A lifeline for pools? “Digital boilers” provide innovative rethink of waste heat reuse

Swimming pools threatened with closure because of skyrocketing heating bills could get a reprieve from a new technology for waste heat reuse that is being described as a potential game changer.

A UK start-up, Deep Green, has successfully trialled the scheme at a public pool in Exmouth that has cut its bills by around £20,000 per year. Unusually, the system involves locating a data centre underneath the pool, thereby generating a win-win, both for the pool owner (who gets lots of free heat), and Deep Green, who are able to reduce the costs of offering computing services for applications like cloud computing and AI.

While waste heat reuse is nothing new, the technology developed by Deep Green – which has been in R&D with the company for the past five years – appears to be a successful deployment of a new “heat demand approach”, whereby a data centre can be located wherever heat is needed.

Mark Bjornsgaard, CEO of Deep Green, said: “By utilising a modular approach and building our data-centres within ‘the fabric of society’, we bring the heat to the user, reducing energy lost in transportation and increasing the efficiency of energy recovery.”

Up until now, waste heat has often been successfully reused, including from data centres, but it has tended to involve very large-scale projects, requiring large amounts of public infrastructure (miles of piping, and so on) to distribute and utilise the heat.

One widely reported example of a data centre reusing waste heat is the Amazon AWS data centre located outside Dublin, from which heat will be piped to heat buildings in the city.

Deep Green’s system draws upon techniques used to cool electronic components. Immersion cooling, as it is known in the server world, is an approach whereby components (and even entire servers) are submerged in a liquid coolant, which is electrically insulating but thermally conductive. Heat can transferred from the components – as the coolant is heated and circulated in heat exchangers – to where it is needed.

Much more heat can be absorbed by liquid than if it was being transferred to the surrounding air. In this case, the cooling liquid – or dielectric fluid – is mineral oil.

The data centre equipment provided by Deep Green is around the size of a home kitchen appliance (0.7 metre x 1 metre x 0.6 metre), and the company also takes responsibility for maintaining the equipment (and it pays in advance for the energy costs required to run it).

The firm is offering the system to other premises that require heat, not just pools, and Bjornsgaard has said around 30% of all industrial and commercial heat needs could be addressed in this way, including things like distilleries, laundrettes and residential premises.

Now the technology is live and ready, says the firm, and it is now launching with a solution that it says is ready to scale across the thousands of pools and other local businesses in the UK that need heat.

Exmouth Leisure Centre has provided the initial trial, and says it has been able to cut its gas use by 62%, reducing its bills by £20,000 per year. Up to 20 public pools could be supplied with the technology this year. Speaking to The Guardian, Jane Nickerson of Swim England said the technology “could be a game changer for us.”