Direct current: a promising pathway to energy security

Summary

• Direct current distribution can reduce repeated power conversions and preserve electrical capacity for IT equipment.
• Hybrid AC and DC architectures may support battery storage and renewable generation while retaining AC power for cooling and auxiliary systems.
• Wider DC adoption depends on early infrastructure design, advanced protection systems, standards and coordination across the supply chain.

The future of data centres won’t be defined by computing power alone, but increasingly by energy efficiency – and DC is a very promising pathway to energy productivity

Traditionally, computing power has defined market edge in the data centre market. Competitiveness now has a new shape, and the industry is shifting from ‘performance per rack’ to ‘performance per megawatt’. It’s easy to see why: energy security is never far from headlines, be it for geopolitical or environmental reasons. Supply is less of a certainty, whilst the demands of AI infrastructure outstrip new generation and distribution, making existing supply more expensive. The International Energy Agency (IEA) expects global data centre electricity demand to more than double by 2030, while next generation AI server racks could reach power densities of 1 MW and beyond, compared with almost 200 kW in today’s high-density racks. Against this backdrop, it is not only computing power and access to energy that define a data centre, but energy productivity.

The pathway to energy productivity

Direct current (DC) technology is emerging as one of the most promising pathways to energy productivity in data centres. Today’s alternating current (AC) architecture requires multiple AC/DC and DC/AC conversions before power reaches the processors. Electrical capacity should be preserved for revenue-generating IT equipment rather than being consumed by auxiliary systems. The footprint of direct current architecture is more compact, while eliminating redundant conversion steps and cutting heat losses of conventional AC systems. This is less wasteful, simplifying power flows and reducing conversion losses, and can deliver efficiency gains of more than 5%, according to a recent BCG and ABB report. In a 500 MW data centre, efficiency gains of 5% over a year could power a city the size of Washington D.C. for almost a full week.

Notably, DC architecture is future-ready when it comes to the evolving mix of power sources. A growing share of power assets, including solar PV arrays, battery energy storage systems (BESS), and some emerging on-site generation are DC-native, enabling more effective integration of renewable power generation and battery storage assets in data centres.

Implementing energy productivity

Early choices to enable DC integration and hybrid AC/DC architecture are integral to avoid expensive and inefficient retrofitting. The most critical decisions happen at the design stage, requiring a systems-level approach that allows AC and DC technologies to evolve and work together across the data centre infrastructure.

In this environment, cooling has become mission critical, no longer separately designed and separately optimised to power. A brief interruption in coolant flow at high power density can degrade GPU performance – the cooling system has now become part of the performance guarantee. While DC distribution gains ground, AC power will continue to play an important role in data centre infrastructure, particularly in the grey space, which houses much of the cooling infrastructure and other auxiliary systems.

High efficiency motors and ultra-low harmonic drives help maximise performance per megawatt by reducing energy consumption and improving power quality in AC-powered grey space cooling applications, while drives supporting both conventional AC and emerging DC architectures enable operators to capture the efficiency benefits from evolving DC power distribution technologies, including those introduced in the white space to power IT racks and support their cooling systems. When power and cooling are integrated from the start, it reduces complexity, reduces handoffs and improves reliability.

Challenges ahead

There are challenges to be overcome before DC power is integrated at scale and industry is rightly moving with caution on pace. For example, identifying the right solutions to meet requirements for battery energy storage, not just for backup, but to use for load balancing in normal operations, and integrating renewable and alternative energy sources.

Data centres integrating DC power also need advanced DC protection, including fast-acting and solid-state protection technologies. Meeting these challenges will require collaboration across the value chain. At ABB, we’re working with hyperscalers, cooling OEMs, the Open Compute Project, and UL on standards, certification and testing, and continue the commitment to our local-for-local approach, serving customers with locally manufactured technologies to provide solutions.

The direction of travel is clear

Data centres are the infrastructure at the heart of one of the most significant industrial revolutions. Competition for power supply is fierce as industry seeks to meet demands of the AI build-out. Even as renewables and alternative fuels add to energy supply, grid constraints and the investment and time needed to overcome these limitations hamper progress.

DC architecture enables more from less, making better use of existing power capacity. DC technology has been delivering efficiency benefits for over 25 years in marine, mining, ports and industrial automation. ABB was among the pioneers in demonstrating the energy-saving potential of DC in vessels with DC-based onboard power systems that in some cases achieved fuel savings of up to 27% and launched the industry’s first solid state circuit breaker in 2022. That’s the trajectory DC brings to data centres: proven technology, first mover advantages, and built-in reliability. The shift to DC-first architecture is gaining momentum, and the pace and path forward depend on collaboration across the entire ecosystem.

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