Decarbonising datacentres: Turning the hot air about heat reuse into real-life use cases

Overcoming the barriers to widescale heat reuse

As with any new technology, there are a number of challenges that need to be overcome first to take full advantage of the opportunity and promise of heat reuse.

One of them is the proximity to the heat demand. For example, the closer a datacentre is to homes or businesses in need of heat, the better. This could be achieved with government support and policy-making in the UK, as many European Union member countries have already done.

Where datacentres cannot be situated near existing heat demand, applications such as greenhouses or sustainable farms could be purposely located there to make use of this low-carbon, low-cost energy, which is a path Norwegian colocation firm Green Mountain is pursuing.

The captured heat also has to have a price in order to secure the return on investment, and to let the competition drive the change.

There are a number of facilities around the world already demonstrating the feasibility of installation, environmental benefits and enormous savings resulting from recovering waste heat.

These include Amazon’s partnership reusing the waste heat from the neighbouring Westin Building Exchange at its Seattle headquarters and Facebook’s newly constructed WHR system at its Odense datacentre, which feeds the warm water from its cooling system to the town’s district heating system, similar to the case of Yandex DC in Mäntsälä, Finland.

Using waste heat to improve datacentre energy-efficiency

In urban areas, waste heat can be captured from datacentres and then distributed at point of use to deliver hot water and space heating. There is a drive towards the installation of edge facilities, which comprise smaller, distributed datacentres on the outskirts of urban areas, close to potential heat demand.

Also, chip and rack densities are growing in line with workloads and the need to cut future emissions is likely to drive increasing interest towards developing more efficient, liquid-cooling approaches, which will result in higher temperatures for the available secondary heat.

Utilising the waste heat would greatly reduce the carbon footprint of datacentre operations overnight and, in so doing, make a significant contribution to the UK’s journey to net-zero.

This topic is the subject of an investigation at London South Bank University (LSBU) to explore opportunities, identify challenges and understand the benefits of datacentre waste heat recovery, both for the datacentre itself and for the UK as a whole.

“This project brings together engineering disciplines in a smart way to share resources and minimise emissions and shows the nature of real-world research that goes on in the School of Engineering at LSBU,” says Asa Barber, the university’s dean of engineering.

The need for continuous operation and observing strict temperature control requirements typically make datacentres an excellent candidate for participation in heat networks.

Air-cooled datacentres, which currently dominate the market, can be incorporated into low-temperature heat networks.

One approach for integrating a datacentre into a low-temperature heat network is demonstrated by the GreenSCIES project, which aims to deliver an easily replicable blueprint for a smart local energy network in any urban area.

The detailed design delivered by this project will provide an ultra-low-temperature 5th generation (5G) heat network with distributed low-carbon heat pumps to supply heating/cooling.

It does this by using ambient loop to exchange energy between buildings to recover waste heat from datacentres and London Underground ventilation air.

The waste heat captured by the network is then distributed to its planned point of use and can be upgraded to a higher temperature by a heat pump located in a decentralised energy centre.

This provides (low-carbon) heat at the temperature needed, which can be delivered virtually emission-free.

The energy centres will be supplied with electricity from solar photovoltaic panels, which will also charge electric vehicles enabled with vehicle-to-grid charging/storage alongside large-scale batteries.

“GreenSCIES provides a real-life example of how energy can be recovered and reused in a much more sustainable way,” says Catarina Marques, GreenSCIES project manager at the LSBU.

Combining heat, power and mobility in one place creates synergies with ultra-low emissions and at an attractive cost for the consumer. It also provides the opportunity for the community to own and operate its own local energy system.

It is hoped GreenSCIES will be the first large smart energy system in the UK that integrates energy technologies across heat, power and transport, providing a model for wide-scale replication.

The GreenSCIES system does not necessarily need to involve a datacentre – there are many other potential sources of heat that can be used. However, datacentres are often situated in the right place (urban areas), close to regions of high-density heat demand, and have good characteristics for use in this type of application, including steady temperatures and having a continuous need for cooling.

As of 2018, there were probably just under 500 large datacentres in the UK, together consuming between 11TWh and 42TWh of electrical energy. From a heat generation standpoint, this corresponds to the equivalent of 2.5-10% of the nation’s domestic heat demand, according to data from energy regulator Ofgem.

Therefore, the benefits to residents and businesses in communities where datacentres are present could be huge if that energy is reused, which is why the LSBU launched its investigation into how much heat energy is potentially available to be used, rather than wasted.