Plans to heat districts with datacenters may prove too hot to handle

Report points out the difficulties of getting such a system right

Using waste heat from datacenters for district heating makes sense from an environmental standpoint, yet there are implementation challenges and potential pitfalls introduced with any government regulations covering it.

Digital trade association TechUK has published a report on using DCs as part of district heating networks that outlines both the benefits and the practical hurdles. This was submitted alongside TechUK's response to a government consultation on its proposals for heat network zoning.

The British government's plan is that datacenters will be the next industry to feed into new-build heat networks. A like-minded project was announced last year by the Department for Energy Security and Net Zero (DESNZ) to connect 10,000 new homes to nearby bit barns in two boroughs to the west of central London.

TechUK points out there is a distinction between district heating, which might serve various buildings in an area, and community heating projects that typically cover just a single apartment block or estate.

Potential advantages of hooking datacenters into heat networks include lowering the carbon footprint of the entire system and cutting the cost of heating for households struggling to pay for their energy needs.

For datacenter operators it can reduce the amount of electricity and water required for cooling IT infrastructure, and it might even become a source of revenue.

However, TechUK warns that any regulations covering this must strike the right balance. It refers to Germany's recently enacted legislation requiring all businesses that consume more than 2.5 GWh of energy annually to recycle their residual heat or offer it to external parties.

The move was criticized for imposing targets without taking into consideration the complex infrastructure necessary for datacenter heat to be reused, the report states, and UK government should learn from other jurisdictions when developing its own regulations on heat reuse.

There are additional obstacles that need to be considered, says TechUK. Firstly, the latest fifth generation of heat network designs can operate with the lower temperature waste heat produced by a datacenter, yet most current heat networks operating in the UK are third gen systems, which have lower energy efficiency and higher carbon intensity.

TechUK notes that when a datacenter is first built, it will have minimal occupancy, and may take more than ten years to fill. This means heat exports during the early years could be light, creating uncertainty for the stakeholders in a district heating network.

District heating projects cannot assume the heat produced by a data dormitory will increase over time, the report adds. Servers typically have a lifecycle of three to five years, and technology improvements generally reduce the overall heat they produce.

This means is it hard to make accurate projections on how much heat a datacenter will produce in the future, even with the current trend of AI workloads driving demand for more powerful and energy-hungry infrastructure.

Another factor is the varying seasons in the UK, with demand for heating lower during the summer months, which is just when a datacenter is most in need of cooling. A district heating network must therefore consider the off-season for demand so that datacenters can maintain viable cooling options in hot weather.

Perhaps an obvious challenge is the proximity of a data dormitory to an appropriate heat network. Smaller bit barns tend to be positioned within urban areas - where the demand is - yet they generate less heat, while the massive datacenter campuses favoured by the hyperscalers are located in outlying regions, which might prove to be a challenge for any new zoning networks, the report says.

Heat pumps can't be an afterthought

TechUK also warns that successful reuse of residual datacenter heat requires choices to be made at the planning and design stages, as retrofitting may be difficult. The infrastructure required includes pre-established pipes, fluid pumps, heat pumps, and heat exchangers.

Retrofitting these infrastructure components could incur substantial costs and resource allocation, and existing bit barns may face "significant obstacles" in connecting to heat networks. The report asserts that any regulatory requirements regarding residual heat should not be compulsory for existing sites because of this.

One ask if for regulators to give operators reasonable lead times, allowing them to develop designs that can integrate well with heat networks for the efficient channeling of residual heat.

Other factors include security as the government consultation suggests that heat network operators may have a right of site access to heat sources such as datacenters, which poses a potential conflict with the bit barn's duty to keep infrastructure secure and their clients' data safe.

There are also financial risks for the datacenter operator. If they make an investment to connect to a heat network, but their bit barn does not reach the required occupancy levels, a reduced heat output may fail to cover the initial outlay.

With all these potential pitfalls, it makes you wonder if it is really worth the trouble, especially for datacenter operators. But they should start planning for the possibility that they may soon be required to offer waste heat for reuse, according to Mark Boost, CEO of UK-based cloud operator Civo.

"TechUK's report is an important wake-up call for our industry. For too long, the tech industry has dragged its feet on sustainability in datacenters, making tweaks around the edges without changing the model," he told us.

"While I do not necessarily think that strict regulation on datacenter heat reuse is the answer, I would urge the tech sector to take action now – before being mandated to do so."

Allan Kaye, managing director at datacenter infrastructure provider Vesper Technologies, said there is already growing interest from clients in advanced cooling technologies such as immersion and direct-to-chip liquid cooling that lend themselves naturally to heat reuse applications.

"They not only allow for very high-power densities in AI and high-performance computing applications but with heat already captured in liquid coolant, it can be straightforward to connect to external heating networks," he said.

Kaye told us that if government initiatives can strike the right balance, reusing datacenter heat could be "a real sustainability success story."

Boost at Civo agreed, and claimed that the UK has the potential to be a leader in this area. "With the Spring Budget fast approaching, I implore the Treasury to invest in and back our domestic ecosystem – not shuffle more money into the hands of Silicon Valley," he said. ®

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