Does every data centre need generators?

The industry needs to re-evaluate the need for total generator backup capacity, according to Jamie Cameron, Associate Director, Cundall. The industry standard of ‘5 9s’ availability may be achievable without generators, and working towards this requires a change of mindset, a reduction outlook and ignoring the status quo.

For years, generators have been considered a necessity for all data centre builds. In truth, they may be causing more of a problem than they are worth. Traditional data centre design has required all newly built data centres to ensure the site’s full load can be backed up with total generator capacity. This may not be the case for every site. 

In fact, Uptime Institute, an unbiased advisory which details technical requirements for resiliency tiers of data centres to improve the performance of business-critical infrastructure, highlights that on-site power production should be considered the primary power source.

They state local utility power should only be used as an economical alternative. With this requirement, many operators believe they need full generator backup, leading them to ignore sites that can’t provide this. This thinking hurts the company’s bottom line and heavily impacts its sustainability targets.

For the industry to achieve net zero carbon in data centres, operators need to move away from this outdated view of data centres. They should instead consider whether complete or partial generator backup is required based on the specifications of their individual project rather than the status quo. 

Voltage needs for data centres

The scale of data centre campuses is increasing, especially as Machine Learning becomes a key focus for colocation providers and technology companies. This requires developing hyperscale campuses that connect to the grid at higher voltage levels. However, the increased requirements significantly impact the reliability of data centres. Understanding the difference between distribution networks and transmission networks becomes vital, as distribution networks typically operate at 11-33kV, whilst transmission networks operate at voltages of 132kW and even higher. 

As engineers will tell you, adopting an analytical approach to design is necessary. Data centre developers should also adopt this approach to assess their system’s reliability and performance of substations. This is necessary to determine the need for total generator backup capacity. 

The data centre industry typically uses a standard of ‘5 9s’ availability. This means that there needs to be 99.999% uptime or availability. It’s a useful measure to manage risk attributed to failures in a system. Despite this, for sites connecting to the grid at 132kV+, generators often yield very small benefits. Many sites can achieve ‘5 9s’ without any generators at all. 

The use of generators also introduces additional costs – both financial and environmental. This cost is predominantly due to the embodied carbon from equipment production and emissions during routine testing. At Cundall, we have seen the effects of this with data centres with over 50 generators running idle outside of maintenance and testing. We have also seen sites achieve ‘5 9s’ without a single generator on the campus. 

Switching on to a change mindset

The first step on the pathway of change is a change of mindset. As an industry, we need to dispel the myth that backup generators are a total necessity. This belief is what is causing tenants to include them in their mandatory leasing requirements. Backup generators are only a ‘necessity’ because people think they are.

So, how can we challenge this? End customers need to review their site’s grid and data centre reliability on a case-by-case basis to determine which site will suit them best.

Next comes a reimagining of resilience. Traditionally, customers have assessed resilience only at the level of individual sites. However, a more comprehensive approach is necessary – particularly when considering multiple independent sites connected across grid segments.

With this broader perspective and building redundancy into the IT infrastructure, generator backup can be allocated exclusively for critical network traffic. If the grid connection to one data centre fails, this traffic can then be rerouted to an alternative data centre connected to the grid at a different location. 

In practice, some hyperscalers already use this technique to improve their resilience. If the entire industry adopted it, we could circumvent the need for generators alone, instead providing resilience through the grid.

First comes reduction

Companies often ignore data that showcases the reliability of data centres, instead choosing to continue with a perceived need for generators. If they were to take a different approach, data centre operators could find locations that are better suited to their projects. This approach could yield significant cost and environmental benefits. 

Generators will still have a place in data centre projects. However, each project is different. For the data centre industry to meet the net zero carbon commitments pledged in the COP21 Paris Agreement, we can’t continue with a ‘business as usual approach’. Reduction is the first step, which can only be achieved by reassessing our current practices. So, when you are looking at a site for your next data centre, make sure first to ask, ‘does this data centre need generators?’.