Are data centres reliable sources of heat for Dublin’s planned district heating systems?

West of the Newcastle Road out near Adamstown, trucks were carrying construction materials into a huge site last Thursday, where the skeleton of a data centre was rising from the dirt.

The walls at the entrance bore the names EdgeConnex and Winthrop Technologies, which build data centres around the world, including several in Dublin.

EdgeConnex Ireland Ltd got permission from South Dublin County Council in March 2022 to put two single-storey data centres here. These are just two of dozens in Dublin.

A June report from the consultancy Bitpower Energy Solutions found 82 operational data centres in Ireland, 77 of which were in the Dublin metropolitan area.

These suck in huge amounts of energy to run racks and racks of servers that let people do things like send emails, stream TV shows, listen to music, and publish news articles.

As the electricity flows through these machines, flipping miniscule switches on and off – 0 1 0 1 – it generates heat. Cooling systems pump it away to keep them happy.

EdgeConnex’s planning application included a “heat recovery feasibility” report, which looked at how practical it would be to pipe waste heat away from the centre to help warm homes and businesses through a district heating system.

In these systems, a district heating company is set up to send hot water via big pipes into a neighbourhood, which can be circulated through small pipes and radiators in people’s houses or in public buildings or in shops or offices to keep them warm.

Codema, Dublin’s energy agency, has already helped get one such system up and running in the Dublin area – using waste heat from an Amazon data centre in Tallaght. And it’s working on more in South Dublin and Fingal.

But are data centres reliable sources of heat for district heating systems for decades into the future? As technology changes, will they get more efficient and waste less heat, for example?

And if things change, what will become of the multi-million-euro district-heating systems relying on them that are now being planned around Dublin?

The push for district heating

Waste heat from an Amazon data centre is already helping to heat buildings in Tallaght through a district heating system.

“The initial phase of the system in Tallaght is already operational and supplying heat to that TU Dublin campus and SDCC County Hall,” said Joe Hayden, Codema’s project implementation lead, by email.

To the north, “Fingal County Council are currently assessing the feasibility of developing a District Heating System in Dublin 15,” according to a council spokesperson. “It is anticipated that this assessment will continue into the autumn.”

The push for district heating in Tallaght, Blanchardstown and Dublin city – where the plan is to start by using waste heat from the Poolbeg waste-to-energy incinerator – is part of the push to reduce Dublin’s carbon emissions.

Rather than a gas- or oil-fired boiler heating each home or other building, many can be heated all at once from a central energy source that emits less carbon, is the idea. And using heat that would be wasted is better than just wasting it and making more.

A presentation from Codema at Fingal County Council’s climate action committee in June detailed a plan to take waste heat from an Amazon centre and pump it into a district heating system around Blanchardstown.

Phase 1 would use 10km of pipes to link in TU Dublin, Connolly Hospital, and the Sports Ireland campus, the presentation says. Phase 2 would add 15km of pipes and link up social homes, and the pharma companies Alexion and Bristol Meyers Squibb, it says.

Building the two phases of the system would cost about €58 million, the Codema presentation says.

Reliable sources?

“What scares me is the potential that these data centers are not permanent infrastructures,” says Patrick Brodie, an assistant professor at UCD’s School of Information and Media Studies.

“Ultimately, the design of a data centre, a big shed, with room for computers, is meant to get them up quickly, and to make them be able to scale up and scale back very easily right. And also, potentially to be able to abandon quite quickly, right?” Brodie says.

He points to the case of a data centre in Quebec that Swedish telecoms company Ericsson opened in 2016 and then abandoned. “They shut it down, and sold it to essentially, an asset management company who rent apparently, a few racks of servers in it,” Brodie said.

A company abandoning a data centre – and no other company wanting to take it over and keep it operating, would be quite rare.

However, even if companies do not abandon their Dublin data centres, technology is always changing – and if the servers inside the centres become more efficient in their use of energy, then that’s less waste heat for a district heating system.

But Jon Summers, who is on the advisory board of the Data Centre Alliance, a trade association, says data centres are going to keep generating waste heat.

“I think the heat is not going to go away,” said Summers, who is scientific lead in data centres at the state-owned, Gothenburg-based Research Institutes of Sweden (RISE).

“I mean, if you look at the history of compute, you know, we’re in a fast trajectory now where a lot of applications requiring intensive compute,” Summers says.

“The one that’s on most people’s mind these days is obviously things like generative AI with the large language models, he says.

At the moment, the servers in most data centres are on racks and are cooled by air moving around. But technology is changing and some or all of them could work differently in the future, which could affect how much waste heat they generate.

If they start using superconductors working at low temperatures, “What we might see, the data centre might have to move into the world of cryogenics,” Summers says.

“Because of quantum computing, because of superconductive computing, because of cold CMOS computing, which are very futuristic looks for the data centre,” he says.

“I think data centers will probably have to deal with things that are really hot, and things that are really, really cold,” he says.

Meanwhile, even before that future arrives, if it does, the amount of waste heat a data centre generates can vary.

For example, they’ve more extra heat in the summer, when households need less of it, and less waste heat available in the winter.

“When we want the heat, they don’t have enough of it. We don’t want the heat, they have too much of it,” Summers says.

This is something EdgeConnex points out in the heat recovery feasibility report for data centres out near Adamstown.

In the winter, the data centre would want to keep heat generated by the servers so it doesn’t get too cold inside, the report says.

“It is only once ambient temperatures reach 20°C that the full heat load of the servers is rejected into the atmosphere,” it says.

Switching heat sources

Variations in the amount of waste heat a data centre can provide to a district heating system aren’t a huge problem though, says Hayden, of Codema.

Because the waste heat isn’t going to be the only source of heat for a district heating system, he says.

For example, in the Tallaght scheme that’s up and running, air heated by racks of servers in the Amazon centre warms water, which flows into a nearby energy centre.

“This provides the energy centre with hot water at approximately 25 degrees C,” Hadyen says. “Heat pumps then lift this from 25DegC to 70eDegC (higher in winter).”

The heat pumps run on electricity from the grid, he says. Hot water then flows from the energy centre through pipes into buildings to heat them.

“The data centre is just one heat source but the plan is to add other low carbon heat sources as the system develops and grows,” he says.

“The pipe network is independent of the heat source, but of course in this early stage of the scheme’s development we are somewhat reliant on Amazon being around for the near future,” he says.

Although Amazon is providing the waste heat for free, buying electricity to run the heat pumps costs money, Hadyen says.

The prices customers have to pay for heat from the district heating system “will depend on the business used to develop the DH [district heating] project, such as a Joint Venture, a CoOp, non profit”, says Hayden.

“But in general they will be calculated based on recovering the costs of providing the heat to the customer,” he says.

Brodie, the UCD assistant professor, says he worries about data centres being integrated like this into the country’s energy system – their waste heat, perhaps their battery storage systems.

At the start the data-centre owners might provide these things for free. But that might not always be the case, Brodie says.

“That’s another technology that is commercializable in a particular way, right?” he says.