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district heating

Should we use data centres to heat our homes - or is it greenwashing?

The waste heat from data centres can be used for climate-friendly heating systems – but data centres are major energy consumers.

IRELAND IS THE worst country in the EU at using renewable energy to heat things up and cool things down.

In 2020, only 6% of the energy consumed for heating and cooling in Ireland came from renewable sources. 2021 was worse again at just 5.2%. In both years, it was the lowest proportion of any EU country and well below the union-wide average.

A major national heat study carried out by the Sustainable Energy Authority of Ireland last year tried to identify how to reverse an upwards trend in Ireland’s emissions from heating.

It found that up to 50% of heat demand from buildings could be met by low-carbon sources through a type of system called ‘district heating’, which effectively delivers heat through insulated pipes instead of individual buildings generating their own heat.

District heating can be powered by fossil fuels, but also works very well with renewable sources, which has garnered it favour in some countries’ plans to cut greenhouse gas emissions.

The concept is nothing new: it’s widespread in plenty of European countries, particularly in Sweden, Denmark, Lithuania and Estonia.

For Ireland, though, it is a relatively new idea. One plan that has been in the works for many years is to develop a district heating system in the Docklands area of Dublin, which could provide heating for tens of thousands of homes by using heat created by the Poolbeg incinerator as it burns waste. 

Up-and-running as of last week is a district heating scheme for Tallaght which is set to heat South Dublin County Council offices, Tallaght library, part of the TU Dublin campus, and 133 apartments (with plans to expand to a greater number of apartments in the future).

Unlike the Poolbeg-fuelled plan for the Docklands, however, the Tallaght scheme was carried out in partnership with an Amazon Web Services data centre and will be powered by waste heat that the data centre creates.

The very presence of data centres in Ireland has been a major source of contention in recent years due to the massive amounts of energy they consume.

In 2021, data centres used 14% of all metered electricity – more than rural homes, which collectively accounted for 12%. 

The Journal’s investigative platform Noteworthy recently found that direct onsite carbon emissions from data centres have risen by a massive 35 times within a decade.

Looking forward, should Ireland be leveraging data centres to develop a network of district heating systems, or is the impact of data centres on the energy grid and emissions too great to be mitigated?

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Speaking to The Journal, Dr Patrick Bresnihan, a lecturer in Maynooth University’s Department of Geography, said that Ireland’s district heating infrastructure (or lack thereof) is “far behind” other countries.

He said that current development is being “partly driven by the data centre industry” but that he believes that “isn’t the way we should be developing district heating”.

“It should be developed separately from data centres. The data centres that do exist, they should be brought into district heating, they do produce a lot of waste heat. But I would be worried – which is probably the best word – about the role that data centres may play in developing district heating in Ireland,” Dr Bresnihan said.

The problem is that data centres use too much energy and they shouldn’t be allowed to continue to grow when we have such problems with energy security and the need to reduce energy consumption overall.”

Dr Bresnihan said that rather than limiting data centre expansion, proposed solutions that emerge rely instead on technological innovations like a district heating systems that use waste heat.

However, he says the benefit of these is “relatively minimal” compared to the energy consumption data centres are responsible for.

Additionally, he suggests that reliance on private enterprises for energy supplies can render systems “quite vulnerable”.

“You should develop public infrastructure based on strategic plans, long-term investment, and what is best for the population and what is affordable. But if you build infrastructure around data centres, they can leave, they have no requirement to stay here.

“And once they leave, then what happens? Our energy infrastructures, which are so, so important, need to be developed along different principles and with different considerations, not with the data centres at the heart of it.”

If data centres are to be used in heating schemes, though, he said that such schemes should be funded in part by those data centres.

“I think if district heating systems are going to be developed and if they are going to be built to use waste heat from data centres, then those data centres should pay for a large part of those district heating systems,” Dr Bresnihan said.

“I think another reason why that might be important is that it locks them into that infrastructure. They might be less likely to just leave because they have some kind of financial commitment there.

“The district heating schemes should be about sustainability and making our heating systems more efficient and so on but they should also be about making energy cheaper. There may be a way in which if the developer or the data centre developer has to pay something that could go towards offsetting energy prices for households, for example.”

‘We have to get the best out of them’

In Denmark, district heating accounts for 46% of domestic heating and hot water consumption.

Professor Jakob Zinck Thellufsen, an associate professor at Aalborg University in Denmark, researches energy planning and renewable energy systems, including district heating. In 2018, he conducted research into the viability of district heating systems for Ireland.

“I investigated what could potentially be the benefits of district heating in a country where it historically hasn’t been but where there is clearly a heat demand,” Professor Thellufsen told The Journal.

He found that it is possible to achieve a “more efficient and, if you look at it from a socioeconomic point of view, a cheaper energy system by going to these district heating systems”.

He noted that Irish cities are less densely populated than Danish ones – district heating is most effective in urban areas where people live more closely to each other – but that nonetheless, the study’s conclusions were that “compared to people having their old gas or electric boiler at home, it is more efficient if we in the cities can implement district heating compared to other individual solutions”.

“Economically, it’s typically cheaper to have a good, well-operating district heating plant than it is to have an individual solution [such as a gas or electric boiler]. And comfort-wise, there’s some benefits too for some people, because all the technical part is handled by a central actor instead of you as an individual at home figuring [it] out.”

Denmark has also ventured into using waste heat from data centres for district heating systems, including a partnership between a Facebook data centre and Danish district heating company Fjernvarme Fyn. 

“If you have to have these data centres and the electricity consumption they come with, then the excess heat you can get from these processes would be really beneficial to the heating system,” Professor Thellufsen said.

“But obviously if you don’t gain these benefits, it is a burden to the energy system to have data centres, so when we have them, we have to also consider how we can get the best out of them.”

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