As much as 40% of the average data centre’s energy usage can be attributed solely to cooling. Alternatives to traditional air-cooling systems, such as immersion cooling, are becoming more popular and have made systems more efficient by using less energy and water. However, with data usage increasingly nearly exponentially each year, these efficiency gains may struggle to keep pace with demand.
Moreover, given that summer temperatures in excess of 40°C have been observed in the UK, a system change is clearly needed sooner than later. In this regard, it can be argued that wasted energy is a wasted opportunity. This is because fundamentally, in the data centre market, current processes generate a large amount of heat that is being rejected to the environment – heat that could be leveraged.
Regardless of the challenges our environment continues to face, digital systems will remain vital due to the value they bring. Leveraging heat reclaimed from data centres could soon be key because reducing heat supply chains will be central to increasing local resilience. The need for continuous operation and observing strict temperature control requirements also make data centres an excellent choice for use in heat networks, while also creating new revenue streams for data centres through selling waste heat on to be utilised elsewhere.
Waste heat potential
Waste heat from an immersion-based system can reach 40-60°C. Temperatures in this range are ideal for fourth generation district heat networks, and can be utilised through technologies such as modern plate heat exchangers. This allows these schemes to use close approaches within a single degree to create more efficient systems where little heat is wasted. With this in mind, it is unsurprising that demand for such schemes continues to grow.
Recently, Alfa Laval helped install such a system in a Danish data centre, where the residual heat from servers was used to power a local heating network. The resulting saving from this was over 100,000MW/h of energy – enough to provide heat and hot water to 6,900 homes.
Considering this example, it is clear that the potential for heat recovery schemes in the data centre sector is enormous. It should also be noted that a large heat network is not necessary to reuse heat – there are a number of possible alternatives, such as greenhouses, swimming pools and fish farms, which can draw similar benefits.
Pairing this mechanism with ancillary systems, such as heat pumps and energy storage, could allow communities to reduce their heating bills, become more resilient to climate change, and create a sense of community between industry and the public. This circularity has the potential to create a positive feedback loop.
However, while the engineering first appears relatively straightforward, the overall situation is more complex than it may seem. Namely, current laws may potentially prove a hinderance to revolutionary ideas. This is key in the question of data centres as heat providers.
Both globally and in the UK, the so-called ‘private wire’ is heavily regulated, requiring a host of back-ups and redundancy systems. While these regulations are important to safeguard consumers, it is one of the main roadblocks to allowing data centres to use their vast amounts of waste heat productively.
Here, legislative amendments or new frameworks would be necessary to facilitate data centre connections to the grid. This could be achieved by allowing data centre operators to spin out heat operating companies, meaning the regulations for private wire would only cover the provider instead of the whole data centre.
Bringing data into the mix
There is still the need for developments in legal frameworks surrounding using waste heat from data centres. However, the potential for using this resource is fundamentally critical in the search to replace carbon-intensive heating systems and build resilience to climate change.
Modern heat exchanger technology allows the application of a virtually limitless number of innovative cooling solutions which can produce quality heat for reuse. It is critical that this potential is explored fully if IT infrastructure is to develop in a sustainable manner.