Around the world, the race to build a cleaner energy system is gathering pace. Governments are backing renewable megaprojects, major utilities are expanding grid infrastructure and hyperscale data centers are being developed at a scale few anticipated five years ago.

Yet as these systems grow, so do the pressures placed upon them. Grid capacity is tightening in many regions, new connections are taking longer to secure and the demand profile of AI (artificial intelligence) computing is rising faster than networks can adapt.

Within this landscape, the diesel gen-set occupies a role that is rarely visible but remains essential. It is not a transition technology, nor does it determine the pace or direction of decarbonization. However, it provides the safety net that keeps critical systems operating when the grid is unavailable, delayed or unstable – an increasingly common occurrence, as recent blackouts at Heathrow and across the Iberian Peninsula demonstrate. Hospitals, telecom networks, industrial facilities and large data centers will continue to rely on diesel gen-sets for backup power because no other solution offers equivalent reliability or independence from external infrastructure.

This supporting function will become increasingly important as global demand continues to rise. The combined diesel and natural gas gen-set market will be around 1.4 million units in 2025, increasing to approximately 1.59 million by 2030, with the highest value concentration in large, high-specification engines designed for critical applications.

To understand how these pressures intersect, KGP Auto, working closely with Power Gen Statistics, has developed the Global Generator Set Powertrain Forecast. The dataset tracks gen-set assembly by country, power band, emissions compliance, engine OEM and engine model, and maps how product specifications are expected to evolve as the industry moves toward more regulated, higher-value configurations.

A market hidden in plain sight Cummins Centum Series generator set Demand for gen-set units above 1.6 MW is surging, particularly in North America. (Photo: KHL Staff) To anyone outside the industry, the diesel gen-set goes quietly unnoticed. Yet, their importance is increasing. Power grids are under strain in almost every major market, from Europe’s congested urban hubs to America’s fast-expanding data center corridors. In China – home to the world’s largest electricity system – growth in digital demand is outpacing grid capacity, prompting investment both in new renewables and, separately, in backup and bridging power.

This pressure is compounded by the rapid rise of hyperscale data center computing. There are around 12,000 significant data centers worldwide, and though hyperscale sites make up less than 10% of that total, they account for the majority of global server capacity and roughly 60% to 70% of data center electricity demand. Their growth is extraordinary:

7 GW of data center energy requirement will come online in 2025 10 GW of new capacity will break ground in 2025 500 hyperscale facilities are now in planning or construction This wave of investment has reshaped gen-set demand at the top end of the power spectrum. Demand for gen-set units above 1.6 MW is surging. In North America alone, production of large gen-sets will climb from 5,925 units in 2025 to more than 10,000 by 2030. If data centers are the new steel mills of the digital age, diesel gen-sets are the blast furnaces keeping them alive when the grid falters.

These dynamics set the stage for the broader fuel and technology mix taking shape in the gen-set sector.

Diesel vs. gas: A tale of two fuels Despite growing interest in the affordability and carbon benefits of natural gas, particularly in North America and China, diesel remains the dominant technology. The logic is simple: diesel offers reliable startup, rapid load acceptance and complete independence from external infrastructure.

For critical facilities - hospitals, telecom networks and especially data centers – that independence is non-negotiable. In regions where natural gas is cheap and widely available, large gas gen-sets supply prime power for industrial sites and oil and gas operations, and occasionally for data center developments waiting for grid connections. These applications, however, are time-limited and do not replace the need for substantial diesel backup capacity at the same facilities.

Globally, over 65% of the market is less than 56 kW, serving residential, rental and small commercial markets, while the >560 kW category – less than 5% of volume – accounts for half of total market value.As energy requirements increase and legislation tightens, value within the gen-set market is shifting toward higher-specification products. Advanced aftertreatment, enhanced thermal management, upgraded airflow and cooling, more capable turbocharging systems, electronic controls, preventative maintenance features and telematics will all play a greater role over the next five to 15 years. This accelerated technical load will drive value for every level of the supply chain.

Hybridization and low-carbon fuels will play in the periphery in the short term. HVO is gaining traction where supply is reliable, and BESS systems have operational advantages in certain cases when paired with diesel. Neither displaces the fundamental role of the diesel gen-set in guaranteeing power during grid failure, but both will support broader decarbonization efforts, particularly in construction and agriculture.

Patchwork of rules, minefield of responsibilities If the commercial side of the market is booming, the legislative landscape is far more turbulent.

Mobile gen-sets are heading toward a global tightening cycle. Europe’s Stage VI, expected in the early 2030s, will introduce stricter limits on NOx, PM and N₂O, while the U.S. could see CARB’s Tier 5 arriving as early as 2028, though federal alignment remains uncertain. India’s move to Bharat Stage V for construction in 2025 and agriculture, now delayed to around 2028, is causing significant disruption, echoing the upheaval previously triggered by China’s adoption of State IV.But the real battleground is stationary gen-set regulation. Unlike mobile gen-sets, where national legislation mandates the engine OEM carries compliance liability, stationary gen-set requirements are often subject to stringent local air quality limits and environmental certification and shift responsibility to the site, not the manufacturer. For example, a gen-set installed 10 years ago in Frankfurt or Singapore previously wouldn’t have required much in the way of aftertreatment or local government red tape. Now, it would likely require Stage V-equivalent SCR and DPF, a stack-height analysis, noise abatement, runtime limits and ongoing monitoring.

This fragmentation wastes value. A sophisticated engine designed for clean, low-NOx operation can slip out of compliance through poor integration or lack of site-specific engineering – issues that don’t fall on the OEM, but on assemblers, installers, EPC contractors and ultimately the operator.

It raises a provocative question: Will more countries move toward India’s approach, where mobile and stationary gen-sets share a unified emissions regime? Such alignment could simplify compliance, reduce grey market imports and allow value to flow more evenly across the supply chain, rather than getting tangled in red tape.

The backbone of a net-zero future The irony of the energy transition is that the technologies that will enable it most – large-scale renewables, AI infrastructure and digitalized industry – are also the technologies most vulnerable to power instability. Every new solar farm, data hub, fast-charging depot or hydrogen plant adds complexity to a grid already under strain.

Against this backdrop, the global gen-set market is not fading. Its technical and commercial importance continues to increase.

By 2030, we anticipate that only around 22% of global installed gen-set production will be unregulated – down from roughly 75% in 2020 – as EU and EFTA, North America, China, India, Chile, Turkey and others escalate standards.

Yet, the fundamentals remain unchanged. Diesel gen-sets will continue to anchor emergency power well beyond the next decade. Alternative fuels will expand. Battery systems will mature. Hydrogen might find its niche. But the backbone of global resilience will still be built on engines.

In a world chasing clean electricity at an unprecedented scale, the gen-set isn’t the star of the show. It’s the safety net beneath it – the one technology that makes everything else possible.

About the Author: James Dorling is director of Non-Road, Knibb, Gormezano and Partners, an international management and technology consultancy.