
Power with the hyperscalers
Work to manage the industry’s power consumption starts with the customer, says Craig McKesson, chief customer and marketing officer at T5 Data Centers in Atlanta. By “customer” he does not mean the average Netflix watcher at home, but the hyperscalers, which he says “are probably 70% of the buying power of the industry” and have a lot of influence “all the way down the chain”.
“We need to think what changes we can make. What will the data centre operator of the future do? What about different ways of cooling? Data centres don’t need to be run at 65°F [18°C], but can work at 85°F [29°C] instead,” he says. “A typical data centre operates at only has 60% utilisation of power, so 40% of the infrastructure is unused. We need to be conscious of the whole ecosystem.”
In Oslo, Stack Infrastructure has been doing just that, says Halvor Bjerke (pictured), CEO of Nordics for Stack Infrastructure in EMEA. “We’ve been running this for almost a year,” he says. “We’ve done a winter, so we know it works. We are providing between 3MW and 3.5MW, and that makes 25-28GWh this winter.”
“Otherwise you dump it [surplus heat] into the air. It means we can provide the heat directly in the cold months, from late August to April.” During that period, Oslo’s high temperature falls from 16°C in August to –5°C in February. “From May to mid-August, we have mechanical cooling. That means for 65% of the year, [the surplus heat] goes to district heating.”
When I ask if Stack is paid by Hafslund Oslo Celsio, the supplier of Oslo’s district heating system, Bjerke replies, “Yes, a little.” But makes it clear this is not a profit centre for the company, as it “was very expensive” to set up.
Despite there being “very little in this financially” for the company, it is undeterred. “It’s in our DNA to be green,” says Bjerke. “We’ve been running on green power for almost 20 years, using hydropower in Norway.”
Stack is now planning to feed a district heating system in Stockholm by retrofitting an existing data centre, and to connect a new data centre in Copenhagen to a local district heating system while it is being built. However, Bjerke notes that “you need a certain critical load” to connect a data centre to the district heating system. “It needs to be more than 1.5MW – a critical level to make it viable.”
“Stockholm is not live yet. The plan is to kick off after New Year,” he tells me. This city has an established district heating infrastructure managed by Stockholm Exergi, which is 50% owned by the city, providing heating to more than 800,000 inhabitants and 400 hospitals, data centres and other businesses.
The heating company says: “Stockholm Exergi treats waste and recycles energy. District heating is part of the circular economy and helps us to use the Earth’s resources efficiently.”
Circular economy
Bjerke says the next project on his list is “a campus in Copenhagen” which will be built “hopefully, in two to three years”. This new data centre is to be built just west of the Danish capital. There has not been a final decision on its size, but Bjerke ventures that it will be “probably 50MW”, and says Stack wants to identify possible users of its surplus heat in its neighbourhood.
“Since we have an energy crisis in Europe now, we need to push,” he says. “We want to do something now that works.”
Of course, this presupposes that there are district heating systems available for data centres to supply. Frankfurt, one of Europe’s biggest data centre concentrations, has had district heating since the late 1800s, and there is an ambition to extend the provision in order to halve the city’s total energy demand by 2050.
Vattenfall – which is 100% owned by the Swedish state – operates a district heating system in Amsterdam, which is the largest heat grid in the Netherlands. “The main heat source is gas,” says the company, “but plans are to use all available fossil-free heat sources to replace it.”
In London, the biggest home of data centres in Europe, Vattenfall is working with Cory, a waste recycling company, to build a 10,500-home district heating system. But it is unclear whether data centres are included in these plans.
Similarly in Paris, district heating company CPCU, which is part-owned by the city, has been operating for decades, but it is hard to find any mention of data centres in its plans. Away from existing or planned district heating systems in western Europe, there is continuing pressure to move the majority of the data centre industry to renewable power sources; primarily solar and wind power.
When the wind blows
Alan Greenshields, Swiss-based EMEA director at US battery company ESS, crisply points out that data centres need to run 24 hours a day. “It’s sunny by day, dark at night,” he says. Wind, then? He points to Portugal, which “has a lot of sun in the summer, a lot of wind in the winter, but that’s not the case in Scotland”.
There can be a lot of wind across the UK as a whole. In the first few minutes of Sunday, 30 October, wind was producing almost 51% of Britain’s demand for electricity – 11.7GW out of the 23GW needed. By dawn, wind had dropped, but over the day wind-generated power still met 43% to 44% of demand.
But that was a windy day. During the previous two weeks, electricity supply from wind fell as low as 1GW. This variability in supply makes energy storage vital.
“If we can power data centres with renewable energy, it’s a huge contribution to decarbonisation,” says Greenshields. “Long-duration energy storage is one of the key technologies to enable the decarbonisation of the energy system.”
The problem is that “there have been fewer than 10 new [battery] technologies in 150 years”, says Greenshields. “That shows how difficult batteries are – one of the most complicated products around – and new a battery technology has not displaced the predecessors”.
The acid truth
There is still a huge reliance on lead-acid batteries, which were invented in 1859. “Their job is to keep the computers running until you can transfer the data to another data centre,” says Greenshields. “Usually 15 to 30 minutes is enough, but nothing like enough if you want to power your data centre on renewable energy.”
Greenshields points out some uncomfortable truths. “Batteries are unstable,” he says. High-capacity lithium-ion (Li-ion) batteries, as used in laptops and phones, only last a few years – one of the reasons we replace these devices so frequently. They need clever power management software to prevent them exploding: just search on YouTube for some horrific videos of batteries blowing up.
“Peak solar generation is five-and-a-half to six hours,” he says, then the sun goes down. At night you need an alternative to wind power “and that’s likely to be gas”. This means 30% of your energy supply comes from solar energy and 60% from gas. “The heavy lifting is by gas,” says Greenfield.
Chris Pennington, Iron Mountain’s director of energy and sustainability, says resolving carbon responsibility by buying renewable power for a data centre is “only part of the journey”.
“A typical approach is to buy a corresponding amount of renewable energy, such as from a solar farm,” he says. But how much should you buy? “You need to find ways so every hour is matched. What’s the true carbon content of your energy? What hours is it carbon-free? Which of the hours are not? Once we have that data you can look at alternative clean energy sources.”
That means examining energy consumption 24 hours a day, every day, and identifying how the carbon consumption is offset. “We’ve built a platform that enables us to understand how well we match. It tells us how well we’re aligned at any time.”
The data centres’ customers are involved in this by necessity. “It’s still part of their energy budget. We need to remind people that the footprint is still theirs. We do our role – buying carbon-free energy for the facility – and get them to recognise it’s their responsibility.”
But Pennington is optimistic as the pace of change is accelerating. “More people are rowing the boat in the same direction now,” he says.
