Powering the world’s ever-growing appetite for data
Muthvel NandakumaranView bio
Data increasingly underpins every aspect of modern life, and while this makes many things easier and more efficient, every byte we consume requires an ever-growing quantity of electrical energy. Data centres and the other assets that constitute the global IT network require a constant, uninterrupted supply of power to maintain service levels.
This creates a challenge for building more data centres to keep up with the growth in demand for data, as the electricity grid and electricity generation are not always keeping pace. This is why Singapore, for example, put in place a temporary moratorium on new data centre developments, out of concern their power needs would compromise the capability of the grid to supply all the other assets and functions that also require electricity.
Because we cannot change the nature of Data Centres (DCs) – nor can we halt or even slow the uptake of data-based technologies – achieving sustainability for DCs starts with reducing the amount of power they require from the grid.
Solar energy installations can seem like an obvious solution, after all, DCs tend to be large box-like buildings with a large roof area. But the intensity of power use in a DC per square metre of floorspace in a data hall is exponentially greater than the energy used per square metre in assets with similar geometry like retail centres, hospitals, schools and low-rise commercial buildings.
To power a hyperscale DC with solar, the roof area could perhaps supply less than 1 % of energy needs, and then only when the solar PV is receiving sunlight. To have 100% green energy, a DC owner or asset manager can instead source the remaining energy from off-site renewable energy developments or sign a power purchase agreement with a green electricity retailer.
Another feature of DCs is the data halls generate a significant amount of heat. In cold climates, this can be used as an energy source for a district heating network, but in a warm climate such as Singapore or Sydney, there is no immediate use for that heat, so it needs to be dissipated via a cooling system.
The cooling of DCs is a major part of their energy footprint, so as engineers we put considerable thought and ingenuity into ways to reduce the thermal loads within the building, to reduce the energy required for cooling. This is an exciting area of ongoing research that is already resulting in new technologies such as liquid cooling.
From the electrical design perspective, one of the ways we can ensure the power distribution is as efficient as possible is through undertaking detailed calculation in the early stages. That may include a simulation study of the power and heat loads at the planned scale for full utilisation, and incorporating the impact of proposed spatial layout, building envelope and site climate conditions.
These studies also enable us to ensure the electrical design including any required substation, transformers, on-site electrical distribution, building systems and controls will provide the correct type of power distribution and ensure the appropriate stability of energy supply. The electrical system studies and analysis help ensure not only resiliency in the system but also improve system efficiency by reducing the power chain losses which contribute to the Power Usage Effectiveness (PUE) of a DC.
DCs do not respond well to interruptions in the power supply – even momentary ones – so another important element of the electrical design is integrating reliable backup power sources and automation and controls that will bring the back-up online immediately a problem with the mains supply is detected.
A power system engineer also calculates and provides the safe value for protection setting to isolate a fault in the electrical system or other systems, for example, controls that protect operations in event of a fault in the mechanical system that might potentially compromise cooling of the data halls. The control strategy might include measures to migrate certain operations to another zone until the fault is resolved.
The goal is to develop an adaptive strategy for the electrical, mechanical and other systems that avoids having one fragile, single point of failure within the designs. We will look at every aspect of the design ensuring there are appropriate bypasses, redundancies and fail-safes. The point of entry of power to the site will be considered for its reliability, for example. We also scrutinise downstream to identify risk factors. Electrical design for DCs is never just a matter of designing from the switchgear to the data hall, it takes in the whole context of the project.
We apply the frameworks of globally-accepted standards including the Uptime standard or TIA 942. This sets out levels of reliability, for example, to what degree a DC can lose the use of components but still operate, or is it of a standard where every part of the DC has full tolerance for failure.
This set of decisions is very much bounded by the client brief, what tier DC they are commissioning, what standards they seek to meet and what Uptime standard they will target. In the absence of a design brief, we can propose a suitable reliability level to a DC based on the client’s expectations.
In reality, there is no ideal off-the-shelf standard design for a sustainable, energy-efficient DC, due to the number of variables involved. Space must always be optimised for the specific client and specific users, or a specific country with limited land space like Singapore; also systems must be optimised for local conditions and local requirements.
One advantage DCs do have when the goal is an energy-efficient DC is the process of commissioning and post-commissioning verification is built into the development approval requirements by some rating systems and by some jurisdictions, such as Singapore.
For Green Mark certification, we are required to undertake post-construction verification of the DC performance. This ensures we have the opportunity to validate the modelling and design concepts we specified for the project, which also adds to the body of evidence we have to build on for future projects - closing the loop between design, construction and operation. In this way, the challenge of managing the power consumption of DCs generates another kind of power – the power of creative engineering thinking!