A single power outage can cost a data center more than a million dollars, turning what might have been a routine grid failure into a business catastrophe.
When the grid fails, these mission-critical facilities have only seconds to switch to backup generators, maintaining the uninterrupted flow of data that modern commerce, cloud services, and communications require.
Given the high stakes, backup generators are engineered for flawless, consistent performance. They enable the highest levels of uptime reliability, with Tier IV facilities achieving 99.995% availability through multiple independent power paths and redundant components.
To understand how generators are designed and built for such resilient performance, we’ll examine several key areas. The five points below outline an iterative process for delivering robust and reliable power solutions tailored to the unique demands of data centers.
- Correct sizing: First, generators need to be sized correctly. An undersized generator will be unable to power all required electrical loads, potentially resulting in a loss of power for essential systems. Meanwhile, an oversized generator will be unnecessarily expensive to buy and maintain. Load interactions in data centers are complex and dynamic and must be fully understood. The sizing exercise should consider all parts of the generator as a system, including the engine, alternator, voltage regulator, and excitation system. Dynamic conditions – such as system inertia, motor loading, motor type, and generator preload – are also important. By analyzing this dynamic system and evaluating functions in real-world applications, specifiers can ensure they select the most suitable generator for the task at hand.
- Robust design: Next is design. Typically, a generator comprises multiple, interlinked systems, including an engine, alternator, fuel system, voltage regulator, cooling system, exhaust system, and generator controller. In each case, the systems utilize the most robust materials and components to ensure high reliability and a long lifespan. For example, the engine architecture, injection system, and engine management are designed to achieve optimal generator set performance. Their power and reliability are proven during many hours of arduous tests under rigorous operating conditions, both in the laboratory and on-site.
- Precision manufacturing: Build quality is critical. A single loose connection or substandard component can mean the difference between seamless backup power and a multi-million-dollar outage. This zero-tolerance reality shapes every aspect of manufacturing, from supplier selection to final testing. That means well-honed production processes in modern, high-tech plants, delivering precision and repeatability on the factory floor. Generator manufacturers typically adopt a culture of repetitive processes and a set of deliverables to ensure consistent build standards. They often have access to exclusive engines, sourced or built in-house, and a global procurement policy with strict supplier performance measurement. Once parts and materials arrive, a highly controlled process – including mechanical coupling, mechanical assembly, electrical assembly, testing, final inspection, and packaging – takes place before multi-modal dispatch to the customer. Such a commitment to manufacturing excellence is vital when supplying generators for mission-critical applications like data centers.
- Ensuring durability: Once on site, durability becomes equally paramount. Generators are often located outside, exposing them to all types of weather. Therefore, they are usually contained within walk-in enclosures made from high-grade materials such as aluminum. These enclosures are designed to withstand wind loads exceeding 135 mph. They are developed using computational fluid dynamics tools to optimize airflow, ensuring generators operate efficiently even on the hottest days. Ultimately, it’s about protecting the generators from wind, rain, and heat, ensuring they remain in optimal condition and ready at all times.
- Sustainability considerations: Beyond reliability, today’s data center generators must also meet sustainability demands. It’s worth remembering that most generators for data centers are for backup only, meaning their environmental impact through emissions is low. Many hyperscale operators have high public profiles and a social responsibility to be green. Therefore, there is a continued effort to enhance the long-term sustainability of generators. This trend has led to the increasing adoption of renewable fuels, such as hydrotreated vegetable oil (HVO), which is derived from waste products and residues, including vegetable oils, animal fats, and used cooking oils. The technical and performance characteristics of HVO make it an increasingly popular sustainable alternative to fossil diesel for mission-critical power in data centers. For end users, it can reduce net carbon emissions by up to 90% across the lifecycle compared to fossil diesel while also reducing NOx. Crucially, HVO is a drop-in fuel, meaning it can replace traditional fuels like diesel without the need for modifications. These factors present a compelling case for HVO, which has been adopted by numerous data centers worldwide.
To sum up, generators have emerged as a reliable and trusted source of backup power for data centers. They are a flexible, scalable, and well-proven technology that can be deployed instantly to ensure business continuity.
Looking to the longer term, generators using HVO will continue to serve as a “ride-through” option until new technologies can be deployed at scale. Rehlko is focusing all its efforts on sustainable and resilient power solutions and will continue to invest in all potential technologies that help deliver cleaner and more resilient data centers for tomorrow.