Data centres could save enough energy to heat 300,000 homes

Irish data centres could boost their global 'green' reputation with Nexalus cooling system using waste heat from electronics
Data centres could save enough energy to heat 300,000 homes

Dr Cathal Wilson, Prof Anthony Robinson and Kenneth O'Mahony, co-founders of Nexalus, innovative technology that cools and captures the hot water produced by electronics for reuse as 'green' energy.

Implementing innovative new hot water cooling technology in data centres could reduce their energy consumption by 35% and offset 1.2 million tonnes in carbon emissions, say the scientists behind Irish startup Nexalus.

Headquartered in Cork and with R&D facilities in Trinity College Dublin and in Westmeath, Nexalus integrates its cooling system with electronics that produce excessive heat, most notably wasted CPU thermal output.

The Nexalus technology can lift the thermal energy at a water temperature suitable for reuse — between 40°C to 60°C — which means that the historically wasted CPU thermal output can be redeployed to residential, industrial and food production sectors, in turn displacing the use of fossil fuels.

Nexalus uses thermal-fluid science and engineering to cool, capture and reuse waste heat. Co-founded by Dr Cathal Wilson, COO, Dr Anthony Robinson, CSO, and Mr Kenneth O’Mahony, CEO, Nexalus is also working with the ICT sector, High Performing Computing (HPC), Bitcoin, the gaming industry, automotive and others.

However, the 'green' opportunity for this unique technology is most evident in Ireland's 66 active data centres (plus 29 currently in development), the EU's largest data centre market, which currently wastes 3.0TWhrs of energy annually.

“At the rate that data centres are growing here, our technology could help capture and reuse enough energy to meet the electricity needs of half the homes in the country,” said Dr Cathal Wilson, COO, Nexalus.

“It's fantastic that data centres are so successful in Ireland, and with the right planning they could help us improve our circular economy. There is a great opportunity to deploy modular data centres and co-locate them with, for example, food sector companies to reuse the captured thermal energy on-site.” 

The potential carbon saving from data centres alone equates to 19% of Ireland’s climate action target for 2030. The recaptured 'green energy' could provide hot water and heating to over 300,000 homes annually, or 15% of all Irish homes.

Prof Anthony Robinson, co-founder and chief science officer with Nexalus, said: “When developing technology for data centres we had to consider the multiple heat problems which arise from thousands of powerful servers all operating under one roof, while also tackling heat capture and reuse.

“Our technology allows data centres to solve these problems simultaneously by integrating liquid cooling directly into ‘sealed server’ technology. In sealing the server and then dealing with the heat and energy management problems at source, the larger energy problem becomes modular — and thus scalable — and more of an energy transport issue, which is comparatively straight-forward to solve.” 

Big energy reuse opportunity for data centres

A 20MW data centre that implements a Nexalus hot-water cooling system will:

  • Reduce energy consumption by 35%, giving a PUE of 1.04 and resulting in an electrical consumption cost saving of over €5.5m  annually.
  • Increase server/compute density 3x to 10x.
  • Reduce CO2e emissions by 23,000 tonnes.
  • Increase Energy Reuse Factor (ERF) by up to 90%.
  • Generate a new clean energy resource in the form of heat and hot water for 6,000 domestic homes annually.
  • Create a new revenue stream, from the sale of this green energy to district heating or neighbouring businesses and industry, of €4m annually.
  • Off-set an additional 24,000 tonnes of CO2e in the homes receiving this new green energy.

With the Nexalus Combined Heat and Compute (CHC) data centre technology, each server is thermally isolated from its surroundings, and heat is recovered from the processors via a patented jet impingement Enflux/Vortex (CPU/GPU) water-cooled direct contact heat exchangers.

All of the lower-powered supporting electronic components, RAM, VRM, power supplies and storage are air-cooled with the Nexalus NXQ air-water heat exchanger, which itself is a heat recovery device embedded in the server.

This means that all of the heat generated within the sealed server can now be recovered into a liquid stream, which can be easily transported for use elsewhere.

As a result, Nexalus view data centres not just as hubs for processing data, but as thermal power stations. For example, a Central Processing Unit (CPU), is extremely effective at converting electrical energy into thermal energy, due to its favourable electrical and thermal properties.

Dr Wilson notes that Nexalus is first to global markets with its heat recovery and reuse solution. He says the solution is adaptable to various environments and can be implemented easily at scale, without the requirement for complicated additional infrastructure.

Prof Robinson adds: “At Nexalus, we are one of very few companies that are innovating in the space where heat and energy problems are viewed as one. Having the capacity to develop technologies that exist at both ends, as well as bridging between them, is where our Nexalus innovations happen.

“The importance of modularity cannot be stressed enough. Being pluggable and hot-swappable not only allows for ease of installation and maintenance, but facilitates economies of scale. Our solution, therefore, is equally viable for a single rack in a hotel as it is for a mobile cryptocurrency container or a hyperscale data centre.

“This itself then creates an equally scalable and broad energy market, where the heat, being at temperatures ideal for comfort, space and process heating, can be deployed into the likes of residential, industrial and food production sectors, which displaces the use of fossil fuels and accompanied generation of greenhouse gas emissions.” 

Nexalus emerged from blue skies/platform research in the CONNECT SFI research centre in Trinity College Dublin and is supported by Enterprise Ireland. Visit for more.

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