In the realm of sustainability and energy efficiency, the concept of reusing exponential levels of heat emitted from data centres is emerging as a promising solution. Notoriously known for being resource-hungry, innovative approaches through heat reuse are reshaping the functionality of data centres. By repurposing excess heat generated during operations, data centres have the potential to transcend their role as mere powerhouses of computation and evolve into invaluable contributors to local communities.
John Hall, Managing Director, nLighten UK, discusses the progress heat reuse is making, delving into its potential to revolutionise energy management, reduce environmental impact and foster symbiotic relationships between technological process and sustainable living.
A few years ago, if you walked into a data centre hall you would probably need to wear a warm coat as the temperature inside was kept to 16-18°C to maintain the efficient running of the installed IT equipment.
As IT equipment became more powerful, it was designed to work efficiently at higher temperatures, thus reducing the amount of energy consumed for cooling systems. Data centres also introduced air path segregation in the form of aisle containment to aid efficient air movement. Now, typical server supply air temperatures in a data hall are maintained at around 25-27°C with temporary excursions as high as 32°C, depending on the operating standard used.
However, with increasing power consumption of latest CPU and GPUs, the volume of cooling required to maintain these temperatures has increased and will continue to do so, not least due to the growing adoption of AI and HPC. For example, the latest GPUs are forecast to consume between 700W and 1kW of power, several times the previous power consumption.
New cooling solutions such as rear door heat exchangers, immersion cooling and direct liquid cooling control temperatures effectively at these higher power densities. The real efficiency gain now, however, is at community level where sever heat recovery can provide a valuable source of heat instead of being released into the environment.
This by-product of data centre operations can positively contribute to regional energy efficiency and emissions reductions. As the demand for data processing continues to surge, this is a positive step for the data centre industry which is under constant pressure to address its substantial energy consumption and environmental impact.
Growing potential
Northern Europe has significant potential for heat reuse with the growing demand for regional Edge data centres. Increasingly, these are being strategically located close to end-users and therefore ideally positioned to export excess heat to the local community. In the UK, for example, the government is looking to encourage data centre owners to explore how they can export heat and may in future introduce mandatory connections to heat networks.
Further elaborating on the subject, Tom Bishop, Director of Project Management, Concert, added: “In the Nordic countries, success stories abound where data centres have been strategically located in proximity to residential areas. There, local communities have successfully leveraged the heat generated by data to warm nearby homes and communal facilities. This innovative approach showcases the feasibility of integrating data centres into the fabric of everyday living for mutual environmental and societal benefits, setting a positive precedent for other regions.
“The utilisation of low-grade heat in UK housing within district heating networks is currently underappreciated and underutilised,” added Bishop. “To optimise energy efficiency and reduce carbon emissions, it is imperative that the government prioritises retrofitting older homes and designing newer housing with the capacity to harness low-grade heat within district heating networks. This would spearhead a transformative shift towards more sustainable communities.”
Agriculture is one sector that stands to benefit from heat reuse. Greenhouses need consistent heat year-round. Heat exported from data centres is an ideal substitute for traditional methods of warming with a minimal impact on the environment. Another exciting application is district heating where the heat is transported to residential, leisure and commercial buildings for heating spaces and hot water.
For example, in 2023 the City of Eschborn and the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH in Germany signed an agreement with nLighten to reuse the heat exported from its Edge data centre – by constructing an 800 metre supply line. The recovered heat will warm several city buildings, including the city’s public swimming pool complex, contributing positively to the local energy infrastructure. Pioneering initiatives such as this offer great future potential for nLighten with its rapidly expanding regional Edge data centre network in Europe, located near the main economic centres of each country.
Key considerations
The deployment of heat exchange networks for heat export and re-use typically requires collaboration between the data centre owners, local authorities and sometimes energy providers. Moreover, the implementation of heat reuse projects involves technical, economic and regulatory challenges. These include the appropriate infrastructure to transport the heat and the proximity and scale of potential heat users to achieve a viable heat reuse system. Sometimes heavy capital investment is required so a long-term operating model is necessary to achieve desirable unit prices. The data centre itself must also be well occupied to ensure heat production.
As Edge data centres continue to grow in number, their locality presents a unique opportunity for community emissions reduction by offsetting other forms of heating – which may use fossil fuels. The smaller size of Edge data centres often makes their volume of heat more viable for use compared to very large central data centres of high capacity.
