The increasing power demands of data centres are making sustainability an ever more central concern for those who operate them. Many are putting technologies in place to achieve this goal, but effective ways of measuring the efficiency of these methods are key for industry players serious about maximising impact.
One of the key opportunities that players are investigating is the reuse of waste heat for residential and commercial buildings in local communities.
“Data centres can provide a carbon-free heat source for the community, helping the journey towards emissions reduction and the energy transition,” says Chad McCarthy, CTO and co-founder of nLighten, a European digital infrastructure platform and data centre provider headquartered in Amsterdam.
Feeling the heat
But McCarthy explains that traditional carbon-free energy (CFE) indicators for data centres focus just on electricity consumption. If heat recovery can also be included, that stands to quantify the benefits of so-called ‘sector coupling’, which is the practice of synergistic energy recovery and reuse between energy producers and users.
McCarthy explains two ways in which this sector coupling can be achieved for data centres. One is via direct export, removing high-temperature heat from cooling systems in data centres and transferring it to district heating systems. Another method is grid stabilisation, whereby data centres can offset the depletion of renewables in the grid at times when weather conditions are unfavourable for the likes of solar and wind power.
For these reasons, nLighten has now extended the traditional CFE measurement, which measures the percentage of carbon-free energy supplied and consumed on an hourly basis, to include heat recovery and the positive effect of grid stabilisation. The company believes this integrated carbon-free energy score (ICFEn) will provide a more holistic way of pinpointing what needs to be done to move towards net-zero emissions.
Transparent metric
“We’re trying to redefine the data centre a little bit,” says McCarthy. “That’s why this measurement metric is useful, because it helps to quantify efforts. As data centres get more complex in terms of on-site power generation with the growth of AI and start to integrate grid stabilisation, it’s a really useful model because you can see transparently the effects of what you’ve done.”
As an example of where this measurement can be used, nLighten partnered last year with local entities in the town of Eschborn near Frankfurt, Germany, on an agreement to supply the public indoor swimming pool and a nearby office building with carbon-free heat.
Tests so far have yielded promise, says McCarthy. “We’re not releasing numbers today, but we’ve seen positive results in our integrated carbon-free energy score.”
He points out that the company’s environmental strategy aligns well with the distributed edge data-centre footprint that nLighten has established. This set-up distributes the heat sources so they can be shared locally, benefiting nearby communities with low distribution costs and often displacing high-emission heat sources.
Green growth
Co-founded in 2021 by McCarthy and CEO Harro Beusker, veterans with many years of wide-ranging experience in the data centre sector, nLighten’s aim is to help drive the next stage of the industry’s evolution and align facilities with the green transition.
The company has rapidly expanded since it launched its edge data centre platform in 2023, showing an ambitious trajectory. Starting in Germany, it now has 34 data centres in Europe, also across Belgium, France, the Netherlands, Spain, Switzerland and the UK. The company plans further expansion in the second half of the year, with McCarthy anticipating around 50 nLighten data centres by the end of 2024.
By establishing a footprint in both new and established European markets, as well as focusing strongly on sustainability and environmentally friendly community initiatives, he believes the company is on the right growth path for the next phase of the data centre evolution.
“It’s really about how the data centre can assist the energy transition and be a lever for environmental improvement,” says McCarthy. “In a number of locations, we’ve found very synergistic coupling effects between the data centre and other energy uses.”
He adds there is much to do, but that initiatives like the company’s ICFEn can significantly help advance the market. “The energy transition is something that takes time and that I think no one has completely solved today, but it’s a very positive step to have something we can use to show improvements.”
